From 79bd9814e5ec9a288d6599f53aeac0b548fdfe52 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 22 Nov 2013 18:20:42 -0500 Subject: cgroup, memcg: move cgroup_event implementation to memcg cgroup_event is way over-designed and tries to build a generic flexible event mechanism into cgroup - fully customizable event specification for each user of the interface. This is utterly unnecessary and overboard especially in the light of the planned unified hierarchy as there's gonna be single agent. Simply generating events at fixed points, or if that's too restrictive, configureable cadence or single set of configureable points should be enough. Thankfully, memcg is the only user and gets to keep it. Replacing it with something simpler on sane_behavior is strongly recommended. This patch moves cgroup_event and "cgroup.event_control" implementation to mm/memcontrol.c. Clearing of events on cgroup destruction is moved from cgroup_destroy_locked() to mem_cgroup_css_offline(), which shouldn't make any noticeable difference. cgroup_css() and __file_cft() are exported to enable the move; however, this will soon be reverted once the event code is updated to be memcg specific. Note that "cgroup.event_control" will now exist only on the hierarchy with memcg attached to it. While this change is visible to userland, it is unlikely to be noticeable as the file has never been meaningful outside memcg. Aside from the above change, this is pure code relocation. v2: Per Li Zefan's comments, init/Kconfig updated accordingly and poll.h inclusion moved from cgroup.c to memcontrol.c. Signed-off-by: Tejun Heo Acked-by: Li Zefan Acked-by: Kirill A. Shutemov Acked-by: Michal Hocko Cc: Johannes Weiner Cc: Balbir Singh --- kernel/cgroup.c | 253 +------------------------------------------------------- 1 file changed, 3 insertions(+), 250 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 8bd9cfdc70d7..4bccaa7dda35 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -56,11 +56,8 @@ #include #include #include /* TODO: replace with more sophisticated array */ -#include -#include #include /* used in cgroup_attach_task */ #include -#include #include @@ -156,36 +153,6 @@ struct css_id { unsigned short stack[0]; /* Array of Length (depth+1) */ }; -/* - * cgroup_event represents events which userspace want to receive. - */ -struct cgroup_event { - /* - * css which the event belongs to. - */ - struct cgroup_subsys_state *css; - /* - * Control file which the event associated. - */ - struct cftype *cft; - /* - * eventfd to signal userspace about the event. - */ - struct eventfd_ctx *eventfd; - /* - * Each of these stored in a list by the cgroup. - */ - struct list_head list; - /* - * All fields below needed to unregister event when - * userspace closes eventfd. - */ - poll_table pt; - wait_queue_head_t *wqh; - wait_queue_t wait; - struct work_struct remove; -}; - /* The list of hierarchy roots */ static LIST_HEAD(cgroup_roots); @@ -235,8 +202,8 @@ static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], * keep accessing it outside the said locks. This function may return * %NULL if @cgrp doesn't have @subsys_id enabled. */ -static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp, - struct cgroup_subsys *ss) +struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp, + struct cgroup_subsys *ss) { if (ss) return rcu_dereference_check(cgrp->subsys[ss->subsys_id], @@ -2663,7 +2630,7 @@ static const struct inode_operations cgroup_dir_inode_operations = { /* * Check if a file is a control file */ -static inline struct cftype *__file_cft(struct file *file) +struct cftype *__file_cft(struct file *file) { if (file_inode(file)->i_fop != &cgroup_file_operations) return ERR_PTR(-EINVAL); @@ -3949,202 +3916,6 @@ static void cgroup_dput(struct cgroup *cgrp) deactivate_super(sb); } -/* - * Unregister event and free resources. - * - * Gets called from workqueue. - */ -static void cgroup_event_remove(struct work_struct *work) -{ - struct cgroup_event *event = container_of(work, struct cgroup_event, - remove); - struct cgroup_subsys_state *css = event->css; - - remove_wait_queue(event->wqh, &event->wait); - - event->cft->unregister_event(css, event->cft, event->eventfd); - - /* Notify userspace the event is going away. */ - eventfd_signal(event->eventfd, 1); - - eventfd_ctx_put(event->eventfd); - kfree(event); - css_put(css); -} - -/* - * Gets called on POLLHUP on eventfd when user closes it. - * - * Called with wqh->lock held and interrupts disabled. - */ -static int cgroup_event_wake(wait_queue_t *wait, unsigned mode, - int sync, void *key) -{ - struct cgroup_event *event = container_of(wait, - struct cgroup_event, wait); - struct cgroup *cgrp = event->css->cgroup; - unsigned long flags = (unsigned long)key; - - if (flags & POLLHUP) { - /* - * If the event has been detached at cgroup removal, we - * can simply return knowing the other side will cleanup - * for us. - * - * We can't race against event freeing since the other - * side will require wqh->lock via remove_wait_queue(), - * which we hold. - */ - spin_lock(&cgrp->event_list_lock); - if (!list_empty(&event->list)) { - list_del_init(&event->list); - /* - * We are in atomic context, but cgroup_event_remove() - * may sleep, so we have to call it in workqueue. - */ - schedule_work(&event->remove); - } - spin_unlock(&cgrp->event_list_lock); - } - - return 0; -} - -static void cgroup_event_ptable_queue_proc(struct file *file, - wait_queue_head_t *wqh, poll_table *pt) -{ - struct cgroup_event *event = container_of(pt, - struct cgroup_event, pt); - - event->wqh = wqh; - add_wait_queue(wqh, &event->wait); -} - -/* - * Parse input and register new cgroup event handler. - * - * Input must be in format ' '. - * Interpretation of args is defined by control file implementation. - */ -static int cgroup_write_event_control(struct cgroup_subsys_state *dummy_css, - struct cftype *cft, const char *buffer) -{ - struct cgroup *cgrp = dummy_css->cgroup; - struct cgroup_event *event; - struct cgroup_subsys_state *cfile_css; - unsigned int efd, cfd; - struct fd efile; - struct fd cfile; - char *endp; - int ret; - - efd = simple_strtoul(buffer, &endp, 10); - if (*endp != ' ') - return -EINVAL; - buffer = endp + 1; - - cfd = simple_strtoul(buffer, &endp, 10); - if ((*endp != ' ') && (*endp != '\0')) - return -EINVAL; - buffer = endp + 1; - - event = kzalloc(sizeof(*event), GFP_KERNEL); - if (!event) - return -ENOMEM; - - INIT_LIST_HEAD(&event->list); - init_poll_funcptr(&event->pt, cgroup_event_ptable_queue_proc); - init_waitqueue_func_entry(&event->wait, cgroup_event_wake); - INIT_WORK(&event->remove, cgroup_event_remove); - - efile = fdget(efd); - if (!efile.file) { - ret = -EBADF; - goto out_kfree; - } - - event->eventfd = eventfd_ctx_fileget(efile.file); - if (IS_ERR(event->eventfd)) { - ret = PTR_ERR(event->eventfd); - goto out_put_efile; - } - - cfile = fdget(cfd); - if (!cfile.file) { - ret = -EBADF; - goto out_put_eventfd; - } - - /* the process need read permission on control file */ - /* AV: shouldn't we check that it's been opened for read instead? */ - ret = inode_permission(file_inode(cfile.file), MAY_READ); - if (ret < 0) - goto out_put_cfile; - - event->cft = __file_cft(cfile.file); - if (IS_ERR(event->cft)) { - ret = PTR_ERR(event->cft); - goto out_put_cfile; - } - - if (!event->cft->ss) { - ret = -EBADF; - goto out_put_cfile; - } - - /* - * Determine the css of @cfile, verify it belongs to the same - * cgroup as cgroup.event_control, and associate @event with it. - * Remaining events are automatically removed on cgroup destruction - * but the removal is asynchronous, so take an extra ref. - */ - rcu_read_lock(); - - ret = -EINVAL; - event->css = cgroup_css(cgrp, event->cft->ss); - cfile_css = css_from_dir(cfile.file->f_dentry->d_parent, event->cft->ss); - if (event->css && event->css == cfile_css && css_tryget(event->css)) - ret = 0; - - rcu_read_unlock(); - if (ret) - goto out_put_cfile; - - if (!event->cft->register_event || !event->cft->unregister_event) { - ret = -EINVAL; - goto out_put_css; - } - - ret = event->cft->register_event(event->css, event->cft, - event->eventfd, buffer); - if (ret) - goto out_put_css; - - efile.file->f_op->poll(efile.file, &event->pt); - - spin_lock(&cgrp->event_list_lock); - list_add(&event->list, &cgrp->event_list); - spin_unlock(&cgrp->event_list_lock); - - fdput(cfile); - fdput(efile); - - return 0; - -out_put_css: - css_put(event->css); -out_put_cfile: - fdput(cfile); -out_put_eventfd: - eventfd_ctx_put(event->eventfd); -out_put_efile: - fdput(efile); -out_kfree: - kfree(event); - - return ret; -} - static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css, struct cftype *cft) { @@ -4169,11 +3940,6 @@ static struct cftype cgroup_base_files[] = { .release = cgroup_pidlist_release, .mode = S_IRUGO | S_IWUSR, }, - { - .name = "cgroup.event_control", - .write_string = cgroup_write_event_control, - .mode = S_IWUGO, - }, { .name = "cgroup.clone_children", .flags = CFTYPE_INSANE, @@ -4666,7 +4432,6 @@ static int cgroup_destroy_locked(struct cgroup *cgrp) __releases(&cgroup_mutex) __acquires(&cgroup_mutex) { struct dentry *d = cgrp->dentry; - struct cgroup_event *event, *tmp; struct cgroup_subsys *ss; struct cgroup *child; bool empty; @@ -4741,18 +4506,6 @@ static int cgroup_destroy_locked(struct cgroup *cgrp) dget(d); cgroup_d_remove_dir(d); - /* - * Unregister events and notify userspace. - * Notify userspace about cgroup removing only after rmdir of cgroup - * directory to avoid race between userspace and kernelspace. - */ - spin_lock(&cgrp->event_list_lock); - list_for_each_entry_safe(event, tmp, &cgrp->event_list, list) { - list_del_init(&event->list); - schedule_work(&event->remove); - } - spin_unlock(&cgrp->event_list_lock); - return 0; }; -- cgit v1.2.3 From fba94807837850e211f8975e1970e23e7804ff4d Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 22 Nov 2013 18:20:43 -0500 Subject: cgroup, memcg: move cgroup->event_list[_lock] and event callbacks into memcg cgroup_event is being moved from cgroup core to memcg and the implementation is already moved by the previous patch. This patch moves the data fields and callbacks. * cgroup->event_list[_lock] are moved to mem_cgroup. * cftype->[un]register_event() are moved to cgroup_event. This makes it impossible for individual cftype definitions to specify their event callbacks. This is worked around by simply hard-coding filename to event callback mapping in cgroup_write_event_control(). This is awkward and inflexible, which is actually desirable given that we don't want to grow more usages of this feature. * eventfd_ctx declaration is removed from cgroup.h, which makes vmpressure.h miss eventfd_ctx declaration. Include eventfd.h from vmpressure.h. v2: Use file name from dentry instead of cftype. This will allow removing all cftype handling in the function. Signed-off-by: Tejun Heo Acked-by: Li Zefan Acked-by: Kirill A. Shutemov Acked-by: Michal Hocko Cc: Johannes Weiner Cc: Balbir Singh --- include/linux/cgroup.h | 24 ------------- include/linux/vmpressure.h | 1 + kernel/cgroup.c | 2 -- mm/memcontrol.c | 87 ++++++++++++++++++++++++++++++++-------------- 4 files changed, 61 insertions(+), 53 deletions(-) (limited to 'kernel') diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 40c2427806c9..612adc5b87c5 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -29,7 +29,6 @@ struct cgroup_subsys; struct inode; struct cgroup; struct css_id; -struct eventfd_ctx; extern int cgroup_init_early(void); extern int cgroup_init(void); @@ -239,10 +238,6 @@ struct cgroup { struct rcu_head rcu_head; struct work_struct destroy_work; - /* List of events which userspace want to receive */ - struct list_head event_list; - spinlock_t event_list_lock; - /* directory xattrs */ struct simple_xattrs xattrs; }; @@ -506,25 +501,6 @@ struct cftype { int (*trigger)(struct cgroup_subsys_state *css, unsigned int event); int (*release)(struct inode *inode, struct file *file); - - /* - * register_event() callback will be used to add new userspace - * waiter for changes related to the cftype. Implement it if - * you want to provide this functionality. Use eventfd_signal() - * on eventfd to send notification to userspace. - */ - int (*register_event)(struct cgroup_subsys_state *css, - struct cftype *cft, struct eventfd_ctx *eventfd, - const char *args); - /* - * unregister_event() callback will be called when userspace - * closes the eventfd or on cgroup removing. - * This callback must be implemented, if you want provide - * notification functionality. - */ - void (*unregister_event)(struct cgroup_subsys_state *css, - struct cftype *cft, - struct eventfd_ctx *eventfd); }; /* diff --git a/include/linux/vmpressure.h b/include/linux/vmpressure.h index 3f3788d49362..9dd1914f1a6c 100644 --- a/include/linux/vmpressure.h +++ b/include/linux/vmpressure.h @@ -7,6 +7,7 @@ #include #include #include +#include struct vmpressure { unsigned long scanned; diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 4bccaa7dda35..feda7c54fa6b 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1352,8 +1352,6 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp) INIT_LIST_HEAD(&cgrp->pidlists); mutex_init(&cgrp->pidlist_mutex); cgrp->dummy_css.cgroup = cgrp; - INIT_LIST_HEAD(&cgrp->event_list); - spin_lock_init(&cgrp->event_list_lock); simple_xattrs_init(&cgrp->xattrs); } diff --git a/mm/memcontrol.c b/mm/memcontrol.c index d00368110b08..2fcacb18404b 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -248,6 +248,22 @@ struct cgroup_event { * Each of these stored in a list by the cgroup. */ struct list_head list; + /* + * register_event() callback will be used to add new userspace + * waiter for changes related to this event. Use eventfd_signal() + * on eventfd to send notification to userspace. + */ + int (*register_event)(struct cgroup_subsys_state *css, + struct cftype *cft, struct eventfd_ctx *eventfd, + const char *args); + /* + * unregister_event() callback will be called when userspace closes + * the eventfd or on cgroup removing. This callback must be set, + * if you want provide notification functionality. + */ + void (*unregister_event)(struct cgroup_subsys_state *css, + struct cftype *cft, + struct eventfd_ctx *eventfd); /* * All fields below needed to unregister event when * userspace closes eventfd. @@ -362,6 +378,10 @@ struct mem_cgroup { atomic_t numainfo_updating; #endif + /* List of events which userspace want to receive */ + struct list_head event_list; + spinlock_t event_list_lock; + struct mem_cgroup_per_node *nodeinfo[0]; /* WARNING: nodeinfo must be the last member here */ }; @@ -5992,7 +6012,7 @@ static void cgroup_event_remove(struct work_struct *work) remove_wait_queue(event->wqh, &event->wait); - event->cft->unregister_event(css, event->cft, event->eventfd); + event->unregister_event(css, event->cft, event->eventfd); /* Notify userspace the event is going away. */ eventfd_signal(event->eventfd, 1); @@ -6012,7 +6032,7 @@ static int cgroup_event_wake(wait_queue_t *wait, unsigned mode, { struct cgroup_event *event = container_of(wait, struct cgroup_event, wait); - struct cgroup *cgrp = event->css->cgroup; + struct mem_cgroup *memcg = mem_cgroup_from_css(event->css); unsigned long flags = (unsigned long)key; if (flags & POLLHUP) { @@ -6025,7 +6045,7 @@ static int cgroup_event_wake(wait_queue_t *wait, unsigned mode, * side will require wqh->lock via remove_wait_queue(), * which we hold. */ - spin_lock(&cgrp->event_list_lock); + spin_lock(&memcg->event_list_lock); if (!list_empty(&event->list)) { list_del_init(&event->list); /* @@ -6034,7 +6054,7 @@ static int cgroup_event_wake(wait_queue_t *wait, unsigned mode, */ schedule_work(&event->remove); } - spin_unlock(&cgrp->event_list_lock); + spin_unlock(&memcg->event_list_lock); } return 0; @@ -6059,12 +6079,13 @@ static void cgroup_event_ptable_queue_proc(struct file *file, static int cgroup_write_event_control(struct cgroup_subsys_state *css, struct cftype *cft, const char *buffer) { - struct cgroup *cgrp = css->cgroup; + struct mem_cgroup *memcg = mem_cgroup_from_css(css); struct cgroup_event *event; struct cgroup_subsys_state *cfile_css; unsigned int efd, cfd; struct fd efile; struct fd cfile; + const char *name; char *endp; int ret; @@ -6118,6 +6139,31 @@ static int cgroup_write_event_control(struct cgroup_subsys_state *css, goto out_put_cfile; } + /* + * Determine the event callbacks and set them in @event. This used + * to be done via struct cftype but cgroup core no longer knows + * about these events. The following is crude but the whole thing + * is for compatibility anyway. + */ + name = cfile.file->f_dentry->d_name.name; + + if (!strcmp(name, "memory.usage_in_bytes")) { + event->register_event = mem_cgroup_usage_register_event; + event->unregister_event = mem_cgroup_usage_unregister_event; + } else if (!strcmp(name, "memory.oom_control")) { + event->register_event = mem_cgroup_oom_register_event; + event->unregister_event = mem_cgroup_oom_unregister_event; + } else if (!strcmp(name, "memory.pressure_level")) { + event->register_event = vmpressure_register_event; + event->unregister_event = vmpressure_unregister_event; + } else if (!strcmp(name, "memory.memsw.usage_in_bytes")) { + event->register_event = mem_cgroup_usage_register_event; + event->unregister_event = mem_cgroup_usage_unregister_event; + } else { + ret = -EINVAL; + goto out_put_cfile; + } + /* * Verify @cfile should belong to @css. Also, remaining events are * automatically removed on cgroup destruction but the removal is @@ -6135,21 +6181,15 @@ static int cgroup_write_event_control(struct cgroup_subsys_state *css, if (ret) goto out_put_cfile; - if (!event->cft->register_event || !event->cft->unregister_event) { - ret = -EINVAL; - goto out_put_css; - } - - ret = event->cft->register_event(css, event->cft, - event->eventfd, buffer); + ret = event->register_event(css, event->cft, event->eventfd, buffer); if (ret) goto out_put_css; efile.file->f_op->poll(efile.file, &event->pt); - spin_lock(&cgrp->event_list_lock); - list_add(&event->list, &cgrp->event_list); - spin_unlock(&cgrp->event_list_lock); + spin_lock(&memcg->event_list_lock); + list_add(&event->list, &memcg->event_list); + spin_unlock(&memcg->event_list_lock); fdput(cfile); fdput(efile); @@ -6175,8 +6215,6 @@ static struct cftype mem_cgroup_files[] = { .name = "usage_in_bytes", .private = MEMFILE_PRIVATE(_MEM, RES_USAGE), .read = mem_cgroup_read, - .register_event = mem_cgroup_usage_register_event, - .unregister_event = mem_cgroup_usage_unregister_event, }, { .name = "max_usage_in_bytes", @@ -6236,14 +6274,10 @@ static struct cftype mem_cgroup_files[] = { .name = "oom_control", .read_map = mem_cgroup_oom_control_read, .write_u64 = mem_cgroup_oom_control_write, - .register_event = mem_cgroup_oom_register_event, - .unregister_event = mem_cgroup_oom_unregister_event, .private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL), }, { .name = "pressure_level", - .register_event = vmpressure_register_event, - .unregister_event = vmpressure_unregister_event, }, #ifdef CONFIG_NUMA { @@ -6291,8 +6325,6 @@ static struct cftype memsw_cgroup_files[] = { .name = "memsw.usage_in_bytes", .private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE), .read = mem_cgroup_read, - .register_event = mem_cgroup_usage_register_event, - .unregister_event = mem_cgroup_usage_unregister_event, }, { .name = "memsw.max_usage_in_bytes", @@ -6483,6 +6515,8 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css) mutex_init(&memcg->thresholds_lock); spin_lock_init(&memcg->move_lock); vmpressure_init(&memcg->vmpressure); + INIT_LIST_HEAD(&memcg->event_list); + spin_lock_init(&memcg->event_list_lock); return &memcg->css; @@ -6555,7 +6589,6 @@ static void mem_cgroup_invalidate_reclaim_iterators(struct mem_cgroup *memcg) static void mem_cgroup_css_offline(struct cgroup_subsys_state *css) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); - struct cgroup *cgrp = css->cgroup; struct cgroup_event *event, *tmp; /* @@ -6563,12 +6596,12 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css) * Notify userspace about cgroup removing only after rmdir of cgroup * directory to avoid race between userspace and kernelspace. */ - spin_lock(&cgrp->event_list_lock); - list_for_each_entry_safe(event, tmp, &cgrp->event_list, list) { + spin_lock(&memcg->event_list_lock); + list_for_each_entry_safe(event, tmp, &memcg->event_list, list) { list_del_init(&event->list); schedule_work(&event->remove); } - spin_unlock(&cgrp->event_list_lock); + spin_unlock(&memcg->event_list_lock); kmem_cgroup_css_offline(memcg); -- cgit v1.2.3 From b36824c75c7855585d6476eef2b234f6e0e68872 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 22 Nov 2013 18:20:44 -0500 Subject: cgroup: unexport cgroup_css() and remove __file_cft() Now that cgroup_event is made memcg specific, the temporarily exported functions are no longer necessary. Unexport cgroup_css() and remove __file_cft() which doesn't have any user left. Signed-off-by: Tejun Heo Acked-by: Li Zefan Acked-by: Kirill A. Shutemov --- include/linux/cgroup.h | 5 ----- kernel/cgroup.c | 14 ++------------ 2 files changed, 2 insertions(+), 17 deletions(-) (limited to 'kernel') diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 612adc5b87c5..8d9fa8967c9e 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -883,11 +883,6 @@ unsigned short css_id(struct cgroup_subsys_state *css); struct cgroup_subsys_state *css_from_dir(struct dentry *dentry, struct cgroup_subsys *ss); -/* XXX: temporary */ -struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp, - struct cgroup_subsys *ss); -struct cftype *__file_cft(struct file *file); - #else /* !CONFIG_CGROUPS */ static inline int cgroup_init_early(void) { return 0; } diff --git a/kernel/cgroup.c b/kernel/cgroup.c index feda7c54fa6b..c0248e16461d 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -202,8 +202,8 @@ static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], * keep accessing it outside the said locks. This function may return * %NULL if @cgrp doesn't have @subsys_id enabled. */ -struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp, - struct cgroup_subsys *ss) +static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp, + struct cgroup_subsys *ss) { if (ss) return rcu_dereference_check(cgrp->subsys[ss->subsys_id], @@ -2625,16 +2625,6 @@ static const struct inode_operations cgroup_dir_inode_operations = { .removexattr = cgroup_removexattr, }; -/* - * Check if a file is a control file - */ -struct cftype *__file_cft(struct file *file) -{ - if (file_inode(file)->i_fop != &cgroup_file_operations) - return ERR_PTR(-EINVAL); - return __d_cft(file->f_dentry); -} - static int cgroup_create_file(struct dentry *dentry, umode_t mode, struct super_block *sb) { -- cgit v1.2.3 From ac1e69aa78e2e799a8d5475595ba744bdf29b597 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 29 Nov 2013 10:42:58 -0500 Subject: cgroup: don't skip seq_open on write only opens on pidlist files Currently, cgroup_pidlist_open() skips seq_open() and pidlist loading if the file is opened write-only, which is a sensible optimization as pidlist loading can be costly and there often are occasions where tasks or cgroup.procs is opened write-only. However, pidlist init and release are planned to be moved to cgroup_pidlist_start/stop() respectively which would make this optimization unnecessary. This patch removes the optimization and always fully initializes pidlist files regardless of open mode. This will help moving pidlist handling to start/stop by unifying rw paths and removes the need for specifying cftype->release() in addition to .release in cgroup_pidlist_operations as file->f_op is now always overridden. As pidlist files were the only user of cftype->release(), the next patch will remove the method. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- kernel/cgroup.c | 13 +------------ 1 file changed, 1 insertion(+), 12 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 34fd1be0d9bf..1e09ded0387a 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -3781,12 +3781,7 @@ static void cgroup_release_pid_array(struct cgroup_pidlist *l) static int cgroup_pidlist_release(struct inode *inode, struct file *file) { struct cgroup_pidlist *l; - if (!(file->f_mode & FMODE_READ)) - return 0; - /* - * the seq_file will only be initialized if the file was opened for - * reading; hence we check if it's not null only in that case. - */ + l = ((struct seq_file *)file->private_data)->private; cgroup_release_pid_array(l); return seq_release(inode, file); @@ -3811,10 +3806,6 @@ static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type) struct cgroup_pidlist *l; int retval; - /* Nothing to do for write-only files */ - if (!(file->f_mode & FMODE_READ)) - return 0; - /* have the array populated */ retval = pidlist_array_load(cgrp, type, &l); if (retval) @@ -3894,7 +3885,6 @@ static struct cftype cgroup_base_files[] = { .name = "cgroup.procs", .open = cgroup_procs_open, .write_u64 = cgroup_procs_write, - .release = cgroup_pidlist_release, .mode = S_IRUGO | S_IWUSR, }, { @@ -3919,7 +3909,6 @@ static struct cftype cgroup_base_files[] = { .flags = CFTYPE_INSANE, /* use "procs" instead */ .open = cgroup_tasks_open, .write_u64 = cgroup_tasks_write, - .release = cgroup_pidlist_release, .mode = S_IRUGO | S_IWUSR, }, { -- cgit v1.2.3 From b9f3cecaba592d4e98cd155c91b1414323ed51e8 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 29 Nov 2013 10:42:58 -0500 Subject: cgroup: remove cftype->release() Now that pidlist files don't use cftype->release(), it doesn't have any user left. Remove it. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- include/linux/cgroup.h | 2 -- kernel/cgroup.c | 3 --- 2 files changed, 5 deletions(-) (limited to 'kernel') diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 492fa01ec2d3..5207c28c2402 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -499,8 +499,6 @@ struct cftype { * kick type for multiplexing. */ int (*trigger)(struct cgroup_subsys_state *css, unsigned int event); - - int (*release)(struct inode *inode, struct file *file); }; /* diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 1e09ded0387a..b59e3453eae7 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2448,12 +2448,9 @@ static int cgroup_file_open(struct inode *inode, struct file *file) static int cgroup_file_release(struct inode *inode, struct file *file) { struct cfent *cfe = __d_cfe(file->f_dentry); - struct cftype *cft = __d_cft(file->f_dentry); struct cgroup_subsys_state *css = cfe->css; int ret = 0; - if (cft->release) - ret = cft->release(inode, file); if (css->ss) css_put(css); if (file->f_op == &cgroup_seqfile_operations) -- cgit v1.2.3 From b1a21367314f36a819c0676e0999f34db12ee6ed Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 29 Nov 2013 10:42:58 -0500 Subject: cgroup: implement delayed destruction for cgroup_pidlist Currently, pidlists are reference counted from file open and release methods. This means that holding onto an open file may waste memory and reads may return data which is very stale. Both aren't critical because pidlists are keyed and shared per namespace and, well, the user isn't supposed to have large delay between open and reads. cgroup is planned to be converted to use kernfs and it'd be best if we can stick to just the seq_file operations - start, next, stop and show. This can be achieved by loading pidlist on demand from start and release with time delay from stop, so that consecutive reads don't end up reloading the pidlist on each iteration. This would remove the need for hooking into open and release while also avoiding issues with holding onto pidlist for too long. This patch implements delayed release of pidlist. As pidlists could be lingering on cgroup removal waiting for the timer to expire, cgroup free path needs to queue the destruction work item immediately and flush. As those work items are self-destroying, each work item can't be flushed directly. A new workqueue - cgroup_pidlist_destroy_wq - is added to serve as flush domain. Note that this patch just adds delayed release on top of the current implementation and doesn't change where pidlist is loaded and released. Following patches will make those changes. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- kernel/cgroup.c | 102 ++++++++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 77 insertions(+), 25 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index b59e3453eae7..acdcddf8ab82 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -61,6 +61,14 @@ #include +/* + * pidlists linger the following amount before being destroyed. The goal + * is avoiding frequent destruction in the middle of consecutive read calls + * Expiring in the middle is a performance problem not a correctness one. + * 1 sec should be enough. + */ +#define CGROUP_PIDLIST_DESTROY_DELAY HZ + /* * cgroup_mutex is the master lock. Any modification to cgroup or its * hierarchy must be performed while holding it. @@ -94,6 +102,12 @@ static DEFINE_MUTEX(cgroup_root_mutex); */ static struct workqueue_struct *cgroup_destroy_wq; +/* + * pidlist destructions need to be flushed on cgroup destruction. Use a + * separate workqueue as flush domain. + */ +static struct workqueue_struct *cgroup_pidlist_destroy_wq; + /* * Generate an array of cgroup subsystem pointers. At boot time, this is * populated with the built in subsystems, and modular subsystems are @@ -167,6 +181,7 @@ static int cgroup_destroy_locked(struct cgroup *cgrp); static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], bool is_add); static int cgroup_file_release(struct inode *inode, struct file *file); +static void cgroup_pidlist_destroy_all(struct cgroup *cgrp); /** * cgroup_css - obtain a cgroup's css for the specified subsystem @@ -830,11 +845,7 @@ static void cgroup_free_fn(struct work_struct *work) */ deactivate_super(cgrp->root->sb); - /* - * if we're getting rid of the cgroup, refcount should ensure - * that there are no pidlists left. - */ - BUG_ON(!list_empty(&cgrp->pidlists)); + cgroup_pidlist_destroy_all(cgrp); simple_xattrs_free(&cgrp->xattrs); @@ -2449,13 +2460,12 @@ static int cgroup_file_release(struct inode *inode, struct file *file) { struct cfent *cfe = __d_cfe(file->f_dentry); struct cgroup_subsys_state *css = cfe->css; - int ret = 0; if (css->ss) css_put(css); if (file->f_op == &cgroup_seqfile_operations) single_release(inode, file); - return ret; + return 0; } /* @@ -3454,6 +3464,8 @@ struct cgroup_pidlist { struct cgroup *owner; /* protects the other fields */ struct rw_semaphore rwsem; + /* for delayed destruction */ + struct delayed_work destroy_dwork; }; /* @@ -3469,6 +3481,7 @@ static void *pidlist_allocate(int count) else return kmalloc(count * sizeof(pid_t), GFP_KERNEL); } + static void pidlist_free(void *p) { if (is_vmalloc_addr(p)) @@ -3477,6 +3490,49 @@ static void pidlist_free(void *p) kfree(p); } +/* + * Used to destroy all pidlists lingering waiting for destroy timer. None + * should be left afterwards. + */ +static void cgroup_pidlist_destroy_all(struct cgroup *cgrp) +{ + struct cgroup_pidlist *l, *tmp_l; + + mutex_lock(&cgrp->pidlist_mutex); + list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links) + mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0); + mutex_unlock(&cgrp->pidlist_mutex); + + flush_workqueue(cgroup_pidlist_destroy_wq); + BUG_ON(!list_empty(&cgrp->pidlists)); +} + +static void cgroup_pidlist_destroy_work_fn(struct work_struct *work) +{ + struct delayed_work *dwork = to_delayed_work(work); + struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist, + destroy_dwork); + struct cgroup_pidlist *tofree = NULL; + + mutex_lock(&l->owner->pidlist_mutex); + down_write(&l->rwsem); + + /* + * Destroy iff we didn't race with a new user or get queued again. + * Queued state won't change as it can only be queued while locked. + */ + if (!l->use_count && !delayed_work_pending(dwork)) { + list_del(&l->links); + pidlist_free(l->list); + put_pid_ns(l->key.ns); + tofree = l; + } + + up_write(&l->rwsem); + mutex_unlock(&l->owner->pidlist_mutex); + kfree(tofree); +} + /* * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries * Returns the number of unique elements. @@ -3547,6 +3603,7 @@ static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, return l; } init_rwsem(&l->rwsem); + INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn); down_write(&l->rwsem); l->key.type = type; l->key.ns = get_pid_ns(ns); @@ -3752,26 +3809,12 @@ static const struct seq_operations cgroup_pidlist_seq_operations = { static void cgroup_release_pid_array(struct cgroup_pidlist *l) { - /* - * the case where we're the last user of this particular pidlist will - * have us remove it from the cgroup's list, which entails taking the - * mutex. since in pidlist_find the pidlist->lock depends on cgroup-> - * pidlist_mutex, we have to take pidlist_mutex first. - */ - mutex_lock(&l->owner->pidlist_mutex); down_write(&l->rwsem); BUG_ON(!l->use_count); - if (!--l->use_count) { - /* we're the last user if refcount is 0; remove and free */ - list_del(&l->links); - mutex_unlock(&l->owner->pidlist_mutex); - pidlist_free(l->list); - put_pid_ns(l->key.ns); - up_write(&l->rwsem); - kfree(l); - return; - } - mutex_unlock(&l->owner->pidlist_mutex); + /* if the last user, arm the destroy work */ + if (!--l->use_count) + mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, + CGROUP_PIDLIST_DESTROY_DELAY); up_write(&l->rwsem); } @@ -4813,6 +4856,15 @@ static int __init cgroup_wq_init(void) */ cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1); BUG_ON(!cgroup_destroy_wq); + + /* + * Used to destroy pidlists and separate to serve as flush domain. + * Cap @max_active to 1 too. + */ + cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy", + 0, 1); + BUG_ON(!cgroup_pidlist_destroy_wq); + return 0; } core_initcall(cgroup_wq_init); -- cgit v1.2.3 From 62236858f3cc558135d1ab6b2af44d22c489bb7f Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 29 Nov 2013 10:42:58 -0500 Subject: cgroup: introduce struct cgroup_pidlist_open_file For pidlist files, seq_file->private pointed to the loaded cgroup_pidlist; however, pidlist loading is planned to be moved to cgroup_pidlist_start() for kernfs conversion and seq_file->private needs to carry more information from open to allow that. This patch introduces struct cgroup_pidlist_open_file which contains type, cgrp and pidlist and updates pidlist seq_file->private to point to it using seq_open_private() and seq_release_private(). Note that this eventually will be replaced by kernfs_open_file. While this patch makes more information available to seq_file operations, they don't use it yet and this patch doesn't introduce any behavior changes except for allocation of the extra private struct. v2: use __seq_open_private() instead of seq_open_private() for brevity as suggested by Li. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- kernel/cgroup.c | 39 +++++++++++++++++++++++++++------------ 1 file changed, 27 insertions(+), 12 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index acdcddf8ab82..ef019c075d5d 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -3468,6 +3468,13 @@ struct cgroup_pidlist { struct delayed_work destroy_dwork; }; +/* seq_file->private points to the following */ +struct cgroup_pidlist_open_file { + enum cgroup_filetype type; + struct cgroup *cgrp; + struct cgroup_pidlist *pidlist; +}; + /* * The following two functions "fix" the issue where there are more pids * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. @@ -3739,7 +3746,8 @@ static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) * after a seek to the start). Use a binary-search to find the * next pid to display, if any */ - struct cgroup_pidlist *l = s->private; + struct cgroup_pidlist_open_file *of = s->private; + struct cgroup_pidlist *l = of->pidlist; int index = 0, pid = *pos; int *iter; @@ -3769,13 +3777,15 @@ static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) static void cgroup_pidlist_stop(struct seq_file *s, void *v) { - struct cgroup_pidlist *l = s->private; - up_read(&l->rwsem); + struct cgroup_pidlist_open_file *of = s->private; + + up_read(&of->pidlist->rwsem); } static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) { - struct cgroup_pidlist *l = s->private; + struct cgroup_pidlist_open_file *of = s->private; + struct cgroup_pidlist *l = of->pidlist; pid_t *p = v; pid_t *end = l->list + l->length; /* @@ -3820,11 +3830,11 @@ static void cgroup_release_pid_array(struct cgroup_pidlist *l) static int cgroup_pidlist_release(struct inode *inode, struct file *file) { - struct cgroup_pidlist *l; + struct cgroup_pidlist_open_file *of; - l = ((struct seq_file *)file->private_data)->private; - cgroup_release_pid_array(l); - return seq_release(inode, file); + of = ((struct seq_file *)file->private_data)->private; + cgroup_release_pid_array(of->pidlist); + return seq_release_private(inode, file); } static const struct file_operations cgroup_pidlist_operations = { @@ -3843,6 +3853,7 @@ static const struct file_operations cgroup_pidlist_operations = { static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type) { struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); + struct cgroup_pidlist_open_file *of; struct cgroup_pidlist *l; int retval; @@ -3853,12 +3864,16 @@ static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type) /* configure file information */ file->f_op = &cgroup_pidlist_operations; - retval = seq_open(file, &cgroup_pidlist_seq_operations); - if (retval) { + of = __seq_open_private(file, &cgroup_pidlist_seq_operations, + sizeof(*of)); + if (!of) { cgroup_release_pid_array(l); - return retval; + return -ENOMEM; } - ((struct seq_file *)file->private_data)->private = l; + + of->type = type; + of->cgrp = cgrp; + of->pidlist = l; return 0; } static int cgroup_tasks_open(struct inode *unused, struct file *file) -- cgit v1.2.3 From e6b817103d168a76e4044ebcdbc08225d77a81cb Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 29 Nov 2013 10:42:59 -0500 Subject: cgroup: refactor cgroup_pidlist_find() Rename cgroup_pidlist_find() to cgroup_pidlist_find_create() and separate out finding proper to cgroup_pidlist_find(). Also, move locking to the caller. This patch is preparation for pidlist restructure and doesn't introduce any behavior changes. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- kernel/cgroup.c | 65 +++++++++++++++++++++++++++++++++------------------------ 1 file changed, 38 insertions(+), 27 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index ef019c075d5d..d58c30d3b828 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -3575,48 +3575,50 @@ static int cmppid(const void *a, const void *b) return *(pid_t *)a - *(pid_t *)b; } +static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, + enum cgroup_filetype type) +{ + struct cgroup_pidlist *l; + /* don't need task_nsproxy() if we're looking at ourself */ + struct pid_namespace *ns = task_active_pid_ns(current); + + lockdep_assert_held(&cgrp->pidlist_mutex); + + list_for_each_entry(l, &cgrp->pidlists, links) + if (l->key.type == type && l->key.ns == ns) + return l; + return NULL; +} + /* * find the appropriate pidlist for our purpose (given procs vs tasks) * returns with the lock on that pidlist already held, and takes care * of the use count, or returns NULL with no locks held if we're out of * memory. */ -static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, - enum cgroup_filetype type) +static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp, + enum cgroup_filetype type) { struct cgroup_pidlist *l; - /* don't need task_nsproxy() if we're looking at ourself */ - struct pid_namespace *ns = task_active_pid_ns(current); - /* - * We can't drop the pidlist_mutex before taking the l->rwsem in case - * the last ref-holder is trying to remove l from the list at the same - * time. Holding the pidlist_mutex precludes somebody taking whichever - * list we find out from under us - compare release_pid_array(). - */ - mutex_lock(&cgrp->pidlist_mutex); - list_for_each_entry(l, &cgrp->pidlists, links) { - if (l->key.type == type && l->key.ns == ns) { - /* make sure l doesn't vanish out from under us */ - down_write(&l->rwsem); - mutex_unlock(&cgrp->pidlist_mutex); - return l; - } - } + lockdep_assert_held(&cgrp->pidlist_mutex); + + l = cgroup_pidlist_find(cgrp, type); + if (l) + return l; + /* entry not found; create a new one */ l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); - if (!l) { - mutex_unlock(&cgrp->pidlist_mutex); + if (!l) return l; - } + init_rwsem(&l->rwsem); INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn); - down_write(&l->rwsem); l->key.type = type; - l->key.ns = get_pid_ns(ns); + /* don't need task_nsproxy() if we're looking at ourself */ + l->key.ns = get_pid_ns(task_active_pid_ns(current)); l->owner = cgrp; list_add(&l->links, &cgrp->pidlists); - mutex_unlock(&cgrp->pidlist_mutex); return l; } @@ -3662,17 +3664,26 @@ static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, sort(array, length, sizeof(pid_t), cmppid, NULL); if (type == CGROUP_FILE_PROCS) length = pidlist_uniq(array, length); - l = cgroup_pidlist_find(cgrp, type); + + mutex_lock(&cgrp->pidlist_mutex); + + l = cgroup_pidlist_find_create(cgrp, type); if (!l) { + mutex_unlock(&cgrp->pidlist_mutex); pidlist_free(array); return -ENOMEM; } - /* store array, freeing old if necessary - lock already held */ + + /* store array, freeing old if necessary */ + down_write(&l->rwsem); pidlist_free(l->list); l->list = array; l->length = length; l->use_count++; up_write(&l->rwsem); + + mutex_unlock(&cgrp->pidlist_mutex); + *lp = l; return 0; } -- cgit v1.2.3 From 069df3b7aeb3f4e926c4da9630c92010909af512 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 29 Nov 2013 10:42:59 -0500 Subject: cgroup: remove cgroup_pidlist->rwsem cgroup_pidlist locking is needlessly complicated. It has outer cgroup->pidlist_mutex to protect the list of pidlists associated with a cgroup and then each pidlist has rwsem to synchronize updates and reads. Given that the only read access is from seq_file operations which are always invoked back-to-back, the rwsem is a giant overkill. All it does is adding unnecessary complexity. This patch removes cgroup_pidlist->rwsem and protects all accesses to pidlists belonging to a cgroup with cgroup->pidlist_mutex. pidlist->rwsem locking is removed if it's nested inside cgroup->pidlist_mutex; otherwise, it's replaced with cgroup->pidlist_mutex locking. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- kernel/cgroup.c | 15 ++++----------- 1 file changed, 4 insertions(+), 11 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index d58c30d3b828..dc39e1774542 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -3462,8 +3462,6 @@ struct cgroup_pidlist { struct list_head links; /* pointer to the cgroup we belong to, for list removal purposes */ struct cgroup *owner; - /* protects the other fields */ - struct rw_semaphore rwsem; /* for delayed destruction */ struct delayed_work destroy_dwork; }; @@ -3522,7 +3520,6 @@ static void cgroup_pidlist_destroy_work_fn(struct work_struct *work) struct cgroup_pidlist *tofree = NULL; mutex_lock(&l->owner->pidlist_mutex); - down_write(&l->rwsem); /* * Destroy iff we didn't race with a new user or get queued again. @@ -3535,7 +3532,6 @@ static void cgroup_pidlist_destroy_work_fn(struct work_struct *work) tofree = l; } - up_write(&l->rwsem); mutex_unlock(&l->owner->pidlist_mutex); kfree(tofree); } @@ -3612,7 +3608,6 @@ static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp, if (!l) return l; - init_rwsem(&l->rwsem); INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn); l->key.type = type; /* don't need task_nsproxy() if we're looking at ourself */ @@ -3675,12 +3670,10 @@ static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, } /* store array, freeing old if necessary */ - down_write(&l->rwsem); pidlist_free(l->list); l->list = array; l->length = length; l->use_count++; - up_write(&l->rwsem); mutex_unlock(&cgrp->pidlist_mutex); @@ -3762,7 +3755,7 @@ static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) int index = 0, pid = *pos; int *iter; - down_read(&l->rwsem); + mutex_lock(&of->cgrp->pidlist_mutex); if (pid) { int end = l->length; @@ -3790,7 +3783,7 @@ static void cgroup_pidlist_stop(struct seq_file *s, void *v) { struct cgroup_pidlist_open_file *of = s->private; - up_read(&of->pidlist->rwsem); + mutex_unlock(&of->cgrp->pidlist_mutex); } static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) @@ -3830,13 +3823,13 @@ static const struct seq_operations cgroup_pidlist_seq_operations = { static void cgroup_release_pid_array(struct cgroup_pidlist *l) { - down_write(&l->rwsem); + mutex_lock(&l->owner->pidlist_mutex); BUG_ON(!l->use_count); /* if the last user, arm the destroy work */ if (!--l->use_count) mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, CGROUP_PIDLIST_DESTROY_DELAY); - up_write(&l->rwsem); + mutex_unlock(&l->owner->pidlist_mutex); } static int cgroup_pidlist_release(struct inode *inode, struct file *file) -- cgit v1.2.3 From 4bac00d16a8760eae7205e41d2c246477d42a210 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 29 Nov 2013 10:42:59 -0500 Subject: cgroup: load and release pidlists from seq_file start and stop respectively Currently, pidlists are reference counted from file open and release methods. This means that holding onto an open file may waste memory and reads may return data which is very stale. Both aren't critical because pidlists are keyed and shared per namespace and, well, the user isn't supposed to have large delay between open and reads. cgroup is planned to be converted to use kernfs and it'd be best if we can stick to just the seq_file operations - start, next, stop and show. This can be achieved by loading pidlist on demand from start and release with time delay from stop, so that consecutive reads don't end up reloading the pidlist on each iteration. This would remove the need for hooking into open and release while also avoiding issues with holding onto pidlist for too long. The previous patches implemented delayed release and restructured pidlist handling so that pidlists can be loaded and released from seq_file start / stop. This patch actually moves pidlist load to start and release to stop. This means that pidlist is pinned only between start and stop and may go away between two consecutive read calls if the two calls are apart by more than CGROUP_PIDLIST_DESTROY_DELAY. cgroup_pidlist_start() thus can't re-use the stored cgroup_pid_list_open_file->pidlist directly. During start, it's only used as a hint indicating whether this is the first start after open or not and pidlist is always looked up or created. pidlist_mutex locking and reference counting are moved out of pidlist_array_load() so that pidlist_array_load() can perform lookup and creation atomically. While this enlarges the area covered by pidlist_mutex, given how the lock is used, it's highly unlikely to be noticeable. v2: Refreshed on top of the updated "cgroup: introduce struct cgroup_pidlist_open_file". Signed-off-by: Tejun Heo Acked-by: Li Zefan --- kernel/cgroup.c | 63 +++++++++++++++++++++++++++++++-------------------------- 1 file changed, 34 insertions(+), 29 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index dc39e1774542..671cbde883e9 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -3473,6 +3473,8 @@ struct cgroup_pidlist_open_file { struct cgroup_pidlist *pidlist; }; +static void cgroup_release_pid_array(struct cgroup_pidlist *l); + /* * The following two functions "fix" the issue where there are more pids * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. @@ -3630,6 +3632,8 @@ static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, struct task_struct *tsk; struct cgroup_pidlist *l; + lockdep_assert_held(&cgrp->pidlist_mutex); + /* * If cgroup gets more users after we read count, we won't have * enough space - tough. This race is indistinguishable to the @@ -3660,8 +3664,6 @@ static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, if (type == CGROUP_FILE_PROCS) length = pidlist_uniq(array, length); - mutex_lock(&cgrp->pidlist_mutex); - l = cgroup_pidlist_find_create(cgrp, type); if (!l) { mutex_unlock(&cgrp->pidlist_mutex); @@ -3673,10 +3675,6 @@ static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, pidlist_free(l->list); l->list = array; l->length = length; - l->use_count++; - - mutex_unlock(&cgrp->pidlist_mutex); - *lp = l; return 0; } @@ -3751,11 +3749,34 @@ static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) * next pid to display, if any */ struct cgroup_pidlist_open_file *of = s->private; - struct cgroup_pidlist *l = of->pidlist; + struct cgroup *cgrp = of->cgrp; + struct cgroup_pidlist *l; int index = 0, pid = *pos; - int *iter; + int *iter, ret; + + mutex_lock(&cgrp->pidlist_mutex); + + /* + * !NULL @of->pidlist indicates that this isn't the first start() + * after open. If the matching pidlist is around, we can use that. + * Look for it. Note that @of->pidlist can't be used directly. It + * could already have been destroyed. + */ + if (of->pidlist) + of->pidlist = cgroup_pidlist_find(cgrp, of->type); + + /* + * Either this is the first start() after open or the matching + * pidlist has been destroyed inbetween. Create a new one. + */ + if (!of->pidlist) { + ret = pidlist_array_load(of->cgrp, of->type, &of->pidlist); + if (ret) + return ERR_PTR(ret); + } + l = of->pidlist; + l->use_count++; - mutex_lock(&of->cgrp->pidlist_mutex); if (pid) { int end = l->length; @@ -3784,6 +3805,8 @@ static void cgroup_pidlist_stop(struct seq_file *s, void *v) struct cgroup_pidlist_open_file *of = s->private; mutex_unlock(&of->cgrp->pidlist_mutex); + if (of->pidlist) + cgroup_release_pid_array(of->pidlist); } static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) @@ -3832,20 +3855,11 @@ static void cgroup_release_pid_array(struct cgroup_pidlist *l) mutex_unlock(&l->owner->pidlist_mutex); } -static int cgroup_pidlist_release(struct inode *inode, struct file *file) -{ - struct cgroup_pidlist_open_file *of; - - of = ((struct seq_file *)file->private_data)->private; - cgroup_release_pid_array(of->pidlist); - return seq_release_private(inode, file); -} - static const struct file_operations cgroup_pidlist_operations = { .read = seq_read, .llseek = seq_lseek, .write = cgroup_file_write, - .release = cgroup_pidlist_release, + .release = seq_release_private, }; /* @@ -3858,26 +3872,17 @@ static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type) { struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); struct cgroup_pidlist_open_file *of; - struct cgroup_pidlist *l; - int retval; - /* have the array populated */ - retval = pidlist_array_load(cgrp, type, &l); - if (retval) - return retval; /* configure file information */ file->f_op = &cgroup_pidlist_operations; of = __seq_open_private(file, &cgroup_pidlist_seq_operations, sizeof(*of)); - if (!of) { - cgroup_release_pid_array(l); + if (!of) return -ENOMEM; - } of->type = type; of->cgrp = cgrp; - of->pidlist = l; return 0; } static int cgroup_tasks_open(struct inode *unused, struct file *file) -- cgit v1.2.3 From 045023658ca1e30dc0bb1f148b42c95b740d3e02 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 29 Nov 2013 10:42:59 -0500 Subject: cgroup: remove cgroup_pidlist->use_count After the recent changes, pidlist ref is held only between cgroup_pidlist_start() and cgroup_pidlist_stop() during which cgroup->pidlist_mutex is also held. IOW, the reference count is redundant now. While in use, it's always one and pidlist_mutex is held - holding the mutex has exactly the same protection. This patch collapses destroy_dwork queueing into cgroup_pidlist_stop() so that pidlist_mutex is not released inbetween and drops pidlist->use_count. This patch shouldn't introduce any behavior changes. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- kernel/cgroup.c | 28 +++++++--------------------- 1 file changed, 7 insertions(+), 21 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 671cbde883e9..a2458031d851 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -3456,8 +3456,6 @@ struct cgroup_pidlist { pid_t *list; /* how many elements the above list has */ int length; - /* how many files are using the current array */ - int use_count; /* each of these stored in a list by its cgroup */ struct list_head links; /* pointer to the cgroup we belong to, for list removal purposes */ @@ -3473,8 +3471,6 @@ struct cgroup_pidlist_open_file { struct cgroup_pidlist *pidlist; }; -static void cgroup_release_pid_array(struct cgroup_pidlist *l); - /* * The following two functions "fix" the issue where there are more pids * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. @@ -3524,10 +3520,10 @@ static void cgroup_pidlist_destroy_work_fn(struct work_struct *work) mutex_lock(&l->owner->pidlist_mutex); /* - * Destroy iff we didn't race with a new user or get queued again. - * Queued state won't change as it can only be queued while locked. + * Destroy iff we didn't get queued again. The state won't change + * as destroy_dwork can only be queued while locked. */ - if (!l->use_count && !delayed_work_pending(dwork)) { + if (!delayed_work_pending(dwork)) { list_del(&l->links); pidlist_free(l->list); put_pid_ns(l->key.ns); @@ -3775,7 +3771,6 @@ static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) return ERR_PTR(ret); } l = of->pidlist; - l->use_count++; if (pid) { int end = l->length; @@ -3804,9 +3799,11 @@ static void cgroup_pidlist_stop(struct seq_file *s, void *v) { struct cgroup_pidlist_open_file *of = s->private; - mutex_unlock(&of->cgrp->pidlist_mutex); if (of->pidlist) - cgroup_release_pid_array(of->pidlist); + mod_delayed_work(cgroup_pidlist_destroy_wq, + &of->pidlist->destroy_dwork, + CGROUP_PIDLIST_DESTROY_DELAY); + mutex_unlock(&of->cgrp->pidlist_mutex); } static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) @@ -3844,17 +3841,6 @@ static const struct seq_operations cgroup_pidlist_seq_operations = { .show = cgroup_pidlist_show, }; -static void cgroup_release_pid_array(struct cgroup_pidlist *l) -{ - mutex_lock(&l->owner->pidlist_mutex); - BUG_ON(!l->use_count); - /* if the last user, arm the destroy work */ - if (!--l->use_count) - mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, - CGROUP_PIDLIST_DESTROY_DELAY); - mutex_unlock(&l->owner->pidlist_mutex); -} - static const struct file_operations cgroup_pidlist_operations = { .read = seq_read, .llseek = seq_lseek, -- cgit v1.2.3 From afb2bc14e1c989cf0635bd04edb5ff55b8c1c7bd Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 29 Nov 2013 10:42:59 -0500 Subject: cgroup: don't guarantee cgroup.procs is sorted if sane_behavior For some reason, tasks and cgroup.procs guarantee that the result is sorted. This is the only reason this whole pidlist logic is necessary instead of just iterating through sorted member tasks. We can't do anything about the existing interface but at least ensure that such expectation doesn't exist for the new interface so that pidlist logic may be removed in the distant future. This patch scrambles the sort order if sane_behavior so that the output is usually not sorted in the new interface. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- include/linux/cgroup.h | 3 +++ kernel/cgroup.c | 51 +++++++++++++++++++++++++++++++++++++++++++++----- 2 files changed, 49 insertions(+), 5 deletions(-) (limited to 'kernel') diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 5207c28c2402..50d8cc37498b 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -275,6 +275,9 @@ enum { * - "tasks" is removed. Everything should be at process * granularity. Use "cgroup.procs" instead. * + * - "cgroup.procs" is not sorted. pids will be unique unless they + * got recycled inbetween reads. + * * - "release_agent" and "notify_on_release" are removed. * Replacement notification mechanism will be implemented. * diff --git a/kernel/cgroup.c b/kernel/cgroup.c index a2458031d851..f9f5fe3526ac 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -3564,11 +3564,49 @@ after: return dest; } +/* + * The two pid files - task and cgroup.procs - guaranteed that the result + * is sorted, which forced this whole pidlist fiasco. As pid order is + * different per namespace, each namespace needs differently sorted list, + * making it impossible to use, for example, single rbtree of member tasks + * sorted by task pointer. As pidlists can be fairly large, allocating one + * per open file is dangerous, so cgroup had to implement shared pool of + * pidlists keyed by cgroup and namespace. + * + * All this extra complexity was caused by the original implementation + * committing to an entirely unnecessary property. In the long term, we + * want to do away with it. Explicitly scramble sort order if + * sane_behavior so that no such expectation exists in the new interface. + * + * Scrambling is done by swapping every two consecutive bits, which is + * non-identity one-to-one mapping which disturbs sort order sufficiently. + */ +static pid_t pid_fry(pid_t pid) +{ + unsigned a = pid & 0x55555555; + unsigned b = pid & 0xAAAAAAAA; + + return (a << 1) | (b >> 1); +} + +static pid_t cgroup_pid_fry(struct cgroup *cgrp, pid_t pid) +{ + if (cgroup_sane_behavior(cgrp)) + return pid_fry(pid); + else + return pid; +} + static int cmppid(const void *a, const void *b) { return *(pid_t *)a - *(pid_t *)b; } +static int fried_cmppid(const void *a, const void *b) +{ + return pid_fry(*(pid_t *)a) - pid_fry(*(pid_t *)b); +} + static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, enum cgroup_filetype type) { @@ -3656,7 +3694,10 @@ static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, css_task_iter_end(&it); length = n; /* now sort & (if procs) strip out duplicates */ - sort(array, length, sizeof(pid_t), cmppid, NULL); + if (cgroup_sane_behavior(cgrp)) + sort(array, length, sizeof(pid_t), fried_cmppid, NULL); + else + sort(array, length, sizeof(pid_t), cmppid, NULL); if (type == CGROUP_FILE_PROCS) length = pidlist_uniq(array, length); @@ -3777,10 +3818,10 @@ static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) while (index < end) { int mid = (index + end) / 2; - if (l->list[mid] == pid) { + if (cgroup_pid_fry(cgrp, l->list[mid]) == pid) { index = mid; break; - } else if (l->list[mid] <= pid) + } else if (cgroup_pid_fry(cgrp, l->list[mid]) <= pid) index = mid + 1; else end = mid; @@ -3791,7 +3832,7 @@ static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) return NULL; /* Update the abstract position to be the actual pid that we found */ iter = l->list + index; - *pos = *iter; + *pos = cgroup_pid_fry(cgrp, *iter); return iter; } @@ -3820,7 +3861,7 @@ static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) if (p >= end) { return NULL; } else { - *pos = *p; + *pos = cgroup_pid_fry(of->cgrp, *p); return p; } } -- cgit v1.2.3 From 44ffc75ba9a63f972dbebd4fab6888db5fcd3b0e Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 5 Dec 2013 12:28:01 -0500 Subject: cgroup, sched: convert away from cftype->read_map() In preparation of conversion to kernfs, cgroup file handling is being consolidated so that it can be easily mapped to the seq_file based interface of kernfs. cftype->read_map() doesn't add any value and being replaced with ->read_seq_string(). Update cpu_stats_show() and cpuacct_stats_show() accordingly. This patch doesn't make any visible behavior changes. Signed-off-by: Tejun Heo Acked-by: Li Zefan Cc: Ingo Molnar Cc: Peter Zijlstra --- kernel/sched/core.c | 10 +++++----- kernel/sched/cpuacct.c | 8 ++++---- 2 files changed, 9 insertions(+), 9 deletions(-) (limited to 'kernel') diff --git a/kernel/sched/core.c b/kernel/sched/core.c index c1808606ee5f..f28ec6722f0b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7257,14 +7257,14 @@ static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota) } static int cpu_stats_show(struct cgroup_subsys_state *css, struct cftype *cft, - struct cgroup_map_cb *cb) + struct seq_file *sf) { struct task_group *tg = css_tg(css); struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; - cb->fill(cb, "nr_periods", cfs_b->nr_periods); - cb->fill(cb, "nr_throttled", cfs_b->nr_throttled); - cb->fill(cb, "throttled_time", cfs_b->throttled_time); + seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods); + seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled); + seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time); return 0; } @@ -7318,7 +7318,7 @@ static struct cftype cpu_files[] = { }, { .name = "stat", - .read_map = cpu_stats_show, + .read_seq_string = cpu_stats_show, }, #endif #ifdef CONFIG_RT_GROUP_SCHED diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c index f64722ff0299..dd88738cd4a9 100644 --- a/kernel/sched/cpuacct.c +++ b/kernel/sched/cpuacct.c @@ -184,7 +184,7 @@ static const char * const cpuacct_stat_desc[] = { }; static int cpuacct_stats_show(struct cgroup_subsys_state *css, - struct cftype *cft, struct cgroup_map_cb *cb) + struct cftype *cft, struct seq_file *sf) { struct cpuacct *ca = css_ca(css); int cpu; @@ -196,7 +196,7 @@ static int cpuacct_stats_show(struct cgroup_subsys_state *css, val += kcpustat->cpustat[CPUTIME_NICE]; } val = cputime64_to_clock_t(val); - cb->fill(cb, cpuacct_stat_desc[CPUACCT_STAT_USER], val); + seq_printf(sf, "%s %lld\n", cpuacct_stat_desc[CPUACCT_STAT_USER], val); val = 0; for_each_online_cpu(cpu) { @@ -207,7 +207,7 @@ static int cpuacct_stats_show(struct cgroup_subsys_state *css, } val = cputime64_to_clock_t(val); - cb->fill(cb, cpuacct_stat_desc[CPUACCT_STAT_SYSTEM], val); + seq_printf(sf, "%s %lld\n", cpuacct_stat_desc[CPUACCT_STAT_SYSTEM], val); return 0; } @@ -224,7 +224,7 @@ static struct cftype files[] = { }, { .name = "stat", - .read_map = cpuacct_stats_show, + .read_seq_string = cpuacct_stats_show, }, { } /* terminate */ }; -- cgit v1.2.3 From 51ffe41178c49738e4d6d17b9bdcf528a262abc8 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 5 Dec 2013 12:28:02 -0500 Subject: cpuset: convert away from cftype->read() In preparation of conversion to kernfs, cgroup file handling is being consolidated so that it can be easily mapped to the seq_file based interface of kernfs. All users of cftype->read() can be easily served, usually better, by seq_file and other methods. Rename cpuset_common_file_read() to cpuset_common_read_seq_string() and convert it to use read_seq_string() interface instead. This not only simplifies the code but also makes it more versatile. Before, the file couldn't output if the result is longer than PAGE_SIZE. After the conversion, seq_file automatically grows the buffer until the output can fit. This patch doesn't make any visible behavior changes except for being able to handle output larger than PAGE_SIZE. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- kernel/cpuset.c | 71 +++++++++++++++++++-------------------------------------- 1 file changed, 24 insertions(+), 47 deletions(-) (limited to 'kernel') diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 4772034b4b17..032929f91648 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -1731,66 +1731,43 @@ out_unlock: * used, list of ranges of sequential numbers, is variable length, * and since these maps can change value dynamically, one could read * gibberish by doing partial reads while a list was changing. - * A single large read to a buffer that crosses a page boundary is - * ok, because the result being copied to user land is not recomputed - * across a page fault. */ - -static size_t cpuset_sprintf_cpulist(char *page, struct cpuset *cs) -{ - size_t count; - - mutex_lock(&callback_mutex); - count = cpulist_scnprintf(page, PAGE_SIZE, cs->cpus_allowed); - mutex_unlock(&callback_mutex); - - return count; -} - -static size_t cpuset_sprintf_memlist(char *page, struct cpuset *cs) -{ - size_t count; - - mutex_lock(&callback_mutex); - count = nodelist_scnprintf(page, PAGE_SIZE, cs->mems_allowed); - mutex_unlock(&callback_mutex); - - return count; -} - -static ssize_t cpuset_common_file_read(struct cgroup_subsys_state *css, - struct cftype *cft, struct file *file, - char __user *buf, size_t nbytes, - loff_t *ppos) +static int cpuset_common_read_seq_string(struct cgroup_subsys_state *css, + struct cftype *cft, + struct seq_file *sf) { struct cpuset *cs = css_cs(css); cpuset_filetype_t type = cft->private; - char *page; - ssize_t retval = 0; - char *s; + ssize_t count; + char *buf, *s; + int ret = 0; - if (!(page = (char *)__get_free_page(GFP_TEMPORARY))) - return -ENOMEM; + count = seq_get_buf(sf, &buf); + s = buf; - s = page; + mutex_lock(&callback_mutex); switch (type) { case FILE_CPULIST: - s += cpuset_sprintf_cpulist(s, cs); + s += cpulist_scnprintf(s, count, cs->cpus_allowed); break; case FILE_MEMLIST: - s += cpuset_sprintf_memlist(s, cs); + s += nodelist_scnprintf(s, count, cs->mems_allowed); break; default: - retval = -EINVAL; - goto out; + ret = -EINVAL; + goto out_unlock; } - *s++ = '\n'; - retval = simple_read_from_buffer(buf, nbytes, ppos, page, s - page); -out: - free_page((unsigned long)page); - return retval; + if (s < buf + count - 1) { + *s++ = '\n'; + seq_commit(sf, s - buf); + } else { + seq_commit(sf, -1); + } +out_unlock: + mutex_unlock(&callback_mutex); + return ret; } static u64 cpuset_read_u64(struct cgroup_subsys_state *css, struct cftype *cft) @@ -1847,7 +1824,7 @@ static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft) static struct cftype files[] = { { .name = "cpus", - .read = cpuset_common_file_read, + .read_seq_string = cpuset_common_read_seq_string, .write_string = cpuset_write_resmask, .max_write_len = (100U + 6 * NR_CPUS), .private = FILE_CPULIST, @@ -1855,7 +1832,7 @@ static struct cftype files[] = { { .name = "mems", - .read = cpuset_common_file_read, + .read_seq_string = cpuset_common_read_seq_string, .write_string = cpuset_write_resmask, .max_write_len = (100U + 6 * MAX_NUMNODES), .private = FILE_MEMLIST, -- cgit v1.2.3 From 6e0755b08dd6a3b5260fafc6969268c2ba261300 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 5 Dec 2013 12:28:03 -0500 Subject: cgroup: remove cftype->read(), ->read_map() and ->write() In preparation of conversion to kernfs, cgroup file handling is being consolidated so that it can be easily mapped to the seq_file based interface of kernfs. After recent updates, ->read() and ->read_map() don't have any user left and ->write() never had any user. Remove them. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- include/linux/cgroup.h | 25 ------------------------- kernel/cgroup.c | 26 ++++---------------------- 2 files changed, 4 insertions(+), 47 deletions(-) (limited to 'kernel') diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 50d8cc37498b..53e11da6e357 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -386,16 +386,6 @@ struct css_set { struct rcu_head rcu_head; }; -/* - * cgroup_map_cb is an abstract callback API for reporting map-valued - * control files - */ - -struct cgroup_map_cb { - int (*fill)(struct cgroup_map_cb *cb, const char *key, u64 value); - void *state; -}; - /* * struct cftype: handler definitions for cgroup control files * @@ -444,9 +434,6 @@ struct cftype { struct cgroup_subsys *ss; int (*open)(struct inode *inode, struct file *file); - ssize_t (*read)(struct cgroup_subsys_state *css, struct cftype *cft, - struct file *file, - char __user *buf, size_t nbytes, loff_t *ppos); /* * read_u64() is a shortcut for the common case of returning a * single integer. Use it in place of read() @@ -456,14 +443,6 @@ struct cftype { * read_s64() is a signed version of read_u64() */ s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft); - /* - * read_map() is used for defining a map of key/value - * pairs. It should call cb->fill(cb, key, value) for each - * entry. The key/value pairs (and their ordering) should not - * change between reboots. - */ - int (*read_map)(struct cgroup_subsys_state *css, struct cftype *cft, - struct cgroup_map_cb *cb); /* * read_seq_string() is used for outputting a simple sequence * using seqfile. @@ -471,10 +450,6 @@ struct cftype { int (*read_seq_string)(struct cgroup_subsys_state *css, struct cftype *cft, struct seq_file *m); - ssize_t (*write)(struct cgroup_subsys_state *css, struct cftype *cft, - struct file *file, - const char __user *buf, size_t nbytes, loff_t *ppos); - /* * write_u64() is a shortcut for the common case of accepting * a single integer (as parsed by simple_strtoull) from diff --git a/kernel/cgroup.c b/kernel/cgroup.c index f9f5fe3526ac..b132ff94fc6f 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2324,8 +2324,6 @@ static ssize_t cgroup_file_write(struct file *file, const char __user *buf, struct cftype *cft = __d_cft(file->f_dentry); struct cgroup_subsys_state *css = cfe->css; - if (cft->write) - return cft->write(css, cft, file, buf, nbytes, ppos); if (cft->write_u64 || cft->write_s64) return cgroup_write_X64(css, cft, file, buf, nbytes, ppos); if (cft->write_string) @@ -2366,8 +2364,6 @@ static ssize_t cgroup_file_read(struct file *file, char __user *buf, struct cftype *cft = __d_cft(file->f_dentry); struct cgroup_subsys_state *css = cfe->css; - if (cft->read) - return cft->read(css, cft, file, buf, nbytes, ppos); if (cft->read_u64) return cgroup_read_u64(css, cft, file, buf, nbytes, ppos); if (cft->read_s64) @@ -2380,25 +2376,12 @@ static ssize_t cgroup_file_read(struct file *file, char __user *buf, * supports string->u64 maps, but can be extended in future. */ -static int cgroup_map_add(struct cgroup_map_cb *cb, const char *key, u64 value) -{ - struct seq_file *sf = cb->state; - return seq_printf(sf, "%s %llu\n", key, (unsigned long long)value); -} - static int cgroup_seqfile_show(struct seq_file *m, void *arg) { struct cfent *cfe = m->private; struct cftype *cft = cfe->type; struct cgroup_subsys_state *css = cfe->css; - if (cft->read_map) { - struct cgroup_map_cb cb = { - .fill = cgroup_map_add, - .state = m, - }; - return cft->read_map(css, cft, &cb); - } return cft->read_seq_string(css, cft, m); } @@ -2444,7 +2427,7 @@ static int cgroup_file_open(struct inode *inode, struct file *file) WARN_ON_ONCE(cfe->css && cfe->css != css); cfe->css = css; - if (cft->read_map || cft->read_seq_string) { + if (cft->read_seq_string) { file->f_op = &cgroup_seqfile_operations; err = single_open(file, cgroup_seqfile_show, cfe); } else if (cft->open) { @@ -2658,12 +2641,11 @@ static umode_t cgroup_file_mode(const struct cftype *cft) if (cft->mode) return cft->mode; - if (cft->read || cft->read_u64 || cft->read_s64 || - cft->read_map || cft->read_seq_string) + if (cft->read_u64 || cft->read_s64 || cft->read_seq_string) mode |= S_IRUGO; - if (cft->write || cft->write_u64 || cft->write_s64 || - cft->write_string || cft->trigger) + if (cft->write_u64 || cft->write_s64 || cft->write_string || + cft->trigger) mode |= S_IWUSR; return mode; -- cgit v1.2.3 From a742c59de66ea080afa3edaf3428b3cdd5aa87cd Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 5 Dec 2013 12:28:03 -0500 Subject: cgroup: unify cgroup_write_X64() and cgroup_write_string() cgroup_write_X64() and cgroup_write_string() both implement about the same buffering logic. Unify the two into cgroup_file_write() which always allocates dynamic buffer for simplicity and uses kstrto*() instead of simple_strto*(). This patch doesn't make any visible behavior changes except for possibly different error value from kstrsto*(). Signed-off-by: Tejun Heo Acked-by: Li Zefan --- kernel/cgroup.c | 112 ++++++++++++++++++-------------------------------------- 1 file changed, 36 insertions(+), 76 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index b132ff94fc6f..eb34caf98124 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2249,90 +2249,50 @@ static int cgroup_sane_behavior_show(struct cgroup_subsys_state *css, /* A buffer size big enough for numbers or short strings */ #define CGROUP_LOCAL_BUFFER_SIZE 64 -static ssize_t cgroup_write_X64(struct cgroup_subsys_state *css, - struct cftype *cft, struct file *file, - const char __user *userbuf, size_t nbytes, - loff_t *unused_ppos) -{ - char buffer[CGROUP_LOCAL_BUFFER_SIZE]; - int retval = 0; - char *end; - - if (!nbytes) - return -EINVAL; - if (nbytes >= sizeof(buffer)) - return -E2BIG; - if (copy_from_user(buffer, userbuf, nbytes)) - return -EFAULT; - - buffer[nbytes] = 0; /* nul-terminate */ - if (cft->write_u64) { - u64 val = simple_strtoull(strstrip(buffer), &end, 0); - if (*end) - return -EINVAL; - retval = cft->write_u64(css, cft, val); - } else { - s64 val = simple_strtoll(strstrip(buffer), &end, 0); - if (*end) - return -EINVAL; - retval = cft->write_s64(css, cft, val); - } - if (!retval) - retval = nbytes; - return retval; -} - -static ssize_t cgroup_write_string(struct cgroup_subsys_state *css, - struct cftype *cft, struct file *file, - const char __user *userbuf, size_t nbytes, - loff_t *unused_ppos) +static ssize_t cgroup_file_write(struct file *file, const char __user *userbuf, + size_t nbytes, loff_t *ppos) { - char local_buffer[CGROUP_LOCAL_BUFFER_SIZE]; - int retval = 0; - size_t max_bytes = cft->max_write_len; - char *buffer = local_buffer; + struct cfent *cfe = __d_cfe(file->f_dentry); + struct cftype *cft = __d_cft(file->f_dentry); + struct cgroup_subsys_state *css = cfe->css; + size_t max_bytes = cft->max_write_len ?: CGROUP_LOCAL_BUFFER_SIZE - 1; + char *buf; + int ret; - if (!max_bytes) - max_bytes = sizeof(local_buffer) - 1; if (nbytes >= max_bytes) return -E2BIG; - /* Allocate a dynamic buffer if we need one */ - if (nbytes >= sizeof(local_buffer)) { - buffer = kmalloc(nbytes + 1, GFP_KERNEL); - if (buffer == NULL) - return -ENOMEM; - } - if (nbytes && copy_from_user(buffer, userbuf, nbytes)) { - retval = -EFAULT; - goto out; - } - buffer[nbytes] = 0; /* nul-terminate */ - retval = cft->write_string(css, cft, strstrip(buffer)); - if (!retval) - retval = nbytes; -out: - if (buffer != local_buffer) - kfree(buffer); - return retval; -} + buf = kmalloc(nbytes + 1, GFP_KERNEL); + if (!buf) + return -ENOMEM; -static ssize_t cgroup_file_write(struct file *file, const char __user *buf, - size_t nbytes, loff_t *ppos) -{ - struct cfent *cfe = __d_cfe(file->f_dentry); - struct cftype *cft = __d_cft(file->f_dentry); - struct cgroup_subsys_state *css = cfe->css; + if (copy_from_user(buf, userbuf, nbytes)) { + ret = -EFAULT; + goto out_free; + } - if (cft->write_u64 || cft->write_s64) - return cgroup_write_X64(css, cft, file, buf, nbytes, ppos); - if (cft->write_string) - return cgroup_write_string(css, cft, file, buf, nbytes, ppos); - if (cft->trigger) { - int ret = cft->trigger(css, (unsigned int)cft->private); - return ret ? ret : nbytes; + buf[nbytes] = '\0'; + + if (cft->write_string) { + ret = cft->write_string(css, cft, strstrip(buf)); + } else if (cft->write_u64) { + unsigned long long v; + ret = kstrtoull(buf, 0, &v); + if (!ret) + ret = cft->write_u64(css, cft, v); + } else if (cft->write_s64) { + long long v; + ret = kstrtoll(buf, 0, &v); + if (!ret) + ret = cft->write_s64(css, cft, v); + } else if (cft->trigger) { + ret = cft->trigger(css, (unsigned int)cft->private); + } else { + ret = -EINVAL; } - return -EINVAL; +out_free: + kfree(buf); + return ret ?: nbytes; } static ssize_t cgroup_read_u64(struct cgroup_subsys_state *css, -- cgit v1.2.3 From 896f5199631560202885715da1b2f018632084e5 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 5 Dec 2013 12:28:04 -0500 Subject: cgroup: unify read path so that seq_file is always used With the recent removal of cftype->read() and ->read_map(), only three operations are remaining, ->read_u64(), ->read_s64() and ->read_seq_string(). Currently, the first two are handled directly while the last is handled through seq_file. It is trivial to serve the first two through the seq_file path too. This patch restructures read path so that all operations are served through cgroup_seqfile_show(). This makes all cgroup files seq_file - single_open/release() are now used by default, cgroup_seqfile_operations is dropped, and cgroup_file_operations uses seq_read() for read. This simplifies the code and makes the read path easy to convert to use kernfs. Note that, while cgroup_file_operations uses seq_read() for read, it still uses generic_file_llseek() for seeking instead of seq_lseek(). This is different from cgroup_seqfile_operations but shouldn't break anything and brings the seeking behavior aligned with kernfs. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- kernel/cgroup.c | 68 +++++++++++++-------------------------------------------- 1 file changed, 15 insertions(+), 53 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index eb34caf98124..ce6db713bbd6 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2295,42 +2295,6 @@ out_free: return ret ?: nbytes; } -static ssize_t cgroup_read_u64(struct cgroup_subsys_state *css, - struct cftype *cft, struct file *file, - char __user *buf, size_t nbytes, loff_t *ppos) -{ - char tmp[CGROUP_LOCAL_BUFFER_SIZE]; - u64 val = cft->read_u64(css, cft); - int len = sprintf(tmp, "%llu\n", (unsigned long long) val); - - return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); -} - -static ssize_t cgroup_read_s64(struct cgroup_subsys_state *css, - struct cftype *cft, struct file *file, - char __user *buf, size_t nbytes, loff_t *ppos) -{ - char tmp[CGROUP_LOCAL_BUFFER_SIZE]; - s64 val = cft->read_s64(css, cft); - int len = sprintf(tmp, "%lld\n", (long long) val); - - return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); -} - -static ssize_t cgroup_file_read(struct file *file, char __user *buf, - size_t nbytes, loff_t *ppos) -{ - struct cfent *cfe = __d_cfe(file->f_dentry); - struct cftype *cft = __d_cft(file->f_dentry); - struct cgroup_subsys_state *css = cfe->css; - - if (cft->read_u64) - return cgroup_read_u64(css, cft, file, buf, nbytes, ppos); - if (cft->read_s64) - return cgroup_read_s64(css, cft, file, buf, nbytes, ppos); - return -EINVAL; -} - /* * seqfile ops/methods for returning structured data. Currently just * supports string->u64 maps, but can be extended in future. @@ -2342,15 +2306,17 @@ static int cgroup_seqfile_show(struct seq_file *m, void *arg) struct cftype *cft = cfe->type; struct cgroup_subsys_state *css = cfe->css; - return cft->read_seq_string(css, cft, m); -} + if (cft->read_seq_string) + return cft->read_seq_string(css, cft, m); -static const struct file_operations cgroup_seqfile_operations = { - .read = seq_read, - .write = cgroup_file_write, - .llseek = seq_lseek, - .release = cgroup_file_release, -}; + if (cft->read_u64) + seq_printf(m, "%llu\n", cft->read_u64(css, cft)); + else if (cft->read_s64) + seq_printf(m, "%lld\n", cft->read_s64(css, cft)); + else + return -EINVAL; + return 0; +} static int cgroup_file_open(struct inode *inode, struct file *file) { @@ -2387,12 +2353,10 @@ static int cgroup_file_open(struct inode *inode, struct file *file) WARN_ON_ONCE(cfe->css && cfe->css != css); cfe->css = css; - if (cft->read_seq_string) { - file->f_op = &cgroup_seqfile_operations; - err = single_open(file, cgroup_seqfile_show, cfe); - } else if (cft->open) { + if (cft->open) err = cft->open(inode, file); - } + else + err = single_open(file, cgroup_seqfile_show, cfe); if (css->ss && err) css_put(css); @@ -2406,9 +2370,7 @@ static int cgroup_file_release(struct inode *inode, struct file *file) if (css->ss) css_put(css); - if (file->f_op == &cgroup_seqfile_operations) - single_release(inode, file); - return 0; + return single_release(inode, file); } /* @@ -2519,7 +2481,7 @@ static ssize_t cgroup_listxattr(struct dentry *dentry, char *buf, size_t size) } static const struct file_operations cgroup_file_operations = { - .read = cgroup_file_read, + .read = seq_read, .write = cgroup_file_write, .llseek = generic_file_llseek, .open = cgroup_file_open, -- cgit v1.2.3 From 5d22444f427511fe7c4733b233680309af5b071c Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 5 Dec 2013 12:28:04 -0500 Subject: cgroup: generalize cgroup_pidlist_open_file In preparation of conversion to kernfs, cgroup file handling is updated so that it can be easily mapped to kernfs. This patch renames cgroup_pidlist_open_file to cgroup_open_file and updates it so that it only contains a field to identify the specific file, ->cfe, and an opaque ->priv pointer. When cgroup is converted to kernfs, this will be replaced by kernfs_open_file which contains about the same information. As whether the file is "cgroup.procs" or "tasks" should now be determined from cgroup_open_file->cfe, the cftype->private for the two files now carry the file type and cgroup_pidlist_start() reads the type through cfe->type->private. This makes the distinction between cgroup_tasks_open() and cgroup_procs_open() unnecessary. cgroup_pidlist_open() is now directly used as the open method. This patch doesn't make any behavior changes. v2: Refreshed on top of the updated "cgroup: introduce struct cgroup_pidlist_open_file". Signed-off-by: Tejun Heo Acked-by: Li Zefan --- kernel/cgroup.c | 66 ++++++++++++++++++++++++++------------------------------- 1 file changed, 30 insertions(+), 36 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index ce6db713bbd6..17272893d3b8 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -3369,10 +3369,9 @@ struct cgroup_pidlist { }; /* seq_file->private points to the following */ -struct cgroup_pidlist_open_file { - enum cgroup_filetype type; - struct cgroup *cgrp; - struct cgroup_pidlist *pidlist; +struct cgroup_open_file { + struct cfent *cfe; + void *priv; }; /* @@ -3689,33 +3688,35 @@ static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) * after a seek to the start). Use a binary-search to find the * next pid to display, if any */ - struct cgroup_pidlist_open_file *of = s->private; - struct cgroup *cgrp = of->cgrp; + struct cgroup_open_file *of = s->private; + struct cgroup *cgrp = of->cfe->css->cgroup; struct cgroup_pidlist *l; + enum cgroup_filetype type = of->cfe->type->private; int index = 0, pid = *pos; int *iter, ret; mutex_lock(&cgrp->pidlist_mutex); /* - * !NULL @of->pidlist indicates that this isn't the first start() + * !NULL @of->priv indicates that this isn't the first start() * after open. If the matching pidlist is around, we can use that. - * Look for it. Note that @of->pidlist can't be used directly. It + * Look for it. Note that @of->priv can't be used directly. It * could already have been destroyed. */ - if (of->pidlist) - of->pidlist = cgroup_pidlist_find(cgrp, of->type); + if (of->priv) + of->priv = cgroup_pidlist_find(cgrp, type); /* * Either this is the first start() after open or the matching * pidlist has been destroyed inbetween. Create a new one. */ - if (!of->pidlist) { - ret = pidlist_array_load(of->cgrp, of->type, &of->pidlist); + if (!of->priv) { + ret = pidlist_array_load(cgrp, type, + (struct cgroup_pidlist **)&of->priv); if (ret) return ERR_PTR(ret); } - l = of->pidlist; + l = of->priv; if (pid) { int end = l->length; @@ -3742,19 +3743,19 @@ static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) static void cgroup_pidlist_stop(struct seq_file *s, void *v) { - struct cgroup_pidlist_open_file *of = s->private; + struct cgroup_open_file *of = s->private; + struct cgroup_pidlist *l = of->priv; - if (of->pidlist) - mod_delayed_work(cgroup_pidlist_destroy_wq, - &of->pidlist->destroy_dwork, + if (l) + mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, CGROUP_PIDLIST_DESTROY_DELAY); - mutex_unlock(&of->cgrp->pidlist_mutex); + mutex_unlock(&of->cfe->css->cgroup->pidlist_mutex); } static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) { - struct cgroup_pidlist_open_file *of = s->private; - struct cgroup_pidlist *l = of->pidlist; + struct cgroup_open_file *of = s->private; + struct cgroup_pidlist *l = of->priv; pid_t *p = v; pid_t *end = l->list + l->length; /* @@ -3765,7 +3766,7 @@ static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) if (p >= end) { return NULL; } else { - *pos = cgroup_pid_fry(of->cgrp, *p); + *pos = cgroup_pid_fry(of->cfe->css->cgroup, *p); return p; } } @@ -3799,10 +3800,10 @@ static const struct file_operations cgroup_pidlist_operations = { * in the cgroup. */ /* helper function for the two below it */ -static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type) +static int cgroup_pidlist_open(struct inode *unused, struct file *file) { - struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); - struct cgroup_pidlist_open_file *of; + struct cfent *cfe = __d_cfe(file->f_dentry); + struct cgroup_open_file *of; /* configure file information */ file->f_op = &cgroup_pidlist_operations; @@ -3812,18 +3813,9 @@ static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type) if (!of) return -ENOMEM; - of->type = type; - of->cgrp = cgrp; + of->cfe = cfe; return 0; } -static int cgroup_tasks_open(struct inode *unused, struct file *file) -{ - return cgroup_pidlist_open(file, CGROUP_FILE_TASKS); -} -static int cgroup_procs_open(struct inode *unused, struct file *file) -{ - return cgroup_pidlist_open(file, CGROUP_FILE_PROCS); -} static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css, struct cftype *cft) @@ -3878,7 +3870,8 @@ static int cgroup_clone_children_write(struct cgroup_subsys_state *css, static struct cftype cgroup_base_files[] = { { .name = "cgroup.procs", - .open = cgroup_procs_open, + .open = cgroup_pidlist_open, + .private = CGROUP_FILE_PROCS, .write_u64 = cgroup_procs_write, .mode = S_IRUGO | S_IWUSR, }, @@ -3902,7 +3895,8 @@ static struct cftype cgroup_base_files[] = { { .name = "tasks", .flags = CFTYPE_INSANE, /* use "procs" instead */ - .open = cgroup_tasks_open, + .open = cgroup_pidlist_open, + .private = CGROUP_FILE_TASKS, .write_u64 = cgroup_tasks_write, .mode = S_IRUGO | S_IWUSR, }, -- cgit v1.2.3 From 7da112792753d71aed44b918395892a1fc53048a Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 5 Dec 2013 12:28:04 -0500 Subject: cgroup: attach cgroup_open_file to all cgroup files In preparation of conversion to kernfs, cgroup file handling is updated so that it can be easily mapped to kernfs. This patch attaches cgroup_open_file, which used to be attached to pidlist files, to all cgroup files, introduces seq_css/cft() accessors to determine the cgroup_subsys_state and cftype associated with a given cgroup seq_file, exports them as public interface. This doesn't cause any behavior changes but unifies cgroup file handling across different file types and will help converting them to kernfs seq_show() interface. v2: Li pointed out that the original patch was using single_open_size() incorrectly assuming that the size param is private data size. Fix it by allocating @of separately and passing it to single_open() and explicitly freeing it in the release path. This isn't the prettiest but this path is gonna be restructured by the following patches pretty soon. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- include/linux/cgroup.h | 33 +++++++++++++++++++++++++++++++++ kernel/cgroup.c | 50 ++++++++++++++++++++------------------------------ 2 files changed, 53 insertions(+), 30 deletions(-) (limited to 'kernel') diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 53e11da6e357..c3d698a72e02 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -21,6 +21,7 @@ #include #include #include +#include #ifdef CONFIG_CGROUPS @@ -489,6 +490,26 @@ struct cftype_set { struct cftype *cfts; }; +/* + * cgroupfs file entry, pointed to from leaf dentry->d_fsdata. Don't + * access directly. + */ +struct cfent { + struct list_head node; + struct dentry *dentry; + struct cftype *type; + struct cgroup_subsys_state *css; + + /* file xattrs */ + struct simple_xattrs xattrs; +}; + +/* seq_file->private points to the following, only ->priv is public */ +struct cgroup_open_file { + struct cfent *cfe; + void *priv; +}; + /* * See the comment above CGRP_ROOT_SANE_BEHAVIOR for details. This * function can be called as long as @cgrp is accessible. @@ -504,6 +525,18 @@ static inline const char *cgroup_name(const struct cgroup *cgrp) return rcu_dereference(cgrp->name)->name; } +static inline struct cgroup_subsys_state *seq_css(struct seq_file *seq) +{ + struct cgroup_open_file *of = seq->private; + return of->cfe->css; +} + +static inline struct cftype *seq_cft(struct seq_file *seq) +{ + struct cgroup_open_file *of = seq->private; + return of->cfe->type; +} + int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts); int cgroup_rm_cftypes(struct cftype *cfts); diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 17272893d3b8..036c05d8e572 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -41,7 +41,6 @@ #include #include #include -#include #include #include #include @@ -130,19 +129,6 @@ static struct cgroupfs_root cgroup_dummy_root; /* dummy_top is a shorthand for the dummy hierarchy's top cgroup */ static struct cgroup * const cgroup_dummy_top = &cgroup_dummy_root.top_cgroup; -/* - * cgroupfs file entry, pointed to from leaf dentry->d_fsdata. - */ -struct cfent { - struct list_head node; - struct dentry *dentry; - struct cftype *type; - struct cgroup_subsys_state *css; - - /* file xattrs */ - struct simple_xattrs xattrs; -}; - /* The list of hierarchy roots */ static LIST_HEAD(cgroup_roots); @@ -2302,9 +2288,8 @@ out_free: static int cgroup_seqfile_show(struct seq_file *m, void *arg) { - struct cfent *cfe = m->private; - struct cftype *cft = cfe->type; - struct cgroup_subsys_state *css = cfe->css; + struct cftype *cft = seq_cft(m); + struct cgroup_subsys_state *css = seq_css(m); if (cft->read_seq_string) return cft->read_seq_string(css, cft, m); @@ -2353,10 +2338,20 @@ static int cgroup_file_open(struct inode *inode, struct file *file) WARN_ON_ONCE(cfe->css && cfe->css != css); cfe->css = css; - if (cft->open) + if (cft->open) { err = cft->open(inode, file); - else - err = single_open(file, cgroup_seqfile_show, cfe); + } else { + struct cgroup_open_file *of; + + err = -ENOMEM; + of = kzalloc(sizeof(*of), GFP_KERNEL); + if (of) { + of->cfe = cfe; + err = single_open(file, cgroup_seqfile_show, of); + if (err) + kfree(of); + } + } if (css->ss && err) css_put(css); @@ -2370,6 +2365,7 @@ static int cgroup_file_release(struct inode *inode, struct file *file) if (css->ss) css_put(css); + kfree(((struct seq_file *)file->private_data)->private); return single_release(inode, file); } @@ -3368,12 +3364,6 @@ struct cgroup_pidlist { struct delayed_work destroy_dwork; }; -/* seq_file->private points to the following */ -struct cgroup_open_file { - struct cfent *cfe; - void *priv; -}; - /* * The following two functions "fix" the issue where there are more pids * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. @@ -3689,9 +3679,9 @@ static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) * next pid to display, if any */ struct cgroup_open_file *of = s->private; - struct cgroup *cgrp = of->cfe->css->cgroup; + struct cgroup *cgrp = seq_css(s)->cgroup; struct cgroup_pidlist *l; - enum cgroup_filetype type = of->cfe->type->private; + enum cgroup_filetype type = seq_cft(s)->private; int index = 0, pid = *pos; int *iter, ret; @@ -3749,7 +3739,7 @@ static void cgroup_pidlist_stop(struct seq_file *s, void *v) if (l) mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, CGROUP_PIDLIST_DESTROY_DELAY); - mutex_unlock(&of->cfe->css->cgroup->pidlist_mutex); + mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex); } static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) @@ -3766,7 +3756,7 @@ static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) if (p >= end) { return NULL; } else { - *pos = cgroup_pid_fry(of->cfe->css->cgroup, *p); + *pos = cgroup_pid_fry(seq_css(s)->cgroup, *p); return p; } } -- cgit v1.2.3 From 2da8ca822d49c8b8781800ad155aaa00e7bb5f1a Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 5 Dec 2013 12:28:04 -0500 Subject: cgroup: replace cftype->read_seq_string() with cftype->seq_show() In preparation of conversion to kernfs, cgroup file handling is updated so that it can be easily mapped to kernfs. This patch replaces cftype->read_seq_string() with cftype->seq_show() which is not limited to single_open() operation and will map directcly to kernfs seq_file interface. The conversions are mechanical. As ->seq_show() doesn't have @css and @cft, the functions which make use of them are converted to use seq_css() and seq_cft() respectively. In several occassions, e.f. if it has seq_string in its name, the function name is updated to fit the new method better. This patch does not introduce any behavior changes. Signed-off-by: Tejun Heo Acked-by: Aristeu Rozanski Acked-by: Vivek Goyal Acked-by: Michal Hocko Acked-by: Daniel Wagner Acked-by: Li Zefan Cc: Jens Axboe Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Johannes Weiner Cc: Balbir Singh Cc: KAMEZAWA Hiroyuki Cc: Neil Horman --- block/blk-throttle.c | 35 ++++++------- block/cfq-iosched.c | 131 ++++++++++++++++++++-------------------------- include/linux/cgroup.h | 9 ++-- kernel/cgroup.c | 34 ++++++------ kernel/cgroup_freezer.c | 7 ++- kernel/cpuset.c | 12 ++--- kernel/sched/core.c | 7 ++- kernel/sched/cpuacct.c | 14 +++-- mm/memcontrol.c | 28 +++++----- net/core/netprio_cgroup.c | 8 +-- security/device_cgroup.c | 7 ++- 11 files changed, 128 insertions(+), 164 deletions(-) (limited to 'kernel') diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 06534049afba..a760857e6b62 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -1303,13 +1303,10 @@ static u64 tg_prfill_cpu_rwstat(struct seq_file *sf, return __blkg_prfill_rwstat(sf, pd, &rwstat); } -static int tg_print_cpu_rwstat(struct cgroup_subsys_state *css, - struct cftype *cft, struct seq_file *sf) +static int tg_print_cpu_rwstat(struct seq_file *sf, void *v) { - struct blkcg *blkcg = css_to_blkcg(css); - - blkcg_print_blkgs(sf, blkcg, tg_prfill_cpu_rwstat, &blkcg_policy_throtl, - cft->private, true); + blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_cpu_rwstat, + &blkcg_policy_throtl, seq_cft(sf)->private, true); return 0; } @@ -1335,19 +1332,17 @@ static u64 tg_prfill_conf_uint(struct seq_file *sf, struct blkg_policy_data *pd, return __blkg_prfill_u64(sf, pd, v); } -static int tg_print_conf_u64(struct cgroup_subsys_state *css, - struct cftype *cft, struct seq_file *sf) +static int tg_print_conf_u64(struct seq_file *sf, void *v) { - blkcg_print_blkgs(sf, css_to_blkcg(css), tg_prfill_conf_u64, - &blkcg_policy_throtl, cft->private, false); + blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_u64, + &blkcg_policy_throtl, seq_cft(sf)->private, false); return 0; } -static int tg_print_conf_uint(struct cgroup_subsys_state *css, - struct cftype *cft, struct seq_file *sf) +static int tg_print_conf_uint(struct seq_file *sf, void *v) { - blkcg_print_blkgs(sf, css_to_blkcg(css), tg_prfill_conf_uint, - &blkcg_policy_throtl, cft->private, false); + blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_uint, + &blkcg_policy_throtl, seq_cft(sf)->private, false); return 0; } @@ -1428,40 +1423,40 @@ static struct cftype throtl_files[] = { { .name = "throttle.read_bps_device", .private = offsetof(struct throtl_grp, bps[READ]), - .read_seq_string = tg_print_conf_u64, + .seq_show = tg_print_conf_u64, .write_string = tg_set_conf_u64, .max_write_len = 256, }, { .name = "throttle.write_bps_device", .private = offsetof(struct throtl_grp, bps[WRITE]), - .read_seq_string = tg_print_conf_u64, + .seq_show = tg_print_conf_u64, .write_string = tg_set_conf_u64, .max_write_len = 256, }, { .name = "throttle.read_iops_device", .private = offsetof(struct throtl_grp, iops[READ]), - .read_seq_string = tg_print_conf_uint, + .seq_show = tg_print_conf_uint, .write_string = tg_set_conf_uint, .max_write_len = 256, }, { .name = "throttle.write_iops_device", .private = offsetof(struct throtl_grp, iops[WRITE]), - .read_seq_string = tg_print_conf_uint, + .seq_show = tg_print_conf_uint, .write_string = tg_set_conf_uint, .max_write_len = 256, }, { .name = "throttle.io_service_bytes", .private = offsetof(struct tg_stats_cpu, service_bytes), - .read_seq_string = tg_print_cpu_rwstat, + .seq_show = tg_print_cpu_rwstat, }, { .name = "throttle.io_serviced", .private = offsetof(struct tg_stats_cpu, serviced), - .read_seq_string = tg_print_cpu_rwstat, + .seq_show = tg_print_cpu_rwstat, }, { } /* terminate */ }; diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 4d5cec1ad80d..744833b630c6 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1632,11 +1632,11 @@ static u64 cfqg_prfill_weight_device(struct seq_file *sf, return __blkg_prfill_u64(sf, pd, cfqg->dev_weight); } -static int cfqg_print_weight_device(struct cgroup_subsys_state *css, - struct cftype *cft, struct seq_file *sf) +static int cfqg_print_weight_device(struct seq_file *sf, void *v) { - blkcg_print_blkgs(sf, css_to_blkcg(css), cfqg_prfill_weight_device, - &blkcg_policy_cfq, 0, false); + blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), + cfqg_prfill_weight_device, &blkcg_policy_cfq, + 0, false); return 0; } @@ -1650,26 +1650,23 @@ static u64 cfqg_prfill_leaf_weight_device(struct seq_file *sf, return __blkg_prfill_u64(sf, pd, cfqg->dev_leaf_weight); } -static int cfqg_print_leaf_weight_device(struct cgroup_subsys_state *css, - struct cftype *cft, - struct seq_file *sf) +static int cfqg_print_leaf_weight_device(struct seq_file *sf, void *v) { - blkcg_print_blkgs(sf, css_to_blkcg(css), cfqg_prfill_leaf_weight_device, - &blkcg_policy_cfq, 0, false); + blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), + cfqg_prfill_leaf_weight_device, &blkcg_policy_cfq, + 0, false); return 0; } -static int cfq_print_weight(struct cgroup_subsys_state *css, struct cftype *cft, - struct seq_file *sf) +static int cfq_print_weight(struct seq_file *sf, void *v) { - seq_printf(sf, "%u\n", css_to_blkcg(css)->cfq_weight); + seq_printf(sf, "%u\n", css_to_blkcg(seq_css(sf))->cfq_weight); return 0; } -static int cfq_print_leaf_weight(struct cgroup_subsys_state *css, - struct cftype *cft, struct seq_file *sf) +static int cfq_print_leaf_weight(struct seq_file *sf, void *v) { - seq_printf(sf, "%u\n", css_to_blkcg(css)->cfq_leaf_weight); + seq_printf(sf, "%u\n", css_to_blkcg(seq_css(sf))->cfq_leaf_weight); return 0; } @@ -1762,23 +1759,17 @@ static int cfq_set_leaf_weight(struct cgroup_subsys_state *css, return __cfq_set_weight(css, cft, val, true); } -static int cfqg_print_stat(struct cgroup_subsys_state *css, struct cftype *cft, - struct seq_file *sf) +static int cfqg_print_stat(struct seq_file *sf, void *v) { - struct blkcg *blkcg = css_to_blkcg(css); - - blkcg_print_blkgs(sf, blkcg, blkg_prfill_stat, &blkcg_policy_cfq, - cft->private, false); + blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat, + &blkcg_policy_cfq, seq_cft(sf)->private, false); return 0; } -static int cfqg_print_rwstat(struct cgroup_subsys_state *css, - struct cftype *cft, struct seq_file *sf) +static int cfqg_print_rwstat(struct seq_file *sf, void *v) { - struct blkcg *blkcg = css_to_blkcg(css); - - blkcg_print_blkgs(sf, blkcg, blkg_prfill_rwstat, &blkcg_policy_cfq, - cft->private, true); + blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat, + &blkcg_policy_cfq, seq_cft(sf)->private, true); return 0; } @@ -1798,23 +1789,19 @@ static u64 cfqg_prfill_rwstat_recursive(struct seq_file *sf, return __blkg_prfill_rwstat(sf, pd, &sum); } -static int cfqg_print_stat_recursive(struct cgroup_subsys_state *css, - struct cftype *cft, struct seq_file *sf) +static int cfqg_print_stat_recursive(struct seq_file *sf, void *v) { - struct blkcg *blkcg = css_to_blkcg(css); - - blkcg_print_blkgs(sf, blkcg, cfqg_prfill_stat_recursive, - &blkcg_policy_cfq, cft->private, false); + blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), + cfqg_prfill_stat_recursive, &blkcg_policy_cfq, + seq_cft(sf)->private, false); return 0; } -static int cfqg_print_rwstat_recursive(struct cgroup_subsys_state *css, - struct cftype *cft, struct seq_file *sf) +static int cfqg_print_rwstat_recursive(struct seq_file *sf, void *v) { - struct blkcg *blkcg = css_to_blkcg(css); - - blkcg_print_blkgs(sf, blkcg, cfqg_prfill_rwstat_recursive, - &blkcg_policy_cfq, cft->private, true); + blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), + cfqg_prfill_rwstat_recursive, &blkcg_policy_cfq, + seq_cft(sf)->private, true); return 0; } @@ -1835,13 +1822,11 @@ static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf, } /* print avg_queue_size */ -static int cfqg_print_avg_queue_size(struct cgroup_subsys_state *css, - struct cftype *cft, struct seq_file *sf) +static int cfqg_print_avg_queue_size(struct seq_file *sf, void *v) { - struct blkcg *blkcg = css_to_blkcg(css); - - blkcg_print_blkgs(sf, blkcg, cfqg_prfill_avg_queue_size, - &blkcg_policy_cfq, 0, false); + blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), + cfqg_prfill_avg_queue_size, &blkcg_policy_cfq, + 0, false); return 0; } #endif /* CONFIG_DEBUG_BLK_CGROUP */ @@ -1851,14 +1836,14 @@ static struct cftype cfq_blkcg_files[] = { { .name = "weight_device", .flags = CFTYPE_ONLY_ON_ROOT, - .read_seq_string = cfqg_print_leaf_weight_device, + .seq_show = cfqg_print_leaf_weight_device, .write_string = cfqg_set_leaf_weight_device, .max_write_len = 256, }, { .name = "weight", .flags = CFTYPE_ONLY_ON_ROOT, - .read_seq_string = cfq_print_leaf_weight, + .seq_show = cfq_print_leaf_weight, .write_u64 = cfq_set_leaf_weight, }, @@ -1866,26 +1851,26 @@ static struct cftype cfq_blkcg_files[] = { { .name = "weight_device", .flags = CFTYPE_NOT_ON_ROOT, - .read_seq_string = cfqg_print_weight_device, + .seq_show = cfqg_print_weight_device, .write_string = cfqg_set_weight_device, .max_write_len = 256, }, { .name = "weight", .flags = CFTYPE_NOT_ON_ROOT, - .read_seq_string = cfq_print_weight, + .seq_show = cfq_print_weight, .write_u64 = cfq_set_weight, }, { .name = "leaf_weight_device", - .read_seq_string = cfqg_print_leaf_weight_device, + .seq_show = cfqg_print_leaf_weight_device, .write_string = cfqg_set_leaf_weight_device, .max_write_len = 256, }, { .name = "leaf_weight", - .read_seq_string = cfq_print_leaf_weight, + .seq_show = cfq_print_leaf_weight, .write_u64 = cfq_set_leaf_weight, }, @@ -1893,114 +1878,114 @@ static struct cftype cfq_blkcg_files[] = { { .name = "time", .private = offsetof(struct cfq_group, stats.time), - .read_seq_string = cfqg_print_stat, + .seq_show = cfqg_print_stat, }, { .name = "sectors", .private = offsetof(struct cfq_group, stats.sectors), - .read_seq_string = cfqg_print_stat, + .seq_show = cfqg_print_stat, }, { .name = "io_service_bytes", .private = offsetof(struct cfq_group, stats.service_bytes), - .read_seq_string = cfqg_print_rwstat, + .seq_show = cfqg_print_rwstat, }, { .name = "io_serviced", .private = offsetof(struct cfq_group, stats.serviced), - .read_seq_string = cfqg_print_rwstat, + .seq_show = cfqg_print_rwstat, }, { .name = "io_service_time", .private = offsetof(struct cfq_group, stats.service_time), - .read_seq_string = cfqg_print_rwstat, + .seq_show = cfqg_print_rwstat, }, { .name = "io_wait_time", .private = offsetof(struct cfq_group, stats.wait_time), - .read_seq_string = cfqg_print_rwstat, + .seq_show = cfqg_print_rwstat, }, { .name = "io_merged", .private = offsetof(struct cfq_group, stats.merged), - .read_seq_string = cfqg_print_rwstat, + .seq_show = cfqg_print_rwstat, }, { .name = "io_queued", .private = offsetof(struct cfq_group, stats.queued), - .read_seq_string = cfqg_print_rwstat, + .seq_show = cfqg_print_rwstat, }, /* the same statictics which cover the cfqg and its descendants */ { .name = "time_recursive", .private = offsetof(struct cfq_group, stats.time), - .read_seq_string = cfqg_print_stat_recursive, + .seq_show = cfqg_print_stat_recursive, }, { .name = "sectors_recursive", .private = offsetof(struct cfq_group, stats.sectors), - .read_seq_string = cfqg_print_stat_recursive, + .seq_show = cfqg_print_stat_recursive, }, { .name = "io_service_bytes_recursive", .private = offsetof(struct cfq_group, stats.service_bytes), - .read_seq_string = cfqg_print_rwstat_recursive, + .seq_show = cfqg_print_rwstat_recursive, }, { .name = "io_serviced_recursive", .private = offsetof(struct cfq_group, stats.serviced), - .read_seq_string = cfqg_print_rwstat_recursive, + .seq_show = cfqg_print_rwstat_recursive, }, { .name = "io_service_time_recursive", .private = offsetof(struct cfq_group, stats.service_time), - .read_seq_string = cfqg_print_rwstat_recursive, + .seq_show = cfqg_print_rwstat_recursive, }, { .name = "io_wait_time_recursive", .private = offsetof(struct cfq_group, stats.wait_time), - .read_seq_string = cfqg_print_rwstat_recursive, + .seq_show = cfqg_print_rwstat_recursive, }, { .name = "io_merged_recursive", .private = offsetof(struct cfq_group, stats.merged), - .read_seq_string = cfqg_print_rwstat_recursive, + .seq_show = cfqg_print_rwstat_recursive, }, { .name = "io_queued_recursive", .private = offsetof(struct cfq_group, stats.queued), - .read_seq_string = cfqg_print_rwstat_recursive, + .seq_show = cfqg_print_rwstat_recursive, }, #ifdef CONFIG_DEBUG_BLK_CGROUP { .name = "avg_queue_size", - .read_seq_string = cfqg_print_avg_queue_size, + .seq_show = cfqg_print_avg_queue_size, }, { .name = "group_wait_time", .private = offsetof(struct cfq_group, stats.group_wait_time), - .read_seq_string = cfqg_print_stat, + .seq_show = cfqg_print_stat, }, { .name = "idle_time", .private = offsetof(struct cfq_group, stats.idle_time), - .read_seq_string = cfqg_print_stat, + .seq_show = cfqg_print_stat, }, { .name = "empty_time", .private = offsetof(struct cfq_group, stats.empty_time), - .read_seq_string = cfqg_print_stat, + .seq_show = cfqg_print_stat, }, { .name = "dequeue", .private = offsetof(struct cfq_group, stats.dequeue), - .read_seq_string = cfqg_print_stat, + .seq_show = cfqg_print_stat, }, { .name = "unaccounted_time", .private = offsetof(struct cfq_group, stats.unaccounted_time), - .read_seq_string = cfqg_print_stat, + .seq_show = cfqg_print_stat, }, #endif /* CONFIG_DEBUG_BLK_CGROUP */ { } /* terminate */ diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index c3d698a72e02..b32a0f8ae9ad 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -444,12 +444,9 @@ struct cftype { * read_s64() is a signed version of read_u64() */ s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft); - /* - * read_seq_string() is used for outputting a simple sequence - * using seqfile. - */ - int (*read_seq_string)(struct cgroup_subsys_state *css, - struct cftype *cft, struct seq_file *m); + + /* generic seq_file read interface */ + int (*seq_show)(struct seq_file *sf, void *v); /* * write_u64() is a shortcut for the common case of accepting diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 036c05d8e572..c45e63328a0a 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2212,10 +2212,9 @@ static int cgroup_release_agent_write(struct cgroup_subsys_state *css, return 0; } -static int cgroup_release_agent_show(struct cgroup_subsys_state *css, - struct cftype *cft, struct seq_file *seq) +static int cgroup_release_agent_show(struct seq_file *seq, void *v) { - struct cgroup *cgrp = css->cgroup; + struct cgroup *cgrp = seq_css(seq)->cgroup; if (!cgroup_lock_live_group(cgrp)) return -ENODEV; @@ -2225,10 +2224,11 @@ static int cgroup_release_agent_show(struct cgroup_subsys_state *css, return 0; } -static int cgroup_sane_behavior_show(struct cgroup_subsys_state *css, - struct cftype *cft, struct seq_file *seq) +static int cgroup_sane_behavior_show(struct seq_file *seq, void *v) { - seq_printf(seq, "%d\n", cgroup_sane_behavior(css->cgroup)); + struct cgroup *cgrp = seq_css(seq)->cgroup; + + seq_printf(seq, "%d\n", cgroup_sane_behavior(cgrp)); return 0; } @@ -2291,8 +2291,8 @@ static int cgroup_seqfile_show(struct seq_file *m, void *arg) struct cftype *cft = seq_cft(m); struct cgroup_subsys_state *css = seq_css(m); - if (cft->read_seq_string) - return cft->read_seq_string(css, cft, m); + if (cft->seq_show) + return cft->seq_show(m, arg); if (cft->read_u64) seq_printf(m, "%llu\n", cft->read_u64(css, cft)); @@ -2559,7 +2559,7 @@ static umode_t cgroup_file_mode(const struct cftype *cft) if (cft->mode) return cft->mode; - if (cft->read_u64 || cft->read_s64 || cft->read_seq_string) + if (cft->read_u64 || cft->read_s64 || cft->seq_show) mode |= S_IRUGO; if (cft->write_u64 || cft->write_s64 || cft->write_string || @@ -3874,7 +3874,7 @@ static struct cftype cgroup_base_files[] = { { .name = "cgroup.sane_behavior", .flags = CFTYPE_ONLY_ON_ROOT, - .read_seq_string = cgroup_sane_behavior_show, + .seq_show = cgroup_sane_behavior_show, }, /* @@ -3899,7 +3899,7 @@ static struct cftype cgroup_base_files[] = { { .name = "release_agent", .flags = CFTYPE_INSANE | CFTYPE_ONLY_ON_ROOT, - .read_seq_string = cgroup_release_agent_show, + .seq_show = cgroup_release_agent_show, .write_string = cgroup_release_agent_write, .max_write_len = PATH_MAX, }, @@ -5274,9 +5274,7 @@ static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css, return count; } -static int current_css_set_cg_links_read(struct cgroup_subsys_state *css, - struct cftype *cft, - struct seq_file *seq) +static int current_css_set_cg_links_read(struct seq_file *seq, void *v) { struct cgrp_cset_link *link; struct css_set *cset; @@ -5301,9 +5299,9 @@ static int current_css_set_cg_links_read(struct cgroup_subsys_state *css, } #define MAX_TASKS_SHOWN_PER_CSS 25 -static int cgroup_css_links_read(struct cgroup_subsys_state *css, - struct cftype *cft, struct seq_file *seq) +static int cgroup_css_links_read(struct seq_file *seq, void *v) { + struct cgroup_subsys_state *css = seq_css(seq); struct cgrp_cset_link *link; read_lock(&css_set_lock); @@ -5349,12 +5347,12 @@ static struct cftype debug_files[] = { { .name = "current_css_set_cg_links", - .read_seq_string = current_css_set_cg_links_read, + .seq_show = current_css_set_cg_links_read, }, { .name = "cgroup_css_links", - .read_seq_string = cgroup_css_links_read, + .seq_show = cgroup_css_links_read, }, { diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c index f0ff64d0ebaa..6c3154e477f6 100644 --- a/kernel/cgroup_freezer.c +++ b/kernel/cgroup_freezer.c @@ -301,10 +301,9 @@ out_unlock: spin_unlock_irq(&freezer->lock); } -static int freezer_read(struct cgroup_subsys_state *css, struct cftype *cft, - struct seq_file *m) +static int freezer_read(struct seq_file *m, void *v) { - struct cgroup_subsys_state *pos; + struct cgroup_subsys_state *css = seq_css(m), *pos; rcu_read_lock(); @@ -458,7 +457,7 @@ static struct cftype files[] = { { .name = "state", .flags = CFTYPE_NOT_ON_ROOT, - .read_seq_string = freezer_read, + .seq_show = freezer_read, .write_string = freezer_write, }, { diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 032929f91648..4410ac6a55f1 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -1732,12 +1732,10 @@ out_unlock: * and since these maps can change value dynamically, one could read * gibberish by doing partial reads while a list was changing. */ -static int cpuset_common_read_seq_string(struct cgroup_subsys_state *css, - struct cftype *cft, - struct seq_file *sf) +static int cpuset_common_seq_show(struct seq_file *sf, void *v) { - struct cpuset *cs = css_cs(css); - cpuset_filetype_t type = cft->private; + struct cpuset *cs = css_cs(seq_css(sf)); + cpuset_filetype_t type = seq_cft(sf)->private; ssize_t count; char *buf, *s; int ret = 0; @@ -1824,7 +1822,7 @@ static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft) static struct cftype files[] = { { .name = "cpus", - .read_seq_string = cpuset_common_read_seq_string, + .seq_show = cpuset_common_seq_show, .write_string = cpuset_write_resmask, .max_write_len = (100U + 6 * NR_CPUS), .private = FILE_CPULIST, @@ -1832,7 +1830,7 @@ static struct cftype files[] = { { .name = "mems", - .read_seq_string = cpuset_common_read_seq_string, + .seq_show = cpuset_common_seq_show, .write_string = cpuset_write_resmask, .max_write_len = (100U + 6 * MAX_NUMNODES), .private = FILE_MEMLIST, diff --git a/kernel/sched/core.c b/kernel/sched/core.c index f28ec6722f0b..7e8cbb9ee4d6 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7256,10 +7256,9 @@ static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota) return ret; } -static int cpu_stats_show(struct cgroup_subsys_state *css, struct cftype *cft, - struct seq_file *sf) +static int cpu_stats_show(struct seq_file *sf, void *v) { - struct task_group *tg = css_tg(css); + struct task_group *tg = css_tg(seq_css(sf)); struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods); @@ -7318,7 +7317,7 @@ static struct cftype cpu_files[] = { }, { .name = "stat", - .read_seq_string = cpu_stats_show, + .seq_show = cpu_stats_show, }, #endif #ifdef CONFIG_RT_GROUP_SCHED diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c index dd88738cd4a9..622e0818f905 100644 --- a/kernel/sched/cpuacct.c +++ b/kernel/sched/cpuacct.c @@ -163,10 +163,9 @@ out: return err; } -static int cpuacct_percpu_seq_read(struct cgroup_subsys_state *css, - struct cftype *cft, struct seq_file *m) +static int cpuacct_percpu_seq_show(struct seq_file *m, void *V) { - struct cpuacct *ca = css_ca(css); + struct cpuacct *ca = css_ca(seq_css(m)); u64 percpu; int i; @@ -183,10 +182,9 @@ static const char * const cpuacct_stat_desc[] = { [CPUACCT_STAT_SYSTEM] = "system", }; -static int cpuacct_stats_show(struct cgroup_subsys_state *css, - struct cftype *cft, struct seq_file *sf) +static int cpuacct_stats_show(struct seq_file *sf, void *v) { - struct cpuacct *ca = css_ca(css); + struct cpuacct *ca = css_ca(seq_css(sf)); int cpu; s64 val = 0; @@ -220,11 +218,11 @@ static struct cftype files[] = { }, { .name = "usage_percpu", - .read_seq_string = cpuacct_percpu_seq_read, + .seq_show = cpuacct_percpu_seq_show, }, { .name = "stat", - .read_seq_string = cpuacct_stats_show, + .seq_show = cpuacct_stats_show, }, { } /* terminate */ }; diff --git a/mm/memcontrol.c b/mm/memcontrol.c index f149521a77e6..9252219376cc 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3014,10 +3014,9 @@ static struct kmem_cache *memcg_params_to_cache(struct memcg_cache_params *p) } #ifdef CONFIG_SLABINFO -static int mem_cgroup_slabinfo_read(struct cgroup_subsys_state *css, - struct cftype *cft, struct seq_file *m) +static int mem_cgroup_slabinfo_read(struct seq_file *m, void *v) { - struct mem_cgroup *memcg = mem_cgroup_from_css(css); + struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m)); struct memcg_cache_params *params; if (!memcg_can_account_kmem(memcg)) @@ -5418,8 +5417,7 @@ static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css, #endif #ifdef CONFIG_NUMA -static int memcg_numa_stat_show(struct cgroup_subsys_state *css, - struct cftype *cft, struct seq_file *m) +static int memcg_numa_stat_show(struct seq_file *m, void *v) { struct numa_stat { const char *name; @@ -5435,7 +5433,7 @@ static int memcg_numa_stat_show(struct cgroup_subsys_state *css, const struct numa_stat *stat; int nid; unsigned long nr; - struct mem_cgroup *memcg = mem_cgroup_from_css(css); + struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m)); for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) { nr = mem_cgroup_nr_lru_pages(memcg, stat->lru_mask); @@ -5474,10 +5472,9 @@ static inline void mem_cgroup_lru_names_not_uptodate(void) BUILD_BUG_ON(ARRAY_SIZE(mem_cgroup_lru_names) != NR_LRU_LISTS); } -static int memcg_stat_show(struct cgroup_subsys_state *css, struct cftype *cft, - struct seq_file *m) +static int memcg_stat_show(struct seq_file *m, void *v) { - struct mem_cgroup *memcg = mem_cgroup_from_css(css); + struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m)); struct mem_cgroup *mi; unsigned int i; @@ -5907,10 +5904,9 @@ static void mem_cgroup_oom_unregister_event(struct mem_cgroup *memcg, spin_unlock(&memcg_oom_lock); } -static int mem_cgroup_oom_control_read(struct cgroup_subsys_state *css, - struct cftype *cft, struct seq_file *sf) +static int mem_cgroup_oom_control_read(struct seq_file *sf, void *v) { - struct mem_cgroup *memcg = mem_cgroup_from_css(css); + struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(sf)); seq_printf(sf, "oom_kill_disable %d\n", memcg->oom_kill_disable); seq_printf(sf, "under_oom %d\n", (bool)atomic_read(&memcg->under_oom)); @@ -6260,7 +6256,7 @@ static struct cftype mem_cgroup_files[] = { }, { .name = "stat", - .read_seq_string = memcg_stat_show, + .seq_show = memcg_stat_show, }, { .name = "force_empty", @@ -6290,7 +6286,7 @@ static struct cftype mem_cgroup_files[] = { }, { .name = "oom_control", - .read_seq_string = mem_cgroup_oom_control_read, + .seq_show = mem_cgroup_oom_control_read, .write_u64 = mem_cgroup_oom_control_write, .private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL), }, @@ -6300,7 +6296,7 @@ static struct cftype mem_cgroup_files[] = { #ifdef CONFIG_NUMA { .name = "numa_stat", - .read_seq_string = memcg_numa_stat_show, + .seq_show = memcg_numa_stat_show, }, #endif #ifdef CONFIG_MEMCG_KMEM @@ -6330,7 +6326,7 @@ static struct cftype mem_cgroup_files[] = { #ifdef CONFIG_SLABINFO { .name = "kmem.slabinfo", - .read_seq_string = mem_cgroup_slabinfo_read, + .seq_show = mem_cgroup_slabinfo_read, }, #endif #endif diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c index 498710dce4a5..56cbb69ba024 100644 --- a/net/core/netprio_cgroup.c +++ b/net/core/netprio_cgroup.c @@ -173,14 +173,14 @@ static u64 read_prioidx(struct cgroup_subsys_state *css, struct cftype *cft) return css->cgroup->id; } -static int read_priomap(struct cgroup_subsys_state *css, struct cftype *cft, - struct seq_file *sf) +static int read_priomap(struct seq_file *sf, void *v) { struct net_device *dev; rcu_read_lock(); for_each_netdev_rcu(&init_net, dev) - seq_printf(sf, "%s %u\n", dev->name, netprio_prio(css, dev)); + seq_printf(sf, "%s %u\n", dev->name, + netprio_prio(seq_css(sf), dev)); rcu_read_unlock(); return 0; } @@ -238,7 +238,7 @@ static struct cftype ss_files[] = { }, { .name = "ifpriomap", - .read_seq_string = read_priomap, + .seq_show = read_priomap, .write_string = write_priomap, }, { } /* terminate */ diff --git a/security/device_cgroup.c b/security/device_cgroup.c index 7c2a0a71049e..d3b6d2cd3a06 100644 --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -274,10 +274,9 @@ static void set_majmin(char *str, unsigned m) sprintf(str, "%u", m); } -static int devcgroup_seq_read(struct cgroup_subsys_state *css, - struct cftype *cft, struct seq_file *m) +static int devcgroup_seq_show(struct seq_file *m, void *v) { - struct dev_cgroup *devcgroup = css_to_devcgroup(css); + struct dev_cgroup *devcgroup = css_to_devcgroup(seq_css(m)); struct dev_exception_item *ex; char maj[MAJMINLEN], min[MAJMINLEN], acc[ACCLEN]; @@ -679,7 +678,7 @@ static struct cftype dev_cgroup_files[] = { }, { .name = "list", - .read_seq_string = devcgroup_seq_read, + .seq_show = devcgroup_seq_show, .private = DEVCG_LIST, }, { } /* terminate */ -- cgit v1.2.3 From 6612f05b88fa309c91a345690411217959bb2486 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 5 Dec 2013 12:28:04 -0500 Subject: cgroup: unify pidlist and other file handling In preparation of conversion to kernfs, cgroup file handling is updated so that it can be easily mapped to kernfs. With the previous changes, the difference between pidlist and other files are very small. Both are served by seq_file in a pretty standard way with the only difference being !pidlist files use single_open(). This patch adds cftype->seq_start(), ->seq_next and ->seq_stop() and implements the matching cgroup_seqfile_start/next/stop() which either emulates single_open() behavior or invokes cftype->seq_*() operations if specified. This allows using single seq_operations for both pidlist and other files and makes cgroup_pidlist_operations and cgorup_pidlist_open() no longer necessary. As cgroup_pidlist_open() was the only user of cftype->open(), the method is dropped together. This brings cftype file interface very close to kernfs interface and mapping shouldn't be too difficult. Once converted to kernfs, most of the plumbing code including cgroup_seqfile_*() will be removed as kernfs provides those facilities. This patch does not introduce any behavior changes. v2: Refreshed on top of the updated "cgroup: introduce struct cgroup_pidlist_open_file". v3: Refreshed on top of the updated "cgroup: attach cgroup_open_file to all cgroup files". Signed-off-by: Tejun Heo Acked-by: Li Zefan --- include/linux/cgroup.h | 6 ++- kernel/cgroup.c | 112 +++++++++++++++++++++++++++---------------------- 2 files changed, 68 insertions(+), 50 deletions(-) (limited to 'kernel') diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index b32a0f8ae9ad..8b9a594f0c92 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -434,7 +434,6 @@ struct cftype { */ struct cgroup_subsys *ss; - int (*open)(struct inode *inode, struct file *file); /* * read_u64() is a shortcut for the common case of returning a * single integer. Use it in place of read() @@ -448,6 +447,11 @@ struct cftype { /* generic seq_file read interface */ int (*seq_show)(struct seq_file *sf, void *v); + /* optional ops, implement all or none */ + void *(*seq_start)(struct seq_file *sf, loff_t *ppos); + void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos); + void (*seq_stop)(struct seq_file *sf, void *v); + /* * write_u64() is a shortcut for the common case of accepting * a single integer (as parsed by simple_strtoull) from diff --git a/kernel/cgroup.c b/kernel/cgroup.c index c45e63328a0a..f9ae38a95af2 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2286,6 +2286,45 @@ out_free: * supports string->u64 maps, but can be extended in future. */ +static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos) +{ + struct cftype *cft = seq_cft(seq); + + if (cft->seq_start) { + return cft->seq_start(seq, ppos); + } else { + /* + * The same behavior and code as single_open(). Returns + * !NULL if pos is at the beginning; otherwise, NULL. + */ + return NULL + !*ppos; + } +} + +static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos) +{ + struct cftype *cft = seq_cft(seq); + + if (cft->seq_next) { + return cft->seq_next(seq, v, ppos); + } else { + /* + * The same behavior and code as single_open(), always + * terminate after the initial read. + */ + ++*ppos; + return NULL; + } +} + +static void cgroup_seqfile_stop(struct seq_file *seq, void *v) +{ + struct cftype *cft = seq_cft(seq); + + if (cft->seq_stop) + cft->seq_stop(seq, v); +} + static int cgroup_seqfile_show(struct seq_file *m, void *arg) { struct cftype *cft = seq_cft(m); @@ -2303,12 +2342,20 @@ static int cgroup_seqfile_show(struct seq_file *m, void *arg) return 0; } +static struct seq_operations cgroup_seq_operations = { + .start = cgroup_seqfile_start, + .next = cgroup_seqfile_next, + .stop = cgroup_seqfile_stop, + .show = cgroup_seqfile_show, +}; + static int cgroup_file_open(struct inode *inode, struct file *file) { struct cfent *cfe = __d_cfe(file->f_dentry); struct cftype *cft = __d_cft(file->f_dentry); struct cgroup *cgrp = __d_cgrp(cfe->dentry->d_parent); struct cgroup_subsys_state *css; + struct cgroup_open_file *of; int err; err = generic_file_open(inode, file); @@ -2338,24 +2385,16 @@ static int cgroup_file_open(struct inode *inode, struct file *file) WARN_ON_ONCE(cfe->css && cfe->css != css); cfe->css = css; - if (cft->open) { - err = cft->open(inode, file); - } else { - struct cgroup_open_file *of; - - err = -ENOMEM; - of = kzalloc(sizeof(*of), GFP_KERNEL); - if (of) { - of->cfe = cfe; - err = single_open(file, cgroup_seqfile_show, of); - if (err) - kfree(of); - } + of = __seq_open_private(file, &cgroup_seq_operations, + sizeof(struct cgroup_open_file)); + if (of) { + of->cfe = cfe; + return 0; } - if (css->ss && err) + if (css->ss) css_put(css); - return err; + return -ENOMEM; } static int cgroup_file_release(struct inode *inode, struct file *file) @@ -2365,8 +2404,7 @@ static int cgroup_file_release(struct inode *inode, struct file *file) if (css->ss) css_put(css); - kfree(((struct seq_file *)file->private_data)->private); - return single_release(inode, file); + return seq_release_private(inode, file); } /* @@ -3777,36 +3815,6 @@ static const struct seq_operations cgroup_pidlist_seq_operations = { .show = cgroup_pidlist_show, }; -static const struct file_operations cgroup_pidlist_operations = { - .read = seq_read, - .llseek = seq_lseek, - .write = cgroup_file_write, - .release = seq_release_private, -}; - -/* - * The following functions handle opens on a file that displays a pidlist - * (tasks or procs). Prepare an array of the process/thread IDs of whoever's - * in the cgroup. - */ -/* helper function for the two below it */ -static int cgroup_pidlist_open(struct inode *unused, struct file *file) -{ - struct cfent *cfe = __d_cfe(file->f_dentry); - struct cgroup_open_file *of; - - /* configure file information */ - file->f_op = &cgroup_pidlist_operations; - - of = __seq_open_private(file, &cgroup_pidlist_seq_operations, - sizeof(*of)); - if (!of) - return -ENOMEM; - - of->cfe = cfe; - return 0; -} - static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css, struct cftype *cft) { @@ -3860,7 +3868,10 @@ static int cgroup_clone_children_write(struct cgroup_subsys_state *css, static struct cftype cgroup_base_files[] = { { .name = "cgroup.procs", - .open = cgroup_pidlist_open, + .seq_start = cgroup_pidlist_start, + .seq_next = cgroup_pidlist_next, + .seq_stop = cgroup_pidlist_stop, + .seq_show = cgroup_pidlist_show, .private = CGROUP_FILE_PROCS, .write_u64 = cgroup_procs_write, .mode = S_IRUGO | S_IWUSR, @@ -3885,7 +3896,10 @@ static struct cftype cgroup_base_files[] = { { .name = "tasks", .flags = CFTYPE_INSANE, /* use "procs" instead */ - .open = cgroup_pidlist_open, + .seq_start = cgroup_pidlist_start, + .seq_next = cgroup_pidlist_next, + .seq_stop = cgroup_pidlist_stop, + .seq_show = cgroup_pidlist_show, .private = CGROUP_FILE_TASKS, .write_u64 = cgroup_tasks_write, .mode = S_IRUGO | S_IWUSR, -- cgit v1.2.3 From 87fb54f1b5a447662854f176eeb1ba92d5ffc1d5 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 6 Dec 2013 15:11:55 -0500 Subject: cgroup: css iterations and css_from_dir() are safe under cgroup_mutex Currently, all css iterations and css_from_dir() require RCU read lock whether the caller is holding cgroup_mutex or not, which is unnecessarily restrictive. They are all safe to use under cgroup_mutex without holding RCU read lock. Factor out cgroup_assert_mutex_or_rcu_locked() from css_from_id() and apply it to all css iteration functions and css_from_dir(). v2: cgroup_assert_mutex_or_rcu_locked() definition doesn't need to be inside CONFIG_PROVE_RCU ifdef as rcu_lockdep_assert() is always defined and conditionalized. Move it outside of the ifdef block. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- kernel/cgroup.c | 56 ++++++++++++++++++++++++++++++-------------------------- 1 file changed, 30 insertions(+), 26 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 2e5fbf9d63e9..c22eecbbbc1c 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -93,6 +93,11 @@ static DEFINE_MUTEX(cgroup_mutex); static DEFINE_MUTEX(cgroup_root_mutex); +#define cgroup_assert_mutex_or_rcu_locked() \ + rcu_lockdep_assert(rcu_read_lock_held() || \ + lockdep_is_held(&cgroup_mutex), \ + "cgroup_mutex or RCU read lock required"); + /* * cgroup destruction makes heavy use of work items and there can be a lot * of concurrent destructions. Use a separate workqueue so that cgroup @@ -2897,9 +2902,9 @@ static void cgroup_enable_task_cg_lists(void) * @parent_css: css whose children to walk * * This function returns the next child of @parent_css and should be called - * under RCU read lock. The only requirement is that @parent_css and - * @pos_css are accessible. The next sibling is guaranteed to be returned - * regardless of their states. + * under either cgroup_mutex or RCU read lock. The only requirement is + * that @parent_css and @pos_css are accessible. The next sibling is + * guaranteed to be returned regardless of their states. */ struct cgroup_subsys_state * css_next_child(struct cgroup_subsys_state *pos_css, @@ -2909,7 +2914,7 @@ css_next_child(struct cgroup_subsys_state *pos_css, struct cgroup *cgrp = parent_css->cgroup; struct cgroup *next; - WARN_ON_ONCE(!rcu_read_lock_held()); + cgroup_assert_mutex_or_rcu_locked(); /* * @pos could already have been removed. Once a cgroup is removed, @@ -2956,10 +2961,10 @@ EXPORT_SYMBOL_GPL(css_next_child); * to visit for pre-order traversal of @root's descendants. @root is * included in the iteration and the first node to be visited. * - * While this function requires RCU read locking, it doesn't require the - * whole traversal to be contained in a single RCU critical section. This - * function will return the correct next descendant as long as both @pos - * and @root are accessible and @pos is a descendant of @root. + * While this function requires cgroup_mutex or RCU read locking, it + * doesn't require the whole traversal to be contained in a single critical + * section. This function will return the correct next descendant as long + * as both @pos and @root are accessible and @pos is a descendant of @root. */ struct cgroup_subsys_state * css_next_descendant_pre(struct cgroup_subsys_state *pos, @@ -2967,7 +2972,7 @@ css_next_descendant_pre(struct cgroup_subsys_state *pos, { struct cgroup_subsys_state *next; - WARN_ON_ONCE(!rcu_read_lock_held()); + cgroup_assert_mutex_or_rcu_locked(); /* if first iteration, visit @root */ if (!pos) @@ -2998,17 +3003,17 @@ EXPORT_SYMBOL_GPL(css_next_descendant_pre); * is returned. This can be used during pre-order traversal to skip * subtree of @pos. * - * While this function requires RCU read locking, it doesn't require the - * whole traversal to be contained in a single RCU critical section. This - * function will return the correct rightmost descendant as long as @pos is - * accessible. + * While this function requires cgroup_mutex or RCU read locking, it + * doesn't require the whole traversal to be contained in a single critical + * section. This function will return the correct rightmost descendant as + * long as @pos is accessible. */ struct cgroup_subsys_state * css_rightmost_descendant(struct cgroup_subsys_state *pos) { struct cgroup_subsys_state *last, *tmp; - WARN_ON_ONCE(!rcu_read_lock_held()); + cgroup_assert_mutex_or_rcu_locked(); do { last = pos; @@ -3044,10 +3049,11 @@ css_leftmost_descendant(struct cgroup_subsys_state *pos) * to visit for post-order traversal of @root's descendants. @root is * included in the iteration and the last node to be visited. * - * While this function requires RCU read locking, it doesn't require the - * whole traversal to be contained in a single RCU critical section. This - * function will return the correct next descendant as long as both @pos - * and @cgroup are accessible and @pos is a descendant of @cgroup. + * While this function requires cgroup_mutex or RCU read locking, it + * doesn't require the whole traversal to be contained in a single critical + * section. This function will return the correct next descendant as long + * as both @pos and @cgroup are accessible and @pos is a descendant of + * @cgroup. */ struct cgroup_subsys_state * css_next_descendant_post(struct cgroup_subsys_state *pos, @@ -3055,7 +3061,7 @@ css_next_descendant_post(struct cgroup_subsys_state *pos, { struct cgroup_subsys_state *next; - WARN_ON_ONCE(!rcu_read_lock_held()); + cgroup_assert_mutex_or_rcu_locked(); /* if first iteration, visit leftmost descendant which may be @root */ if (!pos) @@ -5217,16 +5223,16 @@ __setup("cgroup_disable=", cgroup_disable); * @dentry: directory dentry of interest * @ss: subsystem of interest * - * Must be called under RCU read lock. The caller is responsible for - * pinning the returned css if it needs to be accessed outside the RCU - * critical section. + * Must be called under cgroup_mutex or RCU read lock. The caller is + * responsible for pinning the returned css if it needs to be accessed + * outside the critical section. */ struct cgroup_subsys_state *css_from_dir(struct dentry *dentry, struct cgroup_subsys *ss) { struct cgroup *cgrp; - WARN_ON_ONCE(!rcu_read_lock_held()); + cgroup_assert_mutex_or_rcu_locked(); /* is @dentry a cgroup dir? */ if (!dentry->d_inode || @@ -5249,9 +5255,7 @@ struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss) { struct cgroup *cgrp; - rcu_lockdep_assert(rcu_read_lock_held() || - lockdep_is_held(&cgroup_mutex), - "css_from_id() needs proper protection"); + cgroup_assert_mutex_or_rcu_locked(); cgrp = idr_find(&ss->root->cgroup_idr, id); if (cgrp) -- cgit v1.2.3 From 780cd8b347b52584704438e599274f25c0a0fd13 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 6 Dec 2013 15:11:56 -0500 Subject: cgroup: make for_each_subsys() useable under cgroup_root_mutex We want to use for_each_subsys() in cgroupfs_root handling where only cgroup_root_mutex is held. The only way cgroup_subsys[] can change is through module load/unload, make cgroup_[un]load_subsys() grab cgroup_root_mutex too and update the lockdep annotation in for_each_subsys() to allow either cgroup_mutex or cgroup_root_mutex. * Lockdep annotation is moved from inner 'if' condition to outer 'for' init caluse. There's no reason to execute the assertion every loop. * Loop index @i is renamed to @ssid. Indices iterating through subsys will be [re]named to @ssid gradually. v2: cgroup_assert_mutex_or_root_locked() caused build failure if !CONFIG_LOCKEDP. Conditionalize its definition. The build failure was reported by kbuild test bot. Signed-off-by: Tejun Heo Acked-by: Li Zefan Cc: kbuild test robot --- kernel/cgroup.c | 26 ++++++++++++++++++++------ 1 file changed, 20 insertions(+), 6 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index c22eecbbbc1c..4a7fb4043cff 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -98,6 +98,14 @@ static DEFINE_MUTEX(cgroup_root_mutex); lockdep_is_held(&cgroup_mutex), \ "cgroup_mutex or RCU read lock required"); +#ifdef CONFIG_LOCKDEP +#define cgroup_assert_mutex_or_root_locked() \ + WARN_ON_ONCE(debug_locks && (!lockdep_is_held(&cgroup_mutex) && \ + !lockdep_is_held(&cgroup_root_mutex))) +#else +#define cgroup_assert_mutex_or_root_locked() do { } while (0) +#endif + /* * cgroup destruction makes heavy use of work items and there can be a lot * of concurrent destructions. Use a separate workqueue so that cgroup @@ -237,14 +245,15 @@ static int notify_on_release(const struct cgroup *cgrp) /** * for_each_subsys - iterate all loaded cgroup subsystems * @ss: the iteration cursor - * @i: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end + * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end * - * Should be called under cgroup_mutex. + * Iterates through all loaded subsystems. Should be called under + * cgroup_mutex or cgroup_root_mutex. */ -#define for_each_subsys(ss, i) \ - for ((i) = 0; (i) < CGROUP_SUBSYS_COUNT; (i)++) \ - if (({ lockdep_assert_held(&cgroup_mutex); \ - !((ss) = cgroup_subsys[i]); })) { } \ +#define for_each_subsys(ss, ssid) \ + for (({ cgroup_assert_mutex_or_root_locked(); (ssid) = 0; }); \ + (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ + if (!((ss) = cgroup_subsys[(ssid)])) { } \ else /** @@ -4592,6 +4601,7 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) cgroup_init_cftsets(ss); mutex_lock(&cgroup_mutex); + mutex_lock(&cgroup_root_mutex); cgroup_subsys[ss->subsys_id] = ss; /* @@ -4641,10 +4651,12 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) goto err_unload; /* success! */ + mutex_unlock(&cgroup_root_mutex); mutex_unlock(&cgroup_mutex); return 0; err_unload: + mutex_unlock(&cgroup_root_mutex); mutex_unlock(&cgroup_mutex); /* @ss can't be mounted here as try_module_get() would fail */ cgroup_unload_subsys(ss); @@ -4674,6 +4686,7 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss) BUG_ON(ss->root != &cgroup_dummy_root); mutex_lock(&cgroup_mutex); + mutex_lock(&cgroup_root_mutex); offline_css(cgroup_css(cgroup_dummy_top, ss)); @@ -4708,6 +4721,7 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss) ss->css_free(cgroup_css(cgroup_dummy_top, ss)); RCU_INIT_POINTER(cgroup_dummy_top->subsys[ss->subsys_id], NULL); + mutex_unlock(&cgroup_root_mutex); mutex_unlock(&cgroup_mutex); } EXPORT_SYMBOL_GPL(cgroup_unload_subsys); -- cgit v1.2.3 From 0d80255e42b54419cfc6b10a3ec74b60fe04b8d7 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 6 Dec 2013 15:11:56 -0500 Subject: cgroup: reorder operations in cgroup_create() cgroup_create() currently does the followings. 1. alloc cgroup 2. alloc css's 3. create the directory and commit to cgroup creation 4. online css's 5. create cgroup and css files The sequence performs allocations before other operations but it doesn't buy anything because each of the above steps may fail and should be unrollable. Reorganize the sequence such that cgroup operations are done before css operations. 1. alloc cgroup 2. create the directory and files and commit to cgroup creation 3. alloc css's 4. create files for and online css's This simplifies the code a bit and enables further simplification and separating out css creation from cgroup creation which is necessary for the planned unified hierarchy where css's will be created and destroyed dynamically across the lifetime of a cgroup. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- kernel/cgroup.c | 70 +++++++++++++++++++++++++++------------------------------ 1 file changed, 33 insertions(+), 37 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 4a7fb4043cff..30a2670df3cf 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4144,23 +4144,6 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags)) set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); - for_each_root_subsys(root, ss) { - struct cgroup_subsys_state *css; - - css = ss->css_alloc(cgroup_css(parent, ss)); - if (IS_ERR(css)) { - err = PTR_ERR(css); - goto err_free_all; - } - css_ar[ss->subsys_id] = css; - - err = percpu_ref_init(&css->refcnt, css_release); - if (err) - goto err_free_all; - - init_css(css, ss, cgrp); - } - /* * Create directory. cgroup_create_file() returns with the new * directory locked on success so that it can be populated without @@ -4168,7 +4151,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, */ err = cgroup_create_file(dentry, S_IFDIR | mode, sb); if (err < 0) - goto err_free_all; + goto err_unlock; lockdep_assert_held(&dentry->d_inode->i_mutex); cgrp->serial_nr = cgroup_serial_nr_next++; @@ -4180,10 +4163,41 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, /* hold a ref to the parent's dentry */ dget(parent->dentry); + /* + * @cgrp is now fully operational. If something fails after this + * point, it'll be released via the normal destruction path. + */ + idr_replace(&root->cgroup_idr, cgrp, cgrp->id); + + err = cgroup_addrm_files(cgrp, cgroup_base_files, true); + if (err) + goto err_destroy; + + for_each_root_subsys(root, ss) { + struct cgroup_subsys_state *css; + + css = ss->css_alloc(cgroup_css(parent, ss)); + if (IS_ERR(css)) { + err = PTR_ERR(css); + goto err_destroy; + } + css_ar[ss->subsys_id] = css; + + err = percpu_ref_init(&css->refcnt, css_release); + if (err) + goto err_destroy; + + init_css(css, ss, cgrp); + } + /* creation succeeded, notify subsystems */ for_each_root_subsys(root, ss) { struct cgroup_subsys_state *css = css_ar[ss->subsys_id]; + err = cgroup_populate_dir(cgrp, 1 << ss->subsys_id); + if (err) + goto err_destroy; + err = online_css(css); if (err) goto err_destroy; @@ -4205,30 +4219,12 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, } } - idr_replace(&root->cgroup_idr, cgrp, cgrp->id); - - err = cgroup_addrm_files(cgrp, cgroup_base_files, true); - if (err) - goto err_destroy; - - err = cgroup_populate_dir(cgrp, root->subsys_mask); - if (err) - goto err_destroy; - mutex_unlock(&cgroup_mutex); mutex_unlock(&cgrp->dentry->d_inode->i_mutex); return 0; -err_free_all: - for_each_root_subsys(root, ss) { - struct cgroup_subsys_state *css = css_ar[ss->subsys_id]; - - if (css) { - percpu_ref_cancel_init(&css->refcnt); - ss->css_free(css); - } - } +err_unlock: mutex_unlock(&cgroup_mutex); /* Release the reference count that we took on the superblock */ deactivate_super(sb); -- cgit v1.2.3 From 9d403e99238ed6d7151a2c07db6cf8f6932ef3d5 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 6 Dec 2013 15:11:56 -0500 Subject: cgroup: combine css handling loops in cgroup_create() Now that css operations in cgroup_create() are back-to-back, there isn't much point in allocating css's in one loop and onlining them in another. Merge the two loops so that a css is allocated and onlined on each iteration. css_ar[] is no longer necessary and replaced with a single pointer. This also simplifies the error handling path. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- kernel/cgroup.c | 25 +++++++------------------ 1 file changed, 7 insertions(+), 18 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 30a2670df3cf..39e2295466ec 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4084,7 +4084,7 @@ static void offline_css(struct cgroup_subsys_state *css) static long cgroup_create(struct cgroup *parent, struct dentry *dentry, umode_t mode) { - struct cgroup_subsys_state *css_ar[CGROUP_SUBSYS_COUNT] = { }; + struct cgroup_subsys_state *css = NULL; struct cgroup *cgrp; struct cgroup_name *name; struct cgroupfs_root *root = parent->root; @@ -4173,26 +4173,20 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, if (err) goto err_destroy; + /* let's create and online css's */ for_each_root_subsys(root, ss) { - struct cgroup_subsys_state *css; - css = ss->css_alloc(cgroup_css(parent, ss)); if (IS_ERR(css)) { err = PTR_ERR(css); + css = NULL; goto err_destroy; } - css_ar[ss->subsys_id] = css; err = percpu_ref_init(&css->refcnt, css_release); if (err) goto err_destroy; init_css(css, ss, cgrp); - } - - /* creation succeeded, notify subsystems */ - for_each_root_subsys(root, ss) { - struct cgroup_subsys_state *css = css_ar[ss->subsys_id]; err = cgroup_populate_dir(cgrp, 1 << ss->subsys_id); if (err) @@ -4202,12 +4196,11 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, if (err) goto err_destroy; - /* each css holds a ref to the cgroup's dentry and parent css */ dget(dentry); css_get(css->parent); /* mark it consumed for error path */ - css_ar[ss->subsys_id] = NULL; + css = NULL; if (ss->broken_hierarchy && !ss->warned_broken_hierarchy && parent->parent) { @@ -4237,13 +4230,9 @@ err_free_cgrp: return err; err_destroy: - for_each_root_subsys(root, ss) { - struct cgroup_subsys_state *css = css_ar[ss->subsys_id]; - - if (css) { - percpu_ref_cancel_init(&css->refcnt); - ss->css_free(css); - } + if (css) { + percpu_ref_cancel_init(&css->refcnt); + css->ss->css_free(css); } cgroup_destroy_locked(cgrp); mutex_unlock(&cgroup_mutex); -- cgit v1.2.3 From c81c925ad9b0460a14ec35b52c61158da0733d51 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 6 Dec 2013 15:11:56 -0500 Subject: cgroup: factor out cgroup_subsys_state creation into create_css() Now that all opertations to create a css (cgroup_subsys_state) are collected into a single loop in cgroup_create(), it's easy to factor it out into its own function. Factor out css creation into create_css(). This makes the code easier to follow and will enable decoupling css creation from cgroup creation which is necessary for the planned unified hierarchy. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- kernel/cgroup.c | 95 ++++++++++++++++++++++++++++++++++----------------------- 1 file changed, 57 insertions(+), 38 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 39e2295466ec..d12c29f42feb 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4073,6 +4073,62 @@ static void offline_css(struct cgroup_subsys_state *css) RCU_INIT_POINTER(css->cgroup->subsys[ss->subsys_id], css); } +/** + * create_css - create a cgroup_subsys_state + * @cgrp: the cgroup new css will be associated with + * @ss: the subsys of new css + * + * Create a new css associated with @cgrp - @ss pair. On success, the new + * css is online and installed in @cgrp with all interface files created. + * Returns 0 on success, -errno on failure. + */ +static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss) +{ + struct cgroup *parent = cgrp->parent; + struct cgroup_subsys_state *css; + int err; + + lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex); + lockdep_assert_held(&cgroup_mutex); + + css = ss->css_alloc(cgroup_css(parent, ss)); + if (IS_ERR(css)) + return PTR_ERR(css); + + err = percpu_ref_init(&css->refcnt, css_release); + if (err) + goto err_free; + + init_css(css, ss, cgrp); + + err = cgroup_populate_dir(cgrp, 1 << ss->subsys_id); + if (err) + goto err_free; + + err = online_css(css); + if (err) + goto err_free; + + dget(cgrp->dentry); + css_get(css->parent); + + if (ss->broken_hierarchy && !ss->warned_broken_hierarchy && + parent->parent) { + pr_warning("cgroup: %s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n", + current->comm, current->pid, ss->name); + if (!strcmp(ss->name, "memory")) + pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n"); + ss->warned_broken_hierarchy = true; + } + + return 0; + +err_free: + percpu_ref_cancel_init(&css->refcnt); + ss->css_free(css); + return err; +} + /* * cgroup_create - create a cgroup * @parent: cgroup that will be parent of the new cgroup @@ -4084,7 +4140,6 @@ static void offline_css(struct cgroup_subsys_state *css) static long cgroup_create(struct cgroup *parent, struct dentry *dentry, umode_t mode) { - struct cgroup_subsys_state *css = NULL; struct cgroup *cgrp; struct cgroup_name *name; struct cgroupfs_root *root = parent->root; @@ -4175,41 +4230,9 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, /* let's create and online css's */ for_each_root_subsys(root, ss) { - css = ss->css_alloc(cgroup_css(parent, ss)); - if (IS_ERR(css)) { - err = PTR_ERR(css); - css = NULL; - goto err_destroy; - } - - err = percpu_ref_init(&css->refcnt, css_release); + err = create_css(cgrp, ss); if (err) goto err_destroy; - - init_css(css, ss, cgrp); - - err = cgroup_populate_dir(cgrp, 1 << ss->subsys_id); - if (err) - goto err_destroy; - - err = online_css(css); - if (err) - goto err_destroy; - - dget(dentry); - css_get(css->parent); - - /* mark it consumed for error path */ - css = NULL; - - if (ss->broken_hierarchy && !ss->warned_broken_hierarchy && - parent->parent) { - pr_warning("cgroup: %s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n", - current->comm, current->pid, ss->name); - if (!strcmp(ss->name, "memory")) - pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n"); - ss->warned_broken_hierarchy = true; - } } mutex_unlock(&cgroup_mutex); @@ -4230,10 +4253,6 @@ err_free_cgrp: return err; err_destroy: - if (css) { - percpu_ref_cancel_init(&css->refcnt); - css->ss->css_free(css); - } cgroup_destroy_locked(cgrp); mutex_unlock(&cgroup_mutex); mutex_unlock(&dentry->d_inode->i_mutex); -- cgit v1.2.3 From 1c6727af4b495a9ec74c46d1fc08e508e675899d Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 6 Dec 2013 15:11:56 -0500 Subject: cgroup: implement for_each_css() There are enough places where css's of a cgroup are iterated, which currently uses for_each_root_subsys() + explicit cgroup_css(). This patch implements for_each_css() and replaces the above combination with it. This patch doesn't introduce any behavior changes. v2: Updated to apply cleanly on top of v2 of "cgroup: fix css leaks on online_css() failure" Signed-off-by: Tejun Heo Acked-by: Li Zefan --- kernel/cgroup.c | 57 +++++++++++++++++++++++++++++++-------------------------- 1 file changed, 31 insertions(+), 26 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index d12c29f42feb..329fde82ef7c 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -242,6 +242,21 @@ static int notify_on_release(const struct cgroup *cgrp) return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); } +/** + * for_each_css - iterate all css's of a cgroup + * @css: the iteration cursor + * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end + * @cgrp: the target cgroup to iterate css's of + * + * Should be called under cgroup_mutex. + */ +#define for_each_css(css, ssid, cgrp) \ + for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ + if (!((css) = rcu_dereference_check( \ + (cgrp)->subsys[(ssid)], \ + lockdep_is_held(&cgroup_mutex)))) { } \ + else + /** * for_each_subsys - iterate all loaded cgroup subsystems * @ss: the iteration cursor @@ -1942,8 +1957,8 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, bool threadgroup) { int retval, i, group_size; - struct cgroup_subsys *ss, *failed_ss = NULL; struct cgroupfs_root *root = cgrp->root; + struct cgroup_subsys_state *css, *failed_css = NULL; /* threadgroup list cursor and array */ struct task_struct *leader = tsk; struct task_and_cgroup *tc; @@ -2016,13 +2031,11 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, /* * step 1: check that we can legitimately attach to the cgroup. */ - for_each_root_subsys(root, ss) { - struct cgroup_subsys_state *css = cgroup_css(cgrp, ss); - - if (ss->can_attach) { - retval = ss->can_attach(css, &tset); + for_each_css(css, i, cgrp) { + if (css->ss->can_attach) { + retval = css->ss->can_attach(css, &tset); if (retval) { - failed_ss = ss; + failed_css = css; goto out_cancel_attach; } } @@ -2058,12 +2071,9 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, /* * step 4: do subsystem attach callbacks. */ - for_each_root_subsys(root, ss) { - struct cgroup_subsys_state *css = cgroup_css(cgrp, ss); - - if (ss->attach) - ss->attach(css, &tset); - } + for_each_css(css, i, cgrp) + if (css->ss->attach) + css->ss->attach(css, &tset); /* * step 5: success! and cleanup @@ -2080,13 +2090,11 @@ out_put_css_set_refs: } out_cancel_attach: if (retval) { - for_each_root_subsys(root, ss) { - struct cgroup_subsys_state *css = cgroup_css(cgrp, ss); - - if (ss == failed_ss) + for_each_css(css, i, cgrp) { + if (css == failed_css) break; - if (ss->cancel_attach) - ss->cancel_attach(css, &tset); + if (css->ss->cancel_attach) + css->ss->cancel_attach(css, &tset); } } out_free_group_list: @@ -4375,9 +4383,10 @@ static int cgroup_destroy_locked(struct cgroup *cgrp) __releases(&cgroup_mutex) __acquires(&cgroup_mutex) { struct dentry *d = cgrp->dentry; - struct cgroup_subsys *ss; + struct cgroup_subsys_state *css; struct cgroup *child; bool empty; + int ssid; lockdep_assert_held(&d->d_inode->i_mutex); lockdep_assert_held(&cgroup_mutex); @@ -4413,12 +4422,8 @@ static int cgroup_destroy_locked(struct cgroup *cgrp) * will be invoked to perform the rest of destruction once the * percpu refs of all css's are confirmed to be killed. */ - for_each_root_subsys(cgrp->root, ss) { - struct cgroup_subsys_state *css = cgroup_css(cgrp, ss); - - if (css) - kill_css(css); - } + for_each_css(css, ssid, cgrp) + kill_css(css); /* * Mark @cgrp dead. This prevents further task migration and child -- cgit v1.2.3 From b85d20404cef6493f9d2edbafe83f9c72aece9a8 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 6 Dec 2013 15:11:57 -0500 Subject: cgroup: remove for_each_root_subsys() After the previous patch which introduced for_each_css(), for_each_root_subsys() only has two users left. This patch replaces it with for_each_subsys() + explicit subsys_mask testing and remove for_each_root_subsys() along with cgroupfs_root->subsys_list handling. This patch doesn't introduce any behavior changes. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- include/linux/cgroup.h | 9 +-------- kernel/cgroup.c | 37 +++++++++++++++---------------------- 2 files changed, 16 insertions(+), 30 deletions(-) (limited to 'kernel') diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 8b9a594f0c92..cfaf416492dd 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -319,9 +319,6 @@ struct cgroupfs_root { /* Unique id for this hierarchy. */ int hierarchy_id; - /* A list running through the attached subsystems */ - struct list_head subsys_list; - /* The root cgroup for this hierarchy */ struct cgroup top_cgroup; @@ -617,12 +614,8 @@ struct cgroup_subsys { #define MAX_CGROUP_TYPE_NAMELEN 32 const char *name; - /* - * Link to parent, and list entry in parent's children. - * Protected by cgroup_lock() - */ + /* link to parent, protected by cgroup_lock() */ struct cgroupfs_root *root; - struct list_head sibling; /* list of cftype_sets */ struct list_head cftsets; diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 329fde82ef7c..fb1193bec4af 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -283,10 +283,6 @@ static int notify_on_release(const struct cgroup *cgrp) for ((i) = 0; (i) < CGROUP_BUILTIN_SUBSYS_COUNT && \ (((ss) = cgroup_subsys[i]) || true); (i)++) -/* iterate each subsystem attached to a hierarchy */ -#define for_each_root_subsys(root, ss) \ - list_for_each_entry((ss), &(root)->subsys_list, sibling) - /* iterate across the active hierarchies */ #define for_each_active_root(root) \ list_for_each_entry((root), &cgroup_roots, root_list) @@ -1033,7 +1029,6 @@ static int rebind_subsystems(struct cgroupfs_root *root, cgroup_css(cgroup_dummy_top, ss)); cgroup_css(cgrp, ss)->cgroup = cgrp; - list_move(&ss->sibling, &root->subsys_list); ss->root = root; if (ss->bind) ss->bind(cgroup_css(cgrp, ss)); @@ -1052,7 +1047,6 @@ static int rebind_subsystems(struct cgroupfs_root *root, RCU_INIT_POINTER(cgrp->subsys[i], NULL); cgroup_subsys[i]->root = &cgroup_dummy_root; - list_move(&ss->sibling, &cgroup_dummy_root.subsys_list); /* subsystem is now free - drop reference on module */ module_put(ss->module); @@ -1079,10 +1073,12 @@ static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry) { struct cgroupfs_root *root = dentry->d_sb->s_fs_info; struct cgroup_subsys *ss; + int ssid; mutex_lock(&cgroup_root_mutex); - for_each_root_subsys(root, ss) - seq_printf(seq, ",%s", ss->name); + for_each_subsys(ss, ssid) + if (root->subsys_mask & (1 << ssid)) + seq_printf(seq, ",%s", ss->name); if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) seq_puts(seq, ",sane_behavior"); if (root->flags & CGRP_ROOT_NOPREFIX) @@ -1352,7 +1348,6 @@ static void init_cgroup_root(struct cgroupfs_root *root) { struct cgroup *cgrp = &root->top_cgroup; - INIT_LIST_HEAD(&root->subsys_list); INIT_LIST_HEAD(&root->root_list); root->number_of_cgroups = 1; cgrp->root = root; @@ -4151,7 +4146,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, struct cgroup *cgrp; struct cgroup_name *name; struct cgroupfs_root *root = parent->root; - int err = 0; + int ssid, err = 0; struct cgroup_subsys *ss; struct super_block *sb = root->sb; @@ -4237,10 +4232,12 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, goto err_destroy; /* let's create and online css's */ - for_each_root_subsys(root, ss) { - err = create_css(cgrp, ss); - if (err) - goto err_destroy; + for_each_subsys(ss, ssid) { + if (root->subsys_mask & (1 << ssid)) { + err = create_css(cgrp, ss); + if (err) + goto err_destroy; + } } mutex_unlock(&cgroup_mutex); @@ -4536,7 +4533,6 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss) cgroup_init_cftsets(ss); /* Create the top cgroup state for this subsystem */ - list_add(&ss->sibling, &cgroup_dummy_root.subsys_list); ss->root = &cgroup_dummy_root; css = ss->css_alloc(cgroup_css(cgroup_dummy_top, ss)); /* We don't handle early failures gracefully */ @@ -4626,7 +4622,6 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) return PTR_ERR(css); } - list_add(&ss->sibling, &cgroup_dummy_root.subsys_list); ss->root = &cgroup_dummy_root; /* our new subsystem will be attached to the dummy hierarchy. */ @@ -4702,9 +4697,6 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss) /* deassign the subsys_id */ cgroup_subsys[ss->subsys_id] = NULL; - /* remove subsystem from the dummy root's list of subsystems */ - list_del_init(&ss->sibling); - /* * disentangle the css from all css_sets attached to the dummy * top. as in loading, we need to pay our respects to the hashtable @@ -4901,11 +4893,12 @@ int proc_cgroup_show(struct seq_file *m, void *v) for_each_active_root(root) { struct cgroup_subsys *ss; struct cgroup *cgrp; - int count = 0; + int ssid, count = 0; seq_printf(m, "%d:", root->hierarchy_id); - for_each_root_subsys(root, ss) - seq_printf(m, "%s%s", count++ ? "," : "", ss->name); + for_each_subsys(ss, ssid) + if (root->subsys_mask & (1 << ssid)) + seq_printf(m, "%s%s", count++ ? "," : "", ss->name); if (strlen(root->name)) seq_printf(m, "%sname=%s", count ? "," : "", root->name); -- cgit v1.2.3 From 0be8669dd530f60cf3f59f084518570c1dfb47ee Mon Sep 17 00:00:00 2001 From: Wei Yongjun Date: Mon, 9 Dec 2013 20:38:29 +0800 Subject: cgroup: fix missing unlock on error in cgroup_load_subsys() Add the missing unlock before return from function cgroup_load_subsys() in the error handling case. Signed-off-by: Wei Yongjun Signed-off-by: Tejun Heo Acked-by: Li Zefan --- kernel/cgroup.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index fb1193bec4af..402f7aab8b2d 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4618,6 +4618,7 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) if (IS_ERR(css)) { /* failure case - need to deassign the cgroup_subsys[] slot. */ cgroup_subsys[ss->subsys_id] = NULL; + mutex_unlock(&cgroup_root_mutex); mutex_unlock(&cgroup_mutex); return PTR_ERR(css); } -- cgit v1.2.3 From 10bf2f7e7db993273419ca9f51f5934e4cf71768 Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Thu, 12 Dec 2013 23:17:08 +0400 Subject: cgroup: fix fail path in cgroup_load_subsys() Calling cgroup_unload_subsys() from cgroup_load_subsys() after online_css() failure will result in a NULL ptr dereference on attempt to offline_css(), because online_css() only assigns css to cgroup on success. Let's fix that by skipping calls to offline_css() and css_free() in cgroup_unload_subsys() if there is no css, and freeing css in cgroup_load_subsys() on online_css() failure. Signed-off-by: Vladimir Davydov Signed-off-by: Tejun Heo Acked-by: Li Zefan --- kernel/cgroup.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 402f7aab8b2d..7030f04f2890 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4652,8 +4652,10 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) write_unlock(&css_set_lock); ret = online_css(css); - if (ret) + if (ret) { + ss->css_free(css); goto err_unload; + } /* success! */ mutex_unlock(&cgroup_root_mutex); @@ -4680,6 +4682,7 @@ EXPORT_SYMBOL_GPL(cgroup_load_subsys); void cgroup_unload_subsys(struct cgroup_subsys *ss) { struct cgrp_cset_link *link; + struct cgroup_subsys_state *css; BUG_ON(ss->module == NULL); @@ -4693,7 +4696,9 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss) mutex_lock(&cgroup_mutex); mutex_lock(&cgroup_root_mutex); - offline_css(cgroup_css(cgroup_dummy_top, ss)); + css = cgroup_css(cgroup_dummy_top, ss); + if (css) + offline_css(css); /* deassign the subsys_id */ cgroup_subsys[ss->subsys_id] = NULL; @@ -4720,7 +4725,8 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss) * need to free before marking as null because ss->css_free needs * the cgrp->subsys pointer to find their state. */ - ss->css_free(cgroup_css(cgroup_dummy_top, ss)); + if (css) + ss->css_free(css); RCU_INIT_POINTER(cgroup_dummy_top->subsys[ss->subsys_id], NULL); mutex_unlock(&cgroup_root_mutex); -- cgit v1.2.3 From dd4b0a4676907481256d16d5de0851b315a6f22c Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Sat, 18 Jan 2014 16:56:47 +0900 Subject: cgroup: trivial style updates * Place newline before function opening brace in cgroup_kill_sb(). * Insert space before assignment in attach_task_by_pid() tj: merged two patches into one. Signed-off-by: SeongJae Park Signed-off-by: Tejun Heo --- kernel/cgroup.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 7030f04f2890..680e2be234c4 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1669,7 +1669,8 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, return ERR_PTR(ret); } -static void cgroup_kill_sb(struct super_block *sb) { +static void cgroup_kill_sb(struct super_block *sb) +{ struct cgroupfs_root *root = sb->s_fs_info; struct cgroup *cgrp = &root->top_cgroup; struct cgrp_cset_link *link, *tmp_link; @@ -2117,7 +2118,7 @@ retry_find_task: tsk = find_task_by_vpid(pid); if (!tsk) { rcu_read_unlock(); - ret= -ESRCH; + ret = -ESRCH; goto out_unlock_cgroup; } /* -- cgit v1.2.3