From: Andrew Morton <akpm@linux-foundation.org>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: schwab@suse.de, rpjday@mindspring.com, bbpetkov@yahoo.de,
linux-kernel@vger.kernel.org, muli@il.ibm.com,
satyam@infradead.org, amitkale@netxen.com,
achim_leubner@adaptec.com
Subject: Re: [PATCH 1/1] unify DMA_..BIT_MASK definitions: v3.1
Date: Fri, 5 Oct 2007 15:24:50 -0700 [thread overview]
Message-ID: <20071005152450.a7652b75.akpm@linux-foundation.org> (raw)
In-Reply-To: <4706AC8D.1030100@goop.org>
On Fri, 05 Oct 2007 14:28:45 -0700
Jeremy Fitzhardinge <jeremy@goop.org> wrote:
> Andreas Schwab wrote:
> > #define DMA_BIT_MASK(n) ((u64)-1 >> (64 - (n)))
> >
>
> Yeah, that's cleaner.
>
Well yes, but DMA_BIT_MASK(0) invokes undefined behaviour, generates a
compiler warning and evaluates to 0xffffffffffffffff (with my setup).
That won't be a problem in practice, but it is strictly wrong and doesn't set
a good exmaple for the children ;)
next prev parent reply other threads:[~2007-10-05 22:25 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-18 19:46 [PATCH 1/1] unify DMA_..BIT_MASK definitions: v3.1 Borislav Petkov
2007-09-19 15:03 ` Satyam Sharma
2007-10-05 19:47 ` Andrew Morton
2007-10-05 20:43 ` Jeremy Fitzhardinge
2007-10-05 21:00 ` Andrew Morton
2007-10-05 21:03 ` Robert P. J. Day
2007-10-05 21:23 ` Jeremy Fitzhardinge
2007-10-06 7:54 ` Borislav Petkov
2007-10-05 21:24 ` Andreas Schwab
2007-10-05 21:28 ` Jeremy Fitzhardinge
2007-10-05 22:24 ` Andrew Morton [this message]
2007-10-05 22:32 ` Jeremy Fitzhardinge
2007-10-06 8:37 ` Borislav Petkov
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