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Commit aaddd7d1 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

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: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160310120025.597477199@linutronix.de


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent f2785ddb

include/linux/cpuhotplug.h

+1 −1
Original line number Diff line number Diff line
@@ -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,

};

kernel/cpu.c

+9 −6
Original line number Diff line number Diff line
@@ -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",