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Message-ID: <20080827035501.4b8cc732@infradead.org>
Date: Wed, 27 Aug 2008 03:55:01 -0700
From: Arjan van de Ven <arjan@...radead.org>
To: Ingo Molnar <mingo@...e.hu>
Cc: Tony Luck <tony.luck@...el.com>, linux-kernel@...r.kernel.org
Subject: Re: PATCH] debug: add notifier chain debugging
On Wed, 27 Aug 2008 08:39:15 +0200
Ingo Molnar <mingo@...e.hu> wrote:
>
> * Arjan van de Ven <arjan@...radead.org> wrote:
>
> > The patch below fixes this;
> > Ingo, please replace the patch with this one.
>
> well, this one is now less than cheap on x86:
really it isn't; dereference_function_descriptor is a fall through and
basically free.
>
> as it's rather large. So i kept the config option, and it defaults to
> off.
huh? the consensus was that the config needed to go ... nothing changed
on that front. I agree absolutely with not introducing config options
for things that don't need it; we have too many already anyway.
>
> > + if (!func_ptr_is_kernel_text(nb->notifier_call)) {
> > + WARN(1, "Invalid notifier called!");
> > + nb = next_nb;
> > + continue;
> > + }
>
> and that should be an unlikely() too i guess.
please do not add new unlikely()'s to the kernel.. not on non-hotpaths
at least
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