drm/msm: Fix error handling crashes seen when VRAM allocation fails

If VRAM allocation fails, the error handling path crashes in
msm_drm_uninit(). The following changes are made to fix this:

msm_gem_shrinker_cleanup() is fixed to unregister the shrinker only
if it was init-ed in the first place.

Before calling kms->funcs->destroy(), we check if kms->funcs is also
non-NULL. This is needed for MDP5, since during msm_drm_int(), priv->kms
becomes non-NULL early, but msm_kms_init() is called on it only later
in mdp5_kms_init().

Signed-off-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Andy Gross <andy.gross@linaro.org>

2 files changed, 6 insertions, 3 deletions

diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index fb5c0b0a7594..46568fc80848 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -228,7 +228,7 @@ static int msm_drm_uninit(struct device *dev)
         flush_workqueue(priv->atomic_wq);
         destroy_workqueue(priv->atomic_wq);
 
-        if (kms)
+        if (kms && kms->funcs)
                 kms->funcs->destroy(kms);
 
         if (gpu) {
diff --git a/drivers/gpu/drm/msm/msm_gem_shrinker.c b/drivers/gpu/drm/msm/msm_gem_shrinker.c
index 283d2841ba58..192b2d3a79cb 100644
--- a/drivers/gpu/drm/msm/msm_gem_shrinker.c
+++ b/drivers/gpu/drm/msm/msm_gem_shrinker.c
@@ -163,6 +163,9 @@ void msm_gem_shrinker_init(struct drm_device *dev)
 void msm_gem_shrinker_cleanup(struct drm_device *dev)
 {
         struct msm_drm_private *priv = dev->dev_private;
-        WARN_ON(unregister_vmap_purge_notifier(&priv->vmap_notifier));
-        unregister_shrinker(&priv->shrinker);
+
+        if (priv->shrinker.nr_deferred) {
+                WARN_ON(unregister_vmap_purge_notifier(&priv->vmap_notifier));
+                unregister_shrinker(&priv->shrinker);
+        }
 }