[PATCH V6 1/5] drm: add drm_file_err function to add process info

[Khatri, Sunil]

For rest of the patches which are part of the amdgpu tree will push 
incorporating changes as shared by @Tvrtko Ursulin 
<tvrtko.ursulin at igalia.com> once drm change is merged.

Thanks a lot all for the reviews.

Regards

Sunil Khatri

On 4/17/2025 6:01 PM, Sunil Khatri wrote:
> Add a drm helper function which append the process information for
> the drm_file over drm_err formated output.
>
> 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
>
> v7: Use va_format and %pV to concatenate fmt and vargs (Jani Nikula)
>
> Signed-off-by: Sunil Khatri <sunil.khatri at amd.com>
> ---
>   drivers/gpu/drm/drm_file.c | 34 ++++++++++++++++++++++++++++++++++
>   include/drm/drm_file.h     |  3 +++
>   2 files changed, 37 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
> index c299cd94d3f7..7e64d84d4e2d 100644
> --- a/drivers/gpu/drm/drm_file.c
> +++ b/drivers/gpu/drm/drm_file.c
> @@ -986,6 +986,40 @@ void drm_show_fdinfo(struct seq_file *m, struct file *f)
>   }
>   EXPORT_SYMBOL(drm_show_fdinfo);
>   
> +/**
> + * 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
> + */
> +void drm_file_err(struct drm_file *file_priv, const char *fmt, ...)
> +{
> +	struct task_struct *task;
> +	struct pid *pid;
> +	struct drm_device *dev = file_priv->minor->dev;
> +	va_list args;
> +	struct va_format vaf;
> +
> +	va_start(args, fmt);
> +	vaf.fmt = fmt;
> +	vaf.va = &args;
> +
> +	mutex_lock(&file_priv->client_name_lock);
> +	rcu_read_lock();
> +	pid = rcu_dereference(file_priv->pid);
> +	task = pid_task(pid, PIDTYPE_TGID);
> +
> +	drm_err(dev, "comm: %s pid: %d client: %s %pV", task ? task->comm : "",
> +		task ? task->pid : 0, file_priv->client_name ?: "Unset", &vaf);
> +
> +	va_end(args);
> +	rcu_read_unlock();
> +	mutex_unlock(&file_priv->client_name_lock);
> +}
> +EXPORT_SYMBOL(drm_file_err);
> +
>   /**
>    * mock_drm_getfile - Create a new struct file for the drm device
>    * @minor: drm minor to wrap (e.g. #drm_device.primary)
> diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h
> index 94d365b22505..5c3b2aa3e69d 100644
> --- a/include/drm/drm_file.h
> +++ b/include/drm/drm_file.h
> @@ -446,6 +446,9 @@ static inline bool drm_is_accel_client(const struct drm_file *file_priv)
>   	return file_priv->minor->type == DRM_MINOR_ACCEL;
>   }
>   
> +__printf(2, 3)
> +void drm_file_err(struct drm_file *file_priv, const char *fmt, ...);
> +
>   void drm_file_update_pid(struct drm_file *);
>   
>   struct drm_minor *drm_minor_acquire(struct xarray *minors_xa, unsigned int minor_id);