[PATCH v2 1/4] drm: function to get process name and pid

[Sunil Khatri]

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.

Signed-off-by: Sunil Khatri <sunil.khatri at amd.com>
---
 drivers/gpu/drm/drm_file.c | 34 ++++++++++++++++++++++++++++++++++
 include/drm/drm_file.h     |  1 +
 2 files changed, 35 insertions(+)

diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
index c299cd94d3f7..728a60975f5e 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_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_WARN_ON_ONCE(dev, "Invalid user buffer\n");
+		return;
+	}
+
+	mutex_lock(&file_priv->client_name_lock);
+	rcu_read_lock();
+	pid = rcu_dereference(file_priv->pid);
+	task = pid_task(pid, PIDTYPE_TGID);
+	if (task)
+		snprintf(proc_info, buff_size, "client_name:%s proc:%s pid:%d",
+			 file_priv->client_name ? file_priv->client_name : "Unset",
+			 task->comm, task->pid);
+
+	rcu_read_unlock();
+	mutex_unlock(&file_priv->client_name_lock);
+}
+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 94d365b22505..a972be73a615 100644
--- a/include/drm/drm_file.h
+++ b/include/drm/drm_file.h
@@ -507,6 +507,7 @@ 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);
 
-- 
2.34.1