2023-10-16 02:09:25

by Wenchao Hao

Subject: [PATCH v2 1/2] scsi: core: cleanup scsi_dev_queue_ready()

This is just a cleanup for scsi_dev_queue_ready() to avoid
redundant goto and if statement, it did not change the origin
logic.

Signed-off-by: Wenchao Hao <[email protected]>
---
drivers/scsi/scsi_lib.c | 35 ++++++++++++++++++-----------------
1 file changed, 18 insertions(+), 17 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 40f407ffd26f..b179c24f9c76 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1250,28 +1250,29 @@ static inline int scsi_dev_queue_ready(struct request_queue *q,
int token;

token = sbitmap_get(&sdev->budget_map);
- if (atomic_read(&sdev->device_blocked)) {
- if (token < 0)
- goto out;
+ if (token < 0)
+ return -1;

- if (scsi_device_busy(sdev) > 1)
- goto out_dec;
+ /*
+ * 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;

- /*
- * 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;
}

+ SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev,
+ "unblocking device at zero depth\n"));
+
return token;
-out_dec:
- if (token >= 0)
- sbitmap_put(&sdev->budget_map, token);
-out:
- return -1;
}

/*
--
2.32.0

2023-10-17 21:16:03

by Bart Van Assche

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.

2023-10-18 02:22:31

by Wenchao Hao

Subject: Re: [PATCH v2 1/2] scsi: core: cleanup scsi_dev_queue_ready()

On 2023/10/18 5:15, Bart Van Assche wrote:
> 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".
>

OK, would update.

Thanks.

> Thanks,
>
> Bart.
>