From 073219e995b4a3f8cf1ce8228b7ef440b6994ac0 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Sat, 8 Feb 2014 10:36:58 -0500 Subject: cgroup: clean up cgroup_subsys names and initialization cgroup_subsys is a bit messier than it needs to be. * The name of a subsys can be different from its internal identifier defined in cgroup_subsys.h. Most subsystems use the matching name but three - cpu, memory and perf_event - use different ones. * cgroup_subsys_id enums are postfixed with _subsys_id and each cgroup_subsys is postfixed with _subsys. cgroup.h is widely included throughout various subsystems, it doesn't and shouldn't have claim on such generic names which don't have any qualifier indicating that they belong to cgroup. * cgroup_subsys->subsys_id should always equal the matching cgroup_subsys_id enum; however, we require each controller to initialize it and then BUG if they don't match, which is a bit silly. This patch cleans up cgroup_subsys names and initialization by doing the followings. * cgroup_subsys_id enums are now postfixed with _cgrp_id, and each cgroup_subsys with _cgrp_subsys. * With the above, renaming subsys identifiers to match the userland visible names doesn't cause any naming conflicts. All non-matching identifiers are renamed to match the official names. cpu_cgroup -> cpu mem_cgroup -> memory perf -> perf_event * controllers no longer need to initialize ->subsys_id and ->name. They're generated in cgroup core and set automatically during boot. * Redundant cgroup_subsys declarations removed. * While updating BUG_ON()s in cgroup_init_early(), convert them to WARN()s. BUGging that early during boot is stupid - the kernel can't print anything, even through serial console and the trap handler doesn't even link stack frame properly for back-tracing. This patch doesn't introduce any behavior changes. v2: Rebased on top of fe1217c4f3f7 ("net: net_cls: move cgroupfs classid handling into core"). Signed-off-by: Tejun Heo Acked-by: Neil Horman Acked-by: "David S. Miller" Acked-by: "Rafael J. Wysocki" Acked-by: Michal Hocko Acked-by: Peter Zijlstra Acked-by: Aristeu Rozanski Acked-by: Ingo Molnar Acked-by: Li Zefan Cc: Johannes Weiner Cc: Balbir Singh Cc: KAMEZAWA Hiroyuki Cc: Serge E. Hallyn Cc: Vivek Goyal Cc: Thomas Graf --- mm/memcontrol.c | 22 ++++++++++------------ 1 file changed, 10 insertions(+), 12 deletions(-) (limited to 'mm/memcontrol.c') diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 53385cd4e6f0..04a97bce2270 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -66,8 +66,8 @@ #include -struct cgroup_subsys mem_cgroup_subsys __read_mostly; -EXPORT_SYMBOL(mem_cgroup_subsys); +struct cgroup_subsys memory_cgrp_subsys __read_mostly; +EXPORT_SYMBOL(memory_cgrp_subsys); #define MEM_CGROUP_RECLAIM_RETRIES 5 static struct mem_cgroup *root_mem_cgroup __read_mostly; @@ -538,7 +538,7 @@ static inline struct mem_cgroup *mem_cgroup_from_id(unsigned short id) { struct cgroup_subsys_state *css; - css = css_from_id(id - 1, &mem_cgroup_subsys); + css = css_from_id(id - 1, &memory_cgrp_subsys); return mem_cgroup_from_css(css); } @@ -1072,7 +1072,7 @@ struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p) if (unlikely(!p)) return NULL; - return mem_cgroup_from_css(task_css(p, mem_cgroup_subsys_id)); + return mem_cgroup_from_css(task_css(p, memory_cgrp_id)); } struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm) @@ -1702,7 +1702,7 @@ void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p) rcu_read_lock(); mem_cgrp = memcg->css.cgroup; - task_cgrp = task_cgroup(p, mem_cgroup_subsys_id); + task_cgrp = task_cgroup(p, memory_cgrp_id); ret = cgroup_path(task_cgrp, memcg_name, PATH_MAX); if (ret < 0) { @@ -6187,7 +6187,7 @@ static int memcg_write_event_control(struct cgroup_subsys_state *css, ret = -EINVAL; cfile_css = css_from_dir(cfile.file->f_dentry->d_parent, - &mem_cgroup_subsys); + &memory_cgrp_subsys); if (cfile_css == css && css_tryget(css)) ret = 0; @@ -6566,11 +6566,11 @@ mem_cgroup_css_online(struct cgroup_subsys_state *css) * unfortunate state in our controller. */ if (parent != root_mem_cgroup) - mem_cgroup_subsys.broken_hierarchy = true; + memory_cgrp_subsys.broken_hierarchy = true; } mutex_unlock(&memcg_create_mutex); - return memcg_init_kmem(memcg, &mem_cgroup_subsys); + return memcg_init_kmem(memcg, &memory_cgrp_subsys); } /* @@ -7264,9 +7264,7 @@ static void mem_cgroup_bind(struct cgroup_subsys_state *root_css) mem_cgroup_from_css(root_css)->use_hierarchy = true; } -struct cgroup_subsys mem_cgroup_subsys = { - .name = "memory", - .subsys_id = mem_cgroup_subsys_id, +struct cgroup_subsys memory_cgrp_subsys = { .css_alloc = mem_cgroup_css_alloc, .css_online = mem_cgroup_css_online, .css_offline = mem_cgroup_css_offline, @@ -7292,7 +7290,7 @@ __setup("swapaccount=", enable_swap_account); static void __init memsw_file_init(void) { - WARN_ON(cgroup_add_cftypes(&mem_cgroup_subsys, memsw_cgroup_files)); + WARN_ON(cgroup_add_cftypes(&memory_cgrp_subsys, memsw_cgroup_files)); } static void __init enable_swap_cgroup(void) -- cgit v1.2.3 From 5a17f543ed6808e9085063277fe46795dea484bd Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 11 Feb 2014 11:52:47 -0500 Subject: cgroup: improve css_from_dir() into css_tryget_from_dir() css_from_dir() returns the matching css (cgroup_subsys_state) given a dentry and subsystem. The function doesn't pin the css before returning and requires the caller to be holding RCU read lock or cgroup_mutex and handling pinning on the caller side. Given that users of the function are likely to want to pin the returned css (both existing users do) and that getting and putting css's are very cheap, there's no reason for the interface to be tricky like this. Rename css_from_dir() to css_tryget_from_dir() and make it try to pin the found css and return it only if pinning succeeded. The callers are updated so that they no longer do RCU locking and pinning around the function and just use the returned css. This will also ease converting cgroup to kernfs. Signed-off-by: Tejun Heo Acked-by: Michal Hocko Acked-by: Li Zefan Cc: Steven Rostedt Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Johannes Weiner Cc: Balbir Singh Cc: KAMEZAWA Hiroyuki --- include/linux/cgroup.h | 4 ++-- kernel/cgroup.c | 25 ++++++++++++++++--------- kernel/events/core.c | 17 +---------------- mm/memcontrol.c | 16 +++++++--------- 4 files changed, 26 insertions(+), 36 deletions(-) (limited to 'mm/memcontrol.c') diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index c86ba7ff7a7e..1ba4fc08f776 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -825,8 +825,8 @@ int css_scan_tasks(struct cgroup_subsys_state *css, int cgroup_attach_task_all(struct task_struct *from, struct task_struct *); int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from); -struct cgroup_subsys_state *css_from_dir(struct dentry *dentry, - struct cgroup_subsys *ss); +struct cgroup_subsys_state *css_tryget_from_dir(struct dentry *dentry, + struct cgroup_subsys *ss); #else /* !CONFIG_CGROUPS */ diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 2de8decfd99f..fc2db071d95e 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4978,28 +4978,35 @@ static int __init cgroup_disable(char *str) __setup("cgroup_disable=", cgroup_disable); /** - * css_from_dir - get corresponding css from the dentry of a cgroup dir + * css_tryget_from_dir - get corresponding css from the dentry of a cgroup dir * @dentry: directory dentry of interest * @ss: subsystem of interest * - * 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. + * If @dentry is a directory for a cgroup which has @ss enabled on it, try + * to get the corresponding css and return it. If such css doesn't exist + * or can't be pinned, an ERR_PTR value is returned. */ -struct cgroup_subsys_state *css_from_dir(struct dentry *dentry, - struct cgroup_subsys *ss) +struct cgroup_subsys_state *css_tryget_from_dir(struct dentry *dentry, + struct cgroup_subsys *ss) { struct cgroup *cgrp; - - cgroup_assert_mutex_or_rcu_locked(); + struct cgroup_subsys_state *css; /* is @dentry a cgroup dir? */ if (!dentry->d_inode || dentry->d_inode->i_op != &cgroup_dir_inode_operations) return ERR_PTR(-EBADF); + rcu_read_lock(); + cgrp = __d_cgrp(dentry); - return cgroup_css(cgrp, ss) ?: ERR_PTR(-ENOENT); + css = cgroup_css(cgrp, ss); + + if (!css || !css_tryget(css)) + css = ERR_PTR(-ENOENT); + + rcu_read_unlock(); + return css; } /** diff --git a/kernel/events/core.c b/kernel/events/core.c index 64903731d834..a3c3ab50271a 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -370,11 +370,6 @@ perf_cgroup_match(struct perf_event *event) event->cgrp->css.cgroup); } -static inline bool perf_tryget_cgroup(struct perf_event *event) -{ - return css_tryget(&event->cgrp->css); -} - static inline void perf_put_cgroup(struct perf_event *event) { css_put(&event->cgrp->css); @@ -593,9 +588,7 @@ static inline int perf_cgroup_connect(int fd, struct perf_event *event, if (!f.file) return -EBADF; - rcu_read_lock(); - - css = css_from_dir(f.file->f_dentry, &perf_event_cgrp_subsys); + css = css_tryget_from_dir(f.file->f_dentry, &perf_event_cgrp_subsys); if (IS_ERR(css)) { ret = PTR_ERR(css); goto out; @@ -604,13 +597,6 @@ static inline int perf_cgroup_connect(int fd, struct perf_event *event, cgrp = container_of(css, struct perf_cgroup, css); event->cgrp = cgrp; - /* must be done before we fput() the file */ - if (!perf_tryget_cgroup(event)) { - event->cgrp = NULL; - ret = -ENOENT; - goto out; - } - /* * all events in a group must monitor * the same cgroup because a task belongs @@ -621,7 +607,6 @@ static inline int perf_cgroup_connect(int fd, struct perf_event *event, ret = -EINVAL; } out: - rcu_read_unlock(); fdput(f); return ret; } diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 04a97bce2270..102ab48ffa13 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -6183,17 +6183,15 @@ static int memcg_write_event_control(struct cgroup_subsys_state *css, * automatically removed on cgroup destruction but the removal is * asynchronous, so take an extra ref on @css. */ - rcu_read_lock(); - + cfile_css = css_tryget_from_dir(cfile.file->f_dentry->d_parent, + &memory_cgrp_subsys); ret = -EINVAL; - cfile_css = css_from_dir(cfile.file->f_dentry->d_parent, - &memory_cgrp_subsys); - if (cfile_css == css && css_tryget(css)) - ret = 0; - - rcu_read_unlock(); - if (ret) + if (IS_ERR(cfile_css)) goto out_put_cfile; + if (cfile_css != css) { + css_put(cfile_css); + goto out_put_cfile; + } ret = event->register_event(memcg, event->eventfd, buffer); if (ret) -- cgit v1.2.3 From e61734c55c24cdf11b07e52a74aec4dc4a7f4bd0 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 12 Feb 2014 09:29:50 -0500 Subject: cgroup: remove cgroup->name cgroup->name handling became quite complicated over time involving dedicated struct cgroup_name for RCU protection. Now that cgroup is on kernfs, we can drop all of it and simply use kernfs_name/path() and friends. Replace cgroup->name and all related code with kernfs name/path constructs. * Reimplement cgroup_name() and cgroup_path() as thin wrappers on top of kernfs counterparts, which involves semantic changes. pr_cont_cgroup_name() and pr_cont_cgroup_path() added. * cgroup->name handling dropped from cgroup_rename(). * All users of cgroup_name/path() updated to the new semantics. Users which were formatting the string just to printk them are converted to use pr_cont_cgroup_name/path() instead, which simplifies things quite a bit. As cgroup_name() no longer requires RCU read lock around it, RCU lockings which were protecting only cgroup_name() are removed. v2: Comment above oom_info_lock updated as suggested by Michal. v3: dummy_top doesn't have a kn associated and pr_cont_cgroup_name/path() ended up calling the matching kernfs functions with NULL kn leading to oops. Test for NULL kn and print "/" if so. This issue was reported by Fengguang Wu. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo Acked-by: Peter Zijlstra Acked-by: Michal Hocko Acked-by: Li Zefan Cc: Fengguang Wu Cc: Ingo Molnar Cc: Johannes Weiner Cc: Balbir Singh Cc: KAMEZAWA Hiroyuki --- block/blk-cgroup.h | 12 ++-- fs/kernfs/dir.c | 1 + include/linux/cgroup.h | 63 ++++++++++++--------- kernel/cgroup.c | 146 +++++++++++-------------------------------------- kernel/cpuset.c | 27 +++++---- kernel/sched/debug.c | 3 +- mm/memcontrol.c | 68 ++++++----------------- 7 files changed, 110 insertions(+), 210 deletions(-) (limited to 'mm/memcontrol.c') diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h index 453b528c8e19..15a8d640de57 100644 --- a/block/blk-cgroup.h +++ b/block/blk-cgroup.h @@ -241,12 +241,16 @@ static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) */ static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen) { - int ret; + char *p; - ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen); - if (ret) + p = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen); + if (!p) { strncpy(buf, "", buflen); - return ret; + return -ENAMETOOLONG; + } + + memmove(buf, p, buf + buflen - p); + return 0; } /** diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index a347792c2e5a..939684ebff1e 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -112,6 +112,7 @@ char *kernfs_path(struct kernfs_node *kn, char *buf, size_t buflen) spin_unlock_irqrestore(&kernfs_rename_lock, flags); return p; } +EXPORT_SYMBOL_GPL(kernfs_path); /** * pr_cont_kernfs_name - pr_cont name of a kernfs_node diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index b42251a23129..4d6ff7d40cf6 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -138,11 +138,6 @@ enum { CGRP_SANE_BEHAVIOR, }; -struct cgroup_name { - struct rcu_head rcu_head; - char name[]; -}; - struct cgroup { unsigned long flags; /* "unsigned long" so bitops work */ @@ -179,19 +174,6 @@ struct cgroup { */ u64 serial_nr; - /* - * This is a copy of dentry->d_name, and it's needed because - * we can't use dentry->d_name in cgroup_path(). - * - * You must acquire rcu_read_lock() to access cgrp->name, and - * the only place that can change it is rename(), which is - * protected by parent dir's i_mutex. - * - * Normally you should use cgroup_name() wrapper rather than - * access it directly. - */ - struct cgroup_name __rcu *name; - /* Private pointers for each registered subsystem */ struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT]; @@ -479,12 +461,6 @@ static inline bool cgroup_sane_behavior(const struct cgroup *cgrp) return cgrp->root->flags & CGRP_ROOT_SANE_BEHAVIOR; } -/* Caller should hold rcu_read_lock() */ -static inline const char *cgroup_name(const struct cgroup *cgrp) -{ - return rcu_dereference(cgrp->name)->name; -} - /* returns ino associated with a cgroup, 0 indicates unmounted root */ static inline ino_t cgroup_ino(struct cgroup *cgrp) { @@ -503,14 +479,47 @@ static inline struct cftype *seq_cft(struct seq_file *seq) struct cgroup_subsys_state *seq_css(struct seq_file *seq); +/* + * Name / path handling functions. All are thin wrappers around the kernfs + * counterparts and can be called under any context. + */ + +static inline int cgroup_name(struct cgroup *cgrp, char *buf, size_t buflen) +{ + return kernfs_name(cgrp->kn, buf, buflen); +} + +static inline char * __must_check cgroup_path(struct cgroup *cgrp, char *buf, + size_t buflen) +{ + return kernfs_path(cgrp->kn, buf, buflen); +} + +static inline void pr_cont_cgroup_name(struct cgroup *cgrp) +{ + /* dummy_top doesn't have a kn associated */ + if (cgrp->kn) + pr_cont_kernfs_name(cgrp->kn); + else + pr_cont("/"); +} + +static inline void pr_cont_cgroup_path(struct cgroup *cgrp) +{ + /* dummy_top doesn't have a kn associated */ + if (cgrp->kn) + pr_cont_kernfs_path(cgrp->kn); + else + pr_cont("/"); +} + +char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen); + int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts); int cgroup_rm_cftypes(struct cftype *cfts); bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor); -int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen); -int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen); - int cgroup_task_count(const struct cgroup *cgrp); /* diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 59dfb025f1ac..638df032fb94 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -145,8 +145,6 @@ static int cgroup_root_count; /* hierarchy ID allocation and mapping, protected by cgroup_mutex */ static DEFINE_IDR(cgroup_hierarchy_idr); -static struct cgroup_name root_cgroup_name = { .name = "/" }; - /* * Assign a monotonically increasing serial number to cgroups. It * guarantees cgroups with bigger numbers are newer than those with smaller @@ -888,17 +886,6 @@ static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask); static struct kernfs_syscall_ops cgroup_kf_syscall_ops; static const struct file_operations proc_cgroupstats_operations; -static struct cgroup_name *cgroup_alloc_name(const char *name_str) -{ - struct cgroup_name *name; - - name = kmalloc(sizeof(*name) + strlen(name_str) + 1, GFP_KERNEL); - if (!name) - return NULL; - strcpy(name->name, name_str); - return name; -} - static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft, char *buf) { @@ -958,8 +945,6 @@ static void cgroup_free_fn(struct work_struct *work) cgroup_pidlist_destroy_all(cgrp); kernfs_put(cgrp->kn); - - kfree(rcu_dereference_raw(cgrp->name)); kfree(cgrp); } @@ -1377,7 +1362,6 @@ static void init_cgroup_root(struct cgroupfs_root *root) INIT_LIST_HEAD(&root->root_list); root->number_of_cgroups = 1; cgrp->root = root; - RCU_INIT_POINTER(cgrp->name, &root_cgroup_name); init_cgroup_housekeeping(cgrp); idr_init(&root->cgroup_idr); } @@ -1597,57 +1581,6 @@ static struct file_system_type cgroup_fs_type = { static struct kobject *cgroup_kobj; -/** - * cgroup_path - generate the path of a cgroup - * @cgrp: the cgroup in question - * @buf: the buffer to write the path into - * @buflen: the length of the buffer - * - * Writes path of cgroup into buf. Returns 0 on success, -errno on error. - * - * We can't generate cgroup path using dentry->d_name, as accessing - * dentry->name must be protected by irq-unsafe dentry->d_lock or parent - * inode's i_mutex, while on the other hand cgroup_path() can be called - * with some irq-safe spinlocks held. - */ -int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) -{ - int ret = -ENAMETOOLONG; - char *start; - - if (!cgrp->parent) { - if (strlcpy(buf, "/", buflen) >= buflen) - return -ENAMETOOLONG; - return 0; - } - - start = buf + buflen - 1; - *start = '\0'; - - rcu_read_lock(); - do { - const char *name = cgroup_name(cgrp); - int len; - - len = strlen(name); - if ((start -= len) < buf) - goto out; - memcpy(start, name, len); - - if (--start < buf) - goto out; - *start = '/'; - - cgrp = cgrp->parent; - } while (cgrp->parent); - ret = 0; - memmove(buf, start, buf + buflen - start); -out: - rcu_read_unlock(); - return ret; -} -EXPORT_SYMBOL_GPL(cgroup_path); - /** * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy * @task: target task @@ -1659,16 +1592,14 @@ EXPORT_SYMBOL_GPL(cgroup_path); * function grabs cgroup_mutex and shouldn't be used inside locks used by * cgroup controller callbacks. * - * Returns 0 on success, fails with -%ENAMETOOLONG if @buflen is too short. + * Return value is the same as kernfs_path(). */ -int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen) +char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen) { struct cgroupfs_root *root; struct cgroup *cgrp; - int hierarchy_id = 1, ret = 0; - - if (buflen < 2) - return -ENAMETOOLONG; + int hierarchy_id = 1; + char *path = NULL; mutex_lock(&cgroup_mutex); @@ -1676,14 +1607,15 @@ int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen) if (root) { cgrp = task_cgroup_from_root(task, root); - ret = cgroup_path(cgrp, buf, buflen); + path = cgroup_path(cgrp, buf, buflen); } else { /* if no hierarchy exists, everyone is in "/" */ - memcpy(buf, "/", 2); + if (strlcpy(buf, "/", buflen) < buflen) + path = buf; } mutex_unlock(&cgroup_mutex); - return ret; + return path; } EXPORT_SYMBOL_GPL(task_cgroup_path); @@ -2211,7 +2143,6 @@ static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent, const char *new_name_str) { struct cgroup *cgrp = kn->priv; - struct cgroup_name *name, *old_name; int ret; if (kernfs_type(kn) != KERNFS_DIR) @@ -2226,25 +2157,13 @@ static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent, if (cgroup_sane_behavior(cgrp)) return -EPERM; - name = cgroup_alloc_name(new_name_str); - if (!name) - return -ENOMEM; - mutex_lock(&cgroup_tree_mutex); mutex_lock(&cgroup_mutex); ret = kernfs_rename(kn, new_parent, new_name_str); - if (!ret) { - old_name = rcu_dereference_protected(cgrp->name, true); - rcu_assign_pointer(cgrp->name, name); - } else { - old_name = name; - } mutex_unlock(&cgroup_mutex); mutex_unlock(&cgroup_tree_mutex); - - kfree_rcu(old_name, rcu_head); return ret; } @@ -3719,14 +3638,13 @@ err_free: /** * cgroup_create - create a cgroup * @parent: cgroup that will be parent of the new cgroup - * @name_str: name of the new cgroup + * @name: name of the new cgroup * @mode: mode to set on new cgroup */ -static long cgroup_create(struct cgroup *parent, const char *name_str, +static long cgroup_create(struct cgroup *parent, const char *name, umode_t mode) { struct cgroup *cgrp; - struct cgroup_name *name; struct cgroupfs_root *root = parent->root; int ssid, err; struct cgroup_subsys *ss; @@ -3737,13 +3655,6 @@ static long cgroup_create(struct cgroup *parent, const char *name_str, if (!cgrp) return -ENOMEM; - name = cgroup_alloc_name(name_str); - if (!name) { - err = -ENOMEM; - goto err_free_cgrp; - } - rcu_assign_pointer(cgrp->name, name); - mutex_lock(&cgroup_tree_mutex); /* @@ -3781,7 +3692,7 @@ static long cgroup_create(struct cgroup *parent, const char *name_str, set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); /* create the directory */ - kn = kernfs_create_dir(parent->kn, name->name, mode, cgrp); + kn = kernfs_create_dir(parent->kn, name, mode, cgrp); if (IS_ERR(kn)) { err = PTR_ERR(kn); goto err_free_id; @@ -3839,8 +3750,6 @@ err_unlock: mutex_unlock(&cgroup_mutex); err_unlock_tree: mutex_unlock(&cgroup_tree_mutex); - kfree(rcu_dereference_raw(cgrp->name)); -err_free_cgrp: kfree(cgrp); return err; @@ -4304,12 +4213,12 @@ int proc_cgroup_show(struct seq_file *m, void *v) { struct pid *pid; struct task_struct *tsk; - char *buf; + char *buf, *path; int retval; struct cgroupfs_root *root; retval = -ENOMEM; - buf = kmalloc(PAGE_SIZE, GFP_KERNEL); + buf = kmalloc(PATH_MAX, GFP_KERNEL); if (!buf) goto out; @@ -4337,10 +4246,12 @@ int proc_cgroup_show(struct seq_file *m, void *v) root->name); seq_putc(m, ':'); cgrp = task_cgroup_from_root(tsk, root); - retval = cgroup_path(cgrp, buf, PAGE_SIZE); - if (retval < 0) + path = cgroup_path(cgrp, buf, PATH_MAX); + if (!path) { + retval = -ENAMETOOLONG; goto out_unlock; - seq_puts(m, buf); + } + seq_puts(m, path); seq_putc(m, '\n'); } @@ -4588,16 +4499,17 @@ static void cgroup_release_agent(struct work_struct *work) while (!list_empty(&release_list)) { char *argv[3], *envp[3]; int i; - char *pathbuf = NULL, *agentbuf = NULL; + char *pathbuf = NULL, *agentbuf = NULL, *path; struct cgroup *cgrp = list_entry(release_list.next, struct cgroup, release_list); list_del_init(&cgrp->release_list); raw_spin_unlock(&release_list_lock); - pathbuf = kmalloc(PAGE_SIZE, GFP_KERNEL); + pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); if (!pathbuf) goto continue_free; - if (cgroup_path(cgrp, pathbuf, PAGE_SIZE) < 0) + path = cgroup_path(cgrp, pathbuf, PATH_MAX); + if (!path) goto continue_free; agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); if (!agentbuf) @@ -4605,7 +4517,7 @@ static void cgroup_release_agent(struct work_struct *work) i = 0; argv[i++] = agentbuf; - argv[i++] = pathbuf; + argv[i++] = path; argv[i] = NULL; i = 0; @@ -4755,6 +4667,11 @@ static int current_css_set_cg_links_read(struct seq_file *seq, void *v) { struct cgrp_cset_link *link; struct css_set *cset; + char *name_buf; + + name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL); + if (!name_buf) + return -ENOMEM; read_lock(&css_set_lock); rcu_read_lock(); @@ -4763,14 +4680,17 @@ static int current_css_set_cg_links_read(struct seq_file *seq, void *v) struct cgroup *c = link->cgrp; const char *name = "?"; - if (c != cgroup_dummy_top) - name = cgroup_name(c); + if (c != cgroup_dummy_top) { + cgroup_name(c, name_buf, NAME_MAX + 1); + name = name_buf; + } seq_printf(seq, "Root %d group %s\n", c->root->hierarchy_id, name); } rcu_read_unlock(); read_unlock(&css_set_lock); + kfree(name_buf); return 0; } diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 2d018c795fea..e97a6e88d036 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -2088,10 +2088,9 @@ static void remove_tasks_in_empty_cpuset(struct cpuset *cs) parent = parent_cs(parent); if (cgroup_transfer_tasks(parent->css.cgroup, cs->css.cgroup)) { - rcu_read_lock(); - printk(KERN_ERR "cpuset: failed to transfer tasks out of empty cpuset %s\n", - cgroup_name(cs->css.cgroup)); - rcu_read_unlock(); + printk(KERN_ERR "cpuset: failed to transfer tasks out of empty cpuset "); + pr_cont_cgroup_name(cs->css.cgroup); + pr_cont("\n"); } } @@ -2619,19 +2618,17 @@ void cpuset_print_task_mems_allowed(struct task_struct *tsk) /* Statically allocated to prevent using excess stack. */ static char cpuset_nodelist[CPUSET_NODELIST_LEN]; static DEFINE_SPINLOCK(cpuset_buffer_lock); - struct cgroup *cgrp = task_cs(tsk)->css.cgroup; - rcu_read_lock(); spin_lock(&cpuset_buffer_lock); nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN, tsk->mems_allowed); - printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n", - tsk->comm, cgroup_name(cgrp), cpuset_nodelist); + printk(KERN_INFO "%s cpuset=", tsk->comm); + pr_cont_cgroup_name(cgrp); + pr_cont(" mems_allowed=%s\n", cpuset_nodelist); spin_unlock(&cpuset_buffer_lock); - rcu_read_unlock(); } /* @@ -2681,12 +2678,12 @@ int proc_cpuset_show(struct seq_file *m, void *unused_v) { struct pid *pid; struct task_struct *tsk; - char *buf; + char *buf, *p; struct cgroup_subsys_state *css; int retval; retval = -ENOMEM; - buf = kmalloc(PAGE_SIZE, GFP_KERNEL); + buf = kmalloc(PATH_MAX, GFP_KERNEL); if (!buf) goto out; @@ -2696,14 +2693,16 @@ int proc_cpuset_show(struct seq_file *m, void *unused_v) if (!tsk) goto out_free; + retval = -ENAMETOOLONG; rcu_read_lock(); css = task_css(tsk, cpuset_cgrp_id); - retval = cgroup_path(css->cgroup, buf, PAGE_SIZE); + p = cgroup_path(css->cgroup, buf, PATH_MAX); rcu_read_unlock(); - if (retval < 0) + if (!p) goto out_put_task; - seq_puts(m, buf); + seq_puts(m, p); seq_putc(m, '\n'); + retval = 0; out_put_task: put_task_struct(tsk); out_free: diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index dd52e7ffb10e..30eee3b5293d 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -111,8 +111,7 @@ static char *task_group_path(struct task_group *tg) if (autogroup_path(tg, group_path, PATH_MAX)) return group_path; - cgroup_path(tg->css.cgroup, group_path, PATH_MAX); - return group_path; + return cgroup_path(tg->css.cgroup, group_path, PATH_MAX); } #endif diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 102ab48ffa13..c1c25494f7ae 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1683,15 +1683,8 @@ static void move_unlock_mem_cgroup(struct mem_cgroup *memcg, */ void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p) { - /* - * protects memcg_name and makes sure that parallel ooms do not - * interleave - */ + /* oom_info_lock ensures that parallel ooms do not interleave */ static DEFINE_SPINLOCK(oom_info_lock); - struct cgroup *task_cgrp; - struct cgroup *mem_cgrp; - static char memcg_name[PATH_MAX]; - int ret; struct mem_cgroup *iter; unsigned int i; @@ -1701,36 +1694,14 @@ void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p) spin_lock(&oom_info_lock); rcu_read_lock(); - mem_cgrp = memcg->css.cgroup; - task_cgrp = task_cgroup(p, memory_cgrp_id); + pr_info("Task in "); + pr_cont_cgroup_path(task_cgroup(p, memory_cgrp_id)); + pr_info(" killed as a result of limit of "); + pr_cont_cgroup_path(memcg->css.cgroup); + pr_info("\n"); - ret = cgroup_path(task_cgrp, memcg_name, PATH_MAX); - if (ret < 0) { - /* - * Unfortunately, we are unable to convert to a useful name - * But we'll still print out the usage information - */ - rcu_read_unlock(); - goto done; - } rcu_read_unlock(); - pr_info("Task in %s killed", memcg_name); - - rcu_read_lock(); - ret = cgroup_path(mem_cgrp, memcg_name, PATH_MAX); - if (ret < 0) { - rcu_read_unlock(); - goto done; - } - rcu_read_unlock(); - - /* - * Continues from above, so we don't need an KERN_ level - */ - pr_cont(" as a result of limit of %s\n", memcg_name); -done: - pr_info("memory: usage %llukB, limit %llukB, failcnt %llu\n", res_counter_read_u64(&memcg->res, RES_USAGE) >> 10, res_counter_read_u64(&memcg->res, RES_LIMIT) >> 10, @@ -1745,13 +1716,8 @@ done: res_counter_read_u64(&memcg->kmem, RES_FAILCNT)); for_each_mem_cgroup_tree(iter, memcg) { - pr_info("Memory cgroup stats"); - - rcu_read_lock(); - ret = cgroup_path(iter->css.cgroup, memcg_name, PATH_MAX); - if (!ret) - pr_cont(" for %s", memcg_name); - rcu_read_unlock(); + pr_info("Memory cgroup stats for "); + pr_cont_cgroup_path(iter->css.cgroup); pr_cont(":"); for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) { @@ -3401,7 +3367,7 @@ static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg, struct kmem_cache *s) { struct kmem_cache *new = NULL; - static char *tmp_name = NULL; + static char *tmp_path = NULL, *tmp_name = NULL; static DEFINE_MUTEX(mutex); /* protects tmp_name */ BUG_ON(!memcg_can_account_kmem(memcg)); @@ -3413,18 +3379,20 @@ static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg, * This static temporary buffer is used to prevent from * pointless shortliving allocation. */ - if (!tmp_name) { - tmp_name = kmalloc(PATH_MAX, GFP_KERNEL); + if (!tmp_path || !tmp_name) { + if (!tmp_path) + tmp_path = kmalloc(PATH_MAX, GFP_KERNEL); if (!tmp_name) + tmp_name = kmalloc(NAME_MAX + 1, GFP_KERNEL); + if (!tmp_path || !tmp_name) goto out; } - rcu_read_lock(); - snprintf(tmp_name, PATH_MAX, "%s(%d:%s)", s->name, - memcg_cache_id(memcg), cgroup_name(memcg->css.cgroup)); - rcu_read_unlock(); + cgroup_name(memcg->css.cgroup, tmp_name, NAME_MAX + 1); + snprintf(tmp_path, PATH_MAX, "%s(%d:%s)", s->name, + memcg_cache_id(memcg), tmp_name); - new = kmem_cache_create_memcg(memcg, tmp_name, s->object_size, s->align, + new = kmem_cache_create_memcg(memcg, tmp_path, s->object_size, s->align, (s->flags & ~SLAB_PANIC), s->ctor, s); if (new) new->allocflags |= __GFP_KMEMCG; -- cgit v1.2.3 From 07bc356ed2950048d33d667e933e1b913c6e6b6d Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 13 Feb 2014 06:58:39 -0500 Subject: cgroup: implement cgroup_has_tasks() and unexport cgroup_task_count() cgroup_task_count() read-locks css_set_lock and walks all tasks to count them and then returns the result. The only thing all the users want is determining whether the cgroup is empty or not. This patch implements cgroup_has_tasks() which tests whether cgroup->cset_links is empty, replaces all cgroup_task_count() usages and unexports it. Note that the test isn't synchronized. This is the same as before. The test has always been racy. This will help planned css_set locking update. Signed-off-by: Tejun Heo Acked-by: Li Zefan Acked-by: Michal Hocko Cc: Johannes Weiner Cc: Balbir Singh Cc: KAMEZAWA Hiroyuki --- include/linux/cgroup.h | 8 ++++++-- kernel/cgroup.c | 2 +- kernel/cpuset.c | 2 +- mm/memcontrol.c | 4 ++-- 4 files changed, 10 insertions(+), 6 deletions(-) (limited to 'mm/memcontrol.c') diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index e2ffcdc26cb7..72154fb44fb5 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -457,6 +457,12 @@ static inline bool cgroup_sane_behavior(const struct cgroup *cgrp) return cgrp->root->flags & CGRP_ROOT_SANE_BEHAVIOR; } +/* no synchronization, the result can only be used as a hint */ +static inline bool cgroup_has_tasks(struct cgroup *cgrp) +{ + return !list_empty(&cgrp->cset_links); +} + /* returns ino associated with a cgroup, 0 indicates unmounted root */ static inline ino_t cgroup_ino(struct cgroup *cgrp) { @@ -516,8 +522,6 @@ int cgroup_rm_cftypes(struct cftype *cfts); bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor); -int cgroup_task_count(const struct cgroup *cgrp); - /* * Control Group taskset, used to pass around set of tasks to cgroup_subsys * methods. diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 2469699408bd..ec7746e5ded1 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2391,7 +2391,7 @@ EXPORT_SYMBOL_GPL(cgroup_add_cftypes); * * Return the number of tasks in the cgroup. */ -int cgroup_task_count(const struct cgroup *cgrp) +static int cgroup_task_count(const struct cgroup *cgrp) { int count = 0; struct cgrp_cset_link *link; diff --git a/kernel/cpuset.c b/kernel/cpuset.c index e97a6e88d036..ae190b0a196a 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -467,7 +467,7 @@ static int validate_change(struct cpuset *cur, struct cpuset *trial) * be changed to have empty cpus_allowed or mems_allowed. */ ret = -ENOSPC; - if ((cgroup_task_count(cur->css.cgroup) || cur->attach_in_progress)) { + if ((cgroup_has_tasks(cur->css.cgroup) || cur->attach_in_progress)) { if (!cpumask_empty(cur->cpus_allowed) && cpumask_empty(trial->cpus_allowed)) goto out; diff --git a/mm/memcontrol.c b/mm/memcontrol.c index c1c25494f7ae..d9c6ac1532e6 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4958,7 +4958,7 @@ static int mem_cgroup_force_empty(struct mem_cgroup *memcg) struct cgroup *cgrp = memcg->css.cgroup; /* returns EBUSY if there is a task or if we come here twice. */ - if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children)) + if (cgroup_has_tasks(cgrp) || !list_empty(&cgrp->children)) return -EBUSY; /* we call try-to-free pages for make this cgroup empty */ @@ -5140,7 +5140,7 @@ static int __memcg_activate_kmem(struct mem_cgroup *memcg, * of course permitted. */ mutex_lock(&memcg_create_mutex); - if (cgroup_task_count(memcg->css.cgroup) || memcg_has_children(memcg)) + if (cgroup_has_tasks(memcg->css.cgroup) || memcg_has_children(memcg)) err = -EBUSY; mutex_unlock(&memcg_create_mutex); if (err) -- cgit v1.2.3 From 4d3bb511b5f9980fc3e9ae5939ebc475b231d3fc Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 19 Mar 2014 10:23:54 -0400 Subject: cgroup: drop const from @buffer of cftype->write_string() cftype->write_string() just passes on the writeable buffer from kernfs and there's no reason to add const restriction on the buffer. The only thing const achieves is unnecessarily complicating parsing of the buffer. Drop const from @buffer. Signed-off-by: Tejun Heo Acked-by: Li Zefan Cc: Peter Zijlstra Cc: Paul Mackerras Cc: Ingo Molnar Cc: Arnaldo Carvalho de Melo Cc: Daniel Borkmann Cc: Michal Hocko Cc: Johannes Weiner Cc: Balbir Singh Cc: KAMEZAWA Hiroyuki --- block/blk-throttle.c | 4 ++-- block/cfq-iosched.c | 4 ++-- include/linux/cgroup.h | 2 +- kernel/cgroup.c | 2 +- kernel/cgroup_freezer.c | 2 +- kernel/cpuset.c | 2 +- mm/hugetlb_cgroup.c | 2 +- mm/memcontrol.c | 4 ++-- net/core/netprio_cgroup.c | 2 +- net/ipv4/tcp_memcontrol.c | 2 +- security/device_cgroup.c | 4 ++-- 11 files changed, 15 insertions(+), 15 deletions(-) (limited to 'mm/memcontrol.c') diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 861c363e4129..033745cd7fba 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -1408,13 +1408,13 @@ static int tg_set_conf(struct cgroup_subsys_state *css, struct cftype *cft, } static int tg_set_conf_u64(struct cgroup_subsys_state *css, struct cftype *cft, - const char *buf) + char *buf) { return tg_set_conf(css, cft, buf, true); } static int tg_set_conf_uint(struct cgroup_subsys_state *css, struct cftype *cft, - const char *buf) + char *buf) { return tg_set_conf(css, cft, buf, false); } diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 461187943392..f5de45b6af36 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1701,13 +1701,13 @@ static int __cfqg_set_weight_device(struct cgroup_subsys_state *css, } static int cfqg_set_weight_device(struct cgroup_subsys_state *css, - struct cftype *cft, const char *buf) + struct cftype *cft, char *buf) { return __cfqg_set_weight_device(css, cft, buf, false); } static int cfqg_set_leaf_weight_device(struct cgroup_subsys_state *css, - struct cftype *cft, const char *buf) + struct cftype *cft, char *buf) { return __cfqg_set_weight_device(css, cft, buf, true); } diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 77294fc66603..79993ac066c5 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -454,7 +454,7 @@ struct cftype { * Returns 0 or -ve error code. */ int (*write_string)(struct cgroup_subsys_state *css, struct cftype *cft, - const char *buffer); + char *buffer); /* * trigger() callback can be used to get some kick from the * userspace, when the actual string written is not important diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 60ea16058c42..f5754910e80b 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2143,7 +2143,7 @@ static int cgroup_procs_write(struct cgroup_subsys_state *css, } static int cgroup_release_agent_write(struct cgroup_subsys_state *css, - struct cftype *cft, const char *buffer) + struct cftype *cft, char *buffer) { struct cgroup_root *root = css->cgroup->root; diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c index 2ea98b216bff..2bc4a2256444 100644 --- a/kernel/cgroup_freezer.c +++ b/kernel/cgroup_freezer.c @@ -442,7 +442,7 @@ static void freezer_change_state(struct freezer *freezer, bool freeze) } static int freezer_write(struct cgroup_subsys_state *css, struct cftype *cft, - const char *buffer) + char *buffer) { bool freeze; diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 8d5324583aa4..efbf9baf77ec 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -1610,7 +1610,7 @@ out_unlock: * Common handling for a write to a "cpus" or "mems" file. */ static int cpuset_write_resmask(struct cgroup_subsys_state *css, - struct cftype *cft, const char *buf) + struct cftype *cft, char *buf) { struct cpuset *cs = css_cs(css); struct cpuset *trialcs; diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c index b135853e68f3..595d7fd795e1 100644 --- a/mm/hugetlb_cgroup.c +++ b/mm/hugetlb_cgroup.c @@ -254,7 +254,7 @@ static u64 hugetlb_cgroup_read_u64(struct cgroup_subsys_state *css, } static int hugetlb_cgroup_write(struct cgroup_subsys_state *css, - struct cftype *cft, const char *buffer) + struct cftype *cft, char *buffer) { int idx, name, ret; unsigned long long val; diff --git a/mm/memcontrol.c b/mm/memcontrol.c index d9c6ac1532e6..96f94a9f2faf 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5242,7 +5242,7 @@ static int memcg_update_kmem_limit(struct mem_cgroup *memcg, * RES_LIMIT. */ static int mem_cgroup_write(struct cgroup_subsys_state *css, struct cftype *cft, - const char *buffer) + char *buffer) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); enum res_type type; @@ -6063,7 +6063,7 @@ static void memcg_event_ptable_queue_proc(struct file *file, * Interpretation of args is defined by control file implementation. */ static int memcg_write_event_control(struct cgroup_subsys_state *css, - struct cftype *cft, const char *buffer) + struct cftype *cft, char *buffer) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); struct mem_cgroup_event *event; diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c index f9f3a40d3350..3825f669147b 100644 --- a/net/core/netprio_cgroup.c +++ b/net/core/netprio_cgroup.c @@ -186,7 +186,7 @@ static int read_priomap(struct seq_file *sf, void *v) } static int write_priomap(struct cgroup_subsys_state *css, struct cftype *cft, - const char *buffer) + char *buffer) { char devname[IFNAMSIZ + 1]; struct net_device *dev; diff --git a/net/ipv4/tcp_memcontrol.c b/net/ipv4/tcp_memcontrol.c index 20a0aca9131e..d4f015ad6c84 100644 --- a/net/ipv4/tcp_memcontrol.c +++ b/net/ipv4/tcp_memcontrol.c @@ -103,7 +103,7 @@ static int tcp_update_limit(struct mem_cgroup *memcg, u64 val) } static int tcp_cgroup_write(struct cgroup_subsys_state *css, struct cftype *cft, - const char *buffer) + char *buffer) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); unsigned long long val; diff --git a/security/device_cgroup.c b/security/device_cgroup.c index 7f88bcde7c61..8365909f5f8c 100644 --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -496,7 +496,7 @@ static inline bool has_children(struct dev_cgroup *devcgroup) * parent cgroup has the access you're asking for. */ static int devcgroup_update_access(struct dev_cgroup *devcgroup, - int filetype, const char *buffer) + int filetype, char *buffer) { const char *b; char temp[12]; /* 11 + 1 characters needed for a u32 */ @@ -652,7 +652,7 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup, } static int devcgroup_access_write(struct cgroup_subsys_state *css, - struct cftype *cft, const char *buffer) + struct cftype *cft, char *buffer) { int retval; -- cgit v1.2.3