linux-kernel - [PATCH 4.20 095/183] drm/sun4i: backend: add missing of_node

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Message-Id: <20190225195110.696644933@linuxfoundation.org>
Date:   Mon, 25 Feb 2019 22:11:08 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Julia Lawall <Julia.Lawall@...6.fr>,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.20 095/183] drm/sun4i: backend: add missing of_node_puts

4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 4bb0e6d7258213d4893c2c876712fbba40e712fe ]

The device node iterators perform an of_node_get on each
iteration, so a jump out of the loop requires an of_node_put.

Remote and port also have augmented reference counts, so drop them
on each iteration and at the end of the function, respectively.
Remote is only used for the address it contains, not for the
contents of that address, so the reference count can be dropped
immediately.

The semantic patch that fixes the first part of this problem is
as follows (http://coccinelle.lip6.fr):

// <smpl>
@@
expression root,e;
local idexpression child;
iterator name for_each_child_of_node;
@@

 for_each_available_child_of_node(root, child) {
   ... when != of_node_put(child)
       when != e = child
+  of_node_put(child);
?  break;
   ...
}
... when != child
// </smpl>

Signed-off-by: Julia Lawall <Julia.Lawall@...6.fr>
Signed-off-by: Maxime Ripard <maxime.ripard@...tlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1547369264-24831-5-git-send-email-Julia.Lawall@lip6.fr
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/sun4i/sun4i_backend.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_backend.c b/drivers/gpu/drm/sun4i/sun4i_backend.c
index bf49c55b0f2c7..9f27d5464804b 100644
--- a/drivers/gpu/drm/sun4i/sun4i_backend.c
+++ b/drivers/gpu/drm/sun4i/sun4i_backend.c
@@ -704,17 +704,18 @@ static struct sun4i_frontend *sun4i_backend_find_frontend(struct sun4i_drv *drv,
 		remote = of_graph_get_remote_port_parent(ep);
 		if (!remote)
 			continue;
+		of_node_put(remote);
 
 		/* does this node match any registered engines? */
 		list_for_each_entry(frontend, &drv->frontend_list, list) {
 			if (remote == frontend->node) {
-				of_node_put(remote);
 				of_node_put(port);
+				of_node_put(ep);
 				return frontend;
 			}
 		}
 	}
-
+	of_node_put(port);
 	return ERR_PTR(-EINVAL);
 }
 
-- 
2.19.1