linux-kernel - Re: [PATCH v2 1/2] scsi: core: cleanup scsi_dev_queue

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Date:   Tue, 17 Oct 2023 14:15:34 -0700
From:   Bart Van Assche <bvanassche@....org>
To:     Wenchao Hao <haowenchao2@...wei.com>,
        "James E . J . Bottomley" <jejb@...ux.ibm.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        linux-scsi@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, louhongxiang@...wei.com
Subject: Re: [PATCH v2 1/2] scsi: core: cleanup scsi_dev_queue_ready()

On 10/15/23 19:08, Wenchao Hao wrote:
> +	/*
> +	 * device_blocked is not set at mostly time, so check it first
> +	 * and return token when it is not set.
> +	 */
> +	if (!atomic_read(&sdev->device_blocked))
> +		return token;

This patch looks like an improvement to me. But I don't think that the
above comment is useful. I propose to move it into the patch
description.

> -		/*
> -		 * unblock after device_blocked iterates to zero
> -		 */
> -		if (atomic_dec_return(&sdev->device_blocked) > 0)
> -			goto out_dec;
> -		SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev,
> -				   "unblocking device at zero depth\n"));
> +	/*
> +	 * unblock after device_blocked iterates to zero
> +	 */
 > +	if (scsi_device_busy(sdev) > 1 ||
 > +	    atomic_dec_return(&sdev->device_blocked) > 0) {
 > +		sbitmap_put(&sdev->budget_map, token);
 > +		return -1;
 >   	}

Please make the above comment match the new code, e.g. by changing it
into the following: "Only unblock if no other commands are pending and
if device_blocked has decreased to zero".

Thanks,

Bart.