linux-kernel - Re: [PATCH 2/2] Rewrite jump_label.c to use binary search

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Message-ID: <20100922134650.GA2816@redhat.com>
Date:	Wed, 22 Sep 2010 09:46:50 -0400
From:	Jason Baron <jbaron@...hat.com>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
	rusty@...tcorp.co.au, rostedt@...dmis.com,
	linux-kernel@...r.kernel.org, mingo@...e.hu, hpa@...or.com,
	tglx@...utronix.de, roland@...hat.com, rth@...hat.com,
	mhiramat@...hat.com, fweisbec@...il.com, avi@...hat.com,
	davem@...emloft.net, vgoyal@...hat.com, sam@...nborg.org,
	tony@...eyournoodle.com, Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 2/2] Rewrite jump_label.c to use binary search

On Wed, Sep 22, 2010 at 01:56:48PM +0200, Andi Kleen wrote:
> 
> >> +	for (; entry < stop && entry->key == key; entry++)
> >> +		if (kernel_text_address(entry->code))
> >
> > This does not work for modules I'm afraid, only for the core kernel. You
> > should test for __module_text_address() somewhere.
> 
> I thought it was shared now, but ok.
> 
> > Dumb question: why do you need this test at all ?
> 
> I just copied that from the original code. In fact I was wondering
> too why it's needed. Jason?
> 
> 

It was put there for jump labels that are in __init sections. Without 
this check the code will corrupt itself when we toggle a jump label 
after the __init sections have been freed.

thanks,

-Jason

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