1 files changed, 80 insertions, 0 deletions
diff --git a/tools/testing/selftests/damon/debugfs_target_ids_read_before_terminate_race.c b/tools/testing/selftests/damon/debugfs_target_ids_read_before_terminate_race.c
new file mode 100644
index 000000000000..b06f52a8ce2d
--- /dev/null
+++ b/tools/testing/selftests/damon/debugfs_target_ids_read_before_terminate_race.c
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Author: SeongJae Park <sj@kernel.org>
+ */
+#define _GNU_SOURCE
+
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <time.h>
+#include <unistd.h>
+
+#define DBGFS_MONITOR_ON "/sys/kernel/debug/damon/monitor_on_DEPRECATED"
+#define DBGFS_TARGET_IDS "/sys/kernel/debug/damon/target_ids"
+
+static void turn_damon_on_exit(void)
+{
+	int target_ids_fd = open(DBGFS_TARGET_IDS, O_RDWR);
+	int monitor_on_fd = open(DBGFS_MONITOR_ON, O_RDWR);
+	char pid_str[128];
+
+	snprintf(pid_str, sizeof(pid_str), "%d", getpid());
+	write(target_ids_fd, pid_str, sizeof(pid_str));
+	write(monitor_on_fd, "on\n", 3);
+	close(target_ids_fd);
+	close(monitor_on_fd);
+	usleep(1000);
+	exit(0);
+}
+
+static void try_race(void)
+{
+	int target_ids_fd = open(DBGFS_TARGET_IDS, O_RDWR);
+	int pid = fork();
+	int buf[256];
+
+	if (pid < 0) {
+		fprintf(stderr, "fork() failed\n");
+		exit(1);
+	}
+	if (pid == 0)
+		turn_damon_on_exit();
+	while (true) {
+		int status;
+
+		read(target_ids_fd, buf, sizeof(buf));
+		if (waitpid(-1, &status, WNOHANG) == pid)
+			break;
+	}
+	close(target_ids_fd);
+}
+
+static inline uint64_t ts_to_ms(struct timespec *ts)
+{
+	return (uint64_t)ts->tv_sec * 1000 + (uint64_t)ts->tv_nsec / 1000000;
+}
+
+int main(int argc, char *argv[])
+{
+	struct timespec start_time, now;
+	int runtime_ms;
+
+	if (argc != 2) {
+		fprintf(stderr, "Usage: %s <runtime in ms>\n", argv[0]);
+		exit(1);
+	}
+	runtime_ms = atoi(argv[1]);
+	clock_gettime(CLOCK_MONOTONIC, &start_time);
+	while (true) {
+		try_race();
+		clock_gettime(CLOCK_MONOTONIC, &now);
+		if (ts_to_ms(&now) - ts_to_ms(&start_time) > runtime_ms)
+			break;
+	}
+	return 0;
+}