Re: [PATCH] user_ns: use correct check for single-threadedness

From: Oleg Nesterov
Date: Wed Aug 12 2015 - 10:42:47 EST


On 08/11, Eric W. Biederman wrote:
>
> Oleg Nesterov <oleg@xxxxxxxxxx> writes:
>
> >> Then why we can't simply check thread_group_empty() == T ? Why should we
> >> worry about CLONE_SIGHAND at all?
> >
> > The same for clone() actually... I forgot why we decided to check
> > CLONE_SIGHAND, iirc I suggested CLONE_THREAD initially then we switched
> > to CLONE_SIGHAND "just in case", to make it as strict as possible.
>
> I do agree that making the test be for CLONE_THREAD is safe, makes
> sense, and is less confusing than what we have now.x

Good,

> > How about the patch below?
> >
> > (note that the "or parent" part of the comment is wrong in any case).
>
> It was correct.

Yes, I know,

> You failed to removed it when you removed CLONE_PARENT
> from that test.

Cough... it was you ;) 1f7f4dde5c945f41a7abc2285be43d918029ecc5
"fork: Allow CLONE_PARENT after setns(CLONE_NEWPID)".

Oleg.

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