linux-kernel - Re: [RFC][PATCH 09/11] tty_io: Use do_send_sig_info in __do

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Message-ID: <87h8kylji0.fsf@xmission.com>
Date:   Mon, 16 Jul 2018 20:48:55 -0500
From:   ebiederm@...ssion.com (Eric W. Biederman)
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Oleg Nesterov <oleg@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Wen Yang <wen.yang99@....com.cn>, majiang <ma.jiang@....com.cn>
Subject: Re: [RFC][PATCH 09/11] tty_io: Use do_send_sig_info in __do_SACK to forcibly kill tasks

Linus Torvalds <torvalds@...ux-foundation.org> writes:

> On Mon, Jul 16, 2018 at 12:17 PM Eric W. Biederman
> <ebiederm@...ssion.com> wrote:
>>
>> I should have said it doesn't matter because init does not open ttys and
>> become a member of session groups.  Or at least it never has in my
>> experience.  The only way I know to get that behavior is to boot with
>> init=/bin/bash.
>
> That's hopefully true, yes.
>
> Presumably init does open the console, but hopefull doesn't do setsid.
>
> (We *do* do "setsid()" for the linuxrc running, but that's not done by
> the init thread itself).
>
>> With the force_sig already in do_SAK today my change is not a
>> regression.  As force_sig in a completely different way forces the
>> signal to init.
>
> Ok. A couple of notes in the commit description on this might be good.

Definitely.

>> So I think we want the patch below to clean that up.  Then we don't have
>> to worry about the wrong things sending signals to init by accident, and
>> SEND_SIG_FORCED becomes just SEND_SIG_PRIV that skips the unnecesary
>> allocation of a siginfo struct.
>>
>> Thoughts?
>
> I think the end result is fine, but then I look at that patch of yours
> and it does many other things and that makes me nervous.
>
> Can you separate out the different things it does into separate
> patches to make it easier to read?

I will take a look.

Eric