From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
torvalds@linux-foundation.org, mark.rutland@arm.com,
dhowells@redhat.com, linux-arch@vger.kernel.org,
will.deacon@arm.com, Pablo Neira Ayuso <pablo@netfilter.org>,
Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>,
Florian Westphal <fw@strlen.de>,
"David S. Miller" <davem@davemloft.net>,
netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
netdev@vger.kernel.org
Subject: Re: [PATCH RFC tip/core/rcu 14/15] netfilter: Remove now-redundant smp_read_barrier_depends()
Date: Tue, 10 Oct 2017 08:56:50 -0700 [thread overview]
Message-ID: <20171010155650.GF3521@linux.vnet.ibm.com> (raw)
In-Reply-To: <20171010084334.nbyhryiwyrl6km4u@hirez.programming.kicks-ass.net>
On Tue, Oct 10, 2017 at 10:43:34AM +0200, Peter Zijlstra wrote:
> On Mon, Oct 09, 2017 at 05:22:48PM -0700, Paul E. McKenney wrote:
> > READ_ONCE() now implies smp_read_barrier_depends(), which means that
> > the instances in arpt_do_table(), ipt_do_table(), and ip6t_do_table()
> > are now redundant. This commit removes them and adjusts the comments.
>
> Similar to the previous patch, the lack of READ_ONCE() in the original
> code is a pre-existing bug. It would allow the compiler to tear the load
> and observe a composite of two difference pointer values, or reload the
> private pointer and result in table_base and jumpstacl being part of
> different objects.
>
> It would be good to point out this actually fixes a bug in the code.
Assuming that these changes actually fixed something, agreed. ;-)
Thanx, Paul
prev parent reply other threads:[~2017-10-10 15:56 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20171010001951.GA6476@linux.vnet.ibm.com>
2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 14/15] netfilter: Remove now-redundant smp_read_barrier_depends() Paul E. McKenney
2017-10-10 8:43 ` Peter Zijlstra
2017-10-10 15:56 ` Paul E. McKenney [this message]
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