drm/i915: grab dev->struct_mutex around framebuffer_init

We look at gem state (like obj->tiling/obj->stride), we better have
the relevant locks.

Right now this doesn't matter much since most of these checks are
a curtesy to safe buggy userspace, but I'd like to freeze the tiling
once we have framebuffer objects attached. And then locking matters.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 14 insertions, 5 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 0bbf9215637b..88e560070bec 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -7285,14 +7285,21 @@ intel_framebuffer_create(struct drm_device *dev,
                 return ERR_PTR(-ENOMEM);
         }
 
+        ret = i915_mutex_lock_interruptible(dev);
+        if (ret)
+                goto err;
+
         ret = intel_framebuffer_init(dev, intel_fb, mode_cmd, obj);
-        if (ret) {
-                drm_gem_object_unreference_unlocked(&obj->base);
-                kfree(intel_fb);
-                return ERR_PTR(ret);
-        }
+        mutex_unlock(&dev->struct_mutex);
+        if (ret)
+                goto err;
 
         return &intel_fb->base;
+err:
+        drm_gem_object_unreference_unlocked(&obj->base);
+        kfree(intel_fb);
+
+        return ERR_PTR(ret);
 }
 
 static u32
@@ -9989,6 +9996,8 @@ int intel_framebuffer_init(struct drm_device *dev,
         int pitch_limit;
         int ret;
 
+        WARN_ON(!mutex_is_locked(&dev->struct_mutex));
+
         if (obj->tiling_mode == I915_TILING_Y) {
                 DRM_DEBUG("hardware does not support tiling Y\n");
                 return -EINVAL;