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| author | Luca Ceresoli <luca.ceresoli@bootlin.com> | 2026-03-24 09:58:08 +0100 |
|---|---|---|
| committer | Luca Ceresoli <luca.ceresoli@bootlin.com> | 2026-04-16 09:08:42 +0200 |
| commit | 01b92f0d18214660d9978f0c4dd9507ee8d27d06 (patch) | |
| tree | 863a072a492f391ddba8e70f3372155a27e82c01 | |
| parent | 8065890f5cda3f8a503f3b9d326aab0e9cca39e7 (diff) | |
| download | linux-01b92f0d18214660d9978f0c4dd9507ee8d27d06.tar.gz linux-01b92f0d18214660d9978f0c4dd9507ee8d27d06.zip | |
drm/encoder: add mutex to protect the bridge chain
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 <mripard@kernel.org>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
Link: https://patch.msgid.link/20260324-drm-bridge-alloc-encoder-chain-mutex-v5-1-8bf786c5c7e6@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
| -rw-r--r-- | drivers/gpu/drm/drm_encoder.c | 2 | ||||
| -rw-r--r-- | include/drm/drm_encoder.h | 4 |
2 files changed, 6 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_encoder.c b/drivers/gpu/drm/drm_encoder.c index 8f2bc6a28482..3261f142baea 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 977a9381c8ba..eded7c34481a 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; |