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SubjectRe: WARN_ON() which sometimes sucks

On Wed, 1 Aug 2007, Paul Mackerras wrote:
> It will mean more code on architectures which have a
> conditional-trap-on-nonzero instruction, such as powerpc, since the
> compiler will generate instructions to evaluate !!x. But I don't see
> any reason why ret_warn_on couldn't be a long.

Umm. The WARN_ON() might actually get a "long long" value for all we know.
Ie it's perfectly possible that the WARN_ON might look like

/* Must not have high bits on */
WARN_ON(offset & 0xffffffff00000000);

which on a 32-bit pcc would apparently do the wrong thing entirely as it
stands now. No?

I think I'll commit the !!(x) version, and you guys can try to figure out
what the right thing is long-term. For all I know, the proper solution is
to just revert the whole mess, and *not* make WARN_ON() return a value at
all, since that seems to be the fundamental mistake here.

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