[PATCH v6 1/5] drm: add macro drm_file_err to print process info

[Jani Nikula]

On Thu, 17 Apr 2025, Christian König <christian.koenig at amd.com> wrote:
> Am 17.04.25 um 11:35 schrieb Jani Nikula:
>> On Thu, 17 Apr 2025, Sunil Khatri <sunil.khatri at amd.com> wrote:
>>> Add a drm helper macro which append the process information for
>>> the drm_file over drm_err.
>>>
>>> v5: change to macro from function (Christian Koenig)
>>>     add helper functions for lock/unlock (Christian Koenig)
>>>
>>> v6: remove __maybe_unused and make function inline (Jani Nikula)
>>>     remove drm_print.h
>> I guess I gave all kinds of comments, but in the end my conclusion was:
>> why does *any* of this have to be static inline or macros? Make
>> drm_file_err() a regular function and hide the implementation inside
>> drm_file.c. That's the cleanest approach IMO.
>
> That won't work. The macro is necessary to concatenate the format strings.

I think you can handle them using struct va_format and %pV.

BR,
Jani.


>
> But the drm_task_lock() and drm_task_unlock() functions shouldn't be in the header. Those can be perfectly in drm_file.c or drm_print.c
>
> And we should put drm_file_err into drm_print.h instead of drm_file.h as far as I can see.
>
> Regards,
> Christian.
>
>>
>> BR,
>> Jani.
>>
>>> Signed-off-by: Sunil Khatri <sunil.khatri at amd.com>
>>> ---
>>>  include/drm/drm_file.h | 37 +++++++++++++++++++++++++++++++++++++
>>>  1 file changed, 37 insertions(+)
>>>
>>> diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h
>>> index 94d365b22505..856b38e996c7 100644
>>> --- a/include/drm/drm_file.h
>>> +++ b/include/drm/drm_file.h
>>> @@ -446,6 +446,43 @@ static inline bool drm_is_accel_client(const struct drm_file *file_priv)
>>>  	return file_priv->minor->type == DRM_MINOR_ACCEL;
>>>  }
>>>  
>>> +static inline struct task_struct *drm_task_lock(struct drm_file *file_priv)
>>> +{
>>> +	struct task_struct *task;
>>> +	struct pid *pid;
>>> +
>>> +	mutex_lock(&file_priv->client_name_lock);
>>> +	rcu_read_lock();
>>> +	pid = rcu_dereference(file_priv->pid);
>>> +	task = pid_task(pid, PIDTYPE_TGID);
>>> +	return task;
>>> +}
>>> +
>>> +static inline void drm_task_unlock(struct drm_file *file_priv)
>>> +{
>>> +	rcu_read_unlock();
>>> +	mutex_unlock(&file_priv->client_name_lock);
>>> +}
>>> +/**
>>> + * drm_file_err - Fill info string with process name and pid
>>> + * @file_priv: context of interest for process name and pid
>>> + * @fmt: prinf() like format string
>>> + *
>>> + * This update the user provided buffer with process
>>> + * name and pid information for @file_priv
>>> + */
>>> +#define drm_file_err(file_priv, fmt, ...)						\
>>> +	do {										\
>>> +		struct task_struct *task;						\
>>> +		struct drm_device *dev = file_priv->minor->dev;				\
>>> +											\
>>> +		task = drm_task_lock(file_priv);					\
>>> +		drm_err(dev, "comm: %s pid: %d client: %s " fmt,			\
>>> +			task ? task->comm : "", task ? task->pid : 0,			\
>>> +			file_priv->client_name ?: "Unset", ##__VA_ARGS__);		\
>>> +		drm_task_unlock(file_priv);						\
>>> +	} while (0)
>>> +
>>>  void drm_file_update_pid(struct drm_file *);
>>>  
>>>  struct drm_minor *drm_minor_acquire(struct xarray *minors_xa, unsigned int minor_id);
>

-- 
Jani Nikula, Intel