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Date: Tue, 10 Oct 2017 10:43:34 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
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        "David S. Miller" <davem@davemloft.net>,
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Subject: Re: [PATCH RFC tip/core/rcu 14/15] netfilter: Remove now-redundant
 smp_read_barrier_depends()
Message-ID: <20171010084334.nbyhryiwyrl6km4u@hirez.programming.kicks-ass.net>
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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.