linux-kernel - [PATCH 1/3] drm/bridge: get the bridge returned by drm_bridge_get_prev

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20250709-drm-bridge-alloc-getput-drm_bridge_get_prev_bridge-v1-1-34ba6f395aaa@bootlin.com>
Date: Wed, 09 Jul 2025 17:59:37 +0200
From: Luca Ceresoli <luca.ceresoli@...tlin.com>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 Andrzej Hajda <andrzej.hajda@...el.com>, 
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>
Cc: Hui Pu <Hui.Pu@...ealthcare.com>, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 Luca Ceresoli <luca.ceresoli@...tlin.com>
Subject: [PATCH 1/3] drm/bridge: get the bridge returned by
 drm_bridge_get_prev_bridge()

drm_bridge_get_prev_bridge() returns a bridge pointer that the
caller could hold for a long time. Increment the refcount of the returned
bridge and document it must be put by the caller.

Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
---
 include/drm/drm_bridge.h | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index d2454ba83db36f8f0d475b0b37468c2ebe7e921d..1963fa61b7f3aa41c7112cb9902790962aff8808 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -1316,6 +1316,13 @@ drm_bridge_get_next_bridge(struct drm_bridge *bridge)
  * drm_bridge_get_prev_bridge() - Get the previous bridge in the chain
  * @bridge: bridge object
  *
+ * The caller is responsible of having a reference to @bridge via
+ * drm_bridge_get() or equivalent. This function leaves the refcount of
+ * @bridge unmodified.
+ *
+ * The refcount of the returned bridge is incremented. Use drm_bridge_put()
+ * when done with it.
+ *
  * RETURNS:
  * the previous bridge in the chain, or NULL if @bridge is the first.
  */
@@ -1325,7 +1332,7 @@ drm_bridge_get_prev_bridge(struct drm_bridge *bridge)
 	if (list_is_first(&bridge->chain_node, &bridge->encoder->bridge_chain))
 		return NULL;
 
-	return list_prev_entry(bridge, chain_node);
+	return drm_bridge_get(list_prev_entry(bridge, chain_node));
 }
 
 /**

-- 
2.50.0