Messages in this thread | | | Date | Thu, 19 Jan 2012 01:16:06 +0530 | From | "Srivatsa S. Bhat" <> | Subject | Re: [Update][PATCH] PM / Hibernate: Fix s2disk regression related to unlock_system_sleep() |
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On 01/19/2012 01:00 AM, Tejun Heo wrote:
> Hello, > > On Thu, Jan 19, 2012 at 12:52:32AM +0530, Srivatsa S. Bhat wrote: >> Somehow I don't think its a hack, based on my perception as described >> above. But feel free to prove me wrong :-) > > Thanks for the explanation. Yeah, I agree and it's much simpler this > way, which is nice. So, in short, because freezing state can't change > across lock_system_sleep(), there's no reason to check for freezing > state on unlock and this nicely resolves the freezer problem together. >
Absolutely!
> The only thing to be careful is, then, we need to set and clear SKIP > inside pm_mutex. >
Not exactly. We need to set SKIP before grabbing pm_mutex and clear it inside pm_mutex. The reason is that we decided to set SKIP in the first place just to avoid the freezer from declaring failure when we are blocked on pm_mutex. If we move it to *after* mutex_lock(&pm_mutex), that original intention itself is not satisfied, and we will hit freezing failures - IOW making the set and clear exercise useless!
So, something like this should work perfectly:
lock_system_sleep() { freezer_do_not_count(); mutex_lock(&pm_mutex); current->flags &= ~PF_FREEZER_SKIP; }
But in the interest of making the code look a bit symmetric, we can do:
lock_system_sleep() { freezer_do_not_count(); mutex_lock(&pm_mutex); }
unlock_system_sleep() { current->flags &= ~PF_FREEZER_SKIP; mutex_unlock(&pm_mutex); } Regards, Srivatsa S. Bhat IBM Linux Technology Center
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