[PATCH v3] Input: tests: add test to cover all input_grab_device() function

[Dana Elfassy <delfassy@redhat.com>]

Currently input_grab_device() isn't covered by any tests
Thus, adding a test to cover the cases:
1. The device is grabbed successfully
2. Trying to grab a device that is already grabbed by another input
   handle

Signed-off-by: Dana Elfassy <dangel101@gmail.com>
Tested-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
Changes in v3:
1. Retrieve test_handle variable to try and grab the device that's
currently grabbed by another handle
2. Add verification that test_handle can indeed grab the device after
it's released by the handle that grabbed it
3. Remove duplicated call for input_grab_device() in KUNIT_ASSERT_TRUE()
functions
Changes in v2:
- Use input_put_device() to decrement the refcount increased by get().
- Remove unnecessary struct input_handle test_handle variable.

 drivers/input/tests/input_test.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/input/tests/input_test.c b/drivers/input/tests/input_test.c
index 25bbf51b5c87..1939cc12bae0 100644
--- a/drivers/input/tests/input_test.c
+++ b/drivers/input/tests/input_test.c
@@ -124,10 +124,42 @@ static void input_test_match_device_id(struct kunit *test)
 	KUNIT_ASSERT_FALSE(test, input_match_device_id(input_dev, &id));
 }
 
+static void input_test_grab(struct kunit *test)
+{
+	struct input_dev *input_dev = test->priv;
+	struct input_handle test_handle;
+	struct input_handler handler;
+	struct input_handle handle;
+	struct input_device_id id;
+	int res;
+
+	handler.name = "handler";
+	handler.id_table = &id;
+
+	handle.dev = input_get_device(input_dev);
+	handle.name = dev_name(&input_dev->dev);
+	handle.handler = &handler;
+	res = input_grab_device(&handle);
+	KUNIT_ASSERT_TRUE(test, res == 0);
+
+	test_handle.dev = input_get_device(input_dev);
+	test_handle.name = dev_name(&input_dev->dev);
+	test_handle.handler = &handler;
+	res = input_grab_device(&test_handle);
+	KUNIT_ASSERT_EQ(test, res, -EBUSY);
+
+	input_release_device(&handle);
+	input_put_device(input_dev);
+	res = input_grab_device(&test_handle);
+	KUNIT_ASSERT_TRUE(test, res == 0);
+	input_put_device(input_dev);
+}
+
 static struct kunit_case input_tests[] = {
 	KUNIT_CASE(input_test_polling),
 	KUNIT_CASE(input_test_timestamp),
 	KUNIT_CASE(input_test_match_device_id),
+	KUNIT_CASE(input_test_grab),
 	{ /* sentinel */ }
 };
 
-- 
2.40.1