linux-kernel - [PATCH] sched,tracing: Correct trace_sched_pi

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Date:   Wed, 23 May 2018 16:11:07 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     linux-kernel@...r.kernel.org
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH] sched,tracing: Correct trace_sched_pi_setprio() for deboosting

This mostly a revert of commit b91473ff6e97 ("sched,tracing: Update
trace_sched_pi_setprio()") except for the XXX comments.
Since that commit I see during a deboost a task this:
|futex sched_pi_setprio: comm=futex_requeue_p pid=2234 oldprio=98 newprio=98
|futex sched_switch: prev_comm=futex_requeue_p prev_pid=2234 prev_prio=120

and after the revert, the `newprio' shows the correct value again:

|futex sched_pi_setprio: comm=futex_requeue_p pid=2220 oldprio=98 newprio=120
|futex sched_switch: prev_comm=futex_requeue_p prev_pid=2220 prev_prio=120

Reported-by: Mansky Christian <man@...a.com>
Fixes: b91473ff6e97 ("sched,tracing: Update trace_sched_pi_setprio()")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 include/trace/events/sched.h | 6 +++---
 kernel/sched/core.c          | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index bc01e06bc716..c6fdb5aac723 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -420,9 +420,9 @@ DEFINE_EVENT(sched_stat_runtime, sched_stat_runtime,
  */
 TRACE_EVENT(sched_pi_setprio,
 
-	TP_PROTO(struct task_struct *tsk, struct task_struct *pi_task),
+	TP_PROTO(struct task_struct *tsk, int new_prio),
 
-	TP_ARGS(tsk, pi_task),
+	TP_ARGS(tsk, new_prio),
 
 	TP_STRUCT__entry(
 		__array( char,	comm,	TASK_COMM_LEN	)
@@ -435,7 +435,7 @@ TRACE_EVENT(sched_pi_setprio,
 		memcpy(__entry->comm, tsk->comm, TASK_COMM_LEN);
 		__entry->pid		= tsk->pid;
 		__entry->oldprio	= tsk->prio;
-		__entry->newprio	= pi_task ? pi_task->prio : tsk->prio;
+		__entry->newprio	= new_prio;
 		/* XXX SCHED_DEADLINE bits missing */
 	),
 
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 092f7c4de903..888df643b99b 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3823,7 +3823,7 @@ void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task)
 		goto out_unlock;
 	}
 
-	trace_sched_pi_setprio(p, pi_task);
+	trace_sched_pi_setprio(p, prio);
 	oldprio = p->prio;
 
 	if (oldprio == prio)
-- 
2.17.0