linux-kernel - Re: [tip:perf/urgent] perf hists: Fix determination of a callchain node's childlessness

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Date:	Mon, 18 Apr 2016 11:07:01 -0300
From:	Arnaldo Carvalho de Melo <acme@...hat.com>
To:	Andres Freund <andres@...razel.de>
Cc:	tglx@...utronix.de, a.p.zijlstra@...llo.nl, namhyung@...nel.org,
	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:perf/urgent] perf hists: Fix determination of a callchain
 node's childlessness

Em Sat, Apr 16, 2016 at 12:46:14PM -0700, Andres Freund escreveu:
> Hi,
> 
> Perhaps this should also go into stable? It'd be nice to fix that
> regression for 4.4 and 4.5.

Yeah, that would be good, just send that request to stable@...nel.org.

- Arnaldo
 
> Regards,
> 
> Andres
> 
> On 2016-03-30 23:33:37 -0700, tip-bot for Andres Freund wrote:
> > Commit-ID:  909890355507e92bdaf648e73870f6b5df606da8
> > Gitweb:     http://git.kernel.org/tip/909890355507e92bdaf648e73870f6b5df606da8
> > Author:     Andres Freund <andres@...razel.de>
> > AuthorDate: Wed, 30 Mar 2016 21:02:45 +0200
> > Committer:  Arnaldo Carvalho de Melo <acme@...hat.com>
> > CommitDate: Wed, 30 Mar 2016 18:08:39 -0300
> > 
> > perf hists: Fix determination of a callchain node's childlessness
> > 
> > The 4b3a3212233a ("perf hists browser: Support flat callchains") commit
> > over-aggressively tried to optimize callchain_node__init_have_children().
> > 
> > That lead to --tui mode not allowing to expand call chain elements if a
> > call chain element had only one parent. That's why --inverted callgraphs
> > looked halfway sane, but plain ones didn't.
> > 
> > Revert that individual optimization, it wasn't really related to the
> > rest of the commit.
> > 
> > Signed-off-by: Andres Freund <andres@...razel.de>
> > Acked-by: Namhyung Kim <namhyung@...nel.org>
> > Tested-by: Arnaldo Carvalho de Melo <acme@...hat.com>
> > Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> > Fixes: 4b3a3212233a ("perf hists browser: Support flat callchains")
> > Link: http://lkml.kernel.org/r/20160330190245.GB13305@awork2.anarazel.de
> > Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
> > ---
> >  tools/perf/ui/browsers/hists.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
> > index 4b98165..2a83414 100644
> > --- a/tools/perf/ui/browsers/hists.c
> > +++ b/tools/perf/ui/browsers/hists.c
> > @@ -337,7 +337,7 @@ static void callchain_node__init_have_children(struct callchain_node *node,
> >  	chain = list_entry(node->val.next, struct callchain_list, list);
> >  	chain->has_children = has_sibling;
> >  
> > -	if (node->val.next != node->val.prev) {
> > +	if (!list_empty(&node->val)) {
> >  		chain = list_entry(node->val.prev, struct callchain_list, list);
> >  		chain->has_children = !RB_EMPTY_ROOT(&node->rb_root);
> >  	}