From aa61bec30eca11816789dc25c2090366b0ccfaf8 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 13 Nov 2018 21:32:10 -0700 Subject: [PATCH] blk-mq: ensure mq_ops ->poll() is entered at least once Right now we immediately bail if need_resched() is true, but we need to do at least one loop in case we have entries waiting. So just invert the need_resched() check, putting it at the bottom of the loop. Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe --- block/blk-mq.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index c2751f0a3ccc..ba3c7b6476b7 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -3375,7 +3375,7 @@ static int blk_mq_poll(struct request_queue *q, blk_qc_t cookie, bool spin) hctx->poll_considered++; state = current->state; - while (!need_resched()) { + do { int ret; hctx->poll_invoked++; @@ -3395,7 +3395,7 @@ static int blk_mq_poll(struct request_queue *q, blk_qc_t cookie, bool spin) if (ret < 0 || !spin) break; cpu_relax(); - } + } while (!need_resched()); __set_current_state(TASK_RUNNING); return 0;