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Message-ID: <20070821170443.GA1701@tv-sign.ru>
Date: Tue, 21 Aug 2007 21:04:43 +0400
From: Oleg Nesterov <oleg@...sign.ru>
To: "Serge E. Hallyn" <serue@...ibm.com>
Cc: Daniel Pittman <daniel@...space.net>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
Ingo Molnar <mingo@...e.hu>, Kirill Korotaev <dev@...ru>,
Pavel Emelyanov <xemul@...ru>,
Roland McGrath <roland@...hat.com>,
Sukadev Bhattiprolu <sukadev@...ibm.com>,
containers@...ts.osdl.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC,PATCH] fix /sbin/init signal handling
On 08/21, Serge E. Hallyn wrote:
>
> Quoting Oleg Nesterov (oleg@...sign.ru):
> > @@ -1841,14 +1865,6 @@ relock:
> > if (sig_kernel_ignore(signr)) /* Default is nothing. */
> > continue;
> >
> > - /*
> > - * Init of a pid space gets no signals it doesn't want from
> > - * within that pid space. It can of course get signals from
> > - * its parent pid space.
> > - */
> > - if (current == child_reaper(current))
> > - continue;
> > -
>
> Ok, so the idea is that this will now be caught when the signal is sent,
> using sig_ignored(), (i.e at send_sigqueue, send_group_sigqueue,
> specific_send_sig_info, and __group_send_sig_info) and so doesn't need
> to be checked here?
Yes.
> I was hoping that meant that sig_init_ignore() would always be called
> with current as the sending process, but I guess that's not the case?
Usually current == sender, but if the signal was sent from interrupt
context, current is some random process.
> At least in get_signal_to_deliver() we might resend a signal, though
> I guess we assume the signal comes from current->parent, so maybe we
> can pass that as an argument...
get_signal_to_deliver() might resend a signal, but only when current is
ptraced. In that case the signal will be delivered even if we are init,
no problem. (except that ptracing of sub-namespace init is problem by
itself).
Thanks for looking at this!
Oleg.
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