[Intel-gfx] [PATCH 1/4] drm/i915: grab dev->struct_mutex around framebuffer_init

[Daniel Vetter]

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 at linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/i915/intel_display.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 00271b1..70f4091 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -7276,14 +7276,21 @@ 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
@@ -9981,6 +9988,8 @@ 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;
-- 
1.8.1.4