selftests: add a new test for Media Controller API

This test opens user specified Media Device and calls
MEDIA_IOC_DEVICE_INFO ioctl in a loop once every 10
seconds. This test is for detecting errors in device
removal path.

Usage:
    sudo ./media_device_test -d /dev/mediaX

While test is running, remove the device and
ensure there are no use after free errors and
other Oops in the dmesg. Enable KaSan kernel
config option for use-after-free error detection.
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>

tools/testing/selftests/media_tests/.gitignore

+media_device_test

tools/testing/selftests/media_tests/Makefile

+TEST_PROGS := media_device_test
+all: $(TEST_PROGS)
+
+include ../lib.mk
+
+clean:
+	rm -fr media_device_test

tools/testing/selftests/media_tests/media_device_test.c

+/*
+ * media_devkref_test.c - Media Controller Device Kref API Test
+ *
+ * Copyright (c) 2016 Shuah Khan <shuahkh@osg.samsung.com>
+ * Copyright (c) 2016 Samsung Electronics Co., Ltd.
+ *
+ * This file is released under the GPLv2.
+ */
+
+/*
+ * This file adds a test for Media Controller API.
+ * This test should be run as root and should not be
+ * included in the Kselftest run. This test should be
+ * run when hardware and driver that makes use Media
+ * Controller API are present in the system.
+ *
+ * This test opens user specified Media Device and calls
+ * MEDIA_IOC_DEVICE_INFO ioctl in a loop once every 10
+ * seconds.
+ *
+ * Usage:
+ *	sudo ./media_devkref_test -d /dev/mediaX
+ *
+ *	While test is running, remove the device and
+ *	ensure there are no use after free errors and
+ *	other Oops in the dmesg. Enable KaSan kernel
+ *	config option for use-after-free error detection.
+*/
+
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <string.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <linux/media.h>
+
+int main(int argc, char **argv)
+{
+	int opt;
+	char media_device[256];
+	int count = 0;
+	struct media_device_info mdi;
+	int ret;
+	int fd;
+
+	if (argc < 2) {
+		printf("Usage: %s [-d </dev/mediaX>]\n", argv[0]);
+		exit(-1);
+	}
+
+	/* Process arguments */
+	while ((opt = getopt(argc, argv, "d:")) != -1) {
+		switch (opt) {
+		case 'd':
+			strncpy(media_device, optarg, sizeof(media_device) - 1);
+			media_device[sizeof(media_device)-1] = '\0';
+			break;
+		default:
+			printf("Usage: %s [-d </dev/mediaX>]\n", argv[0]);
+			exit(-1);
+		}
+	}
+
+	if (getuid() != 0) {
+		printf("Please run the test as root - Exiting.\n");
+		exit(-1);
+	}
+
+	/* Open Media device and keep it open */
+	fd = open(media_device, O_RDWR);
+	if (fd == -1) {
+		printf("Media Device open errno %s\n", strerror(errno));
+		exit(-1);
+	}
+
+	printf("\nNote:\n"
+	       "While test is running, remove the device and\n"
+	       "ensure there are no use after free errors and\n"
+	       "other Oops in the dmesg. Enable KaSan kernel\n"
+	       "config option for use-after-free error detection.\n\n");
+
+	while (count < 100) {
+		ret = ioctl(fd, MEDIA_IOC_DEVICE_INFO, &mdi);
+		if (ret < 0)
+			printf("Media Device Info errno %s\n", strerror(errno));
+		printf("Media device model %s driver %s\n",
+			mdi.model, mdi.driver);
+		sleep(10);
+		count++;
+	}
+}