lock: add a new primitive cr_wait_until_greater (v2)

to wait while a futex value bigger than defined value.

v2: s/bigger/greater
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>

include/lock.h

@@ -63,6 +63,25 @@ static always_inline void cr_wait_until(u32 *v, u32 val)
 	}
 }
 
+/*
+ * Wait until futex @v value greater than @val
+ */
+static always_inline s32 cr_wait_until_greater(u32 *v, s32 val)
+{
+	int ret;
+	s32 tmp;
+
+	while (1) {
+		tmp = *v;
+		if (tmp <= val)
+			break;
+		ret = sys_futex(v, FUTEX_WAIT, tmp, NULL, NULL, 0);
+		BUG_ON(ret < 0 && ret != -EWOULDBLOCK);
+	}
+
+	return tmp;
+}
+
 /*
  * Wait while futex @v value is @val
  */