| Date | Mon, 16 Jul 2018 14:51:45 +0200 | From | Oleg Nesterov <> | Subject | Re: [RFC][PATCH 07/11] signal: Deliver group signals via PIDTYPE_TGID not PIDTYPE_PID |
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On 07/10, Eric W. Biederman wrote: > > Now that we can make the distinction use PIDTYPE_TGID rather than > PIDTYPE_PID.
Wai, wait, this doesn't look right...
> There is no immediate effect as they point point at the > same task,
How so? pid_task(pid, PIDTYPE_TGID) will return NULL unless this pid is actually a group leader's pid,
> --- a/kernel/signal.c > +++ b/kernel/signal.c > @@ -1315,7 +1315,7 @@ int kill_pid_info(int sig, struct siginfo *info, struct pid *pid) > > for (;;) { > rcu_read_lock(); > - p = pid_task(pid, PIDTYPE_PID); > + p = pid_task(pid, PIDTYPE_TGID); > if (p) > error = group_send_sig_info(sig, info, p);
So, currently kill(pid_nr) always works, even if pid_nr is a sub-thread's tid.
After this change kill(2) will always fail with -ESRCH in this case.
Or I am totally confused?
> --- a/kernel/time/posix-timers.c > +++ b/kernel/time/posix-timers.c > @@ -347,12 +347,11 @@ int posix_timer_event(struct k_itimer *timr, int si_private) > */ > timr->sigq->info.si_sys_private = si_private; > > + shared = !(timr->it_sigev_notify & SIGEV_THREAD_ID); > rcu_read_lock(); > - task = pid_task(timr->it_pid, PIDTYPE_PID); > - if (task) { > - shared = !(timr->it_sigev_notify & SIGEV_THREAD_ID); > + task = pid_task(timr->it_pid, shared ? PIDTYPE_TGID : PIDTYPE_PID);
This looks fine, afaics without SIGEV_THREAD_ID ->it_pid is alwats task_tgid().
Oleg.
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