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authorChristoph Hellwig <hch@lst.de>2014-09-13 16:40:09 -0700
committerJens Axboe <axboe@fb.com>2014-09-22 12:00:07 -0600
commite2490073cd7c3d6f6ef6e029a208edd4d38efac4 (patch)
tree48465e67b335f6d696d698641365b4a4d1e89d32 /block
parentbf57229745f849e500ba69ff91e35bc8160a7373 (diff)
blk-mq: call blk_mq_start_request from ->queue_rq
When we call blk_mq_start_request from the core blk-mq code before calling into ->queue_rq there is a racy window where the timeout handler can hit before we've fully set up the driver specific part of the command. Move the call to blk_mq_start_request into the driver so the driver can start the request only once it is fully set up. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block')
-rw-r--r--block/blk-mq.c13
1 files changed, 6 insertions, 7 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 32b4797f4186..141f2e06803a 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -384,7 +384,7 @@ void blk_mq_complete_request(struct request *rq)
}
EXPORT_SYMBOL(blk_mq_complete_request);
-static void blk_mq_start_request(struct request *rq)
+void blk_mq_start_request(struct request *rq)
{
struct request_queue *q = rq->q;
@@ -422,16 +422,18 @@ static void blk_mq_start_request(struct request *rq)
rq->nr_phys_segments++;
}
}
+EXPORT_SYMBOL(blk_mq_start_request);
static void __blk_mq_requeue_request(struct request *rq)
{
struct request_queue *q = rq->q;
trace_block_rq_requeue(q, rq);
- clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
- if (q->dma_drain_size && blk_rq_bytes(rq))
- rq->nr_phys_segments--;
+ if (test_and_clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
+ if (q->dma_drain_size && blk_rq_bytes(rq))
+ rq->nr_phys_segments--;
+ }
}
void blk_mq_requeue_request(struct request *rq)
@@ -743,8 +745,6 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
rq = list_first_entry(&rq_list, struct request, queuelist);
list_del_init(&rq->queuelist);
- blk_mq_start_request(rq);
-
ret = q->mq_ops->queue_rq(hctx, rq, list_empty(&rq_list));
switch (ret) {
case BLK_MQ_RQ_QUEUE_OK:
@@ -1186,7 +1186,6 @@ static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
int ret;
blk_mq_bio_to_request(rq, bio);
- blk_mq_start_request(rq);
/*
* For OK queue, we are done. For error, kill it. Any other