diff options
| author | Jens Axboe <axboe@fb.com> | 2017-03-30 12:30:39 -0600 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2017-03-30 12:30:39 -0600 |
| commit | bf4907c05e615f6a1811d61c58d56da52f7e9954 (patch) | |
| tree | e63fd10fd38137403a56861e03bff6f1677d1ba7 /block | |
| parent | 47d752076a92c67f548faa018efd7d4ac51f17f7 (diff) | |
blk-mq: fix schedule-under-preempt for blocking drivers
Commit a4d907b6a33b unified the single and multi queue request handlers,
but in the process, it also screwed up the locking balance and calls
blk_mq_try_issue_directly() with the ctx preempt lock held. This is a
problem for drivers that have set BLK_MQ_F_BLOCKING, since now they
can't reliably sleep.
While in there, protect against similar issues in the future, by adding
a might_sleep() trigger in the BLOCKING path for direct issue or queue
run.
Reported-by: Josef Bacik <josef@toxicpanda.com>
Tested-by: Josef Bacik <josef@toxicpanda.com>
Fixes: a4d907b6a33b ("blk-mq: streamline blk_mq_make_request")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-mq.c | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c index ef63367077ad..061fc2cc88d3 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1121,6 +1121,8 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx) blk_mq_sched_dispatch_requests(hctx); rcu_read_unlock(); } else { + might_sleep(); + srcu_idx = srcu_read_lock(&hctx->queue_rq_srcu); blk_mq_sched_dispatch_requests(hctx); srcu_read_unlock(&hctx->queue_rq_srcu, srcu_idx); @@ -1495,7 +1497,11 @@ static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, __blk_mq_try_issue_directly(rq, cookie, false); rcu_read_unlock(); } else { - unsigned int srcu_idx = srcu_read_lock(&hctx->queue_rq_srcu); + unsigned int srcu_idx; + + might_sleep(); + + srcu_idx = srcu_read_lock(&hctx->queue_rq_srcu); __blk_mq_try_issue_directly(rq, cookie, true); srcu_read_unlock(&hctx->queue_rq_srcu, srcu_idx); } @@ -1595,18 +1601,23 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) list_del_init(&same_queue_rq->queuelist); list_add_tail(&rq->queuelist, &plug->mq_list); + blk_mq_put_ctx(data.ctx); + if (same_queue_rq) blk_mq_try_issue_directly(data.hctx, same_queue_rq, &cookie); + + return cookie; } else if (q->nr_hw_queues > 1 && is_sync) { + blk_mq_put_ctx(data.ctx); blk_mq_bio_to_request(rq, bio); blk_mq_try_issue_directly(data.hctx, rq, &cookie); + return cookie; } else if (q->elevator) { blk_mq_bio_to_request(rq, bio); blk_mq_sched_insert_request(rq, false, true, true, true); - } else if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) { + } else if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) blk_mq_run_hw_queue(data.hctx, true); - } blk_mq_put_ctx(data.ctx); return cookie; |