linux-kernel - [PATCH v3 7/7] x86/power/cpu.c: Don't hibernate/suspend if CPU0 is offline

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Date:	Wed,  9 Nov 2011 16:34:17 -0800
From:	"Fenghua Yu" <fenghua.yu@...el.com>
To:	"Thomas Gleixner" <tglx@...utronix.de>,
	"H Peter Anvin" <hpa@...or.com>, "Ingo Molnar" <mingo@...e.hu>,
	"Linus Torvalds" <torvalds@...ux-foundation.org>,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Tony Luck" <tony.luck@...el.com>,
	"Arjan van de Ven" <arjan.van.de.ven@...el.com>,
	"Suresh B Siddha" <suresh.b.siddha@...el.com>,
	"Len Brown" <len.brown@...el.com>,
	"Randy Dunlap" <rdunlap@...otime.net>,
	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>,
	Peter Zijlstra <peterz@...radead.org>
Cc:	"linux-kernel" <linux-kernel@...r.kernel.org>,
	"linux-pm" <linux-pm@...r.kernel.org>, "x86" <x86@...nel.org>,
	"Fenghua Yu" <fenghua.yu@...el.com>
Subject: [PATCH v3 7/7] x86/power/cpu.c: Don't hibernate/suspend if CPU0 is offline

From: Fenghua Yu <fenghua.yu@...el.com>

Because x86 BIOS requires CPU0 to resume from sleep, suspend or hibernate
can't be executed if CPU0 is detected offline.

Signed-off-by: Fenghua Yu <fenghua.yu@...el.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 f10c0af..a4ec084 100644
--- a/arch/x86/power/cpu.c
+++ b/arch/x86/power/cpu.c
@@ -236,3 +236,47 @@ 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);
-- 
1.6.0.3

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