From: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
To: Tejun Heo <tj@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>,
Linux PM list <linux-pm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
horms@verge.net.au, "pavel@ucw.cz" <pavel@ucw.cz>,
Len Brown <lenb@kernel.org>
Subject: Re: [Update][PATCH] PM / Hibernate: Fix s2disk regression related to unlock_system_sleep()
Date: Thu, 19 Jan 2012 01:16:06 +0530 [thread overview]
Message-ID: <4F17217E.5040805@linux.vnet.ibm.com> (raw)
In-Reply-To: <20120118193040.GA28538@google.com>
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
next prev parent reply other threads:[~2012-01-18 19:46 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-17 22:45 [PATCH] PM / Hibernate: Fix s2disk regression related to unlock_system_sleep() Rafael J. Wysocki
2012-01-17 23:15 ` [Update][PATCH] " Rafael J. Wysocki
2012-01-18 12:59 ` Srivatsa S. Bhat
2012-01-18 15:42 ` Tejun Heo
2012-01-18 16:54 ` Srivatsa S. Bhat
2012-01-18 16:58 ` Tejun Heo
2012-01-18 17:19 ` Srivatsa S. Bhat
2012-01-18 17:30 ` Tejun Heo
2012-01-18 17:33 ` Tejun Heo
2012-01-19 10:37 ` Pavel Machek
2012-01-19 10:55 ` Srivatsa S. Bhat
2012-01-19 17:40 ` Pavel Machek
2012-01-19 18:10 ` Srivatsa S. Bhat
2012-01-18 19:22 ` Srivatsa S. Bhat
2012-01-18 19:30 ` Tejun Heo
2012-01-18 19:46 ` Srivatsa S. Bhat [this message]
2012-01-18 20:29 ` Srivatsa S. Bhat
2012-01-18 22:04 ` Tejun Heo
2012-01-18 22:22 ` Rafael J. Wysocki
2012-01-19 14:40 ` Srivatsa S. Bhat
2012-01-19 22:35 ` Rafael J. Wysocki
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