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Date: Tue, 5 Mar 2002 15:26:31 -0800 (PST)
From: Davide Libenzi <davidel@xmailserver.org>
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To: Hubertus Franke <frankeh@watson.ibm.com>
cc: Rusty Russell <rusty@rustcorp.com.au>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Futexes IV (Fast Lightweight Userspace Semaphores)
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Message-ID: <Pine.LNX.4.44.0203051525460.1475-100000@blue1.dev.mcafeelabs.com>
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On Tue, 5 Mar 2002, Hubertus Franke wrote:

> On Tuesday 05 March 2002 05:39 pm, Davide Libenzi wrote:
> > On Tue, 5 Mar 2002, Rusty Russell wrote:
> > > +	pos_in_page = ((unsigned long)uaddr) % PAGE_SIZE;
> > > +
> > > +	/* Must be "naturally" aligned, and not on page boundary. */
> > > +	if ((pos_in_page % __alignof__(atomic_t)) != 0
> > > +	    || pos_in_page + sizeof(atomic_t) > PAGE_SIZE)
> > > +		return -EINVAL;
> >
> > How can this :
> >
> > 	(pos_in_page % __alignof__(atomic_t)) != 0
> >
> > to be false, and together this :
> >
> > 	pos_in_page + sizeof(atomic_t) > PAGE_SIZE
> >
> > to be true ?
> > This is enough :
> >
> > 	if ((pos_in_page % __alignof__(atomic_t)) != 0)
> >
> >
>
> I believe not all machine have  alignof  == sizeof

Yes but this is always true   alignof >= sizeof




- Davide


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