linux-kernel - Re: [PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to sync_exp_work

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 13 Apr 2017 11:18:32 +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,
        jiangshanlai@...il.com, dipankar@...ibm.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, rostedt@...dmis.org,
        dhowells@...hat.com, edumazet@...gle.com, fweisbec@...il.com,
        oleg@...hat.com, bobby.prani@...il.com
Subject: Re: [PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to
 sync_exp_work_done()

On Wed, Apr 12, 2017 at 09:55:43AM -0700, Paul E. McKenney wrote:
> However, a little future-proofing is a good thing,
> especially given that smp_mb__before_atomic() is only required to
> provide acquire semantics rather than full ordering.  This commit
> therefore adds smp_mb__after_atomic() after the atomic_long_inc()
> in sync_exp_work_done().

Oh!? As far as I'm away the smp_mb__{before,after}_atomic() really must
provide full MB, no confusion about that.

We have other primitives for acquire/release.