Re: 2.6.14-git3: scheduling while atomic from cpufreq on Athlon64

[Lee Revell <rlrevell@joe-job.com>]

On Tue, 2005-11-01 at 11:14 -0800, Ashok Raj wrote:
> On Tue, Nov 01, 2005 at 08:07:19PM +0100, Rafael J. Wysocki wrote:
> > Hi,
> > 
> > > of taking cpucontrol lock in __cpufreq_driver_target().
> > 
> > Yes, that's it.
> > 
> > > The reason is we now enter the same code path from the cpu_up() and cpu_down()
> > > generated cpu notifier callbacks and ends up trying to lock when the 
> > > call path already has the cpucontrol lock.
> > > 
> > > Its happening because we do set_cpus_allowed() in powernowk8_target().
> > 
> > Unfortunately, powernowk8_target() calls schedule() right after
> > set_cpus_allowed(), so it throws "scheduling while atomic" on every call,
> > because of the preempt_disable()/_enable() around it.
> > 
> > Greetings,
> > Rafael
> > 
> 
> Thanks Rafael,
> 
> could you try this patch instead? I hate to keep these state variables 
> and thats why i went with the preempt approach, too bad it seems it wont
> work for more than just the case you mentioned.
> 
> seems ugly, but i dont find a better looking cure...

It can't possibly be uglier than disabling preemption to work around a
locking bug.

Lee