Messages in this thread | | | Date | Mon, 5 Oct 2009 21:44:15 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 2/4] signals: send_signal: use si_fromuser() to detect from_ancestor_ns |
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On 10/05, Sukadev Bhattiprolu wrote: > > Oleg Nesterov [oleg@redhat.com] wrote: > | On 10/05, Sukadev Bhattiprolu wrote: > | > > | > Oleg Nesterov [oleg@redhat.com] wrote: > | > | > | > | --- TTT_32/kernel/signal.c~FU_2_SEND_SIGNAL 2009-10-04 02:21:55.000000000 +0200 > | > | +++ TTT_32/kernel/signal.c 2009-10-04 03:09:44.000000000 +0200 > | > | @@ -928,9 +928,8 @@ static int send_signal(int sig, struct s > | > | int from_ancestor_ns = 0; > | > | > | > | #ifdef CONFIG_PID_NS > | > | - if (!is_si_special(info) && SI_FROMUSER(info) && > | > | - task_pid_nr_ns(current, task_active_pid_ns(t)) <= 0) > | > | - from_ancestor_ns = 1; > | > | + from_ancestor_ns = si_fromuser(info) && > | > | + !task_pid_nr_ns(current, task_active_pid_ns(t)); > | > > | > Makes sense. And we had mentioned earlier that container-init is immune > | > to suicide but should we add a check for 'current == t' above to cover the > | > > | > send_sig(SIGKILL, current, 0); > | > > | > in load_aout_binary() and friends > | > > | > from_ancestor_ns = si_fromuser(info) && (current == t || > | > !task_pid_nr_ns(current, task_active_pid_ns(t))); > | > | I don't think so. > | > | First of all, this is just ugly. If we need this check we should change > | the callers, not send_signal(). > > Well, all I am saying is that the check > > !task_pid_nr_ns(current, task_active_pid_ns(t))) > > excludes container-init sending signal to itself - task_pid_nr_ns() above > would return 1 for container-init and 'from_ancestor_ns' would be 0.
Ah, I misunderstood you, and I misread the "current == t" check above. I wrongly thought that you suggest to suppress "si_fromuser()" when the task sends a signal to itself.
Sorry for confusion.
> But sure, we could use force_sig_info() in caller.
Yes, because this makes the code more explicit imho. And we can avoid the further complicatiions in send_signal() path.
> | So, imho this patch also fixes this case by accident, > > This part I am not sure. But as mentioned above, from_ancestor_ns is 0 > and the SIGKILL will not queued right ?
Yes, you are right, see above.
I meant, it fixes the from-user logic, not from_ancestor_ns logic.
Oleg.
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