On Monday, November 21, 2011, Srivatsa S. Bhat wrote:

On 11/21/2011 11:22 PM, Tejun Heo wrote:

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Hello,

On Mon, Nov 21, 2011 at 10:34:40PM +0530, Srivatsa S. Bhat wrote:

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I haven't tested this solution yet. Let me know if this solution looks
good and I'll send it out as a patch after testing and analyzing some
corner cases, if any.

I tested this, and it works great! I'll send the patch in some time.

Awesome.

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* I think it would be better to remove direct access to pm_mutex and
  use [un]lock_system_sleep() universally.  I don't think hinging it
  on CONFIG_HIBERNATE_CALLBACKS buys us anything.

Which direct access to pm_mutex are you referring to?
Other than suspend/hibernation call paths, I think mem-hotplug is the only
subsystem trying to access pm_mutex. I haven't checked thoroughly though. 

But yes, using lock_system_sleep() for mutually excluding some code path
from suspend/hibernation is good, and that is one reason why I wanted
to fix this API ASAP. But as long as memory hotplug is the only direct user
of pm_mutex, is it justified to remove the CONFIG_HIBERNATE_CALLBACKS
restriction and make it generic? I don't know...

Or, are you saying that we should use these APIs even in suspend/hibernate
call paths? That's not such a bad idea either...

Yeap, all.  It's just confusing to have two different types of access
to a single lock and I don't believe CONFIG_HIBERNATE_CALLBACKS is a
meaningful optimization in this case.

Ok that sounds good, I'll send a separate patch for that.
Rafael, do you also agree that this would be better?

Yes, it would.

Thanks,
Rafael

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