From: jsg <jsg@openbsd.org>
Date: Mon, 27 Sep 2021 03:23:16 +0000 (+0000)
Subject: drm: avoid blocking in drm_clients_info's rcu section
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=40694f2c389f3ce3cbe6496a34a5f1d12d6fe5b1;p=openbsd

drm: avoid blocking in drm_clients_info's rcu section

From Desmond Cheong Zhi Xi
54e51d288b38377e8cd645a83e1ad08cc9d20ccc in linux 5.10.y/5.10.67
5eff9585de220cdd131237f5665db5e6c6bdf590 in mainline linux
---

diff --git a/sys/dev/pci/drm/drm_debugfs.c b/sys/dev/pci/drm/drm_debugfs.c
index 4d36104fae3..0fb8b2bb8b4 100644
--- a/sys/dev/pci/drm/drm_debugfs.c
+++ b/sys/dev/pci/drm/drm_debugfs.c
@@ -91,6 +91,7 @@ static int drm_clients_info(struct seq_file *m, void *data)
 	mutex_lock(&dev->filelist_mutex);
 	list_for_each_entry_reverse(priv, &dev->filelist, lhead) {
 		struct task_struct *task;
+		bool is_current_master = drm_is_current_master(priv);
 
 		rcu_read_lock(); /* locks pid_task()->comm */
 		task = pid_task(priv->pid, PIDTYPE_PID);
@@ -99,7 +100,7 @@ static int drm_clients_info(struct seq_file *m, void *data)
 			   task ? task->comm : "<unknown>",
 			   pid_vnr(priv->pid),
 			   priv->minor->index,
-			   drm_is_current_master(priv) ? 'y' : 'n',
+			   is_current_master ? 'y' : 'n',
 			   priv->authenticated ? 'y' : 'n',
 			   from_kuid_munged(seq_user_ns(m), uid),
 			   priv->magic);