From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Bart Van Assche To: Jens Axboe Cc: linux-block@vger.kernel.org, Christoph Hellwig , "Martin K . Petersen" , =Oleksandr Natalenko , Bart Van Assche , Ming Lei , Hannes Reinecke , Johannes Thumshirn Subject: [PATCH v3 6/6] scsi-mq: Reduce suspend latency Date: Fri, 22 Sep 2017 15:14:05 -0700 Message-Id: <20170922221405.22091-7-bart.vanassche@wdc.com> In-Reply-To: <20170922221405.22091-1-bart.vanassche@wdc.com> References: <20170922221405.22091-1-bart.vanassche@wdc.com> List-ID: Avoid that it can take 200 ms too long to wait for requests to finish. Note: blk_mq_freeze_queue() uses a wait queue to wait for ongoing requests to finish. Signed-off-by: Bart Van Assche Cc: Martin K. Petersen Cc: Ming Lei Cc: Christoph Hellwig Cc: Hannes Reinecke Cc: Johannes Thumshirn --- drivers/scsi/scsi_lib.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index ca84fd2d93ea..c5e66bb0c94d 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -2939,10 +2939,20 @@ scsi_device_quiesce(struct scsi_device *sdev) if (err) return err; - scsi_run_queue(q); - while (atomic_read(&sdev->device_busy)) { - msleep_interruptible(200); + if (q->mq_ops) { + /* + * Ensure write order of the PREEMPT_ONLY queue flag and + * q_usage_counter. See also blk_queue_enter(). + */ + smp_wmb(); + blk_mq_freeze_queue(q); + blk_mq_unfreeze_queue(q); + } else { scsi_run_queue(q); + while (atomic_read(&sdev->device_busy)) { + msleep_interruptible(200); + scsi_run_queue(q); + } } return 0; } -- 2.14.1