Merge branch 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/l…

…inux/kernel/git/tip/tip

Pull smp/hotplug fixes from Thomas Gleixner:
 "This addresses the fallout of the new lockdep mechanism which covers
  completions in the CPU hotplug code.

  The lockdep splats are false positives, but there is no way to
  annotate that reliably. The solution is to split the completions for
  CPU up and down, which requires some reshuffling of the failure
  rollback handling as well"

* 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  smp/hotplug: Hotplug state fail injection
  smp/hotplug: Differentiate the AP completion between up and down
  smp/hotplug: Differentiate the AP-work lockdep class between up and down
  smp/hotplug: Callback vs state-machine consistency
  smp/hotplug: Rewrite AP state machine core
  smp/hotplug: Allow external multi-instance rollback
  smp/hotplug: Add state diagram

include/linux/cpuhotplug.h

@@ -3,8 +3,27 @@
 
 #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_INVALID = -1,
+	CPUHP_OFFLINE = 0,
 	CPUHP_CREATE_THREADS,
 	CPUHP_PERF_PREPARE,
 	CPUHP_PERF_X86_PREPARE,