Re: [PATCH] drm/of: free the right object
From: Daniel Vetter <hidden>
Date: 2021-07-12 14:25:47
Also in:
dri-devel, lkml
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
quoted hunk ↗ jump to hunk
--- 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; }
-- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch