[PATCH 13/29] drm/armada: Use a private mutex to protect priv->linear

[Russell King - ARM Linux]

On Mon, Nov 23, 2015 at 10:32:46AM +0100, Daniel Vetter wrote:
> diff --git a/drivers/gpu/drm/armada/armada_gem.c b/drivers/gpu/drm/armada/armada_gem.c
> index e3a86b96af2a..a43690ab18b9 100644
> --- a/drivers/gpu/drm/armada/armada_gem.c
> +++ b/drivers/gpu/drm/armada/armada_gem.c
> @@ -46,7 +46,7 @@ static size_t roundup_gem_size(size_t size)
>  	return roundup(size, PAGE_SIZE);
>  }
>  
> -/* dev->struct_mutex is held here */
> +/* dev_priv->linear_lock is held here */
>  void armada_gem_free_object(struct drm_gem_object *obj)

This is wrong (unless there's changes which I'm not aware of.)

This function is called from drm_gem_object_free(), which is called from
drm_gem_object_unreference(), both of which contain:

        WARN_ON(!mutex_is_locked(&dev->struct_mutex));

Now, unless you're changing the conditions on which
drm_gem_object_unreference() to be under dev_priv->linear_lock, the
above comment becomes misleading.

It'd also need drm_gem_object_unreference_unlocked() to become per-
driver, so it can take dev_priv->linear_lock, and I don't see anything
in the patches which I've received which does that.

So, I suspect the new comment is basically false.

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