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@bootlin.com>
---
Changes in v3:
- Lock encoder->bridge_chain_mutex directly, no wrappers
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..a25e379237f95c037eddc7602d405f958a4efa44 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;
+ 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);
@@ -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;
+ 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",
--
2.51.0