On Fri, Jul 09, 2021 at 10:07:17PM +0200, Julia Lawall wrote:
There is no need to free a NULL value. Instead, free the object that is leaking due to the iterator.
The semantic patch that finds this problem is as follows:
// <smpl> @@ expression x,e; identifier f; @@ x = f(...); if (x == NULL) { ... when any when != x = e
- of_node_put(x); ...
} // </smpl>
Fixes: 6529007522de ("drm: of: Add drm_of_lvds_get_dual_link_pixel_order") Signed-off-by: Julia Lawall Julia.Lawall@inria.fr
Applied to drm-misc-next, thanks for your patch.
Random rant about this for_each_child_of_node(): - not documented with kerneldoc - very dangerous since the seemingly correct usage leaks
What we've done here for similar refcounted iterators is a 3 step process: - iter_init() - for_each_iter() macro - iter_fini(), which has to be always called after iter_init and cleans up the last reference.
Then it's a lot more obvious that you call iter_fini() when you break out of a loop. Trying to hide that in the for_each macro is a bit much.
Cheers, Daniel
drivers/gpu/drm/drm_of.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c index ca04c34e8251..197c57477344 100644 --- a/drivers/gpu/drm/drm_of.c +++ b/drivers/gpu/drm/drm_of.c @@ -315,7 +315,7 @@ static int drm_of_lvds_get_remote_pixels_type(
remote_port = of_graph_get_remote_port(endpoint); if (!remote_port) {
of_node_put(remote_port);
of_node_put(endpoint); return -EPIPE;