Re: [PATCH] Make WARN_ON/WARN_ON_ONCE no-ops when CONFIG_BUG is off

[Herbert Xu <herbert@gondor.apana.org.au>]

On Fri, Dec 14, 2007 at 11:52:18PM -0600, Matt Mackall wrote:
>
> No. The code as written above should reduce to:
> 
> 	if (val == NULL)
> 		return -EFAULT;
> 
> If I hadn't wanted to return -EFAULT in this case, I would have just written:
> 
> 	WARN_ON(val == NULL);

Well the only reason I introduced

	if (WARN_ON)

is so that what would otherwise be a BUG_ON condition would have
a chance to get written to disk when invoked from an IRQ handler.

> I don't want code that was running safely (ie returning -EFAULT) to
> start crashing the system just because I've, say, disabled printk.
> That's creating an obnoxious heisenbug.

I'm disappointed that it has been used in ways that it shouldn't
have been.

I suppose we'll have to either introduce a new primitive or just
go back to using BUG_ON.

Cheers,
-- 
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