Проблема с pthread_create

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <sys/types.h>
#include <sys/syscall.h>
#include <fcntl.h>
#include <unistd.h>

#include <pthread.h>

#define _GNU_SOURCE
#define _DEBUG

int tfres = 0;

void* line_to_file(void* line);

int main(int argc, char* argv[])
{
    pthread_t tid = 0;
    int tretcode = 0;
    int* p_tretcode = &tretcode;

    printf("Process with PID: %d started\n", getpid());

    if (pthread_create(&tid, NULL, line_to_file, (void *)"test_line\n")) {
        perror("thread creating problem");
        exit(1);
    }

#ifdef _DEBUG
    printf("DEBUG: thread with tid %d has been created\n", (int)tid);
#endif

    pthread_join(tid, (void **)&p_tretcode);
#ifdef _DEBUG
    printf("DEBUG: thread with tid %d has been completed with return code %d\n",
                                                            (int)tid, tretcode);
#endif

    printf("Process with PID: %d preparing to completd\n", getpid());
    return 0;
}

// function working in thread
void* line_to_file(void* line)
{
    int fd = 0;
    pid_t tid = 0;
    char filename[16] = {0};
    ssize_t bytes_written = 0;
    size_t size = strlen(line);

    tid = syscall(SYS_gettid);
    sprintf(filename, "file-%d.dat", tid);

    if ((fd = open(filename, O_CREAT | O_RDWR | O_TRUNC, 0644)) == -1) {
                perror("line_to_file -> creating log file problem");
                tfres = -1;
        pthread_exit((void *)tfres);
    }

    bytes_written = write(fd, line, size);
#ifdef _DEBUG
    printf("DEBUG: bytes_written %d\n", bytes_written);
#endif

    return (void *)tfres;
}// line_to_file