linux-kernel - Re: [PATCH 02/13] jump label v9: base patch

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Date:	Thu, 10 Jun 2010 19:11:25 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Jason Baron <jbaron@...hat.com>
Cc:	linux-kernel@...r.kernel.org, mingo@...e.hu,
	mathieu.desnoyers@...ymtl.ca, hpa@...or.com, tglx@...utronix.de,
	rostedt@...dmis.org, andi@...stfloor.org, roland@...hat.com,
	rth@...hat.com, mhiramat@...hat.com, avi@...hat.com,
	davem@...emloft.net, vgoyal@...hat.com, sam@...nborg.org
Subject: Re: [PATCH 02/13] jump label v9: base patch

On Thu, Jun 10, 2010 at 11:44:52AM -0400, Jason Baron wrote:
> On Thu, Jun 10, 2010 at 12:35:49AM +0200, Frederic Weisbecker wrote:
> > On Wed, Jun 09, 2010 at 05:38:57PM -0400, Jason Baron wrote:
> > > +static int build_jump_label_hashtable(struct jump_entry *start, struct jump_entry *stop)
> > > +{
> > > +	struct jump_entry *iter, *iter_begin;
> > > +	struct jump_label_entry *entry;
> > > +	int count;
> > > +
> > > +	sort_jump_label_entries(start, stop);
> > > +	iter = start;
> > > +	while (iter < stop) {
> > > +		entry = get_jump_label_entry((char *)iter->name);
> > > +		if (!entry) {
> > > +			iter_begin = iter;
> > > +			count = 0;
> > > +			while ((iter < stop) &&
> > > +				(strcmp((char *)iter->name,
> > > +					(char *)iter_begin->name) == 0)) {
> > > +				iter++;
> > > +				count++;
> > > +			}
> > 
> > 
> > 
> > 
> > So, you can have multiple entries with the same name? How can that happen
> > in fact?
> > 
> > 
> 
> this is the case where a single tracepoint such as kmalloc(), is used in
> all over the kernel. So, there is one name or key value associated with
> a kmalloc tracepoint. however, we have to patch the jump or nop into a
> bunch of places in the kernel text.



Ok, sounds fair then.

Thanks.

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