From mboxrd@z Thu Jan 1 00:00:00 1970 From: Geert Uytterhoeven Subject: Re: Patch "sd: Disable support for 256 byte/sector disks" has been added to the 4.0-stable tree Date: Wed, 3 Jun 2015 16:37:46 +0200 Message-ID: References: <14333133244847@kroah.com> <556EC8F4.7030507@suse.cz> <1433338620.2251.57.camel@Odin.com> <1433339669.2251.61.camel@HansenPartnership.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: Received: from mail-oi0-f51.google.com ([209.85.218.51]:36036 "EHLO mail-oi0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932258AbbFCOhr (ORCPT ); Wed, 3 Jun 2015 10:37:47 -0400 In-Reply-To: <1433339669.2251.61.camel@HansenPartnership.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: "jslaby@suse.cz" , "linux-scsi@vger.kernel.org" , "dmarkh@cfl.rr.com" , "hare@suse.de" , "gregkh@linuxfoundation.org" , "stable@vger.kernel.org" , "stable-commits@vger.kernel.org" On Wed, Jun 3, 2015 at 3:54 PM, James Bottomley wrote: > On Wed, 2015-06-03 at 13:37 +0000, James Bottomley wrote: >> On Wed, 2015-06-03 at 11:29 +0200, Jiri Slaby wrote: >> > On 06/03/2015, 08:35 AM, gregkh@linuxfoundation.org wrote: >> > > From 74856fbf441929918c49ff262ace9835048e4e6a Mon Sep 17 00:00:00 2001 >> > > From: Mark Hounschell >> > > Date: Wed, 13 May 2015 10:49:09 +0200 >> > > Subject: sd: Disable support for 256 byte/sector disks >> > > >> > > From: Mark Hounschell >> > > >> > > commit 74856fbf441929918c49ff262ace9835048e4e6a upstream. >> > > >> > > 256 bytes per sector support has been broken since 2.6.X, >> > > and no-one stepped up to fix this. >> > > So disable support for it. >> > > >> > > Signed-off-by: Mark Hounschell >> > > Signed-off-by: Hannes Reinecke >> > > Signed-off-by: James Bottomley >> > > Signed-off-by: Greg Kroah-Hartman >> > > >> > > --- >> > > drivers/scsi/sd.c | 19 +++++-------------- >> > > 1 file changed, 5 insertions(+), 14 deletions(-) >> > > >> > > --- a/drivers/scsi/sd.c >> > > +++ b/drivers/scsi/sd.c >> > > @@ -1624,6 +1624,7 @@ static unsigned int sd_completed_bytes(s >> > > { >> > > u64 start_lba = blk_rq_pos(scmd->request); >> > > u64 end_lba = blk_rq_pos(scmd->request) + (scsi_bufflen(scmd) / 512); >> > > + u64 factor = scmd->device->sector_size / 512; >> > > u64 bad_lba; >> > > int info_valid; >> > > /* >> > > @@ -1645,16 +1646,9 @@ static unsigned int sd_completed_bytes(s >> > > if (scsi_bufflen(scmd) <= scmd->device->sector_size) >> > > return 0; >> > > >> > > - if (scmd->device->sector_size < 512) { >> > > - /* only legitimate sector_size here is 256 */ >> > > - start_lba <<= 1; >> > > - end_lba <<= 1; >> > > - } else { >> > > - /* be careful ... don't want any overflows */ >> > > - unsigned int factor = scmd->device->sector_size / 512; >> > > - do_div(start_lba, factor); >> > > - do_div(end_lba, factor); >> > > - } >> > >> > Hmm, you do 'unsigned int' -> 'u64' switch of factor type here. But this >> > commit: >> > commit ef80d1e18b014af08741cf688e3fdda1fb71363f >> > Author: Geert Uytterhoeven >> > Date: Mon Nov 4 10:21:05 2013 +0100 >> > >> > [SCSI] sd: Do not call do_div() with a 64-bit divisor >> > >> > did the switch in the opposite direction deliberately. >> > >> > So why did you do the change, given sector_size is uint? >> >> Primarily because no-one spotted the reversal and none of the static >> checkers warns about it. >> >> This is the trivial fix, but we should do something about the checkers. > > Actually, I think there's no problem: all the architectures now have the > correct conversion of the base argument. > > Author: Andreas Schwab > Date: Fri Aug 9 15:14:08 2013 +0200 > > m68k: Truncate base in do_div() > > Fixed this in m68k, which was the last one, so it looks like there's no > issue and ef80d1e18b014af08741cf688e3fdda1fb71363f was pointless. FWIW, "[PATCH] mn10300: Truncate base in do_div()" (http://lkml.iu.edu/hypermail/linux/kernel/1308.2/03544.html) hasn't been applied yet. But as mn10300 is little endian, it shouldn't suffer from the bug like m68k did. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds