[PATCH v3 1/4] drm: add devm release action

[Aravind Iddamsetty]

On 25/04/24 18:22, Maxime Ripard wrote:
> On Wed, Apr 24, 2024 at 08:20:32AM -0400, Rodrigo Vivi wrote:
>> On Wed, Apr 24, 2024 at 01:49:16PM +0200, Maxime Ripard wrote:
>>> On Tue, Apr 23, 2024 at 01:42:22PM -0400, Rodrigo Vivi wrote:
>>>> On Tue, Apr 23, 2024 at 02:25:06PM +0530, Aravind Iddamsetty wrote:
>>>>> On 23/04/24 02:24, Rodrigo Vivi wrote:
>>>>>> On Mon, Apr 22, 2024 at 12:27:53PM +0530, Aravind Iddamsetty wrote:
>>>>>>> In scenarios where drm_dev_put is directly called by driver we want to
>>>>>>> release devm_drm_dev_init_release action associated with struct
>>>>>>> drm_device.
>>>>>>>
>>>>>>> v2: Directly expose the original function, instead of introducing a
>>>>>>> helper (Rodrigo)
>>>>>>>
>>>>>>> v3: add kernel-doc (Maxime Ripard)
>>>>>>>
>>>>>>> Cc: Maxime Ripard <mripard at kernel.org>
>>>>>>> Cc: Thomas Hellstr_m <thomas.hellstrom at linux.intel.com>
>>>>>>> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
>>>>>>>
>>>>>> please avoid these empty lines here.... cc, rv-b, sign-offs, links,
>>>>>> etc are all in the same block.
>>>>> ok.
>>>>>>> Reviewed-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
>>>>>>> Signed-off-by: Aravind Iddamsetty <aravind.iddamsetty at linux.intel.com>
>>>>>>> ---
>>>>>>>  drivers/gpu/drm/drm_drv.c | 13 +++++++++++++
>>>>>>>  include/drm/drm_drv.h     |  2 ++
>>>>>>>  2 files changed, 15 insertions(+)
>>>>>>>
>>>>>>> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
>>>>>>> index 243cacb3575c..9d0409165f1e 100644
>>>>>>> --- a/drivers/gpu/drm/drm_drv.c
>>>>>>> +++ b/drivers/gpu/drm/drm_drv.c
>>>>>>> @@ -714,6 +714,19 @@ static int devm_drm_dev_init(struct device *parent,
>>>>>>>  					devm_drm_dev_init_release, dev);
>>>>>>>  }
>>>>>>>  
>>>>>>> +/**
>>>>>>> + * devm_drm_dev_release_action - Call the final release action of the device
>>>>>> Seeing the doc here gave me a second thought....
>>>>>>
>>>>>> the original release should be renamed to _devm_drm_dev_release
>>>>>> and this should be called devm_drm_dev_release without the 'action' word.
>>>>> i believe, was suggested earlier to directly expose the main function, is 
>>>>> there any reason to have a __ version ?
>>>> No no, just ignore me. Just remove the '_action' and don't change the other.
>>>>
>>>> I don't like exposing the a function with '__'. what would '__' that mean?
>>>> This is what I meant on the first comment.
>>>>
>>>> Now, I believe that we don't need the '_action'. What does the 'action' mean?
>>>>
>>>> the devm_drm_dev_release should be enough. But then I got confused and
>>>> I thought it would conflict with the original released function name.
>>>> But I misread it.
>>> I don't think devm_drm_dev_release is a good name either. Just like any
>>> other devm_* function that cancels what a previous one has been doing
>>> (devm_kfree, devm_backlight_device_unregister, devm_nvmem_device_put,
>>> etc.) it should be called devm_drm_dev_put or something similar.
>> I see what you mean, but I don't believe the 'put' is the best option,
>> for 2 reasons:
>> - in general, we have put paired with gets and this has not get equivalent
> Yeah, that's true. _release is fine then I guess.
>
>> - this bypass the regular get/put mechanism and forces the releases that
>>   would be done only after all drm_dev_put() taking ref to zero.
> I don't think it does? devm_release_action will only remove the devm
> action and execute it directly, but this action here is a call to
> drm_dev_put, so we might still have other references taken that would
> defer the device being freed.
yes i.e right, i assumed drm_dev_unplug would close all client handles but no.
So i was thinking if it is ok to iterate over  no of clients and call drm_dev_put in either
drm_dev_unplug or as part of this devm_release.


Thanks,
Aravind.
>
> Maxime