linux-kernel - Re: Why does test_bit() take a volatile addr?

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Message-ID: <20130916072603.GA11007@redhat.com>
Date:	Mon, 16 Sep 2013 10:26:03 +0300
From:	"Michael S. Tsirkin" <mst@...hat.com>
To:	Stephen Rothwell <sfr@...b.auug.org.au>
Cc:	Rusty Russell <rusty@...tcorp.com.au>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: Why does test_bit() take a volatile addr?

On Mon, Sep 16, 2013 at 04:53:44PM +1000, Stephen Rothwell wrote:
> Hi Rusty,
> 
> On Mon, 16 Sep 2013 13:38:35 +0930 Rusty Russell <rusty@...tcorp.com.au> wrote:
> >
> > Predates git, does anyone remember the rationale?
> > 
> > ie:
> >         int test_bit(int nr, const volatile unsigned long *addr)
> 
> Because we sometimes pass volatile pointers to it and gcc will complain
> if you pass a volatile to a non volatile  (I think).

Where are these? I did git grep -W test_bit and looked for volatile,
couldn't find anything.

> -- 
> Cheers,
> Stephen Rothwell                    sfr@...b.auug.org.au


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