On Fri, Sep 22, 2017 at 03:14:05PM -0700, Bart Van Assche wrote:
> 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 <[email protected]>
> Cc: Martin K. Petersen <[email protected]>
> Cc: Ming Lei <[email protected]>
> Cc: Christoph Hellwig <[email protected]>
> Cc: Hannes Reinecke <[email protected]>
> Cc: Johannes Thumshirn <[email protected]>
> ---
>  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);
> +             }

Again, your patch doesn't fix scsi quiesce issue
on block legacy, either on suspend path or revalidate
path of transport spi.

-- 
Ming

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