This patch fixes a bug where child processes of launch_script() can
misbehave due to SIGCHLD being blocked. In the case of `sudo`, this
causes a permanent hang.
Previously a SIGCHLD handler was added to reap fork_exec()'d zombie
processes by calling waitpid(-1, ...). This required other
fork()/waitpid() callers to temporarilly block SIGCHILD to avoid
having the final wait status being intercepted by the SIGCHLD
handler:
7c3370d4fe3fa6cda8655f109e4659afc8ca4269
Since then, the qemu_add_child_watch() interface was added to allow
registration of such processes and reap only from that specific set
of PIDs:
4d54ec7898bd951007cb6122d5315584bd41d0c4
As a result, we can now avoid blocking SIGCHLD in launch_script(), so
drop that behavior.
Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
static int launch_script(const char *setup_script, const char *ifname, int fd)
{
- sigset_t oldmask, mask;
int pid, status;
char *args[3];
char **parg;
- sigemptyset(&mask);
- sigaddset(&mask, SIGCHLD);
- sigprocmask(SIG_BLOCK, &mask, &oldmask);
-
/* try to launch network script */
pid = fork();
if (pid == 0) {
while (waitpid(pid, &status, 0) != pid) {
/* loop */
}
- sigprocmask(SIG_SETMASK, &oldmask, NULL);
if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
return 0;