From: Mandeep Singh Baines <msb@google.com>
Date: Thu, 5 Feb 2009 17:56:08 +0000 (-0800)
Subject: softlockup: convert read_lock in hung_task to rcu_read_lock
X-Git-Tag: v5.15~34266^2~6
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=94be52dc075a32af4aa73d7e10f68734d62d6af2;p=mirror_ubuntu-kernels.git

softlockup: convert read_lock in hung_task to rcu_read_lock

Since the tasklist is protected by rcu list operations, it is safe
to convert the read_lock()s to rcu_read_lock().

Suggested-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mandeep Singh Baines <msb@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---

diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 481ca8b5c2bc..3951a80e7cbe 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -155,7 +155,7 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
 	if (test_taint(TAINT_DIE) || did_panic)
 		return;
 
-	read_lock(&tasklist_lock);
+	rcu_read_lock();
 	do_each_thread(g, t) {
 		if (!--max_count)
 			goto unlock;
@@ -171,7 +171,7 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
 			check_hung_task(t, now, timeout);
 	} while_each_thread(g, t);
  unlock:
-	read_unlock(&tasklist_lock);
+	rcu_read_unlock();
 }
 
 static void update_poll_jiffies(void)