linux-kernel - Re: [PATCH] drm: Replace drm_modeset_lock/unlock_all with DRM_MODESET_LOCK_ALL

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Message-ID: <875zdiacv2.fsf@intel.com>
Date:   Wed, 29 Apr 2020 11:57:05 +0300
From:   Jani Nikula <jani.nikula@...ux.intel.com>
To:     Michal Orzel <michalorzel.eng@...il.com>,
        maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
        tzimmermann@...e.de, airlied@...ux.ie, daniel@...ll.ch
Cc:     intel-gfx@...ts.freedesktop.org,
        Michal Orzel <michalorzel.eng@...il.com>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH] drm: Replace drm_modeset_lock/unlock_all with DRM_MODESET_LOCK_ALL_* helpers

On Tue, 28 Apr 2020, Michal Orzel <michalorzel.eng@...il.com> wrote:
> As suggested by the TODO list for the kernel DRM subsystem, replace
> the deprecated functions that take/drop modeset locks with new helpers.
>
> Signed-off-by: Michal Orzel <michalorzel.eng@...il.com>
> ---
>  drivers/gpu/drm/drm_mode_object.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_mode_object.c b/drivers/gpu/drm/drm_mode_object.c
> index 35c2719..901b078 100644
> --- a/drivers/gpu/drm/drm_mode_object.c
> +++ b/drivers/gpu/drm/drm_mode_object.c
> @@ -402,12 +402,13 @@ int drm_mode_obj_get_properties_ioctl(struct drm_device *dev, void *data,
>  {
>  	struct drm_mode_obj_get_properties *arg = data;
>  	struct drm_mode_object *obj;
> +	struct drm_modeset_acquire_ctx ctx;
>  	int ret = 0;
>  
>  	if (!drm_core_check_feature(dev, DRIVER_MODESET))
>  		return -EOPNOTSUPP;
>  
> -	drm_modeset_lock_all(dev);
> +	DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, 0, ret);

I cry a little every time I look at the DRM_MODESET_LOCK_ALL_BEGIN and
DRM_MODESET_LOCK_ALL_END macros. :(

Currently only six users... but there are ~60 calls to
drm_modeset_lock_all{,_ctx} that I presume are to be replaced. I wonder
if this will come back and haunt us.

BR,
Jani.


>  
>  	obj = drm_mode_object_find(dev, file_priv, arg->obj_id, arg->obj_type);
>  	if (!obj) {
> @@ -427,7 +428,7 @@ int drm_mode_obj_get_properties_ioctl(struct drm_device *dev, void *data,
>  out_unref:
>  	drm_mode_object_put(obj);
>  out:
> -	drm_modeset_unlock_all(dev);
> +	DRM_MODESET_LOCK_ALL_END(ctx, ret);
>  	return ret;
>  }
>  
> @@ -449,12 +450,13 @@ static int set_property_legacy(struct drm_mode_object *obj,
>  {
>  	struct drm_device *dev = prop->dev;
>  	struct drm_mode_object *ref;
> +	struct drm_modeset_acquire_ctx ctx;
>  	int ret = -EINVAL;
>  
>  	if (!drm_property_change_valid_get(prop, prop_value, &ref))
>  		return -EINVAL;
>  
> -	drm_modeset_lock_all(dev);
> +	DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, 0, ret);
>  	switch (obj->type) {
>  	case DRM_MODE_OBJECT_CONNECTOR:
>  		ret = drm_connector_set_obj_prop(obj, prop, prop_value);
> @@ -468,7 +470,7 @@ static int set_property_legacy(struct drm_mode_object *obj,
>  		break;
>  	}
>  	drm_property_change_valid_put(prop, ref);
> -	drm_modeset_unlock_all(dev);
> +	DRM_MODESET_LOCK_ALL_END(ctx, ret);
>  
>  	return ret;
>  }

-- 
Jani Nikula, Intel Open Source Graphics Center