[PATCH v2.1 2/4] drm/atomic: Add accessor macros for the current state, v2.

[Daniel Vetter]

On Thu, Nov 17, 2016 at 02:20:10PM +0100, Maarten Lankhorst wrote:
> With checks! This will allow safe access to the current state,
> while ensuring that the correct locks are held.
> 
> Changes since v1:
> - Constify returned states.
> - Require plane lock to return plane state, don't allow crtc_lock to
>   be sufficient.
> 
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> ---
> diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
> index e527684dd394..9af5aba8c27c 100644
> --- a/include/drm/drm_atomic.h
> +++ b/include/drm/drm_atomic.h
> @@ -334,6 +334,66 @@ __drm_atomic_get_current_plane_state(struct drm_atomic_state *state,
>  	return plane->state;
>  }
>  
> +
> +/**
> + * drm_atomic_get_current_plane_state - get current plane state
> + * @plane: plane to grab
> + *
> + * This function returns the current plane state for the given plane,
> + * with extra locking checks to make sure that the plane state can be
> + * retrieved safely.
> + *
> + * Returns:
> + *
> + * Pointer to the current plane state.
> + */
> +static inline const struct drm_plane_state *
> +drm_atomic_get_current_plane_state(struct drm_plane *plane)
> +{
> +	drm_modeset_lock_assert_held(&plane->mutex);
> +
> +	return plane->state;
> +}
> +
> +/**
> + * drm_atomic_get_current_crtc_state - get current crtc state
> + * @crtc: crtc to grab
> + *
> + * This function returns the current crtc state for the given crtc,
> + * with extra locking checks to make sure that the crtc state can be
> + * retrieved safely.
> + *
> + * Returns:
> + *
> + * Pointer to the current crtc state.
> + */
> +static inline const struct drm_crtc_state *
> +drm_atomic_get_current_crtc_state(struct drm_crtc *crtc)
> +{
> +	drm_modeset_lock_assert_held(&crtc->mutex);
> +
> +	return crtc->state;
> +}
> +
> +/**
> + * drm_atomic_get_current_connector_state - get current connector state
> + * @connector: connector to grab
> + *
> + * This function returns the current connector state for the given connector,
> + * with extra locking checks to make sure that the connector state can be
> + * retrieved safely.
> + *
> + * Returns:
> + *
> + * Pointer to the current connector state.
> + */
> +#define drm_atomic_get_current_connector_state(connector) \
> +({ /* Implemented as macro to avoid including drmP for struct drm_device */ \

Imo that's not a terrible good reason. Eventually will split drm_device.h
out from drmP.h, and then we can nuke the additional include. Can you pls
respin?
-Daniel

> +	struct drm_connector *con__ = (connector); \
> +	drm_modeset_lock_assert_held(&con__->dev->mode_config.connection_mutex); \
> +	(const struct drm_connector_state *)con__->state; \
> +})
> +
>  int __must_check
>  drm_atomic_set_mode_for_crtc(struct drm_crtc_state *state,
>  			     struct drm_display_mode *mode);
> diff --git a/include/drm/drm_modeset_lock.h b/include/drm/drm_modeset_lock.h
> index d918ce45ec2c..3ca4ee838b07 100644
> --- a/include/drm/drm_modeset_lock.h
> +++ b/include/drm/drm_modeset_lock.h
> @@ -109,6 +109,15 @@ static inline bool drm_modeset_is_locked(struct drm_modeset_lock *lock)
>  	return ww_mutex_is_locked(&lock->mutex);
>  }
>  
> +static inline void drm_modeset_lock_assert_held(struct drm_modeset_lock *lock)
> +{
> +#ifdef CONFIG_LOCKDEP
> +	lockdep_assert_held(&lock->mutex.base);
> +#else
> +	WARN_ON(!drm_modeset_is_locked(lock));
> +#endif
> +}
> +
>  int drm_modeset_lock(struct drm_modeset_lock *lock,
>  		struct drm_modeset_acquire_ctx *ctx);
>  int drm_modeset_lock_interruptible(struct drm_modeset_lock *lock,
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch