linux-kernel - Re: [PATCH] perf map: remove extra indirection from map_

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Message-ID: <20181126185334.GA18491@kernel.org>
Date:   Mon, 26 Nov 2018 15:53:34 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Eric Saint-Etienne <eric.saint.etienne@...cle.com>,
        Linux Kernel <linux-kernel@...r.kernel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Eric Saint-Etienne <eric.saintetienne@...il.com>
Subject: Re: [PATCH] perf map: remove extra indirection from map__find()

Em Fri, Nov 23, 2018 at 05:14:25PM +0100, Jiri Olsa escreveu:
> On Fri, Nov 23, 2018 at 02:42:39AM -0800, Eric Saint-Etienne wrote:
> > A double pointer is used in map__find() where a single pointer is enough
> > because the function doesn't affect the rbtree and the rbtree is locked.
> > 
> > Signed-off-by: Eric Saint-Etienne <eric.saint.etienne@...cle.com>
> 
> Acked-by: Jiri Olsa <jolsa@...nel.org>

Thanks, applied.

- Arnaldo
 
> thanks,
> jirka
> 
> > ---
> >  tools/perf/util/map.c | 13 ++++++-------
> >  1 file changed, 6 insertions(+), 7 deletions(-)
> > 
> > diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
> > index 354e545..3dac766 100644
> > --- a/tools/perf/util/map.c
> > +++ b/tools/perf/util/map.c
> > @@ -846,19 +846,18 @@ void maps__remove(struct maps *maps, struct map *map)
> >  
> >  struct map *maps__find(struct maps *maps, u64 ip)
> >  {
> > -	struct rb_node **p, *parent = NULL;
> > +	struct rb_node *p;
> >  	struct map *m;
> >  
> >  	down_read(&maps->lock);
> >  
> > -	p = &maps->entries.rb_node;
> > -	while (*p != NULL) {
> > -		parent = *p;
> > -		m = rb_entry(parent, struct map, rb_node);
> > +	p = maps->entries.rb_node;
> > +	while (p != NULL) {
> > +		m = rb_entry(p, struct map, rb_node);
> >  		if (ip < m->start)
> > -			p = &(*p)->rb_left;
> > +			p = p->rb_left;
> >  		else if (ip >= m->end)
> > -			p = &(*p)->rb_right;
> > +			p = p->rb_right;
> >  		else
> >  			goto out;
> >  	}
> > -- 
> > 1.8.3.1
> > 

-- 

- Arnaldo