Take the encoder chain mutex while iterating over the encoder chain in drm_atomic_bridge_chain_pre_enable() and drm_atomic_bridge_chain_post-disable().
These functions have nested list_for_each_*() loops, which makes them complicated. list_for_each_entry_from() loops could be replaced by drm_for_each_bridge_in_chain_from(), but it would not work in a nested way. Besides, there is no "_reverse" variant of drm_for_each_bridge_in_chain_from(). Keep code simple and readable by explicitly locking around the outer loop. Thankfully there are no return points inside the loops, so the change is trivial and readable. Signed-off-by: Luca Ceresoli <[email protected]> --- 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 66c0a80db8426ffb360248895cfe2a11d6007ed7..00e0a88128d0eeabf25911591ad8c482d6c1caf8 100644 --- a/drivers/gpu/drm/drm_bridge.c +++ b/drivers/gpu/drm/drm_bridge.c @@ -765,6 +765,7 @@ void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge, encoder = bridge->encoder; + drm_encoder_chain_lock(encoder); list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) { limit = NULL; @@ -813,6 +814,7 @@ void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge, /* Jump all bridges that we have already post_disabled */ bridge = limit; } + drm_encoder_chain_unlock(encoder); } EXPORT_SYMBOL(drm_atomic_bridge_chain_post_disable); @@ -859,6 +861,7 @@ void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge, encoder = bridge->encoder; + drm_encoder_chain_lock(encoder); list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) { if (iter->pre_enable_prev_first) { next = iter; @@ -901,6 +904,7 @@ void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge, if (iter == bridge) break; } + drm_encoder_chain_unlock(encoder); } EXPORT_SYMBOL(drm_atomic_bridge_chain_pre_enable); -- 2.51.0
