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From:   Yafang Shao <laoar.shao@gmail.com>
To:     peterz@infradead.org
Cc:     linux-kernel@vger.kernel.org, shaoyafang@didiglobal.com,
        Yafang Shao <laoar.shao@gmail.com>
Subject: [PATCH v2] sched: fair: fix missed CONFIG_SCHEDSTATS
Date:   Thu,  7 Mar 2019 19:20:11 +0800
Message-Id: <1551957611-31457-1-git-send-email-laoar.shao@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

When I'm using trace_sched_stat_{iowait, blocked, wait, sleep} to
measure how long the processes are stalled, there's always no output
from
trace_pipe while there're really some tasks in uninterruptible sleep
state. That makes me confused, so I try to investigate why.
Finally I find the reason is that CONFIG_SCHEDSTATS is not set.

To avoid such kind of confusion, we should not expose these tracepoints
if CONFIG_SCHEDSTATS is not set.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 include/trace/events/sched.h | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 9a4bdfa..f060940 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -241,7 +241,6 @@ static inline long __trace_sched_switch_state(bool preempt, struct task_struct *
 DEFINE_EVENT(sched_process_template, sched_process_free,
 	     TP_PROTO(struct task_struct *p),
 	     TP_ARGS(p));
-	     
 
 /*
  * Tracepoint for a task exiting:
@@ -336,6 +335,7 @@ static inline long __trace_sched_switch_state(bool preempt, struct task_struct *
 		  __entry->pid, __entry->old_pid)
 );
 
+#ifdef CONFIG_SCHEDSTATS
 /*
  * XXX the below sched_stat tracepoints only apply to SCHED_OTHER/BATCH/IDLE
  *     adding sched_stat support to SCHED_FIFO/RR would be welcome.
@@ -395,6 +395,28 @@ static inline long __trace_sched_switch_state(bool preempt, struct task_struct *
 	     TP_PROTO(struct task_struct *tsk, u64 delay),
 	     TP_ARGS(tsk, delay));
 
+#else
+
+#ifndef DEFINE_EVENT_NONE
+#define DEFINE_EVENT_NONE(name, var)		\
+	static inline void trace_##name(var)	\
+	{					\
+	}
+
+DEFINE_EVENT_NONE(sched_stat_wait,
+		  TP_PROTO(struct task_struct *tsk, u64 delay))
+
+DEFINE_EVENT_NONE(sched_stat_sleep,
+		  TP_PROTO(struct task_struct *tsk, u64 delay))
+
+DEFINE_EVENT_NONE(sched_stat_iowait,
+		  TP_PROTO(struct task_struct *tsk, u64 delay))
+
+DEFINE_EVENT_NONE(sched_stat_blocked,
+		  TP_PROTO(struct task_struct *tsk, u64 delay))
+#endif
+#endif
+
 /*
  * Tracepoint for accounting runtime (time the task is executing
  * on a CPU).
-- 
1.8.3.1