linux-kernel - Re: [PATCH 24/24] scsi: aic7xxx: aic79xx_osm: Remove set but unused variabes 'saved_scsiid' and 'saved

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Date:   Thu, 09 Jul 2020 11:14:03 -0700
From:   James Bottomley <jejb@...ux.ibm.com>
To:     Lee Jones <lee.jones@...aro.org>, martin.petersen@...cle.com,
        linux-scsi@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Hannes Reinecke <hare@...e.com>
Subject: Re: [PATCH 24/24] scsi: aic7xxx: aic79xx_osm: Remove set but unused
 variabes 'saved_scsiid' and 'saved_modes'

On Thu, 2020-07-09 at 18:45 +0100, Lee Jones wrote:
> Haven't been used since 2006.
> 
> Fixes the following W=1 kernel build warning(s):
> 
>  drivers/scsi/aic7xxx/aic79xx_osm.c: In function
> ‘ahd_linux_queue_abort_cmd’:
>  drivers/scsi/aic7xxx/aic79xx_osm.c:2155:17: warning: variable
> ‘saved_modes’ set but not used [-Wunused-but-set-variable]
>  drivers/scsi/aic7xxx/aic79xx_osm.c:2148:9: warning: variable
> ‘saved_scsiid’ set but not used [-Wunused-but-set-variable]
> 
> Cc: Hannes Reinecke <hare@...e.com>
> Signed-off-by: Lee Jones <lee.jones@...aro.org>
> ---
>  drivers/scsi/aic7xxx/aic79xx_osm.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/scsi/aic7xxx/aic79xx_osm.c
> b/drivers/scsi/aic7xxx/aic79xx_osm.c
> index 3782a20d58885..b0c6701f64a83 100644
> --- a/drivers/scsi/aic7xxx/aic79xx_osm.c
> +++ b/drivers/scsi/aic7xxx/aic79xx_osm.c
> @@ -2141,14 +2141,12 @@ ahd_linux_queue_abort_cmd(struct scsi_cmnd
> *cmd)
>  	u_int  saved_scbptr;
>  	u_int  active_scbptr;
>  	u_int  last_phase;
> -	u_int  saved_scsiid;
>  	u_int  cdb_byte;
>  	int    retval;
>  	int    was_paused;
>  	int    paused;
>  	int    wait;
>  	int    disconnected;
> -	ahd_mode_state saved_modes;
>  	unsigned long flags;
>  
>  	pending_scb = NULL;
> @@ -2239,7 +2237,7 @@ ahd_linux_queue_abort_cmd(struct scsi_cmnd
> *cmd)
>  		goto done;
>  	}
>  
> -	saved_modes = ahd_save_modes(ahd);
> +	ahd_save_modes(ahd);

Well, this is clearly wrong, since ahd_save_modes has no side effects.

However, I think it also means there's a bug in this code:

>  	ahd_set_modes(ahd, AHD_MODE_SCSI, AHD_MODE_SCSI);

You can't do this without later restoring the mode, so someone needs to
figure out where the missing ahd_restore_modes() should go.

>  	last_phase = ahd_inb(ahd, LASTPHASE);
>  	saved_scbptr = ahd_get_scbptr(ahd);
> @@ -2257,7 +2255,7 @@ ahd_linux_queue_abort_cmd(struct scsi_cmnd
> *cmd)
>  	 * passed in command.  That command is currently active on
> the
>  	 * bus or is in the disconnected state.
>  	 */
> -	saved_scsiid = ahd_inb(ahd, SAVED_SCSIID);
> +	ahd_inb(ahd, SAVED_SCSIID);

I think this can just go.

James