From c09e31cc128cf1aec3a6cd47203508fbf0082873 Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Wed, 24 Dec 2014 15:04:36 +0900 Subject: [PATCH] perf hists browser: Fix segfault when showing callchain When perf report on TUI shows callchain it checks first node has siblings to determine whether it needs to print percentage value. But it missed a case that first node is NULL. So sometimes it segfaults like below: $ perf top -g perf: Segmentation fault -------- backtrace -------- perf[0x4fcefb] /usr/lib/libc.so.6(+0x33b20)[0x7f2a35839b20] perf(rb_next+0x8)[0x47d3d8] perf[0x4f6058] perf[0x4f833b] perf[0x4f8610] perf[0x4f209e] perf(ui_browser__run+0x3a)[0x4f2e6a] perf[0x4f94ee] perf(perf_evlist__tui_browse_hists+0x94)[0x4fbbf4] perf[0x444d10] /usr/lib/libpthread.so.0(+0x7314)[0x7f2a37070314] /usr/lib/libc.so.6(clone+0x6d)[0x7f2a358ee5bd] $ addr2line -e `which perf` 0x4f6058 /home/namhyung/project/linux/tools/perf/ui/browsers/hists.c:553 I don't know why the backtrace didn't print some symbols.. Signed-off-by: Namhyung Kim Fixes: 4087d11cd945 ("perf hists browser: Print overhead percent value for first-level callchain") Cc: Adrian Hunter Cc: Andi Kleen Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Jiri Olsa Cc: Peter Zijlstra Cc: Stephane Eranian Link: http://lkml.kernel.org/r/1419401076-21700-1-git-send-email-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- 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 e6bb04b..788506e 100644 --- a/tools/perf/ui/browsers/hists.c +++ b/tools/perf/ui/browsers/hists.c @@ -550,7 +550,7 @@ static int hist_browser__show_callchain(struct hist_browser *browser, bool need_percent; node = rb_first(root); - need_percent = !!rb_next(node); + need_percent = node && rb_next(node); while (node) { struct callchain_node *child = rb_entry(node, struct callchain_node, rb_node); -- 1.9.1