Re: [PATCH] drm/i915: Only unpin the default ctx object if it exists

[Daniel Vetter <daniel@ffwll.ch>]

On Fri, May 16, 2014 at 06:59:00PM +0100, Chris Wilson wrote:
> Since commit 691e6415c891b8b2b082a120b896b443531c4d45
> Author: Chris Wilson <chris@chris-wilson.co.uk>
> Date:   Wed Apr 9 09:07:36 2014 +0100
> 
>     drm/i915: Always use kref tracking for all contexts.
> 
> we have contexts everywhere, and so we must be careful to distinguish
> fake contexts, which do not have an associated bo, and real ones, which
> do. In particular, we now need to be careful not to dereference NULL
> pointers.
> 
> This is one such example, as the commit highlighted above failed to move
> the unpinning of the default ctx object into the real-context-only
> branch.
> 
> Reported-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=78792
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Ben Widawsky <benjamin.widawsky@intel.com>
> Cc: Mika Kuoppala <mika.kuoppala@intel.com>
> Cc: Jani Nikula <jani.nikula@intel.com>

I'll leave it to Jani to decide whether this is justified for -fixes, it
has my t-d & r-b. Queued for -next, thanks for the patch.
-Daniel

> ---
>  drivers/gpu/drm/i915/i915_gem_context.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
> index 55b3e52..4c7cd24 100644
> --- a/drivers/gpu/drm/i915/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> @@ -454,6 +454,8 @@ void i915_gem_context_fini(struct drm_device *dev)
>  			i915_gem_context_unreference(dctx);
>  			dev_priv->ring[RCS].last_context = NULL;
>  		}
> +
> +		i915_gem_object_ggtt_unpin(dctx->obj);
>  	}
>  
>  	for (i = 0; i < I915_NUM_RINGS; i++) {
> @@ -466,7 +468,6 @@ void i915_gem_context_fini(struct drm_device *dev)
>  		ring->last_context = NULL;
>  	}
>  
> -	i915_gem_object_ggtt_unpin(dctx->obj);
>  	i915_gem_context_unreference(dctx);
>  }
>  
> -- 
> 1.7.9.5
> 

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