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

From: Jani Nikula <jani.nikula@intel.com>
To: Chris Wilson <chris@chris-wilson.co.uk>, intel-gfx@lists.freedesktop.org
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Subject: Re: [PATCH] Revert "drm/i915: Fix mutex->owner inspection race under DEBUG_MUTEXES"
Date: Thu, 15 Jan 2015 09:13:02 +0200	[thread overview]
Message-ID: <878uh4frep.fsf@intel.com> (raw)
In-Reply-To: <1421271587-28490-1-git-send-email-chris@chris-wilson.co.uk>

On Wed, 14 Jan 2015, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> The core fix was applied in
>
> commit a63b03e2d2477586440741677ecac45bcf28d7b1
> Author: Chris Wilson <chris@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.

BR,
Jani.

>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Jani Nikula <jani.nikula@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
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