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rcu: Prevent soft-lockup complaints about no-CBs CPUs

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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>
This commit is contained in:
Paul Gortmaker 2012-12-20 09:35:02 -08:00 committed by Paul E. McKenney
parent d1c3ed669a
commit 353af9c9a8
1 changed files with 2 additions and 1 deletions
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3
kernel/rcutree_plugin.h
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@ -2366,10 +2366,11 @@ static int rcu_nocb_kthread(void *arg)
for (;;) { for (;;) {
/* If not polling, wait for next batch of callbacks. */ /* If not polling, wait for next batch of callbacks. */
if (!rcu_nocb_poll) 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); list = ACCESS_ONCE(rdp->nocb_head);
if (!list) { if (!list) {
schedule_timeout_interruptible(1); schedule_timeout_interruptible(1);
flush_signals(current);
continue; continue;
} }