Messages in this thread Patch in this message | | | From | Jiang Biao <> | Subject | [PATCH] blkcg: not hold blkcg lock when deactivating policy. | Date | Tue, 17 Apr 2018 15:10:33 +0800 |
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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 <jiang.biao2@zte.com.cn> Signed-off-by: Wen Yang <wen.yang99@zte.com.cn> CC: Tejun Heo <tj@kernel.org> CC: Jens Axboe <axboe@kernel.dk> --- block/blk-cgroup.c | 5 ----- 1 file changed, 5 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index c2033a2..2b7f8d0 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -1367,17 +1367,12 @@ 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
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