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nvme: Use BLK_MQ_S_STOPPED instead of QUEUE_FLAG_STOPPED in blk-mq code

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Make nvme_requeue_req() check BLK_MQ_S_STOPPED instead of
QUEUE_FLAG_STOPPED. Remove the QUEUE_FLAG_STOPPED manipulations
that became superfluous because of this change. Change
blk_queue_stopped() tests into blk_mq_queue_stopped().

This patch fixes a race condition: using queue_flag_clear_unlocked()
is not safe if any other function that manipulates the queue flags
can be called concurrently, e.g. blk_cleanup_queue().

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Bart Van Assche 2016-10-28 17:23:40 -07:00 committed by Jens Axboe
parent 3174dd33fa
commit a6eaa8849f
1 changed files with 2 additions and 14 deletions
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16
drivers/nvme/host/core.c
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@ -201,13 +201,7 @@ fail:
void nvme_requeue_req(struct request *req)
{
unsigned long flags;
blk_mq_requeue_request(req, false);
spin_lock_irqsave(req->q->queue_lock, flags);
if (!blk_queue_stopped(req->q))
blk_mq_kick_requeue_list(req->q);
spin_unlock_irqrestore(req->q->queue_lock, flags);
blk_mq_requeue_request(req, !blk_mq_queue_stopped(req->q));
}
EXPORT_SYMBOL_GPL(nvme_requeue_req);
@ -2076,13 +2070,8 @@ void nvme_stop_queues(struct nvme_ctrl *ctrl)
struct nvme_ns *ns;
mutex_lock(&ctrl->namespaces_mutex);
list_for_each_entry(ns, &ctrl->namespaces, list) {
spin_lock_irq(ns->queue->queue_lock);
queue_flag_set(QUEUE_FLAG_STOPPED, ns->queue);
spin_unlock_irq(ns->queue->queue_lock);
list_for_each_entry(ns, &ctrl->namespaces, list)
blk_mq_quiesce_queue(ns->queue);
}
mutex_unlock(&ctrl->namespaces_mutex);
}
EXPORT_SYMBOL_GPL(nvme_stop_queues);
@ -2093,7 +2082,6 @@ void nvme_start_queues(struct nvme_ctrl *ctrl)
mutex_lock(&ctrl->namespaces_mutex);
list_for_each_entry(ns, &ctrl->namespaces, list) {
queue_flag_clear_unlocked(QUEUE_FLAG_STOPPED, ns->queue);
blk_mq_start_stopped_hw_queues(ns->queue, true);
blk_mq_kick_requeue_list(ns->queue);
}