1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Author: SeongJae Park <sj@kernel.org>
4 */
5 #define _GNU_SOURCE
6
7 #include <fcntl.h>
8 #include <stdbool.h>
9 #include <stdint.h>
10 #include <stdio.h>
11 #include <stdlib.h>
12 #include <sys/types.h>
13 #include <sys/wait.h>
14 #include <time.h>
15 #include <unistd.h>
16
17 #define DBGFS_MONITOR_ON "/sys/kernel/debug/damon/monitor_on_DEPRECATED"
18 #define DBGFS_TARGET_IDS "/sys/kernel/debug/damon/target_ids"
19
turn_damon_on_exit(void)20 static void turn_damon_on_exit(void)
21 {
22 int target_ids_fd = open(DBGFS_TARGET_IDS, O_RDWR);
23 int monitor_on_fd = open(DBGFS_MONITOR_ON, O_RDWR);
24 char pid_str[128];
25
26 snprintf(pid_str, sizeof(pid_str), "%d", getpid());
27 write(target_ids_fd, pid_str, sizeof(pid_str));
28 write(monitor_on_fd, "on\n", 3);
29 close(target_ids_fd);
30 close(monitor_on_fd);
31 usleep(1000);
32 exit(0);
33 }
34
try_race(void)35 static void try_race(void)
36 {
37 int target_ids_fd = open(DBGFS_TARGET_IDS, O_RDWR);
38 int pid = fork();
39 int buf[256];
40
41 if (pid < 0) {
42 fprintf(stderr, "fork() failed\n");
43 exit(1);
44 }
45 if (pid == 0)
46 turn_damon_on_exit();
47 while (true) {
48 int status;
49
50 read(target_ids_fd, buf, sizeof(buf));
51 if (waitpid(-1, &status, WNOHANG) == pid)
52 break;
53 }
54 close(target_ids_fd);
55 }
56
ts_to_ms(struct timespec * ts)57 static inline uint64_t ts_to_ms(struct timespec *ts)
58 {
59 return (uint64_t)ts->tv_sec * 1000 + (uint64_t)ts->tv_nsec / 1000000;
60 }
61
main(int argc,char * argv[])62 int main(int argc, char *argv[])
63 {
64 struct timespec start_time, now;
65 int runtime_ms;
66
67 if (argc != 2) {
68 fprintf(stderr, "Usage: %s <runtime in ms>\n", argv[0]);
69 exit(1);
70 }
71 runtime_ms = atoi(argv[1]);
72 clock_gettime(CLOCK_MONOTONIC, &start_time);
73 while (true) {
74 try_race();
75 clock_gettime(CLOCK_MONOTONIC, &now);
76 if (ts_to_ms(&now) - ts_to_ms(&start_time) > runtime_ms)
77 break;
78 }
79 return 0;
80 }
81