[V8] drm: add drm_file_err function to add process info

Commit Message

Sunil Khatri April 17, 2025, 2:51 p.m. UTC

Add a drm helper function which appends the process information for
the drm_file over drm_err formatted 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)

v8: Code formatting and typos (Ursulin tvrtko)

Signed-off-by: Sunil Khatri <[e-mail]>
Reviewed-by: Tvrtko Ursulin <[e-mail]>
---
 drivers/gpu/drm/drm_file.c | 34 ++++++++++++++++++++++++++++++++++
 include/drm/drm_file.h     |  3 +++
 2 files changed, 37 insertions(+)

Patch

diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
index c299cd94d3f7..dd351f601acd 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 - log process name, pid and client_name associated with a drm_file
+ * @file_priv: context of interest for process name and pid
+ * @fmt: printf() like format string
+ *
+ * Helper function for clients which needs to log process details such
+ * as name and pid etc along with user logs.
+ */
+void drm_file_err(struct drm_file *file_priv, const char *fmt, ...)
+{
+	va_list args;
+	struct va_format vaf;
+	struct pid *pid;
+	struct task_struct *task;
+	struct drm_device *dev = file_priv->minor->dev;
+
+	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 : "Unset",
+		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);