Re: [PATCH v2] rcu: fix a race in hlist_nulls_for_each_entry_rcumacro

[Paul E. McKenney]

On Sun, Jun 02, 2013 at 08:27:03PM -0700, David Miller wrote:
> From: Eric Dumazet <eric.dumazet@xxxxxxxxx>
> Date: Sun, 02 Jun 2013 20:12:49 -0700
> 
> > On Sun, 2013-06-02 at 19:58 -0700, David Miller wrote:
> >> From: Eric Dumazet <eric.dumazet@xxxxxxxxx>
> >> Date: Sun, 02 Jun 2013 16:31:35 -0700
> >> 
> >> > On Thu, 2013-05-30 at 12:25 +0400, Roman Gushchin wrote:
> >> >> On 29.05.2013 23:06, Eric Dumazet wrote:
> >> >> > On Wed, 2013-05-29 at 14:09 +0400, Roman Gushchin wrote:
> >> >> >
> >> >> > True, these lookup functions are usually structured the same around the
> >> >> > hlist_nulls_for_each_entry_rcu() loop.
> >> >> >
> >> >> > A barrier() right before the loop seems to be a benefit, the size of
> >> >> > assembly code is reduced by 48 bytes.
> >> >> >
> >> >> > And its one of the documented way to handle this kind of problems
> >> >> > (Documentation/atomic_ops.txt line 114)
> >> >> >
> >> >> > I guess we should amend this documentation, eventually.
> >> >> >
> >> >> > Thanks, please add you "Signed-off-by" if you agree with the patch.
> >> >> >
> >> >> 
> >> >> Signed-off-by: Roman Gushchin <klamm@xxxxxxxxxxxxxx>
> >> >> 
> >> >> Many thanks to you, Paul E. McKenney and David Laight for your
> >> >> patches, help and participation in this discussion.
> >> > 
> >> > Thanks to you !
> >> > 
> >> > David, is there any problem with the patch ?
> >> > 
> >> > http://patchwork.ozlabs.org/patch/247360/ says "Not applicable", please
> >> > tell me what is needed to get it merged.
> >> 
> >> It's not a networking patch, it's a patch for generic RCU upstream.
> >> So it either goes through Paul McKenney, or directly via Linus on
> >> linux-kernel.
> > 
> > Well, whole discussion went on linux kernel, and you were the original
> > committer of this patch five years ago.
> > 
> > http://git.kernel.org/cgit/linux/kernel/git/davem/net-next.git/commit/?id=bbaffaca4810de1a25e32ecaf836eeaacc7a3d11
> > 
> > So please Paul or David make sure the patch goes in.
> > 
> > My only concern is that Paul seems quite busy these days.
> 
> Ok I can take it then, no problem.

Or if you would like to take it:

Acked-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>

Just let me know.  ;-)

							Thanx, Paul

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