From: Dominik Brodowski <linux@dominikbrodowski.net>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: cpufreq@lists.linux.org.uk
Subject: Re: Race in cpufreq_add_dev()?
Date: Mon, 2 Oct 2006 20:27:38 -0400 [thread overview]
Message-ID: <20061003002738.GI9748@dominikbrodowski.de> (raw)
In-Reply-To: <44AD6609.1080604@goop.org>
On Thu, Jul 06, 2006 at 12:35:37PM -0700, Jeremy Fitzhardinge wrote:
> cpufreq_add_dev contains the test:
>
> #ifdef CONFIG_SMP
> /* check whether a different CPU already registered this
> * CPU because it is in the same boat. */
> policy = cpufreq_cpu_get(cpu);
> if (unlikely(policy)) {
> cpufreq_cpu_put(policy);
> cpufreq_debug_enable_ratelimit();
> return 0;
> }
> #endif
>
> I don't see what prevents two CPUs from racing through here. Both could
> perform this test and find that there's no policy for the CPU, and then
> both will attempt to add it. Or is there something else which
> serializes multiple CPUs through this code?
AFAICS it is protected by sysdev_drivers_lock.
Dominik
prev parent reply other threads:[~2006-10-03 0:27 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-06 19:35 Race in cpufreq_add_dev()? Jeremy Fitzhardinge
2006-10-03 0:27 ` Dominik Brodowski [this message]
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