lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Date:	Mon, 4 Nov 2013 19:56:54 -0500
From:	Mike Snitzer <snitzer@...hat.com>
To:	Mikulas Patocka <mpatocka@...hat.com>
Cc:	axboe@...nel.dk, kmo@...erainc.com, dm-devel@...hat.com,
	agk@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH for-next] dm: fix missing bi_remaining accounting

On Mon, Nov 04 2013 at 12:49pm -0500,
Mikulas Patocka <mpatocka@...hat.com> wrote:

> 
> 
> On Mon, 4 Nov 2013, Mike Snitzer wrote:
> 
> > On Mon, Nov 04 2013 at 10:25am -0500,
> > Mikulas Patocka <mpatocka@...hat.com> wrote:
> > 
> > > 
> > > 
> > > On Mon, 4 Nov 2013, Mike Snitzer wrote:
> > > 
> > > > On Mon, Nov 04 2013 at 10:06am -0500,
> > > > Mikulas Patocka <mpatocka@...hat.com> wrote:
> > > > > 
> > > > > The code uses atomic_inc for restoration of bi_remaining. This patch
> > > > > changes it to atomic_set(1) to avoid an interlocked instruction. In the
> > > > > target's bi_endio routine we are sure that bi_remaining is zero
> > > > > (otherwise, the bi_endio routine wouldn't be called) and there are no
> > > > > concurrent users of the bio, so we can replace atomic_inc with
> > > > > atomic_set(1).
> > > > 
> > > > This isn't DM-specific.  Shouldn't the other places in the tree that use
> > > > atomic_inc on bi_remaining should really be converted at the same time?
> > > 
> > > There is no 'atomic_inc.*bi_remaining' in other drivers.
> > 
> > Wrong.  I know btrfs has at least one.  As does bcache afaik.
> 
> grep -r 'atomic_inc.*bi_remaining' * yilds no hits in btrfs or bcache (on 
> git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git , 
> branch remotes/origin/for-next). It only finds 
> drivers/md/dm-cache-target.c, drivers/md/dm-verity.c, 
> drivers/md/dm-snap.c, drivers/md/dm-thin.c. Maybe in other git trees there 
> are more cases of this.

Here is the btrfs one I was thinking of from Chris:
https://patchwork.kernel.org/patch/3123121/

Should probably make its way into linux-block.git, Jens?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists