From: Peter Zijlstra <peterz@infradead.org>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Marco Elver <elver@google.com>,
LKML <linux-kernel@vger.kernel.org>,
kasan-dev <kasan-dev@googlegroups.com>,
Ingo Molnar <mingo@kernel.org>,
Frederic Weisbecker <frederic@kernel.org>,
Will Deacon <will@kernel.org>,
Naresh Kamboju <naresh.kamboju@linaro.org>,
syzbot+23a256029191772c2f02@syzkaller.appspotmail.com,
syzbot+56078ac0b9071335a745@syzkaller.appspotmail.com,
syzbot+867130cb240c41f15164@syzkaller.appspotmail.com
Subject: Re: [patch 3/3] tick: Annotate tick_do_timer_cpu data races
Date: Thu, 17 Dec 2020 11:48:23 +0100 [thread overview]
Message-ID: <20201217104823.GU3040@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20201216211931.GL2657@paulmck-ThinkPad-P72>
On Wed, Dec 16, 2020 at 01:19:31PM -0800, Paul E. McKenney wrote:
> Given that there is no optimization potential, then the main reason to use
> data_race() instead of *_ONCE() is to prevent KCSAN from considering the
> accesses when looking for data races. But that is mostly for debugging
> accesses, in cases when these accesses are not really part of the
> concurrent algorithm.
>
> So if I understand the situation correctly, I would be using *ONCE().
Huh, what, why?
The code doesn't need READ_ONCE(), it merely wants to tell kasan that
the race it observes is fine and as to please shut up.
IOW data_race() is accurate and right.
next prev parent reply other threads:[~2020-12-17 10:49 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-06 21:12 [patch 0/3] tick: Annotate and document the intentionaly racy tick_do_timer_cpu Thomas Gleixner
2020-12-06 21:12 ` [patch 1/3] tick: Remove pointless cpu valid check in hotplug code Thomas Gleixner
2020-12-07 11:59 ` Peter Zijlstra
2020-12-07 17:44 ` Thomas Gleixner
2020-12-11 22:21 ` Frederic Weisbecker
2020-12-12 0:16 ` Thomas Gleixner
2020-12-12 1:20 ` Frederic Weisbecker
2020-12-11 22:31 ` Frederic Weisbecker
2020-12-16 10:50 ` [tip: timers/urgent] " tip-bot2 for Thomas Gleixner
2020-12-06 21:12 ` [patch 2/3] tick/sched: Remove bogus boot "safety" check Thomas Gleixner
2020-12-11 22:41 ` Frederic Weisbecker
2020-12-16 10:50 ` [tip: timers/urgent] " tip-bot2 for Thomas Gleixner
2020-12-06 21:12 ` [patch 3/3] tick: Annotate tick_do_timer_cpu data races Thomas Gleixner
2020-12-07 12:09 ` Peter Zijlstra
2020-12-07 17:46 ` Thomas Gleixner
2020-12-07 18:19 ` Marco Elver
2020-12-07 19:43 ` Thomas Gleixner
2020-12-07 19:44 ` Paul E. McKenney
2020-12-07 21:46 ` Thomas Gleixner
2020-12-07 22:38 ` Paul E. McKenney
2020-12-07 22:46 ` Thomas Gleixner
2020-12-07 22:55 ` Paul E. McKenney
2020-12-08 8:11 ` Peter Zijlstra
2020-12-08 15:03 ` Paul E. McKenney
2020-12-16 0:27 ` Thomas Gleixner
2020-12-16 21:19 ` Paul E. McKenney
2020-12-16 21:23 ` Thomas Gleixner
2020-12-16 21:32 ` Paul E. McKenney
2020-12-17 10:48 ` Peter Zijlstra [this message]
2020-12-17 14:59 ` Paul E. McKenney
2020-12-08 8:01 ` Peter Zijlstra
2020-12-07 11:05 ` [patch 0/3] tick: Annotate and document the intentionaly racy tick_do_timer_cpu Marco Elver
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