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

[tip-bot for Andres Freund]

Commit-ID:  909890355507e92bdaf648e73870f6b5df606da8
Gitweb:     http://git.kernel.org/tip/909890355507e92bdaf648e73870f6b5df606da8
Author:     Andres Freund <andres@xxxxxxxxxxx>
AuthorDate: Wed, 30 Mar 2016 21:02:45 +0200
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
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@xxxxxxxxxxx>
Acked-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Fixes: 4b3a3212233a ("perf hists browser: Support flat callchains")
Link: http://lkml.kernel.org/r/20160330190245.GB13305@xxxxxxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 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);
 	}