new helper: sigsuspend()

guts of saved_sigmask-based sigsuspend/rt_sigsuspend.  Takes
kernel sigset_t *.

Open-coded instances replaced with calling it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 73d9a42..4e5fdd9 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -67,17 +67,8 @@
 asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask)
 {
 	sigset_t blocked;
-
-	current->saved_sigmask = current->blocked;
-
-	mask &= _BLOCKABLE;
 	siginitset(&blocked, mask);
-	set_current_blocked(&blocked);
-
-	current->state = TASK_INTERRUPTIBLE;
-	schedule();
-	set_restore_sigmask();
-	return -ERESTARTNOHAND;
+	return sigsuspend(&blocked);
 }
 
 asmlinkage int