linux-kernel - Re: [PATCH] Make WARN_ON/WARN_ON_ONCE no-ops when CONFIG

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20071215061200.GP19691@waste.org>
Date:	Sat, 15 Dec 2007 00:12:00 -0600
From:	Matt Mackall <mpm@...enic.com>
To:	Herbert Xu <herbert@...dor.apana.org.au>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Dave Jones <davej@...hat.com>
Subject: Re: [PATCH] Make WARN_ON/WARN_ON_ONCE no-ops when CONFIG_BUG is off

On Sat, Dec 15, 2007 at 02:04:49PM +0800, Herbert Xu wrote:
> 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.

Seems we haven't yet reached concensus on what an appropriate use for
BUG_ON is. There's a fairly large camp who think that there are
basically no good reasons to outright crash a machine and that WARN_ON
should replace BUG_ON everywhere.

I tend to agree with this position, except when it comes to handling
filesystems, where panic is often (but not always) the right thing to
do.

-- 
Mathematics is the supreme nostalgia of our time.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/