Re: [PATCH RFC] apm-emulation: apm_mutex breaks ACK; remove it

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On Tue, 17 May 2011, Jiri Kosina wrote:

> On Fri, 13 May 2011, Paul Parsons wrote:
> 
> > apm_mutex is locked by a process (e.g. apm -s) at the start of 
> > apm_ioctl() and remains locked while pm_suspend() is called. Any 
> > subsequent process trying to ACK the suspend (e.g. apmd) is then blocked 
> > at the start of apm_ioctl(), causing the suspend to be delayed for 5 
> > seconds in apm_suspend_notifier() while the ACK times out. In short, 
> > ACKs don't work.
> > 
> > The driver's data structures are sufficiently protected by assorted 
> > locks. And pm_suspend() has its own mutex to prevent reentrancy. 
> > Consequently there is no obvious requirement for apm_mutex, which 
> > evolved from earlier BKL calls. So let's remove it.
> >
> > 
> > Signed-off-by: Paul Parsons <lost.distance@xxxxxxxxx>
> > ---
> > This patch supersedes my previous "apm-emulation: Fix mutex race condition" patch; this patch fixes that earlier bug too.
> 
> Looks good to me (and sorry for the delay). Thanks Paul, will apply.

(unless Rafael sees any potential issue there of course ... but I myself 
don't).

-- 
Jiri Kosina
SUSE Labs
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