1*e6255a29SSeongJae Park // SPDX-License-Identifier: GPL-2.0
2*e6255a29SSeongJae Park /*
3*e6255a29SSeongJae Park * Author: SeongJae Park <sj@kernel.org>
4*e6255a29SSeongJae Park */
5*e6255a29SSeongJae Park #define _GNU_SOURCE
6*e6255a29SSeongJae Park
7*e6255a29SSeongJae Park #include <fcntl.h>
8*e6255a29SSeongJae Park #include <stdbool.h>
9*e6255a29SSeongJae Park #include <stdint.h>
10*e6255a29SSeongJae Park #include <stdio.h>
11*e6255a29SSeongJae Park #include <stdlib.h>
12*e6255a29SSeongJae Park #include <sys/types.h>
13*e6255a29SSeongJae Park #include <sys/wait.h>
14*e6255a29SSeongJae Park #include <time.h>
15*e6255a29SSeongJae Park #include <unistd.h>
16*e6255a29SSeongJae Park
17*e6255a29SSeongJae Park #define DBGFS_MONITOR_ON "/sys/kernel/debug/damon/monitor_on_DEPRECATED"
18*e6255a29SSeongJae Park #define DBGFS_TARGET_IDS "/sys/kernel/debug/damon/target_ids"
19*e6255a29SSeongJae Park
turn_damon_on_exit(void)20*e6255a29SSeongJae Park static void turn_damon_on_exit(void)
21*e6255a29SSeongJae Park {
22*e6255a29SSeongJae Park int target_ids_fd = open(DBGFS_TARGET_IDS, O_RDWR);
23*e6255a29SSeongJae Park int monitor_on_fd = open(DBGFS_MONITOR_ON, O_RDWR);
24*e6255a29SSeongJae Park char pid_str[128];
25*e6255a29SSeongJae Park
26*e6255a29SSeongJae Park snprintf(pid_str, sizeof(pid_str), "%d", getpid());
27*e6255a29SSeongJae Park write(target_ids_fd, pid_str, sizeof(pid_str));
28*e6255a29SSeongJae Park write(monitor_on_fd, "on\n", 3);
29*e6255a29SSeongJae Park close(target_ids_fd);
30*e6255a29SSeongJae Park close(monitor_on_fd);
31*e6255a29SSeongJae Park usleep(1000);
32*e6255a29SSeongJae Park exit(0);
33*e6255a29SSeongJae Park }
34*e6255a29SSeongJae Park
try_race(void)35*e6255a29SSeongJae Park static void try_race(void)
36*e6255a29SSeongJae Park {
37*e6255a29SSeongJae Park int target_ids_fd = open(DBGFS_TARGET_IDS, O_RDWR);
38*e6255a29SSeongJae Park int pid = fork();
39*e6255a29SSeongJae Park int buf[256];
40*e6255a29SSeongJae Park
41*e6255a29SSeongJae Park if (pid < 0) {
42*e6255a29SSeongJae Park fprintf(stderr, "fork() failed\n");
43*e6255a29SSeongJae Park exit(1);
44*e6255a29SSeongJae Park }
45*e6255a29SSeongJae Park if (pid == 0)
46*e6255a29SSeongJae Park turn_damon_on_exit();
47*e6255a29SSeongJae Park while (true) {
48*e6255a29SSeongJae Park int status;
49*e6255a29SSeongJae Park
50*e6255a29SSeongJae Park read(target_ids_fd, buf, sizeof(buf));
51*e6255a29SSeongJae Park if (waitpid(-1, &status, WNOHANG) == pid)
52*e6255a29SSeongJae Park break;
53*e6255a29SSeongJae Park }
54*e6255a29SSeongJae Park close(target_ids_fd);
55*e6255a29SSeongJae Park }
56*e6255a29SSeongJae Park
ts_to_ms(struct timespec * ts)57*e6255a29SSeongJae Park static inline uint64_t ts_to_ms(struct timespec *ts)
58*e6255a29SSeongJae Park {
59*e6255a29SSeongJae Park return (uint64_t)ts->tv_sec * 1000 + (uint64_t)ts->tv_nsec / 1000000;
60*e6255a29SSeongJae Park }
61*e6255a29SSeongJae Park
main(int argc,char * argv[])62*e6255a29SSeongJae Park int main(int argc, char *argv[])
63*e6255a29SSeongJae Park {
64*e6255a29SSeongJae Park struct timespec start_time, now;
65*e6255a29SSeongJae Park int runtime_ms;
66*e6255a29SSeongJae Park
67*e6255a29SSeongJae Park if (argc != 2) {
68*e6255a29SSeongJae Park fprintf(stderr, "Usage: %s <runtime in ms>\n", argv[0]);
69*e6255a29SSeongJae Park exit(1);
70*e6255a29SSeongJae Park }
71*e6255a29SSeongJae Park runtime_ms = atoi(argv[1]);
72*e6255a29SSeongJae Park clock_gettime(CLOCK_MONOTONIC, &start_time);
73*e6255a29SSeongJae Park while (true) {
74*e6255a29SSeongJae Park try_race();
75*e6255a29SSeongJae Park clock_gettime(CLOCK_MONOTONIC, &now);
76*e6255a29SSeongJae Park if (ts_to_ms(&now) - ts_to_ms(&start_time) > runtime_ms)
77*e6255a29SSeongJae Park break;
78*e6255a29SSeongJae Park }
79*e6255a29SSeongJae Park return 0;
80*e6255a29SSeongJae Park }
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