From: Thomas Gleixner <tglx@linutronix.de>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Anna-Maria Behnsen <anna-maria@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Frederic Weisbecker <frederic@kernel.org>,
Peter Xu <peterx@redhat.com>,
Nitesh Narayan Lal <nitesh@redhat.com>,
Alex Belits <abelits@marvell.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
John Stultz <john.stultz@linaro.org>
Subject: Re: [patch 8/8] hrtimer: Avoid more SMP function calls in clock_was_set()
Date: Tue, 27 Apr 2021 21:59:43 +0200 [thread overview]
Message-ID: <877dkno5w0.ffs@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20210427151125.GA171315@fuller.cnet>
On Tue, Apr 27 2021 at 12:11, Marcelo Tosatti wrote:
> On Tue, Apr 27, 2021 at 10:25:45AM +0200, Thomas Gleixner wrote:
> Consider
>
>
> hrtimer_interrupt
> in_hrtirq = 1
> __run_hrtimer
> raw_spin_unlock_irqrestore(&cpu_base->lock, flags)
> settimeofday
> clock_was_set
> lock cpu_base->lock
> update_needs_ipi returns false
> continue to process hrtimers with stale base->offset
Bah. I somehow convinced myself that hrtimer_interrupt() rechecks the
offset before clearing in_hrtirq, but that's not true. It does so when
reprogramming fails, but not for the regular case.
Lemme stare at it some more.
Thanks,
tglx
next prev parent reply other threads:[~2021-04-27 19:59 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-27 8:25 [patch 0/8] hrtimers: Overhaul the clock_was_set() logic Thomas Gleixner
2021-04-27 8:25 ` [patch 1/8] hrtimer: Ensure timerfd notification for HIGHRES=n Thomas Gleixner
2021-04-27 8:25 ` [patch 2/8] hrtimer: Force clock_was_set() handling for the HIGHRES=n, NOHZ=y case Thomas Gleixner
2021-05-12 14:59 ` Peter Zijlstra
2021-05-12 16:40 ` Thomas Gleixner
2021-04-27 8:25 ` [patch 3/8] timerfd: Provide timerfd_resume() Thomas Gleixner
2021-04-27 8:25 ` [patch 4/8] timekeeping: Distangle resume and clock-was-set events Thomas Gleixner
2021-04-27 8:25 ` [patch 5/8] time/timekeeping: Avoid invoking clock_was_set() twice Thomas Gleixner
2021-04-27 8:25 ` [patch 6/8] hrtimer: Add bases argument to clock_was_set() Thomas Gleixner
2021-04-27 8:25 ` [patch 7/8] hrtimer: Avoid unnecessary SMP function calls in clock_was_set() Thomas Gleixner
2021-05-13 14:59 ` Peter Zijlstra
2021-05-14 18:52 ` Thomas Gleixner
2021-05-14 23:28 ` Peter Zijlstra
2021-05-15 0:24 ` Thomas Gleixner
2021-04-27 8:25 ` [patch 8/8] hrtimer: Avoid more " Thomas Gleixner
2021-04-27 15:11 ` Marcelo Tosatti
2021-04-27 19:59 ` Thomas Gleixner [this message]
2021-04-30 7:12 ` [patch V2 " Thomas Gleixner
2021-04-30 16:49 ` Marcelo Tosatti
2021-05-13 7:47 ` Peter Zijlstra
2021-05-14 19:08 ` Thomas Gleixner
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