linux-kernel - [PATCH] signals: work around random wakeups in sigsuspend()

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Date:	Mon, 25 Jan 2016 10:21:46 -0500
From:	Sasha Levin <sasha.levin@...cle.com>
To:	akpm@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org, mingo@...nel.org, oleg@...hat.com,
	peterz@...radead.org, Sasha Levin <sasha.levin@...cle.com>
Subject: [PATCH] signals: work around random wakeups in sigsuspend()

A random wakeup can get us out of sigsuspend() without TIF_SIGPENDING
being set.

Avoid that by making sure we were signaled, like sys_pause() does.

Signed-off-by: Sasha Levin <sasha.levin@...cle.com>
---
 kernel/signal.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index 5da9180..3256c7e 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -3528,8 +3528,10 @@ static int sigsuspend(sigset_t *set)
 	current->saved_sigmask = current->blocked;
 	set_current_blocked(set);
 
-	__set_current_state(TASK_INTERRUPTIBLE);
-	schedule();
+	while (!signal_pending(current)) {
+		__set_current_state(TASK_INTERRUPTIBLE);
+		schedule();
+	}
 	set_restore_sigmask();
 	return -ERESTARTNOHAND;
 }
-- 
1.7.10.4