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Message-Id: <1184537269.25235.28.camel@localhost.localdomain>
Date: Mon, 16 Jul 2007 08:07:49 +1000
From: Benjamin Herrenschmidt <benh@...nel.crashing.org>
To: Al Viro <viro@....linux.org.uk>
Cc: torvalds@...ux-foundation.org, linuxppc-dev@...abs.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] the wrong variable checked after request_irq()
On Sun, 2007-07-15 at 23:02 +0100, Al Viro wrote:
> On Mon, Jul 16, 2007 at 07:40:38AM +1000, Benjamin Herrenschmidt wrote:
> > On Sun, 2007-07-15 at 20:59 +0100, Al Viro wrote:
> > > Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
> >
> > Acked-by: Benjamin Herrenschmidt <benh@...nel.crashing.org>
> >
> > Out of curiosity, how did you pick it up ? You have some automated tool
> > to catch that (or sparse changes) or you just did -lots- of code
> > inspection ?
>
> While testing sparse changes, actually (comparing pointers to null
> pointer constant spelled without a cast to void *)... That gave several
> hundred hits, most of them being immediately obvious (picking the lines
> by file and line number and looking through the list had eliminated all
> but about a dozen or two). Several were not...
Ok. In fact, it would have been nice if gcc had been able to pick it up
for another reason. The old code is:
if (cascade == NULL)
return;
cascade_irq = irq_of_parse_and_map(cascade, 0);
if (cascade == NO_IRQ) {
printk(KERN_ERR "mpic: failed to map cascade interrupt");
return;
}
And NO_IRQ is 0 on powerpc nowadays. Thus the test can never be true :-)
But it looks like gcc doesn't pick that up.
Ben.
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