From: Luca Ceresoli Date: Tue, 24 Mar 2026 08:58:10 +0000 (+0100) Subject: drm/bridge: drm_bridge_attach: lock the encoder chain mutex during insertion X-Git-Tag: v7.2-rc1~141^2~26^2~77 X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=6dc294c4d3666525ee80dc6a4c9e123c36ca773c;p=thirdparty%2Flinux.git 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 Reviewed-by: Louis Chauvet Link: https://patch.msgid.link/20260324-drm-bridge-alloc-encoder-chain-mutex-v5-3-8bf786c5c7e6@bootlin.com Signed-off-by: Luca Ceresoli --- diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c index ba80bebb56856..fed8f1f06d949 100644 --- a/drivers/gpu/drm/drm_bridge.c +++ b/drivers/gpu/drm/drm_bridge.c @@ -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",