From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Davidlohr Bueso <dave@stgolabs.net>
Cc: Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org, mingo@kernel.org,
laijs@cn.fujitsu.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, rostedt@goodmis.org,
dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com,
fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com
Subject: Re: [PATCH tip/core/rcu 01/14] rcu: Protect rcu_boost() lockless accesses with ACCESS_ONCE()
Date: Fri, 9 Jan 2015 05:49:54 -0800 [thread overview]
Message-ID: <20150109134954.GO5280@linux.vnet.ibm.com> (raw)
In-Reply-To: <1420785714.25454.1.camel@stgolabs.net>
On Thu, Jan 08, 2015 at 10:41:54PM -0800, Davidlohr Bueso wrote:
> On Thu, 2015-01-08 at 07:22 -0800, Paul E. McKenney wrote:
> > > Didn't we just obsolete ACCESS_ONCE with that {READ,WRITE}_ONCE stuff?
> >
> > Indeed we did! But that was after I did this commit back on October 29th.
> >
> > I am planning a bulk change to READ_ONCE() and ASSIGN_ONCE() either as
> > the last patch for 3.20 or as the first one for 3.21. Probably as the
> > first for 3.21 to minimize rebasing hassles with any needed 3.20 fixes.
>
> That reminds me, I think the new conversion for stores will most likely
> introduce silly arg bugs:
>
> - ACCESS_ONCE(a) = b;
> + ASSIGN_ONCE(b, a);
I was planning to do mine by hand for this sort of reason.
Or are you thinking of something more subtle than the case where
"b" is an unparenthesized comma-separated expression?
Thanx, Paul
next prev parent reply other threads:[~2015-01-09 13:50 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-07 17:32 [PATCH tip/core/rcu 0/14] Preemptible-RCU updates for 3.20 Paul E. McKenney
2015-01-07 17:32 ` [PATCH tip/core/rcu 01/14] rcu: Protect rcu_boost() lockless accesses with ACCESS_ONCE() Paul E. McKenney
2015-01-07 17:32 ` [PATCH tip/core/rcu 02/14] rcu: Rename "empty" to "empty_norm" in preparation for boost rework Paul E. McKenney
2015-01-07 17:32 ` [PATCH tip/core/rcu 03/14] rcu: Abstract rcu_cleanup_dead_rnp() from rcu_cleanup_dead_cpu() Paul E. McKenney
2015-01-07 17:32 ` [PATCH tip/core/rcu 04/14] rcu: Make rcu_read_unlock_special() propagate ->qsmaskinit bit clearing Paul E. McKenney
2015-01-07 17:32 ` [PATCH tip/core/rcu 05/14] rcu: Don't migrate blocked tasks even if all corresponding CPUs offline Paul E. McKenney
2015-01-07 17:32 ` [PATCH tip/core/rcu 06/14] rcu: Shorten irq-disable region in rcu_cleanup_dead_cpu() Paul E. McKenney
2015-01-07 17:32 ` [PATCH tip/core/rcu 07/14] rcu: Make use of rcu_preempt_has_tasks() Paul E. McKenney
2015-01-07 17:32 ` [PATCH tip/core/rcu 08/14] rcu: Don't spawn rcub kthreads on root rcu_node structure Paul E. McKenney
2015-01-07 17:32 ` [PATCH tip/core/rcu 09/14] rcu: Don't initiate RCU priority boosting on root rcu_node Paul E. McKenney
2015-01-07 17:32 ` [PATCH tip/core/rcu 10/14] rcu: Don't bother affinitying rcub kthreads away from offline CPUs Paul E. McKenney
2015-01-07 17:32 ` [PATCH tip/core/rcu 11/14] rcu: Note quiescent state when CPU goes offline Paul E. McKenney
2015-01-07 17:32 ` [PATCH tip/core/rcu 12/14] rcu: Revert "Allow post-unlock reference for rt_mutex" to avoid priority-inversion Paul E. McKenney
2015-01-07 17:32 ` [PATCH tip/core/rcu 13/14] rcu: Don't scan root rcu_node structure for stalled tasks Paul E. McKenney
2015-01-07 17:32 ` [PATCH tip/core/rcu 14/14] rcu: Remove redundant callback-list initialization Paul E. McKenney
2015-01-08 9:41 ` [PATCH tip/core/rcu 01/14] rcu: Protect rcu_boost() lockless accesses with ACCESS_ONCE() Peter Zijlstra
2015-01-08 15:22 ` Paul E. McKenney
2015-01-09 6:41 ` Davidlohr Bueso
2015-01-09 13:49 ` Paul E. McKenney [this message]
2015-01-09 13:56 ` Peter Zijlstra
2015-01-09 14:07 ` Paul E. McKenney
2015-01-09 16:53 ` Mathieu Desnoyers
2015-01-09 21:58 ` Christian Borntraeger
2015-01-10 0:27 ` Davidlohr Bueso
2015-01-12 8:59 ` Peter Zijlstra
2015-01-12 22:12 ` Paul E. McKenney
2015-01-13 8:18 ` Christian Borntraeger
2015-01-13 9:29 ` Peter Zijlstra
2015-01-13 17:47 ` Paul E. McKenney
2015-01-13 19:12 ` Davidlohr Bueso
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