linux-kernel - [PATCH 3/3] perf ui/browser: Fix stale output of sorted result

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Date:	Fri, 14 Sep 2012 17:35:29 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Namhyung Kim <namhyung.kim@....com>
Subject: [PATCH 3/3] perf ui/browser: Fix stale output of sorted result

From: Namhyung Kim <namhyung.kim@....com>

The hist_entry__sort_snprintf() can return 0 if all of the sort keys
are elided.  In this case a buffer which used for the function would
contain old message or a garbage and printed like below:

  $ perf record -g -e cycles:u abc
  $ perf --report -s comm -c abc
  (...)
  + 100.00%100.00%

Fix it by checking return value.

Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/ui/browsers/hists.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index a21f40bebbac..75b3898ca651 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -664,8 +664,8 @@ static int hist_browser__show_entry(struct hist_browser *browser,
 		if (!browser->b.navkeypressed)
 			width += 1;
 
-		hist_entry__sort_snprintf(entry, s, sizeof(s), browser->hists);
-		slsmg_write_nstring(s, width);
+		if (hist_entry__sort_snprintf(entry, s, sizeof(s), browser->hists))
+			slsmg_write_nstring(s, width);
 		++row;
 		++printed;
 	} else
@@ -981,7 +981,6 @@ static int hist_browser__fprintf_entry(struct hist_browser *browser,
 	if (symbol_conf.use_callchain)
 		folded_sign = hist_entry__folded(he);
 
-	hist_entry__sort_snprintf(he, s, sizeof(s), browser->hists);
 	percent = (he->period * 100.0) / browser->hists->stats.total_period;
 
 	if (symbol_conf.use_callchain)
@@ -995,7 +994,8 @@ static int hist_browser__fprintf_entry(struct hist_browser *browser,
 	if (symbol_conf.show_total_period)
 		printed += fprintf(fp, " %12" PRIu64, he->period);
 
-	printed += fprintf(fp, "%s\n", rtrim(s));
+	if (hist_entry__sort_snprintf(he, s, sizeof(s), browser->hists))
+		printed += fprintf(fp, "%s\n", rtrim(s));
 
 	if (folded_sign == '-')
 		printed += hist_browser__fprintf_callchain(browser, &he->sorted_chain, 1, fp);
-- 
1.7.11.4

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