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Message-Id: <20251003-drm-bridge-alloc-encoder-chain-mutex-v2-3-78bf61580a06@bootlin.com>
Date: Fri, 03 Oct 2025 12:39:25 +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>,
David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
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>
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 v2 3/7] drm/bridge: lock the encoder bridge chain mutex
during insertion
drm_bridge_attach() modifies the encoder bridge chain, so take a mutex
around such operations to allow users of the chain to protect themselves
from chain modifications while iterating.
Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
---
Changes in v2:
- Removed comment before on drm_bridge_detach()
---
drivers/gpu/drm/drm_bridge.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 53e7ece36dd940aabd1c0880f296fce7224a12ac..d2ab7cef0b768b0ff674a77977833da27133912f 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -453,10 +453,12 @@ int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
bridge->dev = encoder->dev;
bridge->encoder = encoder;
+ drm_encoder_chain_lock(encoder);
if (previous)
list_add(&bridge->chain_node, &previous->chain_node);
else
list_add(&bridge->chain_node, &encoder->bridge_chain);
+ drm_encoder_chain_unlock(encoder);
if (bridge->funcs->attach) {
ret = bridge->funcs->attach(bridge, encoder, flags);
@@ -487,7 +489,9 @@ int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
err_reset_bridge:
bridge->dev = NULL;
bridge->encoder = NULL;
+ drm_encoder_chain_lock(encoder);
list_del(&bridge->chain_node);
+ drm_encoder_chain_unlock(encoder);
if (ret != -EPROBE_DEFER)
DRM_ERROR("failed to attach bridge %pOF to encoder %s: %d\n",
--
2.51.0
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