diff options
Diffstat (limited to 'arch/x86/power/cpu.c')
| -rw-r--r-- | arch/x86/power/cpu.c | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/arch/x86/power/cpu.c b/arch/x86/power/cpu.c index 218cdb16163c..120cee1c3f8d 100644 --- a/arch/x86/power/cpu.c +++ b/arch/x86/power/cpu.c @@ -21,6 +21,7 @@ #include <asm/suspend.h> #include <asm/debugreg.h> #include <asm/fpu-internal.h> /* pcntxt_mask */ +#include <asm/cpu.h> #ifdef CONFIG_X86_32 static struct saved_context saved_context; @@ -237,3 +238,84 @@ void restore_processor_state(void) #ifdef CONFIG_X86_32 EXPORT_SYMBOL(restore_processor_state); #endif + +/* + * When bsp_check() is called in hibernate and suspend, cpu hotplug + * is disabled already. So it's unnessary to handle race condition between + * cpumask query and cpu hotplug. + */ +static int bsp_check(void) +{ + if (cpumask_first(cpu_online_mask) != 0) { + pr_warn("CPU0 is offline.\n"); + return -ENODEV; + } + + return 0; +} + +static int bsp_pm_callback(struct notifier_block *nb, unsigned long action, + void *ptr) +{ + int ret = 0; + + switch (action) { + case PM_SUSPEND_PREPARE: + case PM_HIBERNATION_PREPARE: + ret = bsp_check(); + break; +#ifdef CONFIG_DEBUG_HOTPLUG_CPU0 + case PM_RESTORE_PREPARE: + /* + * When system resumes from hibernation, online CPU0 because + * 1. it's required for resume and + * 2. the CPU was online before hibernation + */ + if (!cpu_online(0)) + _debug_hotplug_cpu(0, 1); + break; + case PM_POST_RESTORE: + /* + * When a resume really happens, this code won't be called. + * + * This code is called only when user space hibernation software + * prepares for snapshot device during boot time. So we just + * call _debug_hotplug_cpu() to restore to CPU0's state prior to + * preparing the snapshot device. + * + * This works for normal boot case in our CPU0 hotplug debug + * mode, i.e. CPU0 is offline and user mode hibernation + * software initializes during boot time. + * + * If CPU0 is online and user application accesses snapshot + * device after boot time, this will offline CPU0 and user may + * see different CPU0 state before and after accessing + * the snapshot device. But hopefully this is not a case when + * user debugging CPU0 hotplug. Even if users hit this case, + * they can easily online CPU0 back. + * + * To simplify this debug code, we only consider normal boot + * case. Otherwise we need to remember CPU0's state and restore + * to that state and resolve racy conditions etc. + */ + _debug_hotplug_cpu(0, 0); + break; +#endif + default: + break; + } + return notifier_from_errno(ret); +} + +static int __init bsp_pm_check_init(void) +{ + /* + * Set this bsp_pm_callback as lower priority than + * cpu_hotplug_pm_callback. So cpu_hotplug_pm_callback will be called + * earlier to disable cpu hotplug before bsp online check. + */ + pm_notifier(bsp_pm_callback, -INT_MAX); + return 0; +} + +core_initcall(bsp_pm_check_init); |