linux-kernel - Re: [PATCH 3/7] perf callchain: Add enum match_result for match

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Message-ID: <20160124040511.GA9810@danjae.kornet>
Date:	Sun, 24 Jan 2016 13:05:11 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Jiri Olsa <jolsa@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: Re: [PATCH 3/7] perf callchain: Add enum match_result for
 match_chain()

Hi Jiri,

On Sat, Jan 23, 2016 at 06:01:10PM +0100, Jiri Olsa wrote:
> On Fri, Jan 22, 2016 at 10:41:36PM +0900, Namhyung Kim wrote:
> 
> SNIP
> 
> >  	/* lookup in childrens */
> >  	while (*p) {
> > -		s64 ret;
> > +		enum match_result ret;
> >  
> >  		parent = *p;
> >  		rnode = rb_entry(parent, struct callchain_node, rb_node_in);
> >  
> >  		/* If at least first entry matches, rely to children */
> >  		ret = append_chain(rnode, cursor, period);
> > -		if (ret == 0)
> > +		if (ret == MATCH_EQ)
> >  			goto inc_children_hit;
> >  
> > -		if (ret < 0)
> > +		if (ret == MATCH_LT)
> >  			p = &parent->rb_left;
> >  		else
> >  			p = &parent->rb_right;
> 
> so if we want to use the return values like that you
> probably missed 2 other places

Right!

> 
> 
> ---
> diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
> index 7139d438ee6d..dc08e76aa8d9 100644
> --- a/tools/perf/util/callchain.c
> +++ b/tools/perf/util/callchain.c
> @@ -565,7 +565,7 @@ split_add_child(struct callchain_node *parent,
>  		cnode = list_first_entry(&first->val, struct callchain_list,
>  					 list);
>  
> -		if (match_chain(node, cnode) < 0)
> +		if (match_chain(node, cnode) == MATCH_LT)
>  			pp = &p->rb_left;
>  		else
>  			pp = &p->rb_right;
> @@ -652,7 +652,7 @@ append_chain(struct callchain_node *root,
>  			break;
>  
>  		cmp = match_chain(node, cnode);
> -		if (cmp)
> +		if (cmp != MATCH_EQ)

This has same effect since I chose 0 for MATCH_EQ intentionally.  But
yes, it'd be better making it explicit.  Will change.

Thanks,
Namhyung


>  			break;
>  
>  		found = true;