From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Roman Gushchin <klamm@yandex-team.ru>,
Dipankar Sarma <dipankar@in.ibm.com>,
zhmurov@yandex-team.ru, linux-kernel@vger.kernel.org,
netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
James Morris <jmorris@namei.org>,
Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
Patrick McHardy <kaber@trash.net>
Subject: Re: [PATCH v2] rcu: fix a race in hlist_nulls_for_each_entry_rcu macro
Date: Wed, 22 May 2013 06:00:30 -0700 [thread overview]
Message-ID: <20130522130030.GB3431@linux.vnet.ibm.com> (raw)
In-Reply-To: <1369225727.3301.322.camel@edumazet-glaptop>
On Wed, May 22, 2013 at 05:28:47AM -0700, Eric Dumazet wrote:
> On Wed, 2013-05-22 at 02:58 -0700, Paul E. McKenney wrote:
>
> > Now that I am more awake...
> >
> > The RCU list macros assume that the list header is either statically
> > allocated (in which case no ACCESS_ONCE() or whatever is needed) or
> > that the caller did whatever was necessary to protect the list header,
> > whether that be holding the right lock, using rcu_dereference() when
> > traversing the pointer to the list header, or whatever.
>
> Not sure what you mean, we do hold rcu_read_lock() here.
>
> But when we jump back to begin, we do not do
> "rcu_read_unlock()/rcu_read_lock()" pair.
Right, rcu_read_lock() is part of the protection, but rcu_dereference()
is the other part.
All that aside, I can't claim that I understand what problem the various
patches would solve. ;-)
Thanx, Paul
next prev parent reply other threads:[~2013-05-22 13:00 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-21 9:05 [PATCH] rcu: fix a race in hlist_nulls_for_each_entry_rcu macro Roman Gushchin
2013-05-21 10:40 ` David Laight
2013-05-21 11:55 ` Roman Gushchin
2013-05-21 13:42 ` David Laight
2013-05-21 12:09 ` Paul E. McKenney
2013-05-21 12:46 ` Roman Gushchin
2013-05-21 12:58 ` Paul E. McKenney
2013-05-21 13:37 ` Eric Dumazet
2013-05-21 13:44 ` Eric Dumazet
2013-05-21 14:47 ` Roman Gushchin
2013-05-21 15:16 ` Eric Dumazet
2013-05-21 15:51 ` Roman Gushchin
2013-05-21 15:38 ` Eric Dumazet
2013-05-21 15:51 ` Roman Gushchin
2013-05-21 18:12 ` [PATCH v2] " Roman Gushchin
2013-05-22 2:01 ` Eric Dumazet
2013-05-22 5:49 ` Eric Dumazet
2013-05-22 11:58 ` Roman Gushchin
2013-05-22 12:30 ` Eric Dumazet
2013-05-22 13:07 ` Roman Gushchin
2013-05-22 17:45 ` Paul E. McKenney
2013-05-22 19:17 ` Roman Gushchin
2013-05-25 11:37 ` Paul E. McKenney
2013-05-27 11:34 ` Roman Gushchin
2013-05-27 17:55 ` Roman Gushchin
2013-05-28 0:12 ` Eric Dumazet
2013-05-28 9:10 ` Roman Gushchin
2013-05-29 0:34 ` Eric Dumazet
2013-05-29 1:31 ` Paul E. McKenney
2013-05-29 5:08 ` Eric Dumazet
2013-05-29 10:09 ` Roman Gushchin
2013-05-29 19:06 ` Eric Dumazet
2013-05-30 8:25 ` Roman Gushchin
2013-06-02 23:31 ` Eric Dumazet
2013-06-03 2:58 ` David Miller
2013-06-03 3:12 ` Eric Dumazet
2013-06-03 3:27 ` David Miller
2013-06-03 3:42 ` Paul E. McKenney
2013-06-03 3:47 ` Eric Dumazet
2013-06-03 3:49 ` David Miller
2013-06-03 6:05 ` Paul E. McKenney
2013-06-10 18:29 ` Boris B. Zhmurov
2013-06-10 18:51 ` Eric Dumazet
2013-06-03 3:48 ` Paul E. McKenney
2013-06-03 3:42 ` Paul E. McKenney
2013-05-29 9:17 ` Roman Gushchin
2013-05-29 1:19 ` Paul E. McKenney
2013-05-22 13:27 ` David Laight
2013-05-22 13:27 ` David Laight
2013-05-22 13:36 ` Eric Dumazet
2013-05-22 14:23 ` David Laight
2013-05-22 14:23 ` David Laight
2013-05-22 13:55 ` Roman Gushchin
2013-05-22 9:58 ` Paul E. McKenney
2013-05-22 12:28 ` Eric Dumazet
2013-05-22 13:00 ` Paul E. McKenney [this message]
2013-05-22 14:16 ` Eric Dumazet
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