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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>
hifive-unleashed-5.1
Paul E. McKenney 2014-08-14 10:28:23 -07:00
parent 2aa792e6fa
commit 73a860cd58
2 changed files with 5 additions and 5 deletions
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4
kernel/rcu/tree.c
View File

@ -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"));

6
kernel/rcu/tree_plugin.h
View File

@ -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);
}
}