From fac1c2040203363eab6c6e86ce883cb71390418f Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Wed, 20 Sep 2017 19:00:15 +0200
Subject: [PATCH] smp/hotplug: Add state diagram
Add a state diagram to clarify when which states are ran where.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: bigeasy@linutronix.de
Cc: efault@gmx.de
Cc: rostedt@goodmis.org
Cc: max.byungchul.park@gmail.com
Link: https://lkml.kernel.org/r/20170920170546.661598270@infradead.org
---
include/linux/cpuhotplug.h | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index f24bfb2b9a2dcc..477b2e6f60f72b 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -3,6 +3,24 @@
#include <linux/types.h>
+/*
+ * CPU-up CPU-down
+ *
+ * BP AP BP AP
+ *
+ * OFFLINE OFFLINE
+ * | ^
+ * v |
+ * BRINGUP_CPU->AP_OFFLINE BRINGUP_CPU <- AP_IDLE_DEAD (idle thread/play_dead)
+ * | AP_OFFLINE
+ * v (IRQ-off) ,---------------^
+ * AP_ONLNE | (stop_machine)
+ * | TEARDOWN_CPU <- AP_ONLINE_IDLE
+ * | ^
+ * v |
+ * AP_ACTIVE AP_ACTIVE
+ */
+
enum cpuhp_state {
CPUHP_OFFLINE,
CPUHP_CREATE_THREADS,
--
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