diff options
| author | Ming Lei <ming.lei@redhat.com> | 2017-06-18 14:24:27 -0600 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2017-06-18 14:24:27 -0600 |
| commit | f4560ffe8cec1361b1021d81aca6a4173f8e7c87 (patch) | |
| tree | 957cae770ed234d2e03fef8a6e458296f011369e /block/blk-mq-sched.c | |
| parent | f660174e8bcdb2bf99129f9f7c86e5fc0e830f85 (diff) | |
blk-mq: use QUEUE_FLAG_QUIESCED to quiesce queue
It is required that no dispatch can happen any more once
blk_mq_quiesce_queue() returns, and we don't have such requirement
on APIs of stopping queue.
But blk_mq_quiesce_queue() still may not block/drain dispatch in the
the case of BLK_MQ_S_START_ON_RUN, so use the new introduced flag of
QUEUE_FLAG_QUIESCED and evaluate it inside RCU read-side critical
sections for fixing this issue.
Also blk_mq_quiesce_queue() is implemented via stopping queue, which
limits its uses, and easy to cause race, because any queue restart in
other paths may break blk_mq_quiesce_queue(). With the introduced
flag of QUEUE_FLAG_QUIESCED, we don't need to depend on stopping queue
for quiescing any more.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-mq-sched.c')
| -rw-r--r-- | block/blk-mq-sched.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c index 254d1c164567..9f025289da63 100644 --- a/block/blk-mq-sched.c +++ b/block/blk-mq-sched.c @@ -58,7 +58,8 @@ void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx) bool did_work = false; LIST_HEAD(rq_list); - if (unlikely(blk_mq_hctx_stopped(hctx))) + /* RCU or SRCU read lock is needed before checking quiesced flag */ + if (unlikely(blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q))) return; hctx->run++; |