Re: [PATCH] PM: runtime: fix recursive locking warning of lockdep from rpm_resume

Rafael J. Wysocki
2010-10-22T21:50:14Z

On Friday, October 22, 2010, Alan Stern wrote:
> On Fri, 22 Oct 2010 tom.leiming@gmail.com wrote:
>
> > From: Ming Lei <tom.leiming@gmail.com>
> >
> > For device with no_callbacks flag set, its power lock and its parent's
> > power lock may be held nestedly in rpm_resume, so we should take
> > spin_lock_nested(lock, SINGLE_DEPTH_NESTING) to acquire parent power lock
> > to avoid lockdep warning.
> >
> > Signed-off-by: Ming Lei <tom.leiming@gmail.com>
> > ---
> > drivers/base/power/runtime.c | 2 +-
> > 1 files changed, 1 insertions(+), 1 deletions(-)
> >
> > diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
> > index 1dd8676..126ca49 100644
> > --- a/drivers/base/power/runtime.c
> > +++ b/drivers/base/power/runtime.c
> > @@ -503,7 +503,7 @@ static int rpm_resume(struct device *dev, int rpmflags)
> > * the resume will actually succeed.
> > */
> > if (dev->power.no_callbacks && !parent && dev->parent) {
> > - spin_lock(&dev->parent->power.lock);
> > + spin_lock_nested(&dev->parent->power.lock, SINGLE_DEPTH_NESTING);
> > if (dev->parent->power.disable_depth > 0
> > || dev->parent->power.ignore_children
> > || dev->parent->power.runtime_status == RPM_ACTIVE) {
>
> Quite correct; I don't know why this didn't show up during my testing.
>
> Acked-by: Alan Stern <stern@rowland.harvard.edu>

Applied to suspend-2.6/pm-fixes, will push to Linus early next week.

Thanks,
Rafael