[Intel-gfx] [PATCH] Revert "drm/i915: Fix mutex->owner inspection race under DEBUG_MUTEXES"

[Daniel Vetter]

On Thu, Jan 15, 2015 at 09:13:02AM +0200, Jani Nikula wrote:
> On Wed, 14 Jan 2015, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> > The core fix was applied in
> >
> > commit a63b03e2d2477586440741677ecac45bcf28d7b1
> > Author: Chris Wilson <chris at chris-wilson.co.uk>
> > Date:   Tue Jan 6 10:29:35 2015 +0000
> >
> >     mutex: Always clear owner field upon mutex_unlock()
> >
> > (note the absence of stable@ tag)
> >
> > so we can now revert our band-aid commit 226e5ae9e5f910 for -next.
>
> Daniel, this one is for dinq, not fixes.

I tried to apply it, then noticed that I don't even have the original
patch in there yet. It's sitting in your latest -fixes pull (which means
that patch is not really needed since the real fix in the mutex code
landed). Imo better if we don't ship a kernel with this.
-Daniel

>
> BR,
> Jani.
>
> >
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> > Cc: Jani Nikula <jani.nikula at intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_gem.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> > index b06f051a73de..31219af4b7a5 100644
> > --- a/drivers/gpu/drm/i915/i915_gem.c
> > +++ b/drivers/gpu/drm/i915/i915_gem.c
> > @@ -5082,7 +5082,7 @@ static bool mutex_is_locked_by(struct mutex *mutex, struct task_struct *task)
> >   if (!mutex_is_locked(mutex))
> >   return false;
> >
> > -#if defined(CONFIG_SMP) && !defined(CONFIG_DEBUG_MUTEXES)
> > +#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_MUTEXES)
> >   return mutex->owner == task;
> >  #else
> >   /* Since UP may be pre-empted, we cannot assume that we own the lock */
> > --
> > 2.1.4
> >
>
> --
> Jani Nikula, Intel Open Source Technology Center

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch