[PATCH] drm: function to get process name and pid

[Jani Nikula]

On Fri, 11 Apr 2025, Sunil Khatri <sunil.khatri at amd.com> wrote:
> Add helper function which get the process information for
> the drm_file and updates the user provided character buffer
> with the information of process name and pid as a string.

Where's the user for this function?

BR,
Jani.

>
> Signed-off-by: Sunil Khatri <sunil.khatri at amd.com>
> ---
>  drivers/gpu/drm/drm_file.c | 30 ++++++++++++++++++++++++++++++
>  include/drm/drm_file.h     |  1 +
>  2 files changed, 31 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
> index cb5f22f5bbb6..4434258d21b5 100644
> --- a/drivers/gpu/drm/drm_file.c
> +++ b/drivers/gpu/drm/drm_file.c
> @@ -965,6 +965,36 @@ void drm_show_fdinfo(struct seq_file *m, struct file *f)
>  }
>  EXPORT_SYMBOL(drm_show_fdinfo);
>  
> +/**
> + * drm_process_info - Fill info string with process name and pid
> + * @file_priv: context of interest for process name and pid
> + * @proc_info: user char ptr to write the string to
> + * @buff_size: size of the buffer passed for the string
> + *
> + * This update the user provided buffer with process
> + * name and pid information for @file_priv
> + */
> +void drm_process_info(struct drm_file *file_priv, char *proc_info, size_t buff_size)
> +{
> +	struct task_struct *task;
> +	struct pid *pid;
> +	struct drm_device *dev = file_priv->minor->dev;
> +
> +	if (!proc_info) {
> +		drm_err(dev, "Invalid user buffer\n");
> +		return;
> +	}
> +
> +	rcu_read_lock();
> +	pid = rcu_dereference(file_priv->pid);
> +	task = pid_task(pid, PIDTYPE_TGID);
> +	if (task)
> +		snprintf(proc_info, buff_size, "comm:%s pid:%d", task->comm, task->pid);
> +
> +	rcu_read_unlock();
> +}
> +EXPORT_SYMBOL(drm_process_info);
> +
>  /**
>   * 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 f0ef32e9fa5e..c01b34936968 100644
> --- a/include/drm/drm_file.h
> +++ b/include/drm/drm_file.h
> @@ -501,6 +501,7 @@ void drm_print_memory_stats(struct drm_printer *p,
>  
>  void drm_show_memory_stats(struct drm_printer *p, struct drm_file *file);
>  void drm_show_fdinfo(struct seq_file *m, struct file *f);
> +void drm_process_info(struct drm_file *file_priv, char *proc_info, size_t buff_size);
>  
>  struct file *mock_drm_getfile(struct drm_minor *minor, unsigned int flags);

-- 
Jani Nikula, Intel