Re: [Xenomai] Children of forked process do not die upon receiving SIGKILL in Xenomai?

[Christophe Blaess <mailist@logilin.fr>]

Le 11/09/2012 18:25, Gilles Chanteperdrix a écrit :
> On 09/11/2012 06:22 PM, Soo-Hyun Yoo wrote:
>> Hello,
>>
>> I have a certain process "A" that forks and execs a process "B". B
>> spawns multiple child processes.
>>
>> In the vanilla Linux kernel, I can have A send a SIGTERM or SIGKILL to
>> B and thereby successfully kill B and all of its children.
No, the childs of B remain alive. Try this code.

*test-kill.c*

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

int main(void)
{
     pid_t pid;

     fprintf(stderr, "[%d] I'm A\n", getpid());
     if ((pid = fork()) == 0) {
         fprintf(stderr, "[%d] I'm B\n", getpid());
        if (fork() == 0) {
             while (1) {
                 fprintf(stderr, "[%d] I'm C\n", getpid());
                 sleep(1);
             }
         } else {
             while (1) {
                 fprintf(stderr, "[%d] I'm B\n", getpid());
                 sleep(1);
             }
         }
     }
     sleep(3);
     fprintf(stderr,"A kills B\n");
     kill(pid, 9);
     fprintf(stderr, "and A exits\n");
     exit(0);
}


And you'll see :

$ ./test-kill
[15925] I'm A
[15926] I'm B
[15926] I'm B
[15927] I'm C
[15926] I'm B
[15927] I'm C
[15926] I'm B
[15927] I'm C
A kills B
and A exits
$ [15927] I'm C
[15927] I'm C
[15927] I'm C
[15927] I'm C
[15927] I'm C
[15927] I'm C
[15927] I'm C

To kill B's childs, you need to send the signal to the group of processes.