Commit-ID: 73a860cd58a1eb258e889b615cebf738ab33aa23
Gitweb: http://git.kernel.org/tip/73a860cd58a1eb258e889b615cebf738ab33aa23
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Thu, 14 Aug 2014 10:28:23 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Sun, 7 Sep 2014 16:18:20 -0700
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@xxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
kernel/rcu/tree.c | 4 ++--
kernel/rcu/tree_plugin.h | 6 +++---
2 files changed, 5 insertions(+), 5 deletions(-)
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 @@ static int __noreturn rcu_gp_kthread(void *arg)
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 @@ static int __noreturn rcu_gp_kthread(void *arg)
} 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"));
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index d67cc5c..bbb0a0c 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -2237,7 +2237,7 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp)
(d = ULONG_CMP_GE(ACCESS_ONCE(rnp->completed), c)));
if (likely(d))
break;
- flush_signals(current);
+ WARN_ON(signal_pending(current));
trace_rcu_future_gp(rnp, rdp, c, TPS("ResumeWait"));
}
trace_rcu_future_gp(rnp, rdp, c, TPS("EndWait"));
@@ -2296,7 +2296,7 @@ wait_again:
if (!rcu_nocb_poll)
trace_rcu_nocb_wake(my_rdp->rsp->name, my_rdp->cpu,
"WokeEmpty");
- flush_signals(current);
+ WARN_ON(signal_pending(current));
schedule_timeout_interruptible(1);
/* Rescan in case we were a victim of memory ordering. */
@@ -2375,7 +2375,7 @@ static void nocb_follower_wait(struct rcu_data *rdp)
if (!rcu_nocb_poll)
trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu,
"WokeEmpty");
- flush_signals(current);
+ WARN_ON(signal_pending(current));
schedule_timeout_interruptible(1);
}
}
--
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