From: Stephen Warren <swarren@wwwdotorg.org>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Stephen Warren <swarren@nvidia.com>,
"kexec@lists.infradead.org" <kexec@lists.infradead.org>,
Stephen Boyd <sboyd@codeaurora.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Will Deacon <will.deacon@arm.com>,
Russell King - ARM Linux <linux@arm.linux.org.uk>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] ARM: call disable_nonboot_cpus() from machine_shutdown()
Date: Tue, 29 Jan 2013 15:10:42 -0700 [thread overview]
Message-ID: <510848E2.50203@wwwdotorg.org> (raw)
In-Reply-To: <87obgwb5d1.fsf@xmission.com>
On 01/10/2013 11:28 PM, Eric W. Biederman wrote:
...
> I don't have any problem with generic code in the reboot path
> doing:
> if (cpu_online(0))
> set_cpus_allowed_ptr(current, cpumask_of(0));
It looks like that API just affects the scheduler, and not whether the
other CPUs are actually active/hot-plugged-in. At least for my use-case,
I need something that really disables the other CPUs so they aren't
executing code, hence my tendency to hot-un-plug them using
disable_nonboot_cpus(), rather than just shift task execution off them
using the code above.
I wonder if all architectures shouldn't always do the following in all
reboot/shutdown/kexec cases:
* set_cpus_allowed_ptr() to limit code execution to a single CPU.
* disable_nonboot_cpus() (or equivalent) if it's available to turn off
all the other CPUs.
The issue here would be that disable_nonboot_cpus() isn't always
available; I assume that's part of the reason that there are
arch-specific machine_xxx() hooks, so that architectures can
power-off/reset their CPUs even when hotplug isn't enabled? I wonder if
that can be refactored so that reboot/poweroff/kexec can share some
CPU-disable code with CPU hotplug?
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next prev parent reply other threads:[~2013-01-29 22:10 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-02 21:07 [PATCH] ARM: call disable_nonboot_cpus() from machine_shutdown() Stephen Warren
2013-01-02 21:52 ` Russell King - ARM Linux
2013-01-02 23:59 ` Stephen Boyd
2013-01-03 12:02 ` Will Deacon
2013-01-03 12:21 ` Russell King - ARM Linux
2013-01-03 18:08 ` Jason Gunthorpe
2013-01-03 20:26 ` Stephen Warren
2013-01-06 16:22 ` Will Deacon
2013-01-06 16:40 ` Russell King - ARM Linux
2013-01-07 1:53 ` Eric W. Biederman
2013-01-07 14:25 ` Will Deacon
2013-01-07 14:48 ` Russell King - ARM Linux
2013-01-11 5:59 ` Eric W. Biederman
2013-01-11 10:04 ` Russell King - ARM Linux
2013-01-29 22:01 ` Stephen Warren
2013-01-09 0:06 ` Stephen Warren
2013-01-11 6:28 ` Eric W. Biederman
2013-01-29 22:10 ` Stephen Warren [this message]
2013-01-03 12:03 ` Will Deacon
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