linux-kernel - Re: [PATCH 1/1] exec: do not sleep in TASK_TRACED under ->cred_guard

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Message-ID: <20090904154947.GA17048@redhat.com>
Date:	Fri, 4 Sep 2009 17:49:47 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	David Howells <dhowells@...hat.com>
Cc:	Roland McGrath <roland@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	James Morris <jmorris@...ei.org>,
	Tom Horsley <tom.horsley@....net>,
	linux-kernel@...r.kernel.org, stable@...nel.org
Subject: Re: [PATCH 1/1] exec: do not sleep in TASK_TRACED under
	->cred_guard_mutex

On 09/04, David Howells wrote:
>
> Oleg Nesterov <oleg@...hat.com> wrote:
>
> > -
> > -	/* cred_guard_mutex must be held at least to this point to prevent
> > -	 * ptrace_attach() from altering our determination of the task's
> > -	 * credentials; any time after this it may be unlocked */
> > -
>
> Why are you removing this comment, btw?  In what way does your patch
> invalidate it?

No, the comment is fine. Except, now we have more users of this mutex,
but it only mentions ptrace_attach(). Tried to improve it, but failed
to make the concise and understandable comment,

I tried to collect all comments aboout cred_guard_mutex in one place,
above prepare_bprm_creds()... OK, agreed. Will revert this bit and
resend.

Oleg.

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