[PATCH] drm/locking: Allow NULL crtc in drm_modeset_legacy_acquire_ctx

[Ville Syrjälä]

On Fri, Nov 21, 2014 at 04:40:18PM +0100, Daniel Vetter wrote:
> I've missed checking this and so didn't notice that there's a NULL
> check missing. Since depending upon calling context the crtc might not
> even be there (disable-me-harder does happen around planes, especially
> in cleanup code) we need to dodge the oops and look at the global
> acquire ctx.
> 
> Reported-by: "Jasper St. Pierre" <jstpierre at mecheye.net>
> Cc: "Jasper St. Pierre" <jstpierre at mecheye.net>
> Cc: Rob Clark <robdclark at gmail.com>
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> ---
>  drivers/gpu/drm/drm_modeset_lock.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_modeset_lock.c b/drivers/gpu/drm/drm_modeset_lock.c
> index 474e4d12a2d8..93d28269e3bd 100644
> --- a/drivers/gpu/drm/drm_modeset_lock.c
> +++ b/drivers/gpu/drm/drm_modeset_lock.c
> @@ -209,7 +209,7 @@ EXPORT_SYMBOL(drm_modeset_lock_crtc);
>  struct drm_modeset_acquire_ctx *
>  drm_modeset_legacy_acquire_ctx(struct drm_crtc *crtc)
>  {
> -	if (crtc->acquire_ctx)
> +	if (crtc && crtc->acquire_ctx)
>  		return crtc->acquire_ctx;
>  
>  	WARN_ON(!crtc->dev->mode_config.acquire_ctx);
  	         ^^^^^^

How's that going to work without the crtc?

> -- 
> 2.1.1
> 
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-- 
Ville Syrjälä
Intel OTC