On 02/20, KAMEZAWA Hiroyuki wrote:
>
> SUSv3 says
> ==
> if SIGCHLD is blocked, if wait() or waitpid() return because the status of a
> child process is available, any pending SIGCHLD signal shall be cleared unless
> the status of another child process is available.
> ==
Ingo, Roland, should we implement this?
I must admit, I don't understand the text above, "blocked" is per-thread, but
wait() is process wide (any sub-thread can reap a dead child).
> -static int collect_signal(int sig, struct sigpending *list, siginfo_t *info)
> +static int collect_signal(int sig, struct sigpending *list, siginfo_t *info,
> pid_t checkpid)
> {
> - list_for_each_entry(q, &list->list, list) {
> - if (q->info.si_signo == sig) {
> - if (first) {
> - still_pending = 1;
> - break;
> + if (unlikely(checkpid)) {
> + list_for_each_entry(q, &list->list, list) {
> + if (q->info.si_signo == sig) {
> + if (q->info.si_pid == checkpid)
> + first = q;
> + else
> + still_pending = 1;
> + }
> + }
> + } else {
> + list_for_each_entry(q, &list->list, list) {
> + if (q->info.si_signo == sig) {
> + if (first) {
> + still_pending = 1;
> + break;
> + }
> + first = q;
> }
> - first = q;
I'd suggest to make a separate function, but not complicate collect_signal().
> --- linux-2.6.20-devel.orig/kernel/exit.c
> +++ linux-2.6.20-devel/kernel/exit.c
> @@ -1252,8 +1252,12 @@ static int wait_task_zombie(struct task_
> }
> write_unlock_irq(&tasklist_lock);
> }
> - if (p != NULL)
> + if (p != NULL) {
> release_task(p);
> + /* if we received sigchild from "p" and p is released,
> + we remove sigchild from it. */
current may be ptracer, not a parent. Should be ok, clear_stale_sigchild(pid)
can't have a false positive (until we have namespace for pid_t), but the comment
is misleading a bit.
> + clear_stale_sigchild(current, retval);
But we are not checking that SIGCHLD is blocked?
Oleg.
-
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