From: Ming Lei ming.lei@redhat.com
[ Upstream commit 1b8f21b74c3c9c82fce5a751d7aefb7cc0b8d33d ]
In NVMe's error handler, follows the typical steps of tearing down hardware for recovering controller:
1) stop blk_mq hw queues 2) stop the real hw queues 3) cancel in-flight requests via blk_mq_tagset_busy_iter(tags, cancel_request, ...) cancel_request(): mark the request as abort blk_mq_complete_request(req); 4) destroy real hw queues
However, there may be race between #3 and #4, because blk_mq_complete_request() may run q->mq_ops->complete(rq) remotelly and asynchronously, and ->complete(rq) may be run after #4.
This patch introduces blk_mq_complete_request_sync() for fixing the above race.
Cc: Sagi Grimberg sagi@grimberg.me Cc: Bart Van Assche bvanassche@acm.org Cc: James Smart james.smart@broadcom.com Cc: linux-nvme@lists.infradead.org Reviewed-by: Keith Busch keith.busch@intel.com Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Ming Lei ming.lei@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- block/blk-mq.c | 7 +++++++ include/linux/blk-mq.h | 1 + 2 files changed, 8 insertions(+)
diff --git a/block/blk-mq.c b/block/blk-mq.c index 16f9675c57e6..ce462c313806 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -657,6 +657,13 @@ bool blk_mq_complete_request(struct request *rq) } EXPORT_SYMBOL(blk_mq_complete_request);
+void blk_mq_complete_request_sync(struct request *rq) +{ + WRITE_ONCE(rq->state, MQ_RQ_COMPLETE); + rq->q->mq_ops->complete(rq); +} +EXPORT_SYMBOL_GPL(blk_mq_complete_request_sync); + int blk_mq_request_started(struct request *rq) { return blk_mq_rq_state(rq) != MQ_RQ_IDLE; diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 0e030f5f76b6..7e092bdac27f 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -306,6 +306,7 @@ void blk_mq_add_to_requeue_list(struct request *rq, bool at_head, void blk_mq_kick_requeue_list(struct request_queue *q); void blk_mq_delay_kick_requeue_list(struct request_queue *q, unsigned long msecs); bool blk_mq_complete_request(struct request *rq); +void blk_mq_complete_request_sync(struct request *rq); bool blk_mq_bio_list_merge(struct request_queue *q, struct list_head *list, struct bio *bio); bool blk_mq_queue_stopped(struct request_queue *q);