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>
This commit is contained in:
Christoph Hellwig 2014-09-13 16:40:09 -07:00 committed by Jens Axboe
parent bf57229745
commit e2490073cd
6 changed files with 14 additions and 7 deletions

View File

@ -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

View File

@ -3783,6 +3783,8 @@ static int mtip_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *rq,
if (unlikely(mtip_check_unal_depth(hctx, rq)))
return BLK_MQ_RQ_QUEUE_BUSY;
blk_mq_start_request(rq);
ret = mtip_submit_request(hctx, rq);
if (likely(!ret))
return BLK_MQ_RQ_QUEUE_OK;

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@ -321,6 +321,8 @@ static int null_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *rq,
cmd->rq = rq;
cmd->nq = hctx->driver_data;
blk_mq_start_request(rq);
null_handle_cmd(cmd);
return BLK_MQ_RQ_QUEUE_OK;
}

View File

@ -205,6 +205,8 @@ static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req,
}
}
blk_mq_start_request(req);
num = blk_rq_map_sg(hctx->queue, vbr->req, vbr->sg);
if (num) {
if (rq_data_dir(vbr->req) == WRITE)

View File

@ -1890,6 +1890,7 @@ static int scsi_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req,
scsi_init_cmd_errh(cmd);
cmd->scsi_done = scsi_mq_done;
blk_mq_start_request(req);
reason = scsi_dispatch_cmd(cmd);
if (reason) {
scsi_set_blocked(cmd, reason);

View File

@ -159,6 +159,7 @@ struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag);
struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *, const int ctx_index);
struct blk_mq_hw_ctx *blk_mq_alloc_single_hw_queue(struct blk_mq_tag_set *, unsigned int, int);
void blk_mq_start_request(struct request *rq);
void blk_mq_end_io(struct request *rq, int error);
void __blk_mq_end_io(struct request *rq, int error);