Hi Mauro,
Please see my comments below.
On Mon, Mar 28, 2016 at 03:11:04PM -0300, Mauro Carvalho Chehab wrote:
> Add a note at the headers telling that the link setup
> callbacks are called with the mutex hold. Also, removes a
> double lock at the PM suspend callbacks.
>
> Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxx>
> ---
> drivers/media/media-device.c | 1 -
> drivers/media/v4l2-core/v4l2-mc.c | 4 ----
> include/media/media-device.h | 3 ++-
> include/media/media-entity.h | 3 +++
> 4 files changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
> index 6cfa890af7b4..6af5e6932271 100644
> --- a/drivers/media/media-device.c
> +++ b/drivers/media/media-device.c
> @@ -93,7 +93,6 @@ static struct media_entity *find_entity(struct media_device *mdev, u32 id)
> media_device_for_each_entity(entity, mdev) {
> if (((media_entity_id(entity) == id) && !next) ||
> ((media_entity_id(entity) > id) && next)) {
> - mutex_unlock(&mdev->graph_mutex);
Unrelated to this patch.
Please do also consider compat IOCTL handling code.
> return entity;
> }
> }
> diff --git a/drivers/media/v4l2-core/v4l2-mc.c b/drivers/media/v4l2-core/v4l2-mc.c
> index 2228cd3a846e..d44ff2ec314f 100644
> --- a/drivers/media/v4l2-core/v4l2-mc.c
> +++ b/drivers/media/v4l2-core/v4l2-mc.c
> @@ -348,8 +348,6 @@ int v4l2_pipeline_pm_use(struct media_entity *entity, int use)
> int change = use ? 1 : -1;
> int ret;
>
> - mutex_lock(&mdev->graph_mutex);
What's the motivation for this change and the one below?
As far as I can see, they remove access serialisation of graph state during
graph walk, which certainly is not the right thing to do.
> -
> /* Apply use count to node. */
> entity->use_count += change;
> WARN_ON(entity->use_count < 0);
> @@ -359,8 +357,6 @@ int v4l2_pipeline_pm_use(struct media_entity *entity, int use)
> if (ret < 0)
> entity->use_count -= change;
>
> - mutex_unlock(&mdev->graph_mutex);
> -
> return ret;
> }
> EXPORT_SYMBOL_GPL(v4l2_pipeline_pm_use);
> diff --git a/include/media/media-device.h b/include/media/media-device.h
> index b04cfa907350..e6ad30c323fc 100644
> --- a/include/media/media-device.h
> +++ b/include/media/media-device.h
> @@ -312,7 +312,8 @@ struct media_entity_notify {
> * @enable_source: Enable Source Handler function pointer
> * @disable_source: Disable Source Handler function pointer
> *
> - * @link_notify: Link state change notification callback
> + * @link_notify: Link state change notification callback. This callback is
> + * Called with the graph_mutex hold.
I don't mind adding documentation such as this, but I'd put it into a
separate patch.
> *
> * This structure represents an abstract high-level media device. It allows easy
> * access to entities and provides basic media device-level support. The
> diff --git a/include/media/media-entity.h b/include/media/media-entity.h
> index 6dc9e4e8cbd4..0b16ebe36db7 100644
> --- a/include/media/media-entity.h
> +++ b/include/media/media-entity.h
> @@ -179,6 +179,9 @@ struct media_pad {
> * @link_validate: Return whether a link is valid from the entity point of
> * view. The media_entity_pipeline_start() function
> * validates all links by calling this operation. Optional.
> + *
> + * Note: Those ioctls should not touch the struct media_device.@graph_mutex
> + * field, as they're called with it already hold.
> */
> struct media_entity_operations {
> int (*link_setup)(struct media_entity *entity,
--
Kind regards,
Sakari Ailus
e-mail: sakari.ailus@xxxxxx XMPP: sailus@xxxxxxxxxxxxxx
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