linux-kernel - Re: [PATCH 1/3] jump label: add enabled/disabled state to jump label key entries

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Message-ID: <20101124145401.GA2815@redhat.com>
Date:	Wed, 24 Nov 2010 09:54:01 -0500
From:	Jason Baron <jbaron@...hat.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	rostedt@...dmis.org, mingo@...e.hu, mathieu.desnoyers@...ymtl.ca,
	hpa@...or.com, tglx@...utronix.de, andi@...stfloor.org,
	roland@...hat.com, rth@...hat.com, masami.hiramatsu.pt@...achi.com,
	fweisbec@...il.com, avi@...hat.com, davem@...emloft.net,
	sam@...nborg.org, ddaney@...iumnetworks.com,
	michael@...erman.id.au, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] jump label: add enabled/disabled state to jump
	label key entries

On Wed, Nov 24, 2010 at 09:20:09AM +0100, Peter Zijlstra wrote:
> On Tue, 2010-11-23 at 16:27 -0500, Jason Baron wrote:
> >         struct hlist_head modules;
> >         unsigned long key;
> > +       u32 nr_entries : 31,
> > +              enabled :  1;
> >  }; 
> 
> I still don't see why you do this, why not simply mandate that the key
> is of type atomic_t* and use *key as enabled state?
> 

Because I want to use *key as a pointer directly to 'struct jump_label_entry'.
In this way jump_label_enable(), jump_label_disable(), become O(1) operations.
That way we don't need any hashing.

thanks,

-Jason
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