From 9d5e2d69705fed4ab527f5a283b90ae602f4e0fd Mon Sep 17 00:00:00 2001 From: Jiang Biao Date: Wed, 18 Apr 2018 08:37:18 -0600 Subject: [PATCH] blkcg: don't hold blkcg lock when deactivating policy [ Upstream commit 946b81da114b8ba5c74bb01e57c0c6eca2bdc801 ] As described in the comment of blkcg_activate_policy(), *Update of each blkg is protected by both queue and blkcg locks so that holding either lock and testing blkcg_policy_enabled() is always enough for dereferencing policy data.* with queue lock held, there is no need to hold blkcg lock in blkcg_deactivate_policy(). Similar case is in blkcg_activate_policy(), which has removed holding of blkcg lock in commit 4c55f4f9ad3001ac1fefdd8d8ca7641d18558e23. Signed-off-by: Jiang Biao Signed-off-by: Wen Yang CC: Tejun Heo Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- block/blk-cgroup.c | 5 ----- 1 file changed, 5 deletions(-) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index d3f56ba..00b133c 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -1374,17 +1374,12 @@ void blkcg_deactivate_policy(struct request_queue *q, __clear_bit(pol->plid, q->blkcg_pols); list_for_each_entry(blkg, &q->blkg_list, q_node) { - /* grab blkcg lock too while removing @pd from @blkg */ - spin_lock(&blkg->blkcg->lock); - if (blkg->pd[pol->plid]) { if (pol->pd_offline_fn) pol->pd_offline_fn(blkg->pd[pol->plid]); pol->pd_free_fn(blkg->pd[pol->plid]); blkg->pd[pol->plid] = NULL; } - - spin_unlock(&blkg->blkcg->lock); } spin_unlock_irq(q->queue_lock); -- 2.7.4