From 353af9c9a866b07492b15a4efd18ec93123d3a1d Mon Sep 17 00:00:00 2001
From: Paul Gortmaker <paul.gortmaker@windriver.com>
Date: Thu, 20 Dec 2012 09:35:02 -0800
Subject: [PATCH] rcu: Prevent soft-lockup complaints about no-CBs CPUs
The wait_event() at the head of the rcu_nocb_kthread() can result in
soft-lockup complaints if the CPU in question does not register RCU
callbacks for an extended period. This commit therefore changes
the wait_event() to a wait_event_interruptible().
Reported-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcutree_plugin.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index f6e5ec2932b4a..43dba2d798ac7 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -2366,10 +2366,11 @@ static int rcu_nocb_kthread(void *arg)
for (;;) {
/* If not polling, wait for next batch of callbacks. */
if (!rcu_nocb_poll)
- wait_event(rdp->nocb_wq, rdp->nocb_head);
+ wait_event_interruptible(rdp->nocb_wq, rdp->nocb_head);
list = ACCESS_ONCE(rdp->nocb_head);
if (!list) {
schedule_timeout_interruptible(1);
+ flush_signals(current);
continue;
}
--
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