linux-kernel - Re: PATCH [1/1]: audit: acquire creds selectively to reduce atomic op overhead

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Message-ID: <21411.1300219487@redhat.com>
Date:	Tue, 15 Mar 2011 20:04:47 +0000
From:	David Howells <dhowells@...hat.com>
To:	Tony Jones <tonyj@...e.de>
Cc:	dhowells@...hat.com, linux-kernel@...r.kernel.org,
	linux-audit@...hat.com, Eric Paris <eparis@...hat.com>,
	Al Viro <viro@...iv.linux.org.uk>
Subject: Re: PATCH [1/1]: audit: acquire creds selectively to reduce atomic op overhead

Tony Jones <tonyj@...e.de> wrote:

> Agree. Also I believe it is safe to use tsk->cred directly as tsk == current 
> or tsk is being created by copy_process.  

You can't quite access it like that without sparse throwing a warning.  The
pointer is marked with an __rcu attribute, so you need to use something like
this:

	cred = rcu_dereference_check(tsk->cred, (tsk == current ||
						 called_from_copy_process());

David
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