mutli-threads with different singnal mask demo

/*
* Howto
*1. gcc  -o multi_thread_signal multi_thread_signal.c  -lpthread
*2. ./multi_thread_signal &
*3. ps -aux to see the PID of multi_thread_signal application
*4. use kill -10 <PID_OF_multi_thread_signal_APP> to send signal SIGUSR1 to others thread 
*5. use kill -12 <PID_OF_multi_thread_signal_APP> to send signal SIGUSR2 to ic2 thread
*6. use kiill -3 <PID_OF_multi_thread_signal_APP> to send signal SIGQUIT to spi thread
*7. use kill -2 <PID_OF_multi_thread_signal_APP> to kill all threads and end the process 
* */
#include <pthread.h>
#include <stdio.h>
#include <sys/signal.h>

void spi_sghandler(int sig)
{
    printf("spi_thread %ld caught signal %d\n", (long int)pthread_self(), sig);
}
void ic2_sghandler(int sig)
{
    printf("ic2_thread %ld caught signal %d\n", (long int)pthread_self(), sig);
}
void others_sghandler(int sig)
{
    printf("Others_thread %ld caught signal %d\n", (long int)pthread_self(), sig);
}

/*SPI thread support SIGQUIT SIGINT and signal action is */
void* spi_threads (void* unused)
{
    int rc =0;
    struct sigaction act;
    sigset_t new;
    /*register signal handler first befor signal can be action*/
    act.sa_handler = spi_sghandler;
    sigaction(SIGQUIT, &act, NULL);
    sigaddset(&new, SIGQUIT);
    pthread_sigmask(SIG_UNBLOCK, &new, NULL);

    printf("It's spi %ld\n",(long int) pthread_self());
    while(1)
    {
        rc = sleep(100);
        printf("SPI wake_up%d\n",rc);
    }
    return NULL;
}
/*ic2 thread support SIGINT and SIGUSR2 */
void* ic2_threads (void* unused)
{
    int rc;
    struct sigaction act;
    sigset_t new;
    /*register signal handler first befor signal can be action*/
    act.sa_handler = ic2_sghandler;
    sigaction(SIGUSR2, &act, NULL);
    sigaddset(&new, SIGUSR2);
    pthread_sigmask(SIG_UNBLOCK, &new, NULL);
    printf("It's ic2 %ld\n",(long int) pthread_self());
    while(1)
    {
        rc=sleep(100);
        printf("ic2 wake_up%d\n",rc);
    }
    return NULL;
}
/*Others thread support SIGINT and SIGUSR1 */
void* others_threads (void* unused)
{
    int rc = 0;
    struct sigaction act;
    sigset_t new;
    /*register signal handler first befor signal can be action*/
    act.sa_handler = others_sghandler;
    sigaction(SIGUSR1, &act, NULL);
    sigaddset(&new, SIGUSR1);
    pthread_sigmask(SIG_UNBLOCK, &new, NULL);

    printf("Others %ld\n",(long int) pthread_self());
    while(1)
    {
        rc=sleep(100);
        printf("Others wake_up%d\n",rc);
    }
    return NULL;
}
/* The main program.  */

int main ()
{
    pthread_t thread_spi;
    pthread_t thread_ic2;
    pthread_t thread_others;
    int rc =0;
    sigset_t new;
    sigfillset(&new);/*support all signal*/
    sigdelset(&new, SIGINT);/*re_move SIG_INT for we try to BLOCK*/
    /*Main thead Just Support SIG_INT only */
    pthread_sigmask(SIG_BLOCK, &new, NULL);
    /* sub-threads can inherit signal from main thread*/

    pthread_create  (&thread_spi,  NULL, &spi_threads, NULL);
    pthread_create  (&thread_ic2,  NULL, &ic2_threads, NULL);
    pthread_create  (&thread_others,  NULL, &others_threads, NULL);
    while(1)
    {
        rc=sleep(100);
        /*if rc not zero, we are wakeup by signal*/
        printf("Main wake_up %d\n",rc);
    }
    return 0;
}