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Date: Tue, 06 Mar 2007 10:47:29 -0800 (PST)
Message-Id: <20070306.104729.43502575.davem@davemloft.net>
To: heiko.carstens@de.ibm.com
Cc: schwidefsky@de.ibm.com, linux-kernel@vger.kernel.org,
       linux-s390@vger.kernel.org
Subject: Re: [S390] Use generic bug.
From: David Miller <davem@davemloft.net>
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From: Heiko Carstens <heiko.carstens@de.ibm.com>
Date: Tue, 6 Mar 2007 12:59:17 +0100

> On Mon, Mar 05, 2007 at 02:56:29PM -0800, David Miller wrote:
> > From: Martin Schwidefsky <schwidefsky@de.ibm.com>
> > Date: Mon, 5 Mar 2007 23:43:54 +0100
> > 
> > > +	if (__builtin_constant_p(__ret_warn_on)) {	\
> > > +		if (__ret_warn_on)			\
> > > +			__EMIT_BUG(BUGFLAG_WARNING);	\
> > 
> > I see we'll have this construct on powerpc, parisc and now s390.
> > 
> > But if it's going to trigger essentially at compile time, I
> > think it's much better to BUILD_BUG_ON() in this case instead
> > of counting on the code path to actually run and the user to
> > notice and report the kernel log message.
> 
> So something like WARN_ON(1) won't compile, but BUG_ON(1) still
> would? Seems odd to me.
> Also since there is nothing like WARN(), you have to use WARN_ON(1).
> Btw.: sparc64 has plenty of these ;)

I see.  It's for case where we can't put the test into the
WARN_ON() call.

Thanks for the explanation, I hadn't considered such cases.