[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