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>

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 0bbf9215637bcf3e02ecbe8733452a1db9341e8b..88e560070bec26d565f99d7b5d6b8af0143d16c8 100644 (file)
--- 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;