Merge tag 'v3.2-rc2' into staging/for_v3.3

* tag 'v3.2-rc2': (3068 commits)
  Linux 3.2-rc2
  hfs: add sanity check for file name length
  fsl-rio: fix compile error
  blackfin: Fixup export.h includes
  Blackfin: add serial TX IRQ in individual platform resource
  virtio-pci: fix use after free
  ACPI / cpuidle: Remove acpi_idle_suspend (to fix suspend regression)
  drm/radeon/kms/combios: fix dynamic allocation of PM clock modes
  [CPUFREQ] db8500: fix build error due to undeclared i variable
  bma023: Add SFI translation for this device
  vrtc: change its year offset from 1960 to 1972
  ce4100: fix a build error
  arm/imx: fix imx6q mmc error when mounting rootfs
  arm/imx: fix AUTO_ZRELADDR selection
  arm/imx: fix the references to ARCH_MX3
  ARM: mx51/53: set pwm clock parent to ipg_perclk
  btrfs: rename the option to nospace_cache
  drm/radeon/kms/pm: switch to dynamically allocating clock mode array
  drm/radeon/kms: optimize r600_pm_profile_init
  drm/radeon/kms/pm: add a proper pm profile init function for fusion
  ...

Conflicts:
	drivers/media/radio/Kconfig

1 files changed, 75 insertions, 1 deletions

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 12b7458f23b1..563f13609470 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -10,11 +10,12 @@
 #include <linux/sched.h>
 #include <linux/unistd.h>
 #include <linux/cpu.h>
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/kthread.h>
 #include <linux/stop_machine.h>
 #include <linux/mutex.h>
 #include <linux/gfp.h>
+#include <linux/suspend.h>
 
 #ifdef CONFIG_SMP
 /* Serializes the updates to cpu_online_mask, cpu_present_mask */
@@ -476,6 +477,79 @@ static int alloc_frozen_cpus(void)
 	return 0;
 }
 core_initcall(alloc_frozen_cpus);
+
+/*
+ * Prevent regular CPU hotplug from racing with the freezer, by disabling CPU
+ * hotplug when tasks are about to be frozen. Also, don't allow the freezer
+ * to continue until any currently running CPU hotplug operation gets
+ * completed.
+ * To modify the 'cpu_hotplug_disabled' flag, we need to acquire the
+ * 'cpu_add_remove_lock'. And this same lock is also taken by the regular
+ * CPU hotplug path and released only after it is complete. Thus, we
+ * (and hence the freezer) will block here until any currently running CPU
+ * hotplug operation gets completed.
+ */
+void cpu_hotplug_disable_before_freeze(void)
+{
+	cpu_maps_update_begin();
+	cpu_hotplug_disabled = 1;
+	cpu_maps_update_done();
+}
+
+
+/*
+ * When tasks have been thawed, re-enable regular CPU hotplug (which had been
+ * disabled while beginning to freeze tasks).
+ */
+void cpu_hotplug_enable_after_thaw(void)
+{
+	cpu_maps_update_begin();
+	cpu_hotplug_disabled = 0;
+	cpu_maps_update_done();
+}
+
+/*
+ * When callbacks for CPU hotplug notifications are being executed, we must
+ * ensure that the state of the system with respect to the tasks being frozen
+ * or not, as reported by the notification, remains unchanged *throughout the
+ * duration* of the execution of the callbacks.
+ * Hence we need to prevent the freezer from racing with regular CPU hotplug.
+ *
+ * This synchronization is implemented by mutually excluding regular CPU
+ * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
+ * Hibernate notifications.
+ */
+static int
+cpu_hotplug_pm_callback(struct notifier_block *nb,
+			unsigned long action, void *ptr)
+{
+	switch (action) {
+
+	case PM_SUSPEND_PREPARE:
+	case PM_HIBERNATION_PREPARE:
+		cpu_hotplug_disable_before_freeze();
+		break;
+
+	case PM_POST_SUSPEND:
+	case PM_POST_HIBERNATION:
+		cpu_hotplug_enable_after_thaw();
+		break;
+
+	default:
+		return NOTIFY_DONE;
+	}
+
+	return NOTIFY_OK;
+}
+
+
+int cpu_hotplug_pm_sync_init(void)
+{
+	pm_notifier(cpu_hotplug_pm_callback, 0);
+	return 0;
+}
+core_initcall(cpu_hotplug_pm_sync_init);
+
 #endif /* CONFIG_PM_SLEEP_SMP */
 
 /**