perf top browser: Handle empty active symbols list

Commit-ID:  3166fc8fb6a2f52273d545e970297524e02c3e39
Gitweb:     http://git.kernel.org/tip/3166fc8fb6a2f52273d545e970297524e02c3e39
Author:     Arnaldo Carvalho de Melo <[email protected]>
AuthorDate: Tue, 1 Mar 2011 10:21:44 -0300
Committer:  Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Tue, 1 Mar 2011 10:21:44 -0300

perf top browser: Handle empty active symbols list

Fixing a SEGV. An empty list could happen when not being able to resolve symbols, for instance when --vmlinux invalid-file is used.

Cc: Frederic Weisbecker <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Tom Zanussi <[email protected]>
LKML-Reference: <new-submission>

---
 tools/perf/util/ui/browsers/top.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

index e9381ec..5a06538 100644
@@ -76,6 +76,12 @@ static void perf_top_browser__update_rb_tree(struct perf_top_browser *browser)
 	browser->root = RB_ROOT;
 	browser->b.top = NULL;
 	browser->sum_ksamples = perf_top__decay_samples(top, &browser->root);
+	/*
+ 	 * No active symbols
+ 	 */
+	if (top->rb_entries == 0)
+		return;
+
 	perf_top__find_widths(top, &browser->root, &browser->dso_width,
 			      &browser->dso_short_width,
                               &browser->sym_width);