Commit d720f986 authored by Qais Yousef's avatar Qais Yousef Committed by Thomas Gleixner
Browse files

cpu/hotplug: Provide bringup_hibernate_cpu() 



arm64 uses cpu_up() in the resume from hibernation code to ensure that the
CPU on which the system hibernated is online. Provide a core function for
this.

[ tglx: Split out from the combo arm64 patch ]

Signed-off-by: default avatarQais Yousef <qais.yousef@arm.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lkml.kernel.org/r/20200323135110.30522-9-qais.yousef@arm.com
parent 5efbe6a6

include/linux/cpu.h

+1 −0
Original line number Diff line number Diff line
@@ -93,6 +93,7 @@ int add_cpu(unsigned int cpu); 
void notify_cpu_starting(unsigned int cpu);

extern void cpu_maps_update_begin(void);

extern void cpu_maps_update_done(void);

int bringup_hibernate_cpu(unsigned int sleep_cpu);



#else	/* CONFIG_SMP */

#define cpuhp_tasks_frozen	0

kernel/cpu.c

+23 −0
Original line number Diff line number Diff line
@@ -1275,6 +1275,29 @@ int add_cpu(unsigned int cpu) 
}

EXPORT_SYMBOL_GPL(add_cpu);



/**

 * bringup_hibernate_cpu - Bring up the CPU that we hibernated on

 * @sleep_cpu: The cpu we hibernated on and should be brought up.

 *

 * On some architectures like arm64, we can hibernate on any CPU, but on

 * wake up the CPU we hibernated on might be offline as a side effect of

 * using maxcpus= for example.

 */

int bringup_hibernate_cpu(unsigned int sleep_cpu)

{

	int ret;



	if (!cpu_online(sleep_cpu)) {

		pr_info("Hibernated on a CPU that is offline! Bringing CPU up.\n");

		ret = cpu_up(sleep_cpu);

		if (ret) {

			pr_err("Failed to bring hibernate-CPU up!\n");

			return ret;

		}

	}

	return 0;

}



#ifdef CONFIG_PM_SLEEP_SMP

static cpumask_var_t frozen_cpus;

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