linux-kernel - Re: [PATCH][next] scsi: scsi_debug: remove a redundant assignment to variable ret

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Message-ID: <a2515a3d-1dbb-48b6-a489-25aba3358068@stanley.mountain>
Date: Thu, 17 Oct 2024 11:57:10 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: John Garry <john.g.garry@...cle.com>
Cc: Colin Ian King <colin.i.king@...il.com>,
	"James E . J . Bottomley" <James.Bottomley@...senpartnership.com>,
	"Martin K . Petersen" <martin.petersen@...cle.com>,
	linux-scsi@...r.kernel.org, kernel-janitors@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] scsi: scsi_debug: remove a redundant assignment to
 variable ret

On Wed, Oct 16, 2024 at 08:16:16AM +0100, John Garry wrote:
> On 02/10/2024 16:10, Dan Carpenter wrote:
> > On Wed, Oct 02, 2024 at 02:50:43PM +0100, Colin Ian King wrote:
> > > The variable ret is being assigned a value that is never read, the
> > > following break statement exits the loop where ret is being re-assigned
> > > a new value. Remove the redundant assignment.
> > > 
> > > Signed-off-by: Colin Ian King<colin.i.king@...il.com>
> > > ---
> > >   drivers/scsi/scsi_debug.c | 4 +---
> > >   1 file changed, 1 insertion(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
> > > index d95f417e24c0..7c60f5acc4a3 100644
> > > --- a/drivers/scsi/scsi_debug.c
> > > +++ b/drivers/scsi/scsi_debug.c
> > > @@ -3686,14 +3686,12 @@ static int do_device_access(struct sdeb_store_info *sip, struct scsi_cmnd *scp,
> > >   		sdeb_data_sector_lock(sip, do_write);
> > >   		ret = sg_copy_buffer(sdb->table.sgl, sdb->table.nents,
> > You would think there would be a:
> > 
> > 	total += ret;
> > 
> > here.
> > 
> > >   		   fsp + (block * sdebug_sector_size),
> > >   		   sdebug_sector_size, sg_skip, do_write);T
> > >   		sdeb_data_sector_unlock(sip, do_write);
> > > -		if (ret != sdebug_sector_size) {
> > > -			ret += (i * sdebug_sector_size);
> > > +		if (ret != sdebug_sector_size)
> > >   			break;
> > > -		}
> > >   		sg_skip += sdebug_sector_size;
> > >   		if (++block >= sdebug_store_sectors)
> > >   			block = 0;
> > >   	}
> > >   	ret = num * sdebug_sector_size;
> >          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > And that this would be a "return total;"
> 
> Right, the function is currently a little messy as there is no variable for
> "total", and we re-assign ret per loop.
> 
> So I think that we can either:
> a. introduce a variable to hold "total"
> b. this change:
> 
> diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
> index af5e3a7f47a9..39218ffc6a31 100644
> --- a/drivers/scsi/scsi_debug.c
> +++ b/drivers/scsi/scsi_debug.c
> @@ -3690,13 +3690,14 @@ static int do_device_access(struct
> sdeb_store_info *sip, struct scsi_cmnd *scp,
>                sdeb_data_sector_unlock(sip, do_write);
>                if (ret != sdebug_sector_size) {
>                        ret += (i * sdebug_sector_size);
> -                       break;
> +                       goto out_unlock;
>                }
>                sg_skip += sdebug_sector_size;
>                if (++block >= sdebug_store_sectors)
>                        block = 0;
>        }
>        ret = num * sdebug_sector_size;
> +out_unlock:
>        sdeb_data_unlock(sip, atomic);
> 
> 
> Maybe a. is better, as b. is maintaining some messiness.
> 

I'm happy with option a.

regards,
dan carpenter