From 10bde81c74863472047f31304064018c40f488ee Mon Sep 17 00:00:00 2001
From: Daniel Bristot de Oliveira <bristot@kernel.org>
Date: Fri, 29 Jul 2022 11:38:52 +0200
Subject: rv/monitor: Add the wip monitor

The wakeup in preemptive (wip) monitor verifies if the
wakeup events always take place with preemption disabled:

                     |
                     |
                     v
                   #==================#
                   H    preemptive    H <+
                   #==================#  |
                     |                   |
                     | preempt_disable   | preempt_enable
                     v                   |
    sched_waking   +------------------+  |
  +--------------- |                  |  |
  |                |  non_preemptive  |  |
  +--------------> |                  | -+
                   +------------------+

The wakeup event always takes place with preemption disabled because
of the scheduler synchronization. However, because the preempt_count
and its trace event are not atomic with regard to interrupts, some
inconsistencies might happen.

The documentation illustrates one of these cases.

Link: https://lkml.kernel.org/r/c98ca678df81115fddc04921b3c79720c836b18f.1659052063.git.bristot@kernel.org

Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Gabriele Paoloni <gpaoloni@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Tao Zhou <tao.zhou@linux.dev>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 include/trace/events/rv.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

(limited to 'include/trace')

diff --git a/include/trace/events/rv.h b/include/trace/events/rv.h
index 20a2e09c6416..e972f27d8df3 100644
--- a/include/trace/events/rv.h
+++ b/include/trace/events/rv.h
@@ -56,6 +56,16 @@ DECLARE_EVENT_CLASS(error_da_monitor,
 		__entry->event,
 		__entry->state)
 );
+
+#ifdef CONFIG_RV_MON_WIP
+DEFINE_EVENT(event_da_monitor, event_wip,
+	    TP_PROTO(char *state, char *event, char *next_state, bool final_state),
+	    TP_ARGS(state, event, next_state, final_state));
+
+DEFINE_EVENT(error_da_monitor, error_wip,
+	     TP_PROTO(char *state, char *event),
+	     TP_ARGS(state, event));
+#endif /* CONFIG_RV_MON_WIP */
 #endif /* CONFIG_DA_MON_EVENTS_IMPLICIT */
 
 #ifdef CONFIG_DA_MON_EVENTS_ID
-- 
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