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-rw-r--r--kernel/cpu.c74
-rw-r--r--kernel/freezer.c2
-rw-r--r--kernel/power/qos.c3
-rw-r--r--kernel/sched.c2
4 files changed, 76 insertions, 5 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 12b7458f23b..aa39dd7a384 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -15,6 +15,7 @@
#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 */
/**
diff --git a/kernel/freezer.c b/kernel/freezer.c
index 66a594e8ad2..7b01de98bb6 100644
--- a/kernel/freezer.c
+++ b/kernel/freezer.c
@@ -67,7 +67,7 @@ static void fake_signal_wake_up(struct task_struct *p)
unsigned long flags;
spin_lock_irqsave(&p->sighand->siglock, flags);
- signal_wake_up(p, 1);
+ signal_wake_up(p, 0);
spin_unlock_irqrestore(&p->sighand->siglock, flags);
}
diff --git a/kernel/power/qos.c b/kernel/power/qos.c
index 1c1797dd1d1..5167d996cd0 100644
--- a/kernel/power/qos.c
+++ b/kernel/power/qos.c
@@ -386,8 +386,7 @@ static int pm_qos_power_open(struct inode *inode, struct file *filp)
pm_qos_add_request(req, pm_qos_class, PM_QOS_DEFAULT_VALUE);
filp->private_data = req;
- if (filp->private_data)
- return 0;
+ return 0;
}
return -EPERM;
}
diff --git a/kernel/sched.c b/kernel/sched.c
index d87c6e5d4e8..0e9344a71be 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -7087,8 +7087,6 @@ static int __init isolated_cpu_setup(char *str)
__setup("isolcpus=", isolated_cpu_setup);
-#define SD_NODES_PER_DOMAIN 16
-
#ifdef CONFIG_NUMA
/**