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

From: Paul E. McKenney
Date: Sun Jun 02 2013 - 23:42:31 EST


On Sun, Jun 02, 2013 at 07:58:26PM -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.

I would be happy to take it.

Thanx, Paul

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