s390/processor: add test_and_set_cpu_flag() and test_and_clear_cpu_flag()

Add test_and_set_cpu_flag() and test_and_clear_cpu_flag() helper functions.
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

arch/s390/include/asm/processor.h

@@ -59,6 +59,22 @@ static __always_inline bool test_cpu_flag(int flag)
 	return S390_lowcore.cpu_flags & (1UL << flag);
 }
 
+static __always_inline bool test_and_set_cpu_flag(int flag)
+{
+	if (test_cpu_flag(flag))
+		return true;
+	set_cpu_flag(flag);
+	return false;
+}
+
+static __always_inline bool test_and_clear_cpu_flag(int flag)
+{
+	if (!test_cpu_flag(flag))
+		return false;
+	clear_cpu_flag(flag);
+	return true;
+}
+
 /*
  * Test CIF flag of another CPU. The caller needs to ensure that
  * CPU hotplug can not happen, e.g. by disabling preemption.