From fac1c2040203363eab6c6e86ce883cb71390418f Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 20 Sep 2017 19:00:15 +0200 Subject: smp/hotplug: Add state diagram Add a state diagram to clarify when which states are ran where. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner 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(+) (limited to 'include/linux/cpuhotplug.h') diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h index f24bfb2b9a2d..477b2e6f60f7 100644 --- a/include/linux/cpuhotplug.h +++ b/include/linux/cpuhotplug.h @@ -3,6 +3,24 @@ #include +/* + * 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, -- cgit From 1db49484f21ed0fcdadd0635a3669f5f386546fa Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 20 Sep 2017 19:00:21 +0200 Subject: smp/hotplug: Hotplug state fail injection 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) Signed-off-by: Thomas Gleixner 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 --- include/linux/cpuhotplug.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/linux/cpuhotplug.h') diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h index 477b2e6f60f7..6d508767e144 100644 --- a/include/linux/cpuhotplug.h +++ b/include/linux/cpuhotplug.h @@ -22,7 +22,8 @@ */ enum cpuhp_state { - CPUHP_OFFLINE, + CPUHP_INVALID = -1, + CPUHP_OFFLINE = 0, CPUHP_CREATE_THREADS, CPUHP_PERF_PREPARE, CPUHP_PERF_X86_PREPARE, -- cgit