From: Thomas Gleixner <tglx@linutronix.de>
Date: Sun, 17 Jul 2011 18:47:54 +0000 (+0200)
Subject: sched: Don't use tasklist_lock for debug prints
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=510f5acc4f4fb07f3f075900dc468d6e380beff6;p=linux-beck.git

sched: Don't use tasklist_lock for debug prints

Avoid taking locks from debug prints, this avoids latencies on -rt,
and improves reliability of the debug code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---

diff --git a/kernel/sched.c b/kernel/sched.c
index ce9a9e7db116..24637c782002 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6021,7 +6021,7 @@ void show_state_filter(unsigned long state_filter)
 	printk(KERN_INFO
 		"  task                        PC stack   pid father\n");
 #endif
-	read_lock(&tasklist_lock);
+	rcu_read_lock();
 	do_each_thread(g, p) {
 		/*
 		 * reset the NMI-timeout, listing all files on a slow
@@ -6037,7 +6037,7 @@ void show_state_filter(unsigned long state_filter)
 #ifdef CONFIG_SCHED_DEBUG
 	sysrq_sched_debug_show();
 #endif
-	read_unlock(&tasklist_lock);
+	rcu_read_unlock();
 	/*
 	 * Only show locks if all tasks are dumped:
 	 */