Re: [PATCH v5 6/8] scsi: Only process PM requests if rpm_status != RPM_ACTIVE

[Can Guo <cang@codeaurora.org>]

On 2020-12-09 13:29, Bart Van Assche wrote:
> Instead of submitting all SCSI commands submitted with scsi_execute() 
> to a
> SCSI device if rpm_status != RPM_ACTIVE, only submit RQF_PM (power
> management requests) if rpm_status != RPM_ACTIVE. This patch makes the
> SCSI core handle the runtime power management status (rpm_status) as it
> should be handled.
> 
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Hannes Reinecke <hare@suse.de>
> Reviewed-by: Jens Axboe <axboe@kernel.dk>

Reviewed-by: Can Guo <cang@codeaurora.org>

> Cc: Can Guo <cang@codeaurora.org>
> Cc: Stanley Chu <stanley.chu@mediatek.com>
> Cc: Alan Stern <stern@rowland.harvard.edu>
> Cc: Ming Lei <ming.lei@redhat.com>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Cc: Martin Kepplinger <martin.kepplinger@puri.sm>
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> ---
>  drivers/scsi/scsi_lib.c | 27 ++++++++++++++-------------
>  1 file changed, 14 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index b7ac14571415..91bc39a4c3c3 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -249,7 +249,8 @@ int __scsi_execute(struct scsi_device *sdev, const
> unsigned char *cmd,
> 
>  	req = blk_get_request(sdev->request_queue,
>  			data_direction == DMA_TO_DEVICE ?
> -			REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, BLK_MQ_REQ_PREEMPT);
> +			REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN,
> +			rq_flags & RQF_PM ? BLK_MQ_REQ_PM : 0);
>  	if (IS_ERR(req))
>  		return ret;
>  	rq = scsi_req(req);
> @@ -1206,6 +1207,8 @@ static blk_status_t
>  scsi_device_state_check(struct scsi_device *sdev, struct request *req)
>  {
>  	switch (sdev->sdev_state) {
> +	case SDEV_CREATED:
> +		return BLK_STS_OK;
>  	case SDEV_OFFLINE:
>  	case SDEV_TRANSPORT_OFFLINE:
>  		/*
> @@ -1232,18 +1235,18 @@ scsi_device_state_check(struct scsi_device
> *sdev, struct request *req)
>  		return BLK_STS_RESOURCE;
>  	case SDEV_QUIESCE:
>  		/*
> -		 * If the devices is blocked we defer normal commands.
> +		 * If the device is blocked we only accept power management
> +		 * commands.
>  		 */
> -		if (req && !(req->rq_flags & RQF_PREEMPT))
> +		if (req && WARN_ON_ONCE(!(req->rq_flags & RQF_PM)))
>  			return BLK_STS_RESOURCE;
>  		return BLK_STS_OK;
>  	default:
>  		/*
>  		 * For any other not fully online state we only allow
> -		 * special commands.  In particular any user initiated
> -		 * command is not allowed.
> +		 * power management commands.
>  		 */
> -		if (req && !(req->rq_flags & RQF_PREEMPT))
> +		if (req && !(req->rq_flags & RQF_PM))
>  			return BLK_STS_IOERR;
>  		return BLK_STS_OK;
>  	}
> @@ -2517,15 +2520,13 @@ void sdev_evt_send_simple(struct scsi_device 
> *sdev,
>  EXPORT_SYMBOL_GPL(sdev_evt_send_simple);
> 
>  /**
> - *	scsi_device_quiesce - Block user issued commands.
> + *	scsi_device_quiesce - Block all commands except power management.
>   *	@sdev:	scsi device to quiesce.
>   *
>   *	This works by trying to transition to the SDEV_QUIESCE state
>   *	(which must be a legal transition).  When the device is in this
> - *	state, only special requests will be accepted, all others will
> - *	be deferred.  Since special requests may also be requeued requests,
> - *	a successful return doesn't guarantee the device will be
> - *	totally quiescent.
> + *	state, only power management requests will be accepted, all others 
> will
> + *	be deferred.
>   *
>   *	Must be called with user context, may sleep.
>   *
> @@ -2587,12 +2588,12 @@ void scsi_device_resume(struct scsi_device 
> *sdev)
>  	 * device deleted during suspend)
>  	 */
>  	mutex_lock(&sdev->state_mutex);
> +	if (sdev->sdev_state == SDEV_QUIESCE)
> +		scsi_device_set_state(sdev, SDEV_RUNNING);
>  	if (sdev->quiesced_by) {
>  		sdev->quiesced_by = NULL;
>  		blk_clear_pm_only(sdev->request_queue);
>  	}
> -	if (sdev->sdev_state == SDEV_QUIESCE)
> -		scsi_device_set_state(sdev, SDEV_RUNNING);
>  	mutex_unlock(&sdev->state_mutex);
>  }
>  EXPORT_SYMBOL(scsi_device_resume);