Re: [PATCH 1/4] drm/atomic: integrate modeset lock with private objects

[Daniel Vetter]

On Wed, Feb 21, 2018 at 09:37:21AM -0500, Rob Clark wrote:
> Follow the same pattern of locking as with other state objects.  This
> avoids boilerplate in the driver.
> 
> Signed-off-by: Rob Clark <robdclark@xxxxxxxxx>

Please also adjust the kernel doc, and I think we can remove the locking
WARN_ON in drm_atomic_get_mst_topology_state after this patch (plus again
adjust the kerneldoc for that please).

Otherwise I think this makes sense, and ecnourages reasonable semantics
for driver private state objects.
-Daniel

> ---
>  drivers/gpu/drm/drm_atomic.c | 9 ++++++++-
>  include/drm/drm_atomic.h     | 5 +++++
>  2 files changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> index fc8c4da409ff..004e621ab307 100644
> --- a/drivers/gpu/drm/drm_atomic.c
> +++ b/drivers/gpu/drm/drm_atomic.c
> @@ -1078,6 +1078,8 @@ drm_atomic_private_obj_init(struct drm_private_obj *obj,
>  {
>  	memset(obj, 0, sizeof(*obj));
>  
> +	drm_modeset_lock_init(&obj->lock);
> +
>  	obj->state = state;
>  	obj->funcs = funcs;
>  }
> @@ -1093,6 +1095,7 @@ void
>  drm_atomic_private_obj_fini(struct drm_private_obj *obj)
>  {
>  	obj->funcs->atomic_destroy_state(obj, obj->state);
> +	drm_modeset_lock_fini(&obj->lock);
>  }
>  EXPORT_SYMBOL(drm_atomic_private_obj_fini);
>  
> @@ -1113,7 +1116,7 @@ struct drm_private_state *
>  drm_atomic_get_private_obj_state(struct drm_atomic_state *state,
>  				 struct drm_private_obj *obj)
>  {
> -	int index, num_objs, i;
> +	int index, num_objs, i, ret;
>  	size_t size;
>  	struct __drm_private_objs_state *arr;
>  	struct drm_private_state *obj_state;
> @@ -1122,6 +1125,10 @@ drm_atomic_get_private_obj_state(struct drm_atomic_state *state,
>  		if (obj == state->private_objs[i].ptr)
>  			return state->private_objs[i].state;
>  
> +	ret = drm_modeset_lock(&obj->lock, state->acquire_ctx);
> +	if (ret)
> +		return ERR_PTR(ret);
> +
>  	num_objs = state->num_private_objs + 1;
>  	size = sizeof(*state->private_objs) * num_objs;
>  	arr = krealloc(state->private_objs, size, GFP_KERNEL);
> diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
> index 09076a625637..9ae53b73c9d2 100644
> --- a/include/drm/drm_atomic.h
> +++ b/include/drm/drm_atomic.h
> @@ -218,6 +218,11 @@ struct drm_private_state_funcs {
>   * &drm_modeset_lock is required to duplicate and update this object's state.
>   */
>  struct drm_private_obj {
> +	/**
> +	 * @lock: Modeset lock to protect the state object.
> +	 */
> +	struct drm_modeset_lock lock;
> +
>  	/**
>  	 * @state: Current atomic state for this driver private object.
>  	 */
> -- 
> 2.14.3
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch