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Tue, 14 Jul 2020 23:29:46 -0700 (PDT) Date: Wed, 15 Jul 2020 07:29:44 +0100 From: Lee Jones To: James Bottomley Cc: Hannes Reinecke , martin.petersen@oracle.com, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, Hannes Reinecke Subject: Re: [PATCH v2 24/24] scsi: aic7xxx: aic79xx_osm: Remove set but unused variabes 'saved_scsiid' and 'saved_modes' Message-ID: <20200715062944.GM1398296@dell> References: <20200713080001.128044-1-lee.jones@linaro.org> <20200713080001.128044-25-lee.jones@linaro.org> <559e47de-fa26-9ae5-a3c5-4adeae606309@suse.de> <1594741430.4545.15.camel@linux.ibm.com> <20200714213951.GL1398296@dell> <1594767794.14804.21.camel@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1594767794.14804.21.camel@linux.ibm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 14 Jul 2020, James Bottomley wrote: > On Tue, 2020-07-14 at 22:39 +0100, Lee Jones wrote: > > On Tue, 14 Jul 2020, James Bottomley wrote: > > > > > On Tue, 2020-07-14 at 09:46 +0200, Hannes Reinecke wrote: > > > > On 7/13/20 10:00 AM, 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 > > > > > Signed-off-by: Lee Jones > > > > > --- > > > > > drivers/scsi/aic7xxx/aic79xx_osm.c | 4 ---- > > > > > 1 file changed, 4 deletions(-) > > > > > > > > > > diff --git a/drivers/scsi/aic7xxx/aic79xx_osm.c > > > > > b/drivers/scsi/aic7xxx/aic79xx_osm.c > > > > > index 3782a20d58885..140c4e74ddd7e 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 +2237,6 @@ ahd_linux_queue_abort_cmd(struct > > > > > scsi_cmnd > > > > > *cmd) > > > > > goto done; > > > > > } > > > > > > > > > > - saved_modes = ahd_save_modes(ahd); > > > > > ahd_set_modes(ahd, AHD_MODE_SCSI, AHD_MODE_SCSI); > > > > > last_phase = ahd_inb(ahd, LASTPHASE); > > > > > saved_scbptr = ahd_get_scbptr(ahd); > > > > > @@ -2257,7 +2254,6 @@ 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); > > > > > if (last_phase != P_BUSFREE > > > > > && SCB_GET_TAG(pending_scb) == active_scbptr) { > > > > > > > > > > > > > > > > > > Reviewed-by: Hannes Reinecke > > > > > > Hey, you don't get to do that ... I asked you to figure out why > > > we're missing an ahd_restore_modes(). Removing the > > > ahd_save_modes() is cosmetic: it gets rid of a warning but doesn't > > > fix the problem. I'd rather keep the warning until the problem is > > > fixed and the problem is we need a mode save/restore around the > > > ahd_set_modes() which is only partially implemented in this > > > function. > > > > I had a look. Traced it back to the dawn of time (time == Git), then > > delved even further back by downloading and trawling through ~10-15 > > tarballs. It looks as though drivers/scsi/aic7xxx/aic79xx_osm.c was > > upstreamed in v2.5.60, nearly 20 years ago. 'saved_modes' has been > > unused since at least then. If no one has complained in 2 decades, > > I'd say it probably isn't an issue worth perusing. > > Well, we have what looks like a fix now. The reason it matters is that > if the bus is not in AHD_MODE_SCSI when the routine is called, it ends > up being in a wrong state when the routine exits, so you abort one > command and screw up another. Ultimately I bet escalation to bus reset > fixes it, so everything appears to work, but it might have worked a lot > better if the original mode were restored. > > This is error handling code, so most installations run just fine > without ever invoking it. Understood. Obviously a *real* fix is better than this warning suppression one. I was just explaining that, try as I might, I couldn't find any non-broken code to use to use as a reference to author a proper fix for this. This being the first mail in my inbox, so I don't know if the proper fix you reference above was a) sent as a patch and/or b) sent to me, but it's great news that you have one either way. Please drop this patch. -- Lee Jones [李琼斯] Senior Technical Lead - Developer Services Linaro.org │ Open source software for Arm SoCs Follow Linaro: Facebook | Twitter | Blog