// https://syzkaller.appspot.com/bug?id=86ced160b3c394018a4d5dd1db69824b7b1b6734
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include <pthread.h>
#include <sched.h>
#include <sys/syscall.h>

const char *tracefs_path = NULL;
int stop = 0;

int write_file(const char *path, const char *val) {
    int fd = open(path, O_WRONLY);
    if (fd < 0) return -1;
    ssize_t res = write(fd, val, strlen(val));
    close(fd);
    return res > 0 ? 0 : -1;
}

void *writer_thread(void *arg) {
    char path[256];
    snprintf(path, sizeof(path), "%s/events/sched/sched_process_exit/enable", tracefs_path);
    while (!__atomic_load_n(&stop, __ATOMIC_RELAXED)) {
        write_file(path, "1");
        write_file(path, "0");
    }
    return NULL;
}

void *reader_thread(void *arg) {
    while (!__atomic_load_n(&stop, __ATOMIC_RELAXED)) {
        usleep(1);
    }
    return NULL;
}

int main() {
    const char *paths[] = {
        "/sys/kernel/tracing",
        "/sys/kernel/debug/tracing"
    };
    
    for (int i = 0; i < 2; i++) {
        char test_path[256];
        snprintf(test_path, sizeof(test_path), "%s/events/sched/sched_process_fork/enable", paths[i]);
        int fd = open(test_path, O_RDWR);
        if (fd >= 0) {
            close(fd);
            tracefs_path = paths[i];
            break;
        }
    }

    if (!tracefs_path) {
        printf("[-] Failed to find tracefs.\n");
        exit(1);
    }
    printf("[+] Found tracefs at %s\n", tracefs_path);

    char baseline_path[256];
    snprintf(baseline_path, sizeof(baseline_path), "%s/events/sched/sched_process_fork/enable", tracefs_path);
    if (write_file(baseline_path, "1") < 0) {
        printf("[-] Failed to enable baseline event: %s\n", strerror(errno));
        exit(1);
    }
    printf("[+] Baseline event enabled.\n");

    pthread_t writer;
    if (pthread_create(&writer, NULL, writer_thread, NULL) != 0) {
        printf("[-] Failed to create writer thread: %s\n", strerror(errno));
        exit(1);
    }
    printf("[+] Writer thread created.\n");

    pthread_t readers[8];
    for (int i = 0; i < 8; i++) {
        if (pthread_create(&readers[i], NULL, reader_thread, NULL) != 0) {
            printf("[-] Failed to create reader thread %d: %s\n", i, strerror(errno));
            exit(1);
        }
    }
    printf("[+] Reader threads created.\n");

    sleep(10);
    __atomic_store_n(&stop, 1, __ATOMIC_RELAXED);
    
    pthread_join(writer, NULL);
    for (int i = 0; i < 8; i++) {
        pthread_join(readers[i], NULL);
    }
    
    // Disable baseline event
    write_file(baseline_path, "0");
    
    printf("[+] Done.\n");
    return 0;
}