From aaddd7d1c740ab3c5efaad7a34650b6dc680c21c Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 10 Mar 2016 12:54:19 +0100 Subject: [PATCH] sched/hotplug: Make activate() the last hotplug step The scheduler can handle per cpu threads before the cpu is set to active and it does not allow user space threads on the cpu before active is set. Attaching to the scheduling domains is also not required before user space threads can be handled. Move the activation to the end of the hotplug state space. That also means that deactivation is the first action when a cpu is shut down. Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160310120025.597477199@linutronix.de Signed-off-by: Thomas Gleixner --- include/linux/cpuhotplug.h | 2 +- kernel/cpu.c | 15 +++++++++------ 2 files changed, 10 insertions(+), 7 deletions(-) diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h index 9e07468bf1c5..386374d19987 100644 --- a/include/linux/cpuhotplug.h +++ b/include/linux/cpuhotplug.h @@ -13,11 +13,11 @@ enum cpuhp_state { CPUHP_AP_ONLINE, CPUHP_TEARDOWN_CPU, CPUHP_AP_ONLINE_IDLE, - CPUHP_AP_ACTIVE, CPUHP_AP_SMPBOOT_THREADS, CPUHP_AP_NOTIFY_ONLINE, CPUHP_AP_ONLINE_DYN, CPUHP_AP_ONLINE_DYN_END = CPUHP_AP_ONLINE_DYN + 30, + CPUHP_AP_ACTIVE, CPUHP_ONLINE, }; diff --git a/kernel/cpu.c b/kernel/cpu.c index d6eeb8c5ef88..d948e44c471e 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -1242,12 +1242,6 @@ static struct cpuhp_step cpuhp_ap_states[] = { [CPUHP_AP_ONLINE] = { .name = "ap:online", }, - /* First state is scheduler control. Interrupts are enabled */ - [CPUHP_AP_ACTIVE] = { - .name = "sched:active", - .startup = sched_cpu_activate, - .teardown = sched_cpu_deactivate, - }, /* Handle smpboot threads park/unpark */ [CPUHP_AP_SMPBOOT_THREADS] = { .name = "smpboot:threads", @@ -1269,6 +1263,15 @@ static struct cpuhp_step cpuhp_ap_states[] = { * The dynamically registered state space is here */ +#ifdef CONFIG_SMP + /* Last state is scheduler control setting the cpu active */ + [CPUHP_AP_ACTIVE] = { + .name = "sched:active", + .startup = sched_cpu_activate, + .teardown = sched_cpu_deactivate, + }, +#endif + /* CPU is fully up and running. */ [CPUHP_ONLINE] = { .name = "online", -- 2.20.1