From: Michael Ellerman <mpe@ellerman.id.au>
To: Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Sebastian Siewior <bigeasy@linutronix.de>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
"David S. Miller" <davem@davemloft.net>,
Fenghua Yu <fenghua.yu@intel.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Len Brown <lenb@kernel.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Tejun Heo <tj@kernel.org>, Tony Luck <tony.luck@intel.com>,
Viresh Kumar <viresh.kumar@linaro.org>,
Paul Mackerras <paulus@samba.org>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [patch 05/13] powerpc/smp: Replace open coded task affinity logic
Date: Thu, 13 Apr 2017 15:47:44 +1000 [thread overview]
Message-ID: <87fuhcamf3.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <20170412201042.518053336@linutronix.de>
Thomas Gleixner <tglx@linutronix.de> writes:
> Init task invokes smp_ops->setup_cpu() from smp_cpus_done(). Init task can
> run on any online CPU at this point, but the setup_cpu() callback requires
> to be invoked on the boot CPU. This is achieved by temporarily setting the
> affinity of the calling user space thread to the requested CPU and reset it
> to the original affinity afterwards.
>
> That's racy vs. CPU hotplug and concurrent affinity settings for that
> thread resulting in code executing on the wrong CPU and overwriting the
> new affinity setting.
>
> That's actually not a problem in this context as neither CPU hotplug nor
> affinity settings can happen, but the access to task_struct::cpus_allowed
> is about to restricted.
>
> Replace it with a call to work_on_cpu_safe() which achieves the same result.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: linuxppc-dev@lists.ozlabs.org
> ---
> arch/powerpc/kernel/smp.c | 26 +++++++++++---------------
> 1 file changed, 11 insertions(+), 15 deletions(-)
LGTM.
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
cheers
next prev parent reply other threads:[~2017-04-13 5:47 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-12 20:07 [patch 00/13] sched/treewide: Clean up various racy task affinity issues Thomas Gleixner
2017-04-12 20:07 ` [patch 01/13] ia64/topology: Remove cpus_allowed manipulation Thomas Gleixner
2017-04-15 14:15 ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-12 20:07 ` [patch 02/13] workqueue: Provide work_on_cpu_safe() Thomas Gleixner
2017-04-13 11:11 ` Dou Liyang
2017-04-13 21:28 ` Thomas Gleixner
2017-04-14 4:18 ` Tejun Heo
2017-04-14 8:54 ` Peter Zijlstra
2017-04-14 9:51 ` Thomas Gleixner
2017-04-14 9:56 ` Peter Zijlstra
2017-04-15 14:16 ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-12 20:07 ` [patch 03/13] ia64/salinfo: Replace racy task affinity logic Thomas Gleixner
2017-04-15 14:17 ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-12 20:07 ` [patch 04/13] ia64/sn/hwperf: " Thomas Gleixner
2017-04-12 20:53 ` [patch V 2 " Thomas Gleixner
2017-04-15 14:17 ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-12 20:07 ` [patch 05/13] powerpc/smp: Replace open coded " Thomas Gleixner
2017-04-13 5:47 ` Michael Ellerman [this message]
2017-04-15 14:18 ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-12 20:07 ` [patch 06/13] sparc/sysfs: Replace racy " Thomas Gleixner
2017-04-13 1:52 ` David Miller
2017-04-13 8:17 ` [patch V2 " Thomas Gleixner
2017-04-15 14:18 ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-12 20:07 ` [patch 07/13] ACPI/processor: Fix error handling in __acpi_processor_start() Thomas Gleixner
2017-04-15 14:19 ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-12 20:07 ` [patch 08/13] ACPI/processor: Replace racy task affinity logic Thomas Gleixner
2017-04-13 11:39 ` Peter Zijlstra
2017-04-13 12:01 ` Thomas Gleixner
2017-04-13 12:52 ` Peter Zijlstra
2017-04-15 14:19 ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-12 20:07 ` [patch 09/13] cpufreq/ia64: " Thomas Gleixner
2017-04-12 20:55 ` [patch V2 " Thomas Gleixner
2017-04-15 14:20 ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-13 2:42 ` [patch 09/13] " Viresh Kumar
2017-04-12 20:07 ` [patch 10/13] cpufreq/sh: " Thomas Gleixner
2017-04-13 2:46 ` Viresh Kumar
2017-04-15 14:20 ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-12 20:07 ` [patch 11/13] cpufreq/sparc-us3: " Thomas Gleixner
2017-04-13 2:48 ` Viresh Kumar
2017-04-15 14:21 ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-12 20:07 ` [patch 12/13] cpufreq/sparc-us2e: " Thomas Gleixner
2017-04-13 2:50 ` Viresh Kumar
2017-04-13 8:19 ` [patch V2 " Thomas Gleixner
2017-04-13 8:22 ` [patch V3 " Thomas Gleixner
2017-04-15 14:21 ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-13 14:50 ` [patch V2 12/13] " David Miller
2017-04-12 20:07 ` [patch 13/13] crypto: n2 - " Thomas Gleixner
2017-04-13 4:56 ` Herbert Xu
2017-04-13 8:20 ` [patch V2 " Thomas Gleixner
2017-04-13 14:51 ` David Miller
2017-04-15 14:22 ` [tip:sched/core] crypto: N2 " tip-bot for Thomas Gleixner
2017-04-13 9:02 ` [patch 00/13] sched/treewide: Clean up various racy task affinity issues Peter Zijlstra
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