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

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Message-ID: <dab8f564-d2b3-de19-f56d-f741046c39c6@gmail.com>
Date:   Thu, 30 Apr 2020 07:52:46 +0200
From:   Michał Orzeł <michalorzel.eng@...il.com>
To:     Jani Nikula <jani.nikula@...ux.intel.com>,
        maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
        tzimmermann@...e.de, airlied@...ux.ie, daniel@...ll.ch
Cc:     intel-gfx@...ts.freedesktop.org, 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 29.04.2020 10:57, Jani Nikula wrote:
> 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.

Hm, so we can either replace all of these calls(I think it's a better option) or abandon the idea of removing this deprecated function.
In the latter scenario, it'd be beneficial to remove this from TODO.

Best regards
Michal

> 
> 
>>  
>>  	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;
>>  }
>