Date: Thu, 28 Aug 2008 03:22:30 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
To: David Miller <davem@davemloft.net>
Cc: dhowells@redhat.com, harvey.harrison@gmail.com, akpm@linux-foundation.org,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH] afs: fsclient.c sparse endian annotations of
	operation_ID
Message-ID: <20080828022230.GF28946@ZenIV.linux.org.uk>
References: <1219788326.6069.40.camel@brick> <28254.1219835544@redhat.com> <20080827.041705.160546703.davem@davemloft.net>
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On Wed, Aug 27, 2008 at 04:17:05AM -0700, David Miller wrote:
> From: David Howells <dhowells@redhat.com>
> Date: Wed, 27 Aug 2008 12:12:24 +0100
> 
> > Harvey Harrison <harvey.harrison@gmail.com> wrote:
> > 
> > > +		if (call->operation_ID != __constant_htonl(FSFETCHDATA64)) {
> > 
> > Doesn't htonl() resolve to this for a constant argument?  Following through
> > the definitions, it certainly looks like it ought to:
> 
> Yes it does.
> 
> The __constant_*() interfaces should only be uses for things that
> must be evaluated at compile time (static data initializations,
> switch statement case values etc.).

It's not just "must be evaluated at compile time"; it's "must be C constant
expressions", which is much stricter.  And no, in the case quoted above
__constant_ form is not needed.  Just use htonl()...
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