Commit e2490073 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

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: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent bf572297

block/blk-mq.c

+6 −7
Original line number Diff line number Diff line
@@ -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;
@@ -422,17 +422,19 @@ 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 (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

drivers/block/mtip32xx/mtip32xx.c

+2 −0
Original line number Diff line number Diff line
@@ -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;

drivers/block/null_blk.c

+2 −0
Original line number Diff line number Diff line
@@ -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;

}

drivers/block/virtio_blk.c

+2 −0
Original line number Diff line number Diff line
@@ -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)

drivers/scsi/scsi_lib.c

+1 −0
Original line number Diff line number Diff line
@@ -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);

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