On 30.04.2020 20:30, Daniel Vetter wrote:
> On Thu, Apr 30, 2020 at 5:38 PM Sean Paul <seanpaul@xxxxxxxxxxxx> wrote:
>>
>> On Wed, Apr 29, 2020 at 4:57 AM Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> wrote:
>>>
>>> On Tue, 28 Apr 2020, Michal Orzel <michalorzel.eng@xxxxxxxxx> 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@xxxxxxxxx>
>>>> ---
>>>> 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.
>>>
>>
>> What's the alternative? Seems like the options without the macros is
>> to use incorrect scope or have a bunch of retry/backoff cargo-cult
>> everywhere (and hope the copy source is done correctly).
>
> Yeah Sean & me had a bunch of bikesheds and this is the least worst
> option we could come up with. You can't make it a function because of
> the control flow. You don't want to open code this because it's tricky
> to get right, if all you want is to just grab all locks. But it is
> magic hidden behind a macro, which occasionally ends up hurting.
> -Daniel
So what are we doing with this problem? Should we replace at once approx. 60 calls?
Michal
>
>> Sean
>>
>>> 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
>
>
>
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