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From:   Jens Axboe <axboe@kernel.dk>
To:     linux-block@vger.kernel.org
Cc:     Jens Axboe <axboe@kernel.dk>
Subject: [PATCH 5/6] blk-mq: ensure mq_ops ->poll() is entered at least once
Date:   Fri, 23 Nov 2018 11:34:10 -0700
Message-Id: <20181123183411.8708-6-axboe@kernel.dk>
In-Reply-To: <20181123183411.8708-1-axboe@kernel.dk>
References: <20181123183411.8708-1-axboe@kernel.dk>
Sender: linux-block-owner@vger.kernel.org
Precedence: bulk

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 <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 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;
-- 
2.17.1