diff options
Diffstat (limited to 'block/blk-cgroup.c')
| -rw-r--r-- | block/blk-cgroup.c | 31 |
1 files changed, 24 insertions, 7 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index e4a4145926f..28d227c5ca7 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -80,7 +80,7 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, blkg->q = q; INIT_LIST_HEAD(&blkg->q_node); blkg->blkcg = blkcg; - blkg->refcnt = 1; + atomic_set(&blkg->refcnt, 1); /* root blkg uses @q->root_rl, init rl only for !root blkgs */ if (blkcg != &blkcg_root) { @@ -185,7 +185,7 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, lockdep_assert_held(q->queue_lock); /* blkg holds a reference to blkcg */ - if (!css_tryget(&blkcg->css)) { + if (!css_tryget_online(&blkcg->css)) { ret = -EINVAL; goto err_free_blkg; } @@ -399,11 +399,8 @@ void __blkg_release_rcu(struct rcu_head *rcu_head) /* release the blkcg and parent blkg refs this blkg has been holding */ css_put(&blkg->blkcg->css); - if (blkg->parent) { - spin_lock_irq(blkg->q->queue_lock); + if (blkg->parent) blkg_put(blkg->parent); - spin_unlock_irq(blkg->q->queue_lock); - } blkg_free(blkg); } @@ -451,7 +448,20 @@ 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); /* @@ -862,6 +872,13 @@ void blkcg_drain_queue(struct request_queue *q) { lockdep_assert_held(q->queue_lock); + /* + * @q could be exiting and already have destroyed all blkgs as + * indicated by NULL root_blkg. If so, don't confuse policies. + */ + if (!q->root_blkg) + return; + blk_throtl_drain(q); } |