[PATCH v2 5/5] irq: Add max local_interrupt_disable() nesting level kunit test case

[Boqun Feng <boqun@kernel.org>]

To confirm the max nesting level of local_interrupt_disable() works, a
kunit test is added to the whole test suite.

Note that when DEBUG_PREEMPT=y, it'll generate a warning which is
expected.

Suggested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Boqun Feng <boqun@kernel.org>
---
 kernel/irq/refcount_interrupt_test.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/kernel/irq/refcount_interrupt_test.c b/kernel/irq/refcount_interrupt_test.c
index ca904dba24b9..38dfccbaa4d4 100644
--- a/kernel/irq/refcount_interrupt_test.c
+++ b/kernel/irq/refcount_interrupt_test.c
@@ -52,6 +52,27 @@ static void test_multiple_irq_change(struct kunit *test)
 	TEST_IRQ_ON();
 }
 
+static void test_max_nesting_irq_change(struct kunit *test)
+{
+	for (int i = 0; i < __IRQ_MASK(HARDIRQ_DISABLE_BITS); i++) {
+		local_interrupt_disable();
+		TEST_IRQ_OFF();
+	}
+
+
+	for (int i = 0; i < __IRQ_MASK(HARDIRQ_DISABLE_BITS); i++) {
+		TEST_IRQ_OFF();
+		local_interrupt_enable();
+	}
+
+	TEST_IRQ_ON();
+
+	local_interrupt_disable();
+	TEST_IRQ_OFF();
+	local_interrupt_enable();
+	TEST_IRQ_ON();
+}
+
 static void test_irq_save(struct kunit *test)
 {
 	unsigned long flags;
@@ -79,6 +100,7 @@ static struct kunit_case test_cases[] = {
 	KUNIT_CASE(test_single_irq_change),
 	KUNIT_CASE(test_nested_irq_change),
 	KUNIT_CASE(test_multiple_irq_change),
+	KUNIT_CASE(test_max_nesting_irq_change),
 	KUNIT_CASE(test_irq_save),
 	{},
 };
-- 
2.51.0