[tip:x86/bsp-hotplug] x86, hotplug, suspend: Online CPU0 for suspend or hibernate

[tip-bot for Fenghua Yu <fenghua.yu@intel.com>]

Commit-ID:  7d3b04f27e44b7bd264249161fdd727a1732aea0
Gitweb:     http://git.kernel.org/tip/7d3b04f27e44b7bd264249161fdd727a1732aea0
Author:     Fenghua Yu <fenghua.yu@intel.com>
AuthorDate: Sat, 25 Aug 2012 10:41:21 -0700
Committer:  H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Sat, 25 Aug 2012 19:26:05 -0700

x86, hotplug, suspend: Online CPU0 for suspend or hibernate

Because x86 BIOS requires CPU0 to resume from sleep, suspend or hibernate can't
be executed if CPU0 is detected offline. To make suspend or hibernate and
further resume succeed, CPU0 must be online.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Link: http://lkml.kernel.org/r/1345916488-8355-6-git-send-email-fenghua.yu@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
---
 arch/x86/power/cpu.c |   44 ++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 44 insertions(+), 0 deletions(-)

diff --git a/arch/x86/power/cpu.c b/arch/x86/power/cpu.c
index 218cdb1..3338609 100644
--- a/arch/x86/power/cpu.c
+++ b/arch/x86/power/cpu.c
@@ -237,3 +237,47 @@ 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) {
+		printk(KERN_WARNING "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;
+	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);