Re: [PATCH] Allow memory hotplug and hibernation in the same kernel

[Andi Kleen <andi@firstfloor.org>]

On Fri, Nov 13, 2009 at 03:51:02PM -0800, Andrew Morton wrote:
> > ...
> >
> > +extern struct mutex pm_mutex;
> 
> Am a bit worried by the new mutex.

It's not a new mutex, just the existing one already used by suspend.
I only extended it's coverage to two more code paths.

> 
> > -extern struct mutex pm_mutex;
> > +static inline void lock_hibernation(void) {}
> > +static inline void unlock_hibernation(void) {}
> > +
> > +#else
> > +
> > +/* Let some subsystems like memory hotadd exclude hibernation */
> > +
> > +static inline void lock_hibernation(void)
> > +{
> > +	mutex_lock(&pm_mutex);
> > +}
> > +
> > +static inline void unlock_hibernation(void)
> > +{
> > +	mutex_unlock(&pm_mutex);
> > +}
> > +#endif
> 
> Has this been carefully reviewed and lockdep-tested to ensure that we
> didn't introduce any ab/ba nasties?

It's a "outer" global mutex for both, so I don't expect ABBA issues.

I tested hotadd/hotremove with lockdep and nothing showed up.

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only.