drm/vmwgfx: Use a per-device semaphore for reservation protection

Don't use a per-master semaphore (ttm lock) for reservation protection, but
rather a per-device semaphore. This is needed since clients connecting using
render nodes aren't master aware.

The ttm lock used should probably be replaced with a reader-write semaphore
once the function down_xx_interruptible() is available.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_context.c b/drivers/gpu/drm/vmwgfx/vmwgfx_context.c
index 1e80152..701d520 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_context.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_context.c
@@ -462,7 +462,6 @@
 	struct vmw_resource *tmp;
 	struct drm_vmw_context_arg *arg = (struct drm_vmw_context_arg *)data;
 	struct ttm_object_file *tfile = vmw_fpriv(file_priv)->tfile;
-	struct vmw_master *vmaster = vmw_master(file_priv->master);
 	int ret;
 
 
@@ -474,7 +473,7 @@
 	if (unlikely(vmw_user_context_size == 0))
 		vmw_user_context_size = ttm_round_pot(sizeof(*ctx)) + 128;
 
-	ret = ttm_read_lock(&vmaster->lock, true);
+	ret = ttm_read_lock(&dev_priv->reservation_sem, true);
 	if (unlikely(ret != 0))
 		return ret;
 
@@ -521,7 +520,7 @@
 out_err:
 	vmw_resource_unreference(&res);
 out_unlock:
-	ttm_read_unlock(&vmaster->lock);
+	ttm_read_unlock(&dev_priv->reservation_sem);
 	return ret;
 
 }