rcu: Replace flush_signals() with WARN_ON(signal_pending())
Currently, when RCU awakens from a wait_event_interruptible() that
might have awakened prematurely, it does a flush_signals(). This is
done on the off-chance that someone figured out how to deliver a signal
to a kthread, which is supposed to be impossible. Given that this
is supposed to be impossible, this commit changes the flush_signals()
calls into WARN_ON(signal_pending()).
Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 9e83cd9..3e002c1 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1796,7 +1796,7 @@
if (rcu_gp_init(rsp))
break;
cond_resched();
- flush_signals(current);
+ WARN_ON(signal_pending(current));
trace_rcu_grace_period(rsp->name,
ACCESS_ONCE(rsp->gpnum),
TPS("reqwaitsig"));
@@ -1842,7 +1842,7 @@
} else {
/* Deal with stray signal. */
cond_resched();
- flush_signals(current);
+ WARN_ON(signal_pending(current));
trace_rcu_grace_period(rsp->name,
ACCESS_ONCE(rsp->gpnum),
TPS("fqswaitsig"));