[CRIU] Re: [PATCH cr 04/10] restore: add interface for creating helper tasks (v2)

[Andrew Vagin]

> > @@ -704,7 +744,7 @@ static int restore_root_task(struct pstree_item *init, struct cr_options *opts)
> >  		return -1;
> >  	}
> >  
> > -	act.sa_flags |= SA_NOCLDWAIT | SA_NOCLDSTOP | SA_SIGINFO | SA_RESTART;
> > +	act.sa_flags |= SA_NOCLDSTOP | SA_SIGINFO | SA_RESTART;
> 
> Plz, explain this hunk.
Before any death signs an error.
The signal will not be delivered if another signal is pending.
Now we have helpers, which can exit and it's expected and we don't want
to skip if any one of restored processes exits, so we wait all zombies
in the sigchld handler.
> 
> >  	act.sa_sigaction = sigchld_handler;
> >  	ret = sigaction(SIGCHLD, &act, &old_act);
> >  	if (ret < 0) {