drm/bridge: drm_bridge_attach: lock the encoder 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.

Reviewed-by: Maxime Ripard <mripard@kernel.org>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
Link: https://patch.msgid.link/20260324-drm-bridge-alloc-encoder-chain-mutex-v5-3-8bf786c5c7e6@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
This commit is contained in:
Luca Ceresoli 2026-03-24 09:58:10 +01:00
parent f6d20e06f4
commit 6dc294c4d3

View File

@ -574,10 +574,12 @@ int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
bridge->dev = encoder->dev;
bridge->encoder = encoder;
mutex_lock(&encoder->bridge_chain_mutex);
if (previous)
list_add(&bridge->chain_node, &previous->chain_node);
else
list_add(&bridge->chain_node, &encoder->bridge_chain);
mutex_unlock(&encoder->bridge_chain_mutex);
if (bridge->funcs->attach) {
ret = bridge->funcs->attach(bridge, encoder, flags);
@ -594,7 +596,9 @@ int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
err_reset_bridge:
bridge->dev = NULL;
bridge->encoder = NULL;
mutex_lock(&encoder->bridge_chain_mutex);
list_del(&bridge->chain_node);
mutex_unlock(&encoder->bridge_chain_mutex);
if (ret != -EPROBE_DEFER)
DRM_ERROR("failed to attach bridge %pOF to encoder %s: %d\n",