Hi,
I noticed a changed behaviour with the PR_SET_PDEATHSIG and SIGKILL
between different kernel versions.
With a kernel 2.6.27.21-78.2.41.fc9.x86_64, the SIGKILL signal is
delivered to the child process when the parent dies but with a 2.6.31
kernel version that don't happen.
The program below shows the problem. I remember there was were some
modifications about not killing the init process of the container from
inside, but in this case, that happens _conceptually_ from outside.
Keeping this feature is very important to be able to wipe out the
container when the parent process of the container dies.
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/prctl.h>
#include <sys/param.h>
#include <sys/poll.h>
#include <signal.h>
#include <sched.h>
#ifndef CLONE_NEWPID
# define CLONE_NEWPID 0x20000000
#endif
int child(void *arg)
{
if (prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0)) {
perror("prctl");
return -1;
}
sleep(3);
printf("I should have gone with my parent\n");
return -1;
}
pid_t clonens(int (*fn)(void *), void *arg, int flags)
{
long stack_size = sysconf(_SC_PAGESIZE);
void *stack = alloca(stack_size) + stack_size;
return clone(fn, stack, flags | SIGCHLD, arg);
}
int main(int argc, char *argv[])
{
pid_t pid;
pid = clonens(child, NULL, CLONE_NEWNS|CLONE_NEWPID);
if (pid < 0) {
perror("clone");
return -1;
}
/* let the child to be ready, ugly but simple code */
sleep(1);
return 0;
}
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