sched, tracing: Fix trace_sched_pi_setprio() for deboosting

BugLink: http://bugs.launchpad.net/bugs/1808399
commit 4ff648decf4712d39f184fc2df3163f43975575a upstream.

Since the following commit:

  b91473ff6e97 ("sched,tracing: Update trace_sched_pi_setprio()")

the sched_pi_setprio trace point shows the "newprio" during a deboost:

  |futex sched_pi_setprio: comm=futex_requeue_p pid"34 oldprio\98 newprio=3D98
  |futex sched_switch: prev_comm=futex_requeue_p prev_pid"34 prev_prio=120

This patch open codes __rt_effective_prio() in the tracepoint as the
'newprio' to get the old behaviour back / the correct priority:

  |futex sched_pi_setprio: comm=futex_requeue_p pid"20 oldprio\98 newprio=3D120
  |futex sched_switch: prev_comm=futex_requeue_p prev_pid"20 prev_prio=120

Peter suggested to open code the new priority so people using tracehook
could get the deadline data out.

Reported-by: Mansky Christian <man@keba.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: b91473ff6e97 ("sched,tracing: Update trace_sched_pi_setprio()")
Link: http://lkml.kernel.org/r/20180524132647.gg6ziuogczdmjjzu@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index bc01e06bc7167fb2557ccb94e21c58e55f9c8fdb..0be866c91f62d055f5a6a3ab25a263a11f111916 100644 (file)
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -435,7 +435,9 @@ 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        = pi_task ?
+                               min(tsk->normal_prio, pi_task->prio) :
+                               tsk->normal_prio;
                /* XXX SCHED_DEADLINE bits missing */
        ),