Date:   Sat,  1 Apr 2023 13:22:07 +0400
From:   Ivan Orlov <ivan.orlov0322@...il.com>
To:     skhan@...uxfoundation.org
Cc:     Ivan Orlov <ivan.orlov0322@...il.com>,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
        himadrispandya@...il.com,
        linux-kernel-mentees@...ts.linuxfoundation.org
Subject: [PATCH] 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@...il.com>
---
 .../selftests/media_tests/video_device_test.c | 131 +++++++++++++-----
 1 file changed, 93 insertions(+), 38 deletions(-)

diff --git a/tools/testing/selftests/media_tests/video_device_test.c b/tools/testing/selftests/media_tests/video_device_test.c
index 0f6aef2e2593..5e6f65ad2ca3 100644
--- a/tools/testing/selftests/media_tests/video_device_test.c
+++ b/tools/testing/selftests/media_tests/video_device_test.c
@@ -13,18 +13,9 @@
  * in the Kselftest run. This test should be run when hardware and driver
  * that makes use of V4L2 API is present.
  *
- * This test opens user specified Video Device and calls video ioctls in a
- * loop once every 10 seconds.
- *
  * Usage:
  *	sudo ./video_device_test -d /dev/videoX
- *
- *	While test is running, remove the device or unbind the driver and
- *	ensure there are no use after free errors and other Oops in the
- *	dmesg.
- *	When possible, enable KaSan kernel config option for use-after-free
- *	error detection.
-*/
+ */
 
 #include <stdio.h>
 #include <unistd.h>
@@ -37,45 +28,67 @@
 #include <time.h>
 #include <linux/videodev2.h>
 
-int main(int argc, char **argv)
+#define PRIORITY_MAX 4
+
+int priority_test(int fd)
 {
-	int opt;
-	char video_dev[256];
-	int count;
-	struct v4l2_tuner vtuner;
-	struct v4l2_capability vcap;
+	/* 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 fd;
+	int result = 0;
 
-	if (argc < 2) {
-		printf("Usage: %s [-d </dev/videoX>]\n", argv[0]);
-		exit(-1);
+	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;
 	}
 
-	/* Process arguments */
-	while ((opt = getopt(argc, argv, "d:")) != -1) {
-		switch (opt) {
-		case 'd':
-			strncpy(video_dev, optarg, sizeof(video_dev) - 1);
-			video_dev[sizeof(video_dev)-1] = '\0';
-			break;
-		default:
-			printf("Usage: %s [-d </dev/videoX>]\n", argv[0]);
-			exit(-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)
+{
+	/*
+	 * This test opens user specified Video Device and calls video ioctls in a
+	 * loop once every 10 seconds.
+	 * While test is running, remove the device or unbind the driver and
+	 * ensure there are no use after free errors and other Oops in the
+	 * dmesg.
+	 * When possible, enable KaSan kernel config option for use-after-free
+	 * error detection.
+	 */
+	int count;
+	struct v4l2_tuner vtuner;
+	struct v4l2_capability vcap;
+	int ret;
 
 	/* 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) {
-		printf("Video Device open errno %s\n", strerror(errno));
-		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"
@@ -98,4 +111,46 @@ int main(int argc, char **argv)
 		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]);
+		exit(-1);
+	}
+
+	/* Process arguments */
+	while ((opt = getopt(argc, argv, "d:")) != -1) {
+		switch (opt) {
+		case 'd':
+			strncpy(video_dev, optarg, sizeof(video_dev) - 1);
+			video_dev[sizeof(video_dev)-1] = '\0';
+			break;
+		default:
+			printf("Usage: %s [-d </dev/videoX>]\n", argv[0]);
+			exit(-1);
+		}
+	}
+
+	/* Open Video device and keep it open */
+	fd = open(video_dev, O_RDWR);
+	if (fd == -1) {
+		printf("Video Device open errno %s\n", strerror(errno));
+		exit(-1);
+	}
+
+	test_result = priority_test(fd);
+	if (!test_result)
+		printf("Priority test - PASSED\n");
+	else
+		printf("Priority test - FAILED\n");
+
+	loop_test(fd);
 }
-- 
2.34.1

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