linux-kernel - Re: [PATCH 2/5] PM / Runtime: Do not run callbacks under lock for power.irq

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Date:	Mon, 12 Sep 2011 23:52:39 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Ming Lei <tom.leiming@...il.com>
Cc:	Linux PM mailing list <linux-pm@...ts.linux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"Linux-sh list" <linux-sh@...r.kernel.org>,
	Magnus Damm <magnus.damm@...il.com>,
	Kevin Hilman <khilman@...com>, jean.pihet@...oldbits.com
Subject: Re: [PATCH 2/5] PM / Runtime: Do not run callbacks under lock for power.irq_safe set

On Monday, September 12, 2011, Ming Lei wrote:
> Hi,
> 
> On Wed, Aug 31, 2011 at 6:20 AM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> > From: Rafael J. Wysocki <rjw@...k.pl>
> >
> > The rpm_suspend() and rpm_resume() routines execute subsystem or PM
> > domain callbacks under power.lock if power.irq_safe is set for the
> > given device.  This is inconsistent with that rpm_idle() does after
> > commit 02b2677 (PM / Runtime: Allow _put_sync() from
> > interrupts-disabled context) and is problematic for subsystems and PM
> > domains wanting to use power.lock for synchronization in their
> > runtime PM callbacks.  For this reason, make runtime PM core functions
> > always release power.lock before invoking subsystem or PM domain
> 
> If power.lock is released, the transition states(resuming or suspending)
> may be observed in rpm_suspend or rpm_resume, then tasks schedule
> will be produced in these two functions,

I don't think so, because the interrupts are still off.

> so the functions below can't be
> 
>       pm_runtime_suspend()
>       pm_runtime_autosuspend()
>       pm_runtime_resume()
>       pm_runtime_put_sync_suspend()
>       pm_runtime_put_sync_autosuspend()
> 
> called in irq-off contexts safely even though irq_safe flag is set.

The patch doesn't cause rpm_suspend() and rpm_resume() to turn interrupts
on if irq_safe is set, it only causes them to release the lock (temporarily).

Thanks,
Rafael
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