[PATCH 1/2] drm/vmwgfx: Fix a couple of lock dependency violations

[Thomas Hellstrom]

Experimental lockdep annotation added to the TTM lock has unveiled a
couple of lock dependency violations in the vmwgfx driver. In both
cases it turns out that the device_private::reservation_sem is not
needed so the offending code is moved out of that lock.

Cc: <stable at vger.kernel.org>
Acked-by: Sinclair Yeh <syeh at vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom at vmware.com>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c |  8 +++-----
 drivers/gpu/drm/vmwgfx/vmwgfx_kms.c     | 14 +++-----------
 2 files changed, 6 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
index 33176d0..1e11489 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
@@ -2780,13 +2780,11 @@ int vmw_execbuf_ioctl(struct drm_device *dev, void *data,
 				  NULL, arg->command_size, arg->throttle_us,
 				  (void __user *)(unsigned long)arg->fence_rep,
 				  NULL);
-
+	ttm_read_unlock(&dev_priv->reservation_sem);
 	if (unlikely(ret != 0))
-		goto out_unlock;
+		return ret;
 
 	vmw_kms_cursor_post_execbuf(dev_priv);
 
-out_unlock:
-	ttm_read_unlock(&dev_priv->reservation_sem);
-	return ret;
+	return 0;
 }
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
index 8725b79..07cda8c 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
@@ -2033,23 +2033,17 @@ int vmw_kms_update_layout_ioctl(struct drm_device *dev, void *data,
 	int i;
 	struct drm_mode_config *mode_config = &dev->mode_config;
 
-	ret = ttm_read_lock(&dev_priv->reservation_sem, true);
-	if (unlikely(ret != 0))
-		return ret;
-
 	if (!arg->num_outputs) {
 		struct drm_vmw_rect def_rect = {0, 0, 800, 600};
 		vmw_du_update_layout(dev_priv, 1, &def_rect);
-		goto out_unlock;
+		return 0;
 	}
 
 	rects_size = arg->num_outputs * sizeof(struct drm_vmw_rect);
 	rects = kcalloc(arg->num_outputs, sizeof(struct drm_vmw_rect),
 			GFP_KERNEL);
-	if (unlikely(!rects)) {
-		ret = -ENOMEM;
-		goto out_unlock;
-	}
+	if (unlikely(!rects))
+		return -ENOMEM;
 
 	user_rects = (void __user *)(unsigned long)arg->rects;
 	ret = copy_from_user(rects, user_rects, rects_size);
@@ -2074,7 +2068,5 @@ int vmw_kms_update_layout_ioctl(struct drm_device *dev, void *data,
 
 out_free:
 	kfree(rects);
-out_unlock:
-	ttm_read_unlock(&dev_priv->reservation_sem);
 	return ret;
 }
-- 
2.1.0