diff options
Diffstat (limited to 'block/blk-cgroup.c')
-rw-r--r-- | block/blk-cgroup.c | 28 |
1 files changed, 19 insertions, 9 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 4e491d9b5292..1039fb9ff5f5 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -336,7 +336,7 @@ static void blkg_destroy(struct blkcg_gq *blkg) * under queue_lock. If it's not pointing to @blkg now, it never * will. Hint assignment itself can race safely. */ - if (rcu_dereference_raw(blkcg->blkg_hint) == blkg) + if (rcu_access_pointer(blkcg->blkg_hint) == blkg) rcu_assign_pointer(blkcg->blkg_hint, NULL); /* @@ -451,7 +451,20 @@ static int blkcg_reset_stats(struct cgroup_subsys_state *css, struct blkcg_gq *blkg; int i; - mutex_lock(&blkcg_pol_mutex); + /* + * XXX: We invoke cgroup_add/rm_cftypes() under blkcg_pol_mutex + * which ends up putting cgroup's internal cgroup_tree_mutex under + * it; however, cgroup_tree_mutex is nested above cgroup file + * active protection and grabbing blkcg_pol_mutex from a cgroup + * file operation creates a possible circular dependency. cgroup + * internal locking is planned to go through further simplification + * and this issue should go away soon. For now, let's trylock + * blkcg_pol_mutex and restart the write on failure. + * + * http://lkml.kernel.org/g/5363C04B.4010400@oracle.com + */ + if (!mutex_trylock(&blkcg_pol_mutex)) + return restart_syscall(); spin_lock_irq(&blkcg->lock); /* @@ -894,7 +907,7 @@ static int blkcg_can_attach(struct cgroup_subsys_state *css, int ret = 0; /* task_lock() is needed to avoid races with exit_io_context() */ - cgroup_taskset_for_each(task, css, tset) { + cgroup_taskset_for_each(task, tset) { task_lock(task); ioc = task->io_context; if (ioc && atomic_read(&ioc->nr_tasks) > 1) @@ -906,17 +919,14 @@ static int blkcg_can_attach(struct cgroup_subsys_state *css, return ret; } -struct cgroup_subsys blkio_subsys = { - .name = "blkio", +struct cgroup_subsys blkio_cgrp_subsys = { .css_alloc = blkcg_css_alloc, .css_offline = blkcg_css_offline, .css_free = blkcg_css_free, .can_attach = blkcg_can_attach, - .subsys_id = blkio_subsys_id, .base_cftypes = blkcg_files, - .module = THIS_MODULE, }; -EXPORT_SYMBOL_GPL(blkio_subsys); +EXPORT_SYMBOL_GPL(blkio_cgrp_subsys); /** * blkcg_activate_policy - activate a blkcg policy on a request_queue @@ -1106,7 +1116,7 @@ int blkcg_policy_register(struct blkcg_policy *pol) /* everything is in place, add intf files for the new policy */ if (pol->cftypes) - WARN_ON(cgroup_add_cftypes(&blkio_subsys, pol->cftypes)); + WARN_ON(cgroup_add_cftypes(&blkio_cgrp_subsys, pol->cftypes)); ret = 0; out_unlock: mutex_unlock(&blkcg_pol_mutex); |