drm/i915: Avoid drm_atomic_state_put(NULL) in intel_display_resume

intel_display_resume() may be called without an atomic state to restore,
i.e. dev_priv->modeset_reset_restore state is NULL. One such case is
following a lid open/close event and the forced modeset in
intel_lid_notify().

Reported-by: Stefan Seyfried <stefan.seyfried@googlemail.com>
Tested-by: Stefan Seyfried <stefan.seyfried@googlemail.com>
Fixes: 0853695c3ba4 ("drm: Add reference counting to drm_atomic_state")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: <drm-intel-fixes@lists.freedesktop.org> # v4.10-rc1+
Link: http://patchwork.freedesktop.org/patch/msgid/20170115125825.18597-1-chris@chris-wilson.co.uk
Reviewed-by: Ander Conselvan de Oliveira <conselvan2@gmail.com>
(cherry picked from commit 3c5e37f169cb67cbd03c6116fbc93e0805815d29)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 8d702cf1a616ad4cd06b21593204e20634d6a7fb..1a01d4189c3f984fb79364dbf701c4baf6678757 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -17027,7 +17027,8 @@ void intel_display_resume(struct drm_device *dev)
 
        if (ret)
                DRM_ERROR("Restoring old state failed with %i\n", ret);
-       drm_atomic_state_put(state);
+       if (state)
+               drm_atomic_state_put(state);
 }
 
 void intel_modeset_gem_init(struct drm_device *dev)