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

[Christian König]

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.

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);