linux-kernel - [PATCH] perf sched: fix wrong conversion of task state

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Message-Id: <1469624093-16601-1-git-send-email-tomoki.sekiyama.qu@hitachi.com>
Date:	Wed, 27 Jul 2016 21:54:53 +0900
From:	Tomoki Sekiyama <tomoki.sekiyama.qu@...achi.com>
To:	linux-kernel@...r.kernel.org
Cc:	ltc-kernel@...ml.intra.hitachi.co.jp,
	masumi.moritani.ju@...achi.com,
	Tomoki Sekiyama <tomoki.sekiyama.qu@...achi.com>,
	Jiri Olsa <jolsa@...nel.org>, David Ahern <dsahern@...il.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Masami Hiramatsu <mhiramat@...nel.org>
Subject: [PATCH] perf sched: fix wrong conversion of task state

sched_out_state() converts the prev_state u64 bitmask to a char in
a wrong way, which may cause wrong results of 'perf sched latency'.
This patch fixes the conversion.

Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama.qu@...achi.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: David Ahern <dsahern@...il.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
---
 tools/perf/builtin-sched.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 0dfe8df..eb2f7f4 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -71,6 +71,7 @@ struct sched_atom {
 };
 
 #define TASK_STATE_TO_CHAR_STR "RSDTtZXxKWP"
+#define TASK_STATE_MASK 0x7ff
 
 enum thread_state {
 	THREAD_SLEEPING = 0,
@@ -899,7 +900,7 @@ static char sched_out_state(u64 prev_state)
 {
 	const char *str = TASK_STATE_TO_CHAR_STR;
 
-	return str[prev_state];
+	return str[ffs(prev_state & TASK_STATE_MASK)];
 }
 
 static int
-- 
2.7.4