Re: [PATCH v1 1/2] block: bypass blk_set_runtime_active for uninitialized q->dev

From: Jens Axboe <axboe@kernel.dk>
To: Stanley Chu <stanley.chu@mediatek.com>,
	linux-scsi@vger.kernel.org, linux-block@vger.kernel.org,
	martin.petersen@oracle.com, jejb@linux.ibm.com,
	matthias.bgg@gmail.com
Cc: linux-mediatek@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org, kuohong.wang@mediatek.com,
	peter.wang@mediatek.com, chun-hung.wu@mediatek.com,
	andy.teng@mediatek.com
Subject: Re: [PATCH v1 1/2] block: bypass blk_set_runtime_active for uninitialized q->dev
Date: Wed, 11 Sep 2019 16:13:16 -0600	[thread overview]
Message-ID: <66fddf12-0dc4-1c73-affd-f8404e87342f@kernel.dk> (raw)
In-Reply-To: <1568183562-18241-2-git-send-email-stanley.chu@mediatek.com>

On 9/11/19 12:32 AM, Stanley Chu wrote:
> Some devices may skip blk_pm_runtime_init() and have null pointer
> in its request_queue->dev. For example, SCSI devices of UFS Well-Known
> LUNs.
> 
> Currently the null pointer is checked by the user of
> blk_set_runtime_active(), i.e., scsi_dev_type_resume(). It is better to
> check it by blk_set_runtime_active() itself instead of by its users.
> 
> Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
> ---
>   block/blk-pm.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/block/blk-pm.c b/block/blk-pm.c
> index 0a028c189897..56ed94f7a2a3 100644
> --- a/block/blk-pm.c
> +++ b/block/blk-pm.c
> @@ -207,6 +207,9 @@ EXPORT_SYMBOL(blk_post_runtime_resume);
>    */
>   void blk_set_runtime_active(struct request_queue *q)
>   {
> +	if (!q->dev)
> +		return;
> +
>   	spin_lock_irq(&q->queue_lock);
>   	q->rpm_status = RPM_ACTIVE;
>   	pm_runtime_mark_last_busy(q->dev);

I'd prefer just doing:

	if (q->dev) {
		...
	}

instead. Other than that little complaint, looks good to me.

-- 
Jens Axboe