From 38dbb7dd4db184da4d2673f4bb963f7006465c37 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 18 Jan 2017 15:37:27 -0700 Subject: [PATCH] blk-cgroup: don't quiesce the queue on policy activate/deactivate There's no potential harm in quiescing the queue, but it also doesn't buy us anything. And we can't run the queue async for policy deactivate, since we could be in the path of tearing the queue down. If we schedule an async run of the queue at that time, we're racing with queue teardown AFTER having we've already torn most of it down. Reported-by: Omar Sandoval Fixes: 4d199c6f1c84 ("blk-cgroup: ensure that we clear the stop bit on quiesced queues") Tested-by: Omar Sandoval Signed-off-by: Jens Axboe --- block/blk-cgroup.c | 20 ++++++++------------ 1 file changed, 8 insertions(+), 12 deletions(-) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index efb97ec37eee..fb59a3edc778 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -1223,10 +1223,9 @@ int blkcg_activate_policy(struct request_queue *q, if (blkcg_policy_enabled(q, pol)) return 0; - if (q->mq_ops) { + if (q->mq_ops) blk_mq_freeze_queue(q); - blk_mq_quiesce_queue(q); - } else + else blk_queue_bypass_start(q); pd_prealloc: if (!pd_prealloc) { @@ -1265,10 +1264,9 @@ pd_prealloc: spin_unlock_irq(q->queue_lock); out_bypass_end: - if (q->mq_ops) { + if (q->mq_ops) blk_mq_unfreeze_queue(q); - blk_mq_start_stopped_hw_queues(q, true); - } else + else blk_queue_bypass_end(q); if (pd_prealloc) pol->pd_free_fn(pd_prealloc); @@ -1292,10 +1290,9 @@ void blkcg_deactivate_policy(struct request_queue *q, if (!blkcg_policy_enabled(q, pol)) return; - if (q->mq_ops) { + if (q->mq_ops) blk_mq_freeze_queue(q); - blk_mq_quiesce_queue(q); - } else + else blk_queue_bypass_start(q); spin_lock_irq(q->queue_lock); @@ -1318,10 +1315,9 @@ void blkcg_deactivate_policy(struct request_queue *q, spin_unlock_irq(q->queue_lock); - if (q->mq_ops) { + if (q->mq_ops) blk_mq_unfreeze_queue(q); - blk_mq_start_stopped_hw_queues(q, true); - } else + else blk_queue_bypass_end(q); } EXPORT_SYMBOL_GPL(blkcg_deactivate_policy); -- 2.20.1