Re: Patch "ata: sata_mv, avoid trigerrable BUG_ON" has been added to the 4.4-stable tree

[Greg KH <greg@kroah.com>]

On Tue, Sep 29, 2020 at 08:33:24AM +0200, Jiri Slaby wrote:
> On 28. 09. 20, 14:30, Greg KH wrote:
> >> commit 4b308d858a1a34dae1e38948f2c0497161d9ddd8
> >> Author: Jiri Slaby <jslaby@suse.cz>
> >> Date:   Thu Oct 31 10:59:46 2019 +0100
> >>
> >>     ata: sata_mv, avoid trigerrable BUG_ON
> >>     
> >>     [ Upstream commit e9f691d899188679746eeb96e6cb520459eda9b4 ]
> >>     
> >>     There are several reports that the BUG_ON on unsupported command in
> >>     mv_qc_prep can be triggered under some circumstances:
> >>     https://bugzilla.suse.com/show_bug.cgi?id=1110252
> >>     https://serverfault.com/questions/888897/raid-problems-after-power-outage
> >>     https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1652185
> >>     https://bugs.centos.org/view.php?id=14998
> >>     
> >>     Let sata_mv handle the failure gracefully: warn about that incl. the
> >>     failed command number and return an AC_ERR_INVALID error. We can do that
> >>     now thanks to the previous patch.
> >>     
> >>     Remove also the long-standing FIXME.
> >>     
> >>     [v2] use %.2x as commands are defined as hexa.
> >>     
> >>     Signed-off-by: Jiri Slaby <jslaby@suse.cz>
> >>     Cc: Jens Axboe <axboe@kernel.dk>
> >>     Cc: linux-ide@vger.kernel.org
> >>     Cc: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
> >>     Signed-off-by: Jens Axboe <axboe@kernel.dk>
> >>     Signed-off-by: Sasha Levin <sashal@kernel.org>
> >>
> >> diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
> >> index 729f26322095e..c24bbdb3f76c8 100644
> >> --- a/drivers/ata/sata_mv.c
> >> +++ b/drivers/ata/sata_mv.c
> >> @@ -2113,12 +2113,10 @@ static void mv_qc_prep(struct ata_queued_cmd *qc)
> >>  		 * non-NCQ mode are: [RW] STREAM DMA and W DMA FUA EXT, none
> >>  		 * of which are defined/used by Linux.  If we get here, this
> >>  		 * driver needs work.
> >> -		 *
> >> -		 * FIXME: modify libata to give qc_prep a return value and
> >> -		 * return error here.
> >>  		 */
> >> -		BUG_ON(tf->command);
> >> -		break;
> >> +		ata_port_err(ap, "%s: unsupported command: %.2x\n", __func__,
> >> +				tf->command);
> >> +		return AC_ERR_INVALID;
> >>  	}
> >>  	mv_crqb_pack_cmd(cw++, tf->nsect, ATA_REG_NSECT, 0);
> >>  	mv_crqb_pack_cmd(cw++, tf->hob_lbal, ATA_REG_LBAL, 0);
> > 
> > This causes a build warning as you can not return a value for a void
> > function :(
> 
> Sure, you need the patch before, i.e. e9f691d899^:
> commit 95364f36701e62dd50eee91e1303187fd1a9f567
> Author: Jiri Slaby <jirislaby@kernel.org>
> Date:   Thu Oct 31 10:59:45 2019 +0100
> 
>     ata: make qc_prep return ata_completion_errors
> 
> 
> 
> And that needs one more patch e9f691d899^^:
> 
> commit 25937580a5065d6fbd92d9c8ebd47145ad80052e
> Author: Jiri Slaby <jirislaby@kernel.org>
> Date:   Thu Oct 31 10:59:44 2019 +0100
> 
>     ata: define AC_ERR_OK

Thanks, that worked!

greg k-h