selftests: media_tests: Add new subtest to video_device_test

Add new subtest to video_device_test to cover the VIDIOC_G_PRIORITY
and VIDIOC_S_PRIORITY ioctl calls. This test tries to set the priority
associated with the file descriptior via ioctl VIDIOC_S_PRIORITY
command from V4L2 API. After that, the test tries to get the new
priority via VIDIOC_G_PRIORITY ioctl command and compares the result
with the v4l2_priority it set before. At the end, the test restores the
old priority.

This test will increase the code coverage for video_device_test, so
I think it might be useful. Additionally, this patch will refactor the
video_device_test a little bit, according to the new functionality.
Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/media_tests/video_device_test.c

@@ -37,15 +37,89 @@
 #include <time.h>
 #include <linux/videodev2.h>
 
-int main(int argc, char **argv)
+#define PRIORITY_MAX 4
+
+int priority_test(int fd)
+{
+	/* This test will try to update the priority associated with a file descriptor */
+
+	enum v4l2_priority old_priority, new_priority, priority_to_compare;
+	int ret;
+	int result = 0;
+
+	ret = ioctl(fd, VIDIOC_G_PRIORITY, &old_priority);
+	if (ret < 0) {
+		printf("Failed to get priority: %s\n", strerror(errno));
+		return -1;
+	}
+	new_priority = (old_priority + 1) % PRIORITY_MAX;
+	ret = ioctl(fd, VIDIOC_S_PRIORITY, &new_priority);
+	if (ret < 0) {
+		printf("Failed to set priority: %s\n", strerror(errno));
+		return -1;
+	}
+	ret = ioctl(fd, VIDIOC_G_PRIORITY, &priority_to_compare);
+	if (ret < 0) {
+		printf("Failed to get new priority: %s\n", strerror(errno));
+		result = -1;
+		goto cleanup;
+	}
+	if (priority_to_compare != new_priority) {
+		printf("Priority wasn't set - test failed\n");
+		result = -1;
+	}
+
+cleanup:
+	ret = ioctl(fd, VIDIOC_S_PRIORITY, &old_priority);
+	if (ret < 0) {
+		printf("Failed to restore priority: %s\n", strerror(errno));
+		return -1;
+	}
+	return result;
+}
+
+int loop_test(int fd)
 {
-	int opt;
-	char video_dev[256];
 	int count;
 	struct v4l2_tuner vtuner;
 	struct v4l2_capability vcap;
 	int ret;
+
+	/* Generate random number of interations */
+	srand((unsigned int) time(NULL));
+	count = rand();
+
+	printf("\nNote:\n"
+	       "While test is running, remove the device or unbind\n"
+	       "driver and ensure there are no use after free errors\n"
+	       "and other Oops in the dmesg. When possible, enable KaSan\n"
+	       "kernel config option for use-after-free error detection.\n\n");
+
+	while (count > 0) {
+		ret = ioctl(fd, VIDIOC_QUERYCAP, &vcap);
+		if (ret < 0)
+			printf("VIDIOC_QUERYCAP errno %s\n", strerror(errno));
+		else
+			printf("Video device driver %s\n", vcap.driver);
+
+		ret = ioctl(fd, VIDIOC_G_TUNER, &vtuner);
+		if (ret < 0)
+			printf("VIDIOC_G_TUNER, errno %s\n", strerror(errno));
+		else
+			printf("type %d rangelow %d rangehigh %d\n",
+				vtuner.type, vtuner.rangelow, vtuner.rangehigh);
+		sleep(10);
+		count--;
+	}
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	int opt;
+	char video_dev[256];
 	int fd;
+	int test_result;
 
 	if (argc < 2) {
 		printf("Usage: %s [-d </dev/videoX>]\n", argv[0]);
@@ -65,10 +139,6 @@ int main(int argc, char **argv)
 		}
 	}
 
-	/* Generate random number of interations */
-	srand((unsigned int) time(NULL));
-	count = rand();
-
 	/* Open Video device and keep it open */
 	fd = open(video_dev, O_RDWR);
 	if (fd == -1) {
@@ -76,26 +146,11 @@ int main(int argc, char **argv)
 		exit(-1);
 	}
 
-	printf("\nNote:\n"
-	       "While test is running, remove the device or unbind\n"
-	       "driver and ensure there are no use after free errors\n"
-	       "and other Oops in the dmesg. When possible, enable KaSan\n"
-	       "kernel config option for use-after-free error detection.\n\n");
-
-	while (count > 0) {
-		ret = ioctl(fd, VIDIOC_QUERYCAP, &vcap);
-		if (ret < 0)
-			printf("VIDIOC_QUERYCAP errno %s\n", strerror(errno));
+	test_result = priority_test(fd);
+	if (!test_result)
+		printf("Priority test - PASSED\n");
 	else
-			printf("Video device driver %s\n", vcap.driver);
+		printf("Priority test - FAILED\n");
 
-		ret = ioctl(fd, VIDIOC_G_TUNER, &vtuner);
-		if (ret < 0)
-			printf("VIDIOC_G_TUNER, errno %s\n", strerror(errno));
-		else
-			printf("type %d rangelow %d rangehigh %d\n",
-				vtuner.type, vtuner.rangelow, vtuner.rangehigh);
-		sleep(10);
-		count--;
-	}
+	loop_test(fd);
 }