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/mips/kernel/signal.c b/arch/mips/kernel/signal.c
index d5a338a..17f6ee3 100644
--- a/arch/mips/kernel/signal.c
+++ b/arch/mips/kernel/signal.c
@@ -255,15 +255,7 @@
 	uset = (sigset_t __user *) regs.regs[4];
 	if (copy_from_user(&newset, uset, sizeof(sigset_t)))
 		return -EFAULT;
-	sigdelsetmask(&newset, ~_BLOCKABLE);
-
-	current->saved_sigmask = current->blocked;
-	set_current_blocked(&newset);
-
-	current->state = TASK_INTERRUPTIBLE;
-	schedule();
-	set_thread_flag(TIF_RESTORE_SIGMASK);
-	return -ERESTARTNOHAND;
+	return sigsuspend(&newset);
 }
 #endif
 
@@ -281,15 +273,7 @@
 	unewset = (sigset_t __user *) regs.regs[4];
 	if (copy_from_user(&newset, unewset, sizeof(newset)))
 		return -EFAULT;
-	sigdelsetmask(&newset, ~_BLOCKABLE);
-
-	current->saved_sigmask = current->blocked;
-	set_current_blocked(&newset);
-
-	current->state = TASK_INTERRUPTIBLE;
-	schedule();
-	set_thread_flag(TIF_RESTORE_SIGMASK);
-	return -ERESTARTNOHAND;
+	return sigsuspend(&newset);
 }
 
 #ifdef CONFIG_TRAD_SIGNALS