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 --- include/linux/cpuhotplug.h | 2 +- kernel/cpu.c | 13 +++++++------ 2 files changed, 8 insertions(+), 7 deletions(-) --- 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, }; --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -1223,12 +1223,6 @@ 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", @@ -1249,6 +1243,13 @@ static struct cpuhp_step cpuhp_ap_states * The dynamically registered state space is here */ + /* Last state is scheduler control setting the cpu active */ + [CPUHP_AP_ACTIVE] = { + .name = "sched:active", + .startup = sched_cpu_activate, + .teardown = sched_cpu_deactivate, + }, + /* CPU is fully up and running. */ [CPUHP_ONLINE] = { .name = "online",