From: Linus Torvalds <torvalds@linux-foundation.org>
To: Paul Mackerras <paulus@samba.org>
Cc: Al Viro <viro@ftp.linux.org.uk>,
Alexey Dobriyan <adobriyan@sw.ru>,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
herbert@gondor.apana.org.au
Subject: Re: WARN_ON() which sometimes sucks
Date: Tue, 31 Jul 2007 21:05:43 -0700 (PDT) [thread overview]
Message-ID: <alpine.LFD.0.999.0707312101410.3582@woody.linux-foundation.org> (raw)
In-Reply-To: <18096.949.934194.648312@cargo.ozlabs.ibm.com>
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.
Linus
next prev parent reply other threads:[~2007-08-01 4:07 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-31 15:55 Alexey Dobriyan
2007-07-31 16:02 ` Al Viro
2007-08-01 3:53 ` Paul Mackerras
2007-08-01 4:05 ` Linus Torvalds [this message]
2007-08-01 4:20 ` Paul Mackerras
2007-08-01 15:17 ` Joe Korty
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