1 files changed, 504 insertions, 0 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c
new file mode 100644
index 0000000..8ea32e8
--- /dev/null
+++ b/kernel/cpu.c
@@ -0,0 +1,504 @@
+/* CPU control.
+ * (C) 2001, 2002, 2003, 2004 Rusty Russell
+ *
+ * This code is licenced under the GPL.
+ */
+#include <linux/proc_fs.h>
+#include <linux/smp.h>
+#include <linux/init.h>
+#include <linux/notifier.h>
+#include <linux/sched.h>
+#include <linux/unistd.h>
+#include <linux/cpu.h>
+#include <linux/module.h>
+#include <linux/kthread.h>
+#include <linux/stop_machine.h>
+#include <linux/mutex.h>
+
+/*
+ * Represents all cpu's present in the system
+ * In systems capable of hotplug, this map could dynamically grow
+ * as new cpu's are detected in the system via any platform specific
+ * method, such as ACPI for e.g.
+ */
+cpumask_t cpu_present_map __read_mostly;
+EXPORT_SYMBOL(cpu_present_map);
+
+#ifndef CONFIG_SMP
+
+/*
+ * Represents all cpu's that are currently online.
+ */
+cpumask_t cpu_online_map __read_mostly = CPU_MASK_ALL;
+EXPORT_SYMBOL(cpu_online_map);
+
+cpumask_t cpu_possible_map __read_mostly = CPU_MASK_ALL;
+EXPORT_SYMBOL(cpu_possible_map);
+
+#else /* CONFIG_SMP */
+
+/* Serializes the updates to cpu_online_map, cpu_present_map */
+static DEFINE_MUTEX(cpu_add_remove_lock);
+
+static __cpuinitdata RAW_NOTIFIER_HEAD(cpu_chain);
+
+/* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
+ * Should always be manipulated under cpu_add_remove_lock
+ */
+static int cpu_hotplug_disabled;
+
+static struct {
+	struct task_struct *active_writer;
+	struct mutex lock; /* Synchronizes accesses to refcount, */
+	/*
+	 * Also blocks the new readers during
+	 * an ongoing cpu hotplug operation.
+	 */
+	int refcount;
+} cpu_hotplug;
+
+void __init cpu_hotplug_init(void)
+{
+	cpu_hotplug.active_writer = NULL;
+	mutex_init(&cpu_hotplug.lock);
+	cpu_hotplug.refcount = 0;
+}
+
+cpumask_t cpu_active_map;
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+void get_online_cpus(void)
+{
+	might_sleep();
+	if (cpu_hotplug.active_writer == current)
+		return;
+	mutex_lock(&cpu_hotplug.lock);
+	cpu_hotplug.refcount++;
+	mutex_unlock(&cpu_hotplug.lock);
+
+}
+EXPORT_SYMBOL_GPL(get_online_cpus);
+
+void put_online_cpus(void)
+{
+	if (cpu_hotplug.active_writer == current)
+		return;
+	mutex_lock(&cpu_hotplug.lock);
+	if (!--cpu_hotplug.refcount && unlikely(cpu_hotplug.active_writer))
+		wake_up_process(cpu_hotplug.active_writer);
+	mutex_unlock(&cpu_hotplug.lock);
+
+}
+EXPORT_SYMBOL_GPL(put_online_cpus);
+
+#endif	/* CONFIG_HOTPLUG_CPU */
+
+/*
+ * The following two API's must be used when attempting
+ * to serialize the updates to cpu_online_map, cpu_present_map.
+ */
+void cpu_maps_update_begin(void)
+{
+	mutex_lock(&cpu_add_remove_lock);
+}
+
+void cpu_maps_update_done(void)
+{
+	mutex_unlock(&cpu_add_remove_lock);
+}
+
+/*
+ * This ensures that the hotplug operation can begin only when the
+ * refcount goes to zero.
+ *
+ * Note that during a cpu-hotplug operation, the new readers, if any,
+ * will be blocked by the cpu_hotplug.lock
+ *
+ * Since cpu_hotplug_begin() is always called after invoking
+ * cpu_maps_update_begin(), we can be sure that only one writer is active.
+ *
+ * Note that theoretically, there is a possibility of a livelock:
+ * - Refcount goes to zero, last reader wakes up the sleeping
+ *   writer.
+ * - Last reader unlocks the cpu_hotplug.lock.
+ * - A new reader arrives at this moment, bumps up the refcount.
+ * - The writer acquires the cpu_hotplug.lock finds the refcount
+ *   non zero and goes to sleep again.
+ *
+ * However, this is very difficult to achieve in practice since
+ * get_online_cpus() not an api which is called all that often.
+ *
+ */
+static void cpu_hotplug_begin(void)
+{
+	cpu_hotplug.active_writer = current;
+
+	for (;;) {
+		mutex_lock(&cpu_hotplug.lock);
+		if (likely(!cpu_hotplug.refcount))
+			break;
+		__set_current_state(TASK_UNINTERRUPTIBLE);
+		mutex_unlock(&cpu_hotplug.lock);
+		schedule();
+	}
+}
+
+static void cpu_hotplug_done(void)
+{
+	cpu_hotplug.active_writer = NULL;
+	mutex_unlock(&cpu_hotplug.lock);
+}
+/* Need to know about CPUs going up/down? */
+int __ref register_cpu_notifier(struct notifier_block *nb)
+{
+	int ret;
+	cpu_maps_update_begin();
+	ret = raw_notifier_chain_register(&cpu_chain, nb);
+	cpu_maps_update_done();
+	return ret;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+EXPORT_SYMBOL(register_cpu_notifier);
+
+void __ref unregister_cpu_notifier(struct notifier_block *nb)
+{
+	cpu_maps_update_begin();
+	raw_notifier_chain_unregister(&cpu_chain, nb);
+	cpu_maps_update_done();
+}
+EXPORT_SYMBOL(unregister_cpu_notifier);
+
+static inline void check_for_tasks(int cpu)
+{
+	struct task_struct *p;
+
+	write_lock_irq(&tasklist_lock);
+	for_each_process(p) {
+		if (task_cpu(p) == cpu &&
+		    (!cputime_eq(p->utime, cputime_zero) ||
+		     !cputime_eq(p->stime, cputime_zero)))
+			printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d\
+				(state = %ld, flags = %x) \n",
+				 p->comm, task_pid_nr(p), cpu,
+				 p->state, p->flags);
+	}
+	write_unlock_irq(&tasklist_lock);
+}
+
+struct take_cpu_down_param {
+	unsigned long mod;
+	void *hcpu;
+};
+
+/* Take this CPU down. */
+static int __ref take_cpu_down(void *_param)
+{
+	struct take_cpu_down_param *param = _param;
+	int err;
+
+	/* Ensure this CPU doesn't handle any more interrupts. */
+	err = __cpu_disable();
+	if (err < 0)
+		return err;
+
+	raw_notifier_call_chain(&cpu_chain, CPU_DYING | param->mod,
+				param->hcpu);
+
+	/* Force idle task to run as soon as we yield: it should
+	   immediately notice cpu is offline and die quickly. */
+	sched_idle_next();
+	return 0;
+}
+
+/* Requires cpu_add_remove_lock to be held */
+static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
+{
+	int err, nr_calls = 0;
+	cpumask_t old_allowed, tmp;
+	void *hcpu = (void *)(long)cpu;
+	unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
+	struct take_cpu_down_param tcd_param = {
+		.mod = mod,
+		.hcpu = hcpu,
+	};
+
+	if (num_online_cpus() == 1)
+		return -EBUSY;
+
+	if (!cpu_online(cpu))
+		return -EINVAL;
+
+	cpu_hotplug_begin();
+	err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE | mod,
+					hcpu, -1, &nr_calls);
+	if (err == NOTIFY_BAD) {
+		nr_calls--;
+		__raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
+					  hcpu, nr_calls, NULL);
+		printk("%s: attempt to take down CPU %u failed\n",
+				__func__, cpu);
+		err = -EINVAL;
+		goto out_release;
+	}
+
+	/* Ensure that we are not runnable on dying cpu */
+	old_allowed = current->cpus_allowed;
+	cpus_setall(tmp);
+	cpu_clear(cpu, tmp);
+	set_cpus_allowed_ptr(current, &tmp);
+	tmp = cpumask_of_cpu(cpu);
+
+	err = __stop_machine(take_cpu_down, &tcd_param, &tmp);
+	if (err) {
+		/* CPU didn't die: tell everyone.  Can't complain. */
+		if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
+					    hcpu) == NOTIFY_BAD)
+			BUG();
+
+		goto out_allowed;
+	}
+	BUG_ON(cpu_online(cpu));
+
+	/* Wait for it to sleep (leaving idle task). */
+	while (!idle_cpu(cpu))
+		yield();
+
+	/* This actually kills the CPU. */
+	__cpu_die(cpu);
+
+	/* CPU is completely dead: tell everyone.  Too late to complain. */
+	if (raw_notifier_call_chain(&cpu_chain, CPU_DEAD | mod,
+				    hcpu) == NOTIFY_BAD)
+		BUG();
+
+	check_for_tasks(cpu);
+
+out_allowed:
+	set_cpus_allowed_ptr(current, &old_allowed);
+out_release:
+	cpu_hotplug_done();
+	if (!err) {
+		if (raw_notifier_call_chain(&cpu_chain, CPU_POST_DEAD | mod,
+					    hcpu) == NOTIFY_BAD)
+			BUG();
+	}
+	return err;
+}
+
+int __ref cpu_down(unsigned int cpu)
+{
+	int err = 0;
+
+	cpu_maps_update_begin();
+
+	if (cpu_hotplug_disabled) {
+		err = -EBUSY;
+		goto out;
+	}
+
+	cpu_clear(cpu, cpu_active_map);
+
+	/*
+	 * Make sure the all cpus did the reschedule and are not
+	 * using stale version of the cpu_active_map.
+	 * This is not strictly necessary becuase stop_machine()
+	 * that we run down the line already provides the required
+	 * synchronization. But it's really a side effect and we do not
+	 * want to depend on the innards of the stop_machine here.
+	 */
+	synchronize_sched();
+
+	err = _cpu_down(cpu, 0);
+
+	if (cpu_online(cpu))
+		cpu_set(cpu, cpu_active_map);
+
+out:
+	cpu_maps_update_done();
+	return err;
+}
+EXPORT_SYMBOL(cpu_down);
+#endif /*CONFIG_HOTPLUG_CPU*/
+
+/* Requires cpu_add_remove_lock to be held */
+static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
+{
+	int ret, nr_calls = 0;
+	void *hcpu = (void *)(long)cpu;
+	unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
+
+	if (cpu_online(cpu) || !cpu_present(cpu))
+		return -EINVAL;
+
+	cpu_hotplug_begin();
+	ret = __raw_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE | mod, hcpu,
+							-1, &nr_calls);
+	if (ret == NOTIFY_BAD) {
+		nr_calls--;
+		printk("%s: attempt to bring up CPU %u failed\n",
+				__func__, cpu);
+		ret = -EINVAL;
+		goto out_notify;
+	}
+
+	/* Arch-specific enabling code. */
+	ret = __cpu_up(cpu);
+	if (ret != 0)
+		goto out_notify;
+	BUG_ON(!cpu_online(cpu));
+
+	cpu_set(cpu, cpu_active_map);
+
+	/* Now call notifier in preparation. */
+	raw_notifier_call_chain(&cpu_chain, CPU_ONLINE | mod, hcpu);
+
+out_notify:
+	if (ret != 0)
+		__raw_notifier_call_chain(&cpu_chain,
+				CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
+	cpu_hotplug_done();
+
+	return ret;
+}
+
+int __cpuinit cpu_up(unsigned int cpu)
+{
+	int err = 0;
+	if (!cpu_isset(cpu, cpu_possible_map)) {
+		printk(KERN_ERR "can't online cpu %d because it is not "
+			"configured as may-hotadd at boot time\n", cpu);
+#if defined(CONFIG_IA64) || defined(CONFIG_X86_64)
+		printk(KERN_ERR "please check additional_cpus= boot "
+				"parameter\n");
+#endif
+		return -EINVAL;
+	}
+
+	cpu_maps_update_begin();
+
+	if (cpu_hotplug_disabled) {
+		err = -EBUSY;
+		goto out;
+	}
+
+	err = _cpu_up(cpu, 0);
+
+out:
+	cpu_maps_update_done();
+	return err;
+}
+
+#ifdef CONFIG_PM_SLEEP_SMP
+static cpumask_t frozen_cpus;
+
+int disable_nonboot_cpus(void)
+{
+	int cpu, first_cpu, error = 0;
+
+	cpu_maps_update_begin();
+	first_cpu = first_cpu(cpu_online_map);
+	/* We take down all of the non-boot CPUs in one shot to avoid races
+	 * with the userspace trying to use the CPU hotplug at the same time
+	 */
+	cpus_clear(frozen_cpus);
+	printk("Disabling non-boot CPUs ...\n");
+	for_each_online_cpu(cpu) {
+		if (cpu == first_cpu)
+			continue;
+		error = _cpu_down(cpu, 1);
+		if (!error) {
+			cpu_set(cpu, frozen_cpus);
+			printk("CPU%d is down\n", cpu);
+		} else {
+			printk(KERN_ERR "Error taking CPU%d down: %d\n",
+				cpu, error);
+			break;
+		}
+	}
+	if (!error) {
+		BUG_ON(num_online_cpus() > 1);
+		/* Make sure the CPUs won't be enabled by someone else */
+		cpu_hotplug_disabled = 1;
+	} else {
+		printk(KERN_ERR "Non-boot CPUs are not disabled\n");
+	}
+	cpu_maps_update_done();
+	return error;
+}
+
+void __ref enable_nonboot_cpus(void)
+{
+	int cpu, error;
+
+	/* Allow everyone to use the CPU hotplug again */
+	cpu_maps_update_begin();
+	cpu_hotplug_disabled = 0;
+	if (cpus_empty(frozen_cpus))
+		goto out;
+
+	printk("Enabling non-boot CPUs ...\n");
+	for_each_cpu_mask_nr(cpu, frozen_cpus) {
+		error = _cpu_up(cpu, 1);
+		if (!error) {
+			printk("CPU%d is up\n", cpu);
+			continue;
+		}
+		printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error);
+	}
+	cpus_clear(frozen_cpus);
+out:
+	cpu_maps_update_done();
+}
+#endif /* CONFIG_PM_SLEEP_SMP */
+
+/**
+ * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers
+ * @cpu: cpu that just started
+ *
+ * This function calls the cpu_chain notifiers with CPU_STARTING.
+ * It must be called by the arch code on the new cpu, before the new cpu
+ * enables interrupts and before the "boot" cpu returns from __cpu_up().
+ */
+void __cpuinit notify_cpu_starting(unsigned int cpu)
+{
+	unsigned long val = CPU_STARTING;
+
+#ifdef CONFIG_PM_SLEEP_SMP
+	if (cpu_isset(cpu, frozen_cpus))
+		val = CPU_STARTING_FROZEN;
+#endif /* CONFIG_PM_SLEEP_SMP */
+	raw_notifier_call_chain(&cpu_chain, val, (void *)(long)cpu);
+}
+
+#endif /* CONFIG_SMP */
+
+/*
+ * cpu_bit_bitmap[] is a special, "compressed" data structure that
+ * represents all NR_CPUS bits binary values of 1<<nr.
+ *
+ * It is used by cpumask_of_cpu() to get a constant address to a CPU
+ * mask value that has a single bit set only.
+ */
+
+/* cpu_bit_bitmap[0] is empty - so we can back into it */
+#define MASK_DECLARE_1(x)	[x+1][0] = 1UL << (x)
+#define MASK_DECLARE_2(x)	MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
+#define MASK_DECLARE_4(x)	MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
+#define MASK_DECLARE_8(x)	MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)
+
+const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {
+
+	MASK_DECLARE_8(0),	MASK_DECLARE_8(8),
+	MASK_DECLARE_8(16),	MASK_DECLARE_8(24),
+#if BITS_PER_LONG > 32
+	MASK_DECLARE_8(32),	MASK_DECLARE_8(40),
+	MASK_DECLARE_8(48),	MASK_DECLARE_8(56),
+#endif
+};
+EXPORT_SYMBOL_GPL(cpu_bit_bitmap);
+
+const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
+EXPORT_SYMBOL(cpu_all_bits);