On Wed, Jul 26, 2006 at 03:40:07PM +0200, Arjan van de Ven wrote:
> Subject: Reorganize the cpufreq cpu hotplug locking to not be totally bizare
> From: Arjan van de Ven <[email protected]>
>
> The patch below moves the cpu hotplugging higher up in the cpufreq
> layering; this is needed to avoid recursive taking of the cpu hotplug
> lock and to otherwise detangle the mess.
>
> The new rules are:
> 1. you must do lock_cpu_hotplug() around the following functions:
> __cpufreq_driver_target
> __cpufreq_governor (for CPUFREQ_GOV_LIMITS operation only)
> __cpufreq_set_policy
> 2. governer methods (.governer) must NOT take the lock_cpu_hotplug()
> lock in any way; they are called with the lock taken already
> 3. if your governer spawns a thread that does things, like calling
> __cpufreq_driver_target, your thread must honor rule #1.
> 4. the policy lock and other cpufreq internal locks nest within
> the lock_cpu_hotplug() lock.
>
> I'm not entirely happy about how the __cpufreq_governor rule ended up
> (conditional locking rule depending on the argument) but basically all
> callers pass this as a constant so it's not too horrible.
>
> The patch also removes the cpufreq_governor() function since during the
> locking audit it turned out to be entirely unused (so no need to fix it)
>
> The patch works on my testbox, but it could use more testing
> (otoh... it can't be much worse than the current code)
>
> Signed-off-by: Arjan van de Ven <[email protected]>
Looks sensible to me. Assuming it passes testing..
Signed-off-by: Dave Jones <[email protected]>
Linus ?
Dave
--
http://www.codemonkey.org.uk
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