[patch] drm/ttm: return -EFAULT on copy_to_user error

[Dan Carpenter]

copy_to/from_user() returns the number of bytes remaining and this
function normally returns negative error codes.  No one uses the
ttm_bo_fbdev_io() function so this change has no impact.

Signed-off-by: Dan Carpenter <error27 at gmail.com>

diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index fe6cb77..fe4a25a 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -444,7 +444,7 @@ ssize_t ttm_bo_fbdev_io(struct ttm_buffer_object *bo, const char __user *wbuf,
 	ttm_bo_unref(&bo);
 
 	if (unlikely(ret != 0))
-		return ret;
+		return -EFAULT;
 
 	*f_pos += io_size;