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

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Date:   Tue, 29 Sep 2020 08:33:24 +0200
From:   Jiri Slaby <jirislaby@...nel.org>
To:     Greg KH <greg@...ah.com>, linux-kernel@...r.kernel.org
Cc:     stable-commits@...r.kernel.org
Subject: Re: Patch "ata: sata_mv, avoid trigerrable BUG_ON" has been added to
 the 4.4-stable tree

On 28. 09. 20, 14:30, Greg KH wrote:
>> commit 4b308d858a1a34dae1e38948f2c0497161d9ddd8
>> Author: Jiri Slaby <jslaby@...e.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@...e.cz>
>>     Cc: Jens Axboe <axboe@...nel.dk>
>>     Cc: linux-ide@...r.kernel.org
>>     Cc: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
>>     Signed-off-by: Jens Axboe <axboe@...nel.dk>
>>     Signed-off-by: Sasha Levin <sashal@...nel.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@...nel.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@...nel.org>
Date:   Thu Oct 31 10:59:44 2019 +0100

    ata: define AC_ERR_OK

thanks,
-- 
js
suse labs