The per-encoder bridge chain is currently assumed to be static once it is fully initialized. Work is in progress to add hot-pluggable bridges, breaking that assumption.
With bridge removal, the encoder chain can change without notice, removing tail bridges. This can be problematic while iterating over the chain. Add a mutex to be taken whenever looping or changing the encoder chain. Reviewed-by: Maxime Ripard <[email protected]> Signed-off-by: Luca Ceresoli <[email protected]> --- Changes in v3: - Removed the drm_encoder_chain_[un]lock() wrappers Changes in v2: - Added documentation to new APIs --- drivers/gpu/drm/drm_encoder.c | 2 ++ include/drm/drm_encoder.h | 4 ++++ 2 files changed, 6 insertions(+) diff --git a/drivers/gpu/drm/drm_encoder.c b/drivers/gpu/drm/drm_encoder.c index 8f2bc6a28482229fd0b030a1958f87753ad7885f..3261f142baea30c516499d23dbf8d0acf5952cd6 100644 --- a/drivers/gpu/drm/drm_encoder.c +++ b/drivers/gpu/drm/drm_encoder.c @@ -129,6 +129,7 @@ static int __drm_encoder_init(struct drm_device *dev, } INIT_LIST_HEAD(&encoder->bridge_chain); + mutex_init(&encoder->bridge_chain_mutex); list_add_tail(&encoder->head, &dev->mode_config.encoder_list); encoder->index = dev->mode_config.num_encoder++; @@ -202,6 +203,7 @@ void drm_encoder_cleanup(struct drm_encoder *encoder) kfree(encoder->name); list_del(&encoder->head); dev->mode_config.num_encoder--; + mutex_destroy(&encoder->bridge_chain_mutex); memset(encoder, 0, sizeof(*encoder)); } diff --git a/include/drm/drm_encoder.h b/include/drm/drm_encoder.h index 977a9381c8ba943b4d3e021635ea14856df8a17d..eded7c34481a2e9b4a1273004627a03f4035b24f 100644 --- a/include/drm/drm_encoder.h +++ b/include/drm/drm_encoder.h @@ -25,6 +25,7 @@ #include <linux/list.h> #include <linux/ctype.h> +#include <linux/mutex.h> #include <drm/drm_crtc.h> #include <drm/drm_mode.h> #include <drm/drm_mode_object.h> @@ -189,6 +190,9 @@ struct drm_encoder { */ struct list_head bridge_chain; + /** @bridge_chain_mutex: protect bridge_chain from changes while iterating */ + struct mutex bridge_chain_mutex; + const struct drm_encoder_funcs *funcs; const struct drm_encoder_helper_funcs *helper_private; -- 2.51.1
