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Date: Tue, 10 Oct 2017 10:43:34 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc: linux-kernel@...r.kernel.org, mingo@...nel.org,
torvalds@...ux-foundation.org, mark.rutland@....com,
dhowells@...hat.com, linux-arch@...r.kernel.org,
will.deacon@....com, Pablo Neira Ayuso <pablo@...filter.org>,
Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>,
Florian Westphal <fw@...len.de>,
"David S. Miller" <davem@...emloft.net>,
netfilter-devel@...r.kernel.org, coreteam@...filter.org,
netdev@...r.kernel.org
Subject: Re: [PATCH RFC tip/core/rcu 14/15] netfilter: Remove now-redundant
smp_read_barrier_depends()
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.
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