linux-kernel - Re: [PATCH 3/4] tty: Iterate only thread group leaders in __do

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Message-ID: <9a854275-7a72-fc54-99fa-66161732fbf9@virtuozzo.com>
Date:   Fri, 12 Jan 2018 11:42:30 +0300
From:   Kirill Tkhai <ktkhai@...tuozzo.com>
To:     Oleg Nesterov <oleg@...hat.com>
Cc:     linux-kernel@...r.kernel.org, gregkh@...uxfoundation.org,
        jslaby@...e.com, viro@...iv.linux.org.uk, keescook@...omium.org,
        serge@...lyn.com, james.l.morris@...cle.com, luto@...nel.org,
        john.johansen@...onical.com, mingo@...nel.org,
        akpm@...ux-foundation.org, mhocko@...e.com, peterz@...radead.org
Subject: Re: [PATCH 3/4] tty: Iterate only thread group leaders in __do_SAK()

On 11.01.2018 21:34, Oleg Nesterov wrote:
> On 01/11, Kirill Tkhai wrote:
>>
>> Since threads can't have additional fd in comparison
>> to thread group leader
> ...
>> as they definitely have the same
>> files struct, as thread group leader.
> 
> Hmm. Why? Iirc CLONE_THREAD doesn't require CLONE_FILES?

Oh, it's really so. Surprise. Thanks for pointing that.
I'll try to find a way, how we can iterate threads fds using rcu.

> Also. The group leader can exit, in this case its ->files == NULL
> but other threads can be alive.

Sure, thanks, Oleg.

Kirill