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// 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;
}
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