smp/hotplug: Hotplug state fail injection

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Add a sysfs file to one-time fail a specific state. This can be used
to test the state rollback code paths.

Something like this (hotplug-up.sh):

  #!/bin/bash

  echo 0 > /debug/sched_debug
  echo 1 > /debug/tracing/events/cpuhp/enable

  ALL_STATES=`cat /sys/devices/system/cpu/hotplug/states | cut -d':' -f1`
  STATES=${1:-$ALL_STATES}

  for state in $STATES
  do
	  echo 0 > /sys/devices/system/cpu/cpu1/online
	  echo 0 > /debug/tracing/trace
	  echo Fail state: $state
	  echo $state > /sys/devices/system/cpu/cpu1/hotplug/fail
	  cat /sys/devices/system/cpu/cpu1/hotplug/fail
	  echo 1 > /sys/devices/system/cpu/cpu1/online

	  cat /debug/tracing/trace > hotfail-${state}.trace

	  sleep 1
  done

Can be used to test for all possible rollback (barring multi-instance)
scenarios on CPU-up, CPU-down is a trivial modification of the above.

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/20170920170546.972581715@infradead.org

...

This commit is contained in:

Peter Zijlstra 2017-09-20 19:00:21 +02:00 • committed by Thomas Gleixner

parent 5ebe7742ff

commit 1db49484f2

2 changed files with 61 additions and 2 deletions

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3

include/linux/cpuhotplug.h

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60

kernel/cpu.c

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