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

[Greg KH <greg@kroah.com>]

On Mon, Sep 28, 2020 at 02:30:57PM +0200, Greg KH wrote:
> On Sun, Sep 27, 2020 at 02:11:18PM -0400, Sasha Levin wrote:
> > This is a note to let you know that I've just added the patch titled
> > 
> >     ata: sata_mv, avoid trigerrable BUG_ON
> > 
> > to the 4.4-stable tree which can be found at:
> >     http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
> > 
> > The filename of the patch is:
> >      ata-sata_mv-avoid-trigerrable-bug_on.patch
> > and it can be found in the queue-4.4 subdirectory.
> > 
> > If you, or anyone else, feels it should not be added to the stable tree,
> > please let <stable@vger.kernel.org> know about it.
> > 
> > 
> > 
> > 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 :(
> 
> I'll drop it from the 4.4 queue now, thanks,

Also dropped from 4.9, 4.14, 4.19, and 5.4 queues for the same issue.

thanks,

greg k-h