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Date:   Wed, 18 Jul 2018 22:22:05 +0100
From:   Al Viro <viro@ZenIV.linux.org.uk>
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Miklos Szeredi <mszeredi@redhat.com>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [RFC] call_with_creds()
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On Wed, Jul 18, 2018 at 01:43:00PM -0700, Linus Torvalds wrote:

> What I really think I'd prefer is to have some simple way to "poison"
> current_cred().  It could be something as simple as a per-thread
> counter, and we'd have current_cred() do
> 
>         WARN_ON_ONCE(in_interrupt() || current->cred_poison);

Why is counter any better than LSB of a pointer?