[PATCH v2 7/7] [RFC] nvme: Fix a race condition
From: Bart Van Assche <hidden>
Date: 2016-09-29 00:02:00
Also in:
linux-nvme, linux-rdma, linux-scsi
Subsystem:
nvm express driver, the rest · Maintainers:
Keith Busch, Jens Axboe, Christoph Hellwig, Sagi Grimberg, Linus Torvalds
Avoid that nvme_queue_rq() is still running when nvme_stop_queues() returns. Untested. Signed-off-by: Bart Van Assche <redacted> Cc: Keith Busch <redacted> Cc: Christoph Hellwig <hch@lst.de> Cc: Sagi Grimberg <sagi@grimberg.me> --- drivers/nvme/host/core.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-)
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index d791fba..98f1f29 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c@@ -201,13 +201,9 @@ fail: void nvme_requeue_req(struct request *req) { - unsigned long flags; - blk_mq_requeue_request(req); - spin_lock_irqsave(req->q->queue_lock, flags); - if (!blk_mq_queue_stopped(req->q)) - blk_mq_kick_requeue_list(req->q); - spin_unlock_irqrestore(req->q->queue_lock, flags); + WARN_ON_ONCE(blk_mq_queue_stopped(req->q)); + blk_mq_kick_requeue_list(req->q); } EXPORT_SYMBOL_GPL(nvme_requeue_req);
@@ -2077,11 +2073,19 @@ EXPORT_SYMBOL_GPL(nvme_kill_queues); void nvme_stop_queues(struct nvme_ctrl *ctrl) { struct nvme_ns *ns; + struct request_queue *q; mutex_lock(&ctrl->namespaces_mutex); list_for_each_entry(ns, &ctrl->namespaces, list) { - blk_mq_cancel_requeue_work(ns->queue); - blk_mq_stop_hw_queues(ns->queue); + q = ns->queue; + blk_mq_quiesce_queue(q); + blk_mq_cancel_requeue_work(q); + blk_mq_stop_hw_queues(q); + /* + * Note: blk_mq_resume_queue() does not affect the value + * of the BLK_MQ_S_STOPPED bit. + */ + blk_mq_resume_queue(q); } mutex_unlock(&ctrl->namespaces_mutex); }
--
2.10.0