linux-kernel - Re: [PATCH v2 5/5] bug: Make BUG() call unreachable()

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Message-ID: <6915585.VegnvotSUi@wuerfel>
Date:	Fri, 28 Feb 2014 09:55:26 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	Josh Triplett <josh@...htriplett.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 5/5] bug: Make BUG() call unreachable()

On Thursday 27 February 2014 16:16:45 Josh Triplett wrote:
> On Thu, Feb 27, 2014 at 08:19:47PM +0100, Arnd Bergmann wrote:
> > On Wednesday 26 February 2014, Josh Triplett wrote:
> > > This doesn't seem any different than compiling out assert() at runtime
> > > in a userspace program, given how the kernel uses BUG() and BUG_ON().
> > > I'd argue that adding unreachable() doesn't seem like it makes the
> > > current implementation of BUG() any worse; either way if you reach it
> > > you have a problem.
> > 
> > I think it's better to get a warning about undefined behavior than
> > to suppress that warning.
> 
> Then at this point I'm going to suggest that you go ahead and submit the
> patch you want on top of the first four patches of this series.

Sure, no problem. I'll wait for your patches to show up in linux-next
and then do a patch on top. I'll be traveling for the next week, so
it may get delayed another few days.

> Please keep in mind the value and code size savings of !CONFIG_BUG, versus
> CONFIG_BUG=y and !CONFIG_DEBUG_BUGVERBOSE; those mean two different
> things.

I think I compared all the options before in the patch I cited,
https://lkml.org/lkml/2013/7/5/222 but I agree that the list
is a bit confusing.

> Meanwhile: Andrew, could you go ahead and apply the first four patches?

Yes please.

	Arnd
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