linux-kernel - Re: [PATCH 1/4] check_unsafe_exec: use while_each_thread() rather than next

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Message-ID: <20131122202412.GA19563@redhat.com>
Date:	Fri, 22 Nov 2013 21:24:12 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc:	akpm@...ux-foundation.org, viro@...IV.linux.org.uk,
	keescook@...omium.org, mhocko@...e.cz, snanda@...omium.org,
	dserrg@...il.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] check_unsafe_exec: use while_each_thread() rather
	than next_thread()

On 11/22, KOSAKI Motohiro wrote:
>
> (11/22/2013 12:54 PM), Oleg Nesterov wrote:
> > next_thread() should be avoided, change check_unsafe_exec()
> > to use while_each_thread(). This also saves 32 bytes.
>
> Just curious.
> Why it should be avoided? Just for cleaner code?

Nobody except signal->curr_target actually need next_thread-like
code, and

> Or is there
> serious issue?

We need to change (fix) this interface. This particular code is
fine, p == current. But in general the code like this can loop
forever if p exits and next_thread(t) can't reach the unhashed
thread.

Oleg.

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