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cpu/hotplug: Provide bringup_hibernate_cpu()

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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: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lkml.kernel.org/r/20200323135110.30522-9-qais.yousef@arm.com
This commit is contained in:
Qais Yousef 2020-03-23 13:51:01 +00:00 committed by Thomas Gleixner
parent 5efbe6a6e1
commit d720f98604
2 changed files with 24 additions and 0 deletions
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1
include/linux/cpu.h
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@ -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

23
kernel/cpu.c
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@ -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;