linux-kernel - [PATCH v4 4/4] Revert "scsi: core: run queue if SCSI device queue isn't ready and queue is idle"

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Message-Id: <20200408080255.v4.4.I630e6ca4cdcf9ab13ea899274745f9e3174eb12b@changeid>
Date:   Wed,  8 Apr 2020 08:04:02 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     axboe@...nel.dk, jejb@...ux.ibm.com, martin.petersen@...cle.com
Cc:     paolo.valente@...aro.org, groeck@...omium.org,
        Gwendal Grignou <gwendal@...omium.org>,
        linux-scsi@...r.kernel.org, linux-block@...r.kernel.org,
        Ming Lei <ming.lei@...hat.com>, sqazi@...gle.com,
        Douglas Anderson <dianders@...omium.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v4 4/4] Revert "scsi: core: run queue if SCSI device queue isn't ready and queue is idle"

This reverts commit 7e70aa789d4a0c89dbfbd2c8a974a4df717475ec.

Now that we have the patches ("blk-mq: In blk_mq_dispatch_rq_list()
"no budget" is a reason to kick") and ("blk-mq: Rerun dispatching in
the case of budget contention") we should no longer need the fix in
the SCSI code.  Revert it, resolving conflicts with other patches that
have touched this code.

With this revert (and the two new patches) I can run the script that
was in commit 7e70aa789d4a ("scsi: core: run queue if SCSI device
queue isn't ready and queue is idle") in a loop with no failure.  If I
do this revert without the two new patches I can easily get a failure.

Signed-off-by: Douglas Anderson <dianders@...omium.org>
---
I don't know for sure that we can revert this patch, but in the very
least the original test case now passes.  If there is any question
about this, we can just drop this patch.

Changes in v4: None
Changes in v3:
- ("Revert "scsi: core: run queue...") new for v3.

Changes in v2: None

 drivers/scsi/scsi_lib.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 610ee41fa54c..b9e28ea76cc0 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1632,12 +1632,7 @@ static bool scsi_mq_get_budget(struct blk_mq_hw_ctx *hctx)
 	struct request_queue *q = hctx->queue;
 	struct scsi_device *sdev = q->queuedata;
 
-	if (scsi_dev_queue_ready(q, sdev))
-		return true;
-
-	if (atomic_read(&sdev->device_busy) == 0 && !scsi_device_blocked(sdev))
-		blk_mq_delay_run_hw_queue(hctx, SCSI_QUEUE_DELAY);
-	return false;
+	return scsi_dev_queue_ready(q, sdev);
 }
 
 static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
-- 
2.26.0.292.g33ef6b2f38-goog