| 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
| ||
|
Message-Id: <20251119-drm-bridge-alloc-getput-drm_of_find_bridge-v1-6-0db98a7fe474@bootlin.com>
Date: Wed, 19 Nov 2025 14:05:37 +0100
From: Luca Ceresoli <luca.ceresoli@...tlin.com>
To: 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>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
Jonathan Corbet <corbet@....net>, Alexey Brodkin <abrodkin@...opsys.com>,
Phong LE <ple@...libre.com>, Liu Ying <victor.liu@....com>,
Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>,
Pengutronix Kernel Team <kernel@...gutronix.de>,
Fabio Estevam <festevam@...il.com>,
Adrien Grassein <adrien.grassein@...il.com>,
Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
Tomi Valkeinen <tomi.valkeinen+renesas@...asonboard.com>,
Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
Geert Uytterhoeven <geert+renesas@...der.be>,
Magnus Damm <magnus.damm@...il.com>, Kevin Hilman <khilman@...libre.com>,
Jerome Brunet <jbrunet@...libre.com>,
Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
Chun-Kuang Hu <chunkuang.hu@...nel.org>,
Philipp Zabel <p.zabel@...gutronix.de>,
Matthias Brugger <matthias.bgg@...il.com>,
AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
Anitha Chrisanthus <anitha.chrisanthus@...el.com>,
Edmund Dea <edmund.j.dea@...el.com>, Inki Dae <inki.dae@...sung.com>,
Seung-Woo Kim <sw0312.kim@...sung.com>,
Kyungmin Park <kyungmin.park@...sung.com>,
Krzysztof Kozlowski <krzk@...nel.org>,
Alim Akhtar <alim.akhtar@...sung.com>
Cc: Hui Pu <Hui.Pu@...ealthcare.com>,
Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
linux-doc@...r.kernel.org, imx@...ts.linux.dev,
linux-arm-kernel@...ts.infradead.org, linux-renesas-soc@...r.kernel.org,
linux-amlogic@...ts.infradead.org, linux-mediatek@...ts.infradead.org,
linux-samsung-soc@...r.kernel.org,
Luca Ceresoli <luca.ceresoli@...tlin.com>
Subject: [PATCH 06/26] drm/bridge: add devm_drm_of_find_bridge
Several drivers (about 20) follow the same pattern:
1. get a pointer to a bridge (typically the next bridge in the chain) by
calling of_drm_find_bridge()
2. store the returned pointer in the private driver data, keep it until
driver .remove
3. dereference the pointer at attach time and possibly at other times
of_drm_find_bridge() is now deprecated because it does not increment the
refcount and should be replaced with drm_of_find_bridge() +
drm_bridge_put().
However some of those drivers have a complex code flow and adding a
drm_bridge_put() call in all the appropriate locations is error-prone,
leads to ugly and more complex code, and can lead to errors over time with
code flow changes.
To handle all those drivers in a straightforward way, add a devm variant of
drm_of_find_bridge() that adds a devm action to invoke drm_bridge_put()
when the said driver is removed. This allows all those drivers to put the
reference automatically and safely with a one line change:
- priv->next_bridge = of_drm_find_bridge(remote_np);
+ priv->next_bridge = devm_drm_of_find_bridge(dev, remote_np);
Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
---
drivers/gpu/drm/drm_bridge.c | 30 ++++++++++++++++++++++++++++++
include/drm/drm_bridge.h | 5 +++++
2 files changed, 35 insertions(+)
diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 09ad825f9cb8..c7baafbe5695 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -1446,6 +1446,36 @@ struct drm_bridge *drm_of_find_bridge(struct device_node *np)
}
EXPORT_SYMBOL(drm_of_find_bridge);
+/**
+ * devm_drm_of_find_bridge - find the bridge corresponding to the device
+ * node in the global bridge list and add a devm
+ * action to put it
+ *
+ * @dev: device requesting the bridge
+ * @np: device node
+ *
+ * On success the returned bridge refcount is incremented, and a devm
+ * action is added to call drm_bridge_put() when @dev is removed. So the
+ * caller does not have to put the returned bridge explicitly.
+ *
+ * RETURNS:
+ * drm_bridge control struct on success, NULL on failure
+ */
+struct drm_bridge *devm_drm_of_find_bridge(struct device *dev, struct device_node *np)
+{
+ struct drm_bridge *bridge = drm_of_find_bridge(np);
+
+ if (bridge) {
+ int err = devm_add_action_or_reset(dev, drm_bridge_put_void, bridge);
+
+ if (err)
+ return ERR_PTR(err);
+ }
+
+ return bridge;
+}
+EXPORT_SYMBOL(devm_drm_of_find_bridge);
+
/**
* of_drm_find_bridge - find the bridge corresponding to the device node in
* the global bridge list
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index e74e91004c48..98d5433f7d35 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -1314,12 +1314,17 @@ int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
#ifdef CONFIG_OF
struct drm_bridge *drm_of_find_bridge(struct device_node *np);
+struct drm_bridge *devm_drm_of_find_bridge(struct device *dev, struct device_node *np);
struct drm_bridge *of_drm_find_bridge(struct device_node *np);
#else
static inline struct drm_bridge *drm_of_find_bridge(struct device_node *np)
{
return NULL;
}
+static inline struct drm_bridge *devm_drm_of_find_bridge(struct device *dev, struct device_node *np)
+{
+ return NULL;
+}
static inline struct drm_bridge *of_drm_find_bridge(struct device_node *np)
{
return NULL;
--
2.51.1
Powered by blists - more mailing lists