From: Rusty Russell <rusty@rustcorp.com.au>
To: Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] Whine about suspicious return values from module's ->init() hook
Date: Wed, 6 Feb 2008 17:55:26 +1100
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On Wednesday 06 February 2008 10:37:52 Andrew Morton wrote:
> On Wed, 6 Feb 2008 09:48:10 +1100
>
> Rusty Russell <rusty@rustcorp.com.au> wrote:
> > > It's a no-brainer.
> >
> > For non-developers, WARN_ON is a noop.
>
> Oh..  Rusty.  The mailing list and bugzilla are *full* of WARN_ON reports
> from testers.  Your statement is empirically wrong.

My apologies.  I had extrapolated from my own behaviour: I don't notice 
WARN_ON unless something else goes wrong to make me look in the logs.

> > BUG_ON() will make us fix it in return for short-term pain.
>
> Pain to our users and testers.  People upon whom we are very dependent and
> to whom we are hugely indebted.  People who I have to spend a lot of time
> defending from the likes of you!

I think you misunderstand.  I proposed that we audit all the code before such 
a change.  We shouldn't do *anything* until we can estimate the impact this 
change will have.

Our users deserve better than "I don't know if this will break anything so I 
used WARN_ON".  They deserve "we have confidence that this change won't break 
any existing code".

Now, if an audit is impractical or unreliable, we are better off with a 
WARN_ON.  But it is still an admission of ignorance.

Cheers,
Rusty.
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