1 files changed, 799 insertions, 0 deletions

diff --git a/kernel/softirq.c b/kernel/softirq.c
new file mode 100644
index 0000000..e7c69a7
--- /dev/null
+++ b/kernel/softirq.c
@@ -0,0 +1,799 @@
+/*
+ *	linux/kernel/softirq.c
+ *
+ *	Copyright (C) 1992 Linus Torvalds
+ *
+ *	Distribute under GPLv2.
+ *
+ *	Rewritten. Old one was good in 2.2, but in 2.3 it was immoral. --ANK (990903)
+ *
+ *	Remote softirq infrastructure is by Jens Axboe.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel_stat.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/notifier.h>
+#include <linux/percpu.h>
+#include <linux/cpu.h>
+#include <linux/freezer.h>
+#include <linux/kthread.h>
+#include <linux/rcupdate.h>
+#include <linux/smp.h>
+#include <linux/tick.h>
+
+#include <asm/irq.h>
+/*
+   - No shared variables, all the data are CPU local.
+   - If a softirq needs serialization, let it serialize itself
+     by its own spinlocks.
+   - Even if softirq is serialized, only local cpu is marked for
+     execution. Hence, we get something sort of weak cpu binding.
+     Though it is still not clear, will it result in better locality
+     or will not.
+
+   Examples:
+   - NET RX softirq. It is multithreaded and does not require
+     any global serialization.
+   - NET TX softirq. It kicks software netdevice queues, hence
+     it is logically serialized per device, but this serialization
+     is invisible to common code.
+   - Tasklets: serialized wrt itself.
+ */
+
+#ifndef __ARCH_IRQ_STAT
+irq_cpustat_t irq_stat[NR_CPUS] ____cacheline_aligned;
+EXPORT_SYMBOL(irq_stat);
+#endif
+
+static struct softirq_action softirq_vec[NR_SOFTIRQS] __cacheline_aligned_in_smp;
+
+static DEFINE_PER_CPU(struct task_struct *, ksoftirqd);
+
+/*
+ * we cannot loop indefinitely here to avoid userspace starvation,
+ * but we also don't want to introduce a worst case 1/HZ latency
+ * to the pending events, so lets the scheduler to balance
+ * the softirq load for us.
+ */
+static inline void wakeup_softirqd(void)
+{
+	/* Interrupts are disabled: no need to stop preemption */
+	struct task_struct *tsk = __get_cpu_var(ksoftirqd);
+
+	if (tsk && tsk->state != TASK_RUNNING)
+		wake_up_process(tsk);
+}
+
+/*
+ * This one is for softirq.c-internal use,
+ * where hardirqs are disabled legitimately:
+ */
+#ifdef CONFIG_TRACE_IRQFLAGS
+static void __local_bh_disable(unsigned long ip)
+{
+	unsigned long flags;
+
+	WARN_ON_ONCE(in_irq());
+
+	raw_local_irq_save(flags);
+	add_preempt_count(SOFTIRQ_OFFSET);
+	/*
+	 * Were softirqs turned off above:
+	 */
+	if (softirq_count() == SOFTIRQ_OFFSET)
+		trace_softirqs_off(ip);
+	raw_local_irq_restore(flags);
+}
+#else /* !CONFIG_TRACE_IRQFLAGS */
+static inline void __local_bh_disable(unsigned long ip)
+{
+	add_preempt_count(SOFTIRQ_OFFSET);
+	barrier();
+}
+#endif /* CONFIG_TRACE_IRQFLAGS */
+
+void local_bh_disable(void)
+{
+	__local_bh_disable((unsigned long)__builtin_return_address(0));
+}
+
+EXPORT_SYMBOL(local_bh_disable);
+
+void __local_bh_enable(void)
+{
+	WARN_ON_ONCE(in_irq());
+
+	/*
+	 * softirqs should never be enabled by __local_bh_enable(),
+	 * it always nests inside local_bh_enable() sections:
+	 */
+	WARN_ON_ONCE(softirq_count() == SOFTIRQ_OFFSET);
+
+	sub_preempt_count(SOFTIRQ_OFFSET);
+}
+EXPORT_SYMBOL_GPL(__local_bh_enable);
+
+/*
+ * Special-case - softirqs can safely be enabled in
+ * cond_resched_softirq(), or by __do_softirq(),
+ * without processing still-pending softirqs:
+ */
+void _local_bh_enable(void)
+{
+	WARN_ON_ONCE(in_irq());
+	WARN_ON_ONCE(!irqs_disabled());
+
+	if (softirq_count() == SOFTIRQ_OFFSET)
+		trace_softirqs_on((unsigned long)__builtin_return_address(0));
+	sub_preempt_count(SOFTIRQ_OFFSET);
+}
+
+EXPORT_SYMBOL(_local_bh_enable);
+
+static inline void _local_bh_enable_ip(unsigned long ip)
+{
+	WARN_ON_ONCE(in_irq() || irqs_disabled());
+#ifdef CONFIG_TRACE_IRQFLAGS
+	local_irq_disable();
+#endif
+	/*
+	 * Are softirqs going to be turned on now:
+	 */
+	if (softirq_count() == SOFTIRQ_OFFSET)
+		trace_softirqs_on(ip);
+	/*
+	 * Keep preemption disabled until we are done with
+	 * softirq processing:
+ 	 */
+ 	sub_preempt_count(SOFTIRQ_OFFSET - 1);
+
+	if (unlikely(!in_interrupt() && local_softirq_pending()))
+		do_softirq();
+
+	dec_preempt_count();
+#ifdef CONFIG_TRACE_IRQFLAGS
+	local_irq_enable();
+#endif
+	preempt_check_resched();
+}
+
+void local_bh_enable(void)
+{
+	_local_bh_enable_ip((unsigned long)__builtin_return_address(0));
+}
+EXPORT_SYMBOL(local_bh_enable);
+
+void local_bh_enable_ip(unsigned long ip)
+{
+	_local_bh_enable_ip(ip);
+}
+EXPORT_SYMBOL(local_bh_enable_ip);
+
+/*
+ * We restart softirq processing MAX_SOFTIRQ_RESTART times,
+ * and we fall back to softirqd after that.
+ *
+ * This number has been established via experimentation.
+ * The two things to balance is latency against fairness -
+ * we want to handle softirqs as soon as possible, but they
+ * should not be able to lock up the box.
+ */
+#define MAX_SOFTIRQ_RESTART 10
+
+asmlinkage void __do_softirq(void)
+{
+	struct softirq_action *h;
+	__u32 pending;
+	int max_restart = MAX_SOFTIRQ_RESTART;
+	int cpu;
+
+	pending = local_softirq_pending();
+	account_system_vtime(current);
+
+	__local_bh_disable((unsigned long)__builtin_return_address(0));
+	trace_softirq_enter();
+
+	cpu = smp_processor_id();
+restart:
+	/* Reset the pending bitmask before enabling irqs */
+	set_softirq_pending(0);
+
+	local_irq_enable();
+
+	h = softirq_vec;
+
+	do {
+		if (pending & 1) {
+			int prev_count = preempt_count();
+
+			h->action(h);
+
+			if (unlikely(prev_count != preempt_count())) {
+				printk(KERN_ERR "huh, entered softirq %td %p"
+				       "with preempt_count %08x,"
+				       " exited with %08x?\n", h - softirq_vec,
+				       h->action, prev_count, preempt_count());
+				preempt_count() = prev_count;
+			}
+
+			rcu_bh_qsctr_inc(cpu);
+		}
+		h++;
+		pending >>= 1;
+	} while (pending);
+
+	local_irq_disable();
+
+	pending = local_softirq_pending();
+	if (pending && --max_restart)
+		goto restart;
+
+	if (pending)
+		wakeup_softirqd();
+
+	trace_softirq_exit();
+
+	account_system_vtime(current);
+	_local_bh_enable();
+}
+
+#ifndef __ARCH_HAS_DO_SOFTIRQ
+
+asmlinkage void do_softirq(void)
+{
+	__u32 pending;
+	unsigned long flags;
+
+	if (in_interrupt())
+		return;
+
+	local_irq_save(flags);
+
+	pending = local_softirq_pending();
+
+	if (pending)
+		__do_softirq();
+
+	local_irq_restore(flags);
+}
+
+#endif
+
+/*
+ * Enter an interrupt context.
+ */
+void irq_enter(void)
+{
+	int cpu = smp_processor_id();
+
+	if (idle_cpu(cpu) && !in_interrupt()) {
+		__irq_enter();
+		tick_check_idle(cpu);
+	} else
+		__irq_enter();
+}
+
+#ifdef __ARCH_IRQ_EXIT_IRQS_DISABLED
+# define invoke_softirq()	__do_softirq()
+#else
+# define invoke_softirq()	do_softirq()
+#endif
+
+/*
+ * Exit an interrupt context. Process softirqs if needed and possible:
+ */
+void irq_exit(void)
+{
+	account_system_vtime(current);
+	trace_hardirq_exit();
+	sub_preempt_count(IRQ_EXIT_OFFSET);
+	if (!in_interrupt() && local_softirq_pending())
+		invoke_softirq();
+
+#ifdef CONFIG_NO_HZ
+	/* Make sure that timer wheel updates are propagated */
+	if (!in_interrupt() && idle_cpu(smp_processor_id()) && !need_resched())
+		tick_nohz_stop_sched_tick(0);
+	rcu_irq_exit();
+#endif
+	preempt_enable_no_resched();
+}
+
+/*
+ * This function must run with irqs disabled!
+ */
+inline void raise_softirq_irqoff(unsigned int nr)
+{
+	__raise_softirq_irqoff(nr);
+
+	/*
+	 * If we're in an interrupt or softirq, we're done
+	 * (this also catches softirq-disabled code). We will
+	 * actually run the softirq once we return from
+	 * the irq or softirq.
+	 *
+	 * Otherwise we wake up ksoftirqd to make sure we
+	 * schedule the softirq soon.
+	 */
+	if (!in_interrupt())
+		wakeup_softirqd();
+}
+
+void raise_softirq(unsigned int nr)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	raise_softirq_irqoff(nr);
+	local_irq_restore(flags);
+}
+
+void open_softirq(int nr, void (*action)(struct softirq_action *))
+{
+	softirq_vec[nr].action = action;
+}
+
+/* Tasklets */
+struct tasklet_head
+{
+	struct tasklet_struct *head;
+	struct tasklet_struct **tail;
+};
+
+static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec);
+static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec);
+
+void __tasklet_schedule(struct tasklet_struct *t)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	t->next = NULL;
+	*__get_cpu_var(tasklet_vec).tail = t;
+	__get_cpu_var(tasklet_vec).tail = &(t->next);
+	raise_softirq_irqoff(TASKLET_SOFTIRQ);
+	local_irq_restore(flags);
+}
+
+EXPORT_SYMBOL(__tasklet_schedule);
+
+void __tasklet_hi_schedule(struct tasklet_struct *t)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	t->next = NULL;
+	*__get_cpu_var(tasklet_hi_vec).tail = t;
+	__get_cpu_var(tasklet_hi_vec).tail = &(t->next);
+	raise_softirq_irqoff(HI_SOFTIRQ);
+	local_irq_restore(flags);
+}
+
+EXPORT_SYMBOL(__tasklet_hi_schedule);
+
+static void tasklet_action(struct softirq_action *a)
+{
+	struct tasklet_struct *list;
+
+	local_irq_disable();
+	list = __get_cpu_var(tasklet_vec).head;
+	__get_cpu_var(tasklet_vec).head = NULL;
+	__get_cpu_var(tasklet_vec).tail = &__get_cpu_var(tasklet_vec).head;
+	local_irq_enable();
+
+	while (list) {
+		struct tasklet_struct *t = list;
+
+		list = list->next;
+
+		if (tasklet_trylock(t)) {
+			if (!atomic_read(&t->count)) {
+				if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state))
+					BUG();
+				t->func(t->data);
+				tasklet_unlock(t);
+				continue;
+			}
+			tasklet_unlock(t);
+		}
+
+		local_irq_disable();
+		t->next = NULL;
+		*__get_cpu_var(tasklet_vec).tail = t;
+		__get_cpu_var(tasklet_vec).tail = &(t->next);
+		__raise_softirq_irqoff(TASKLET_SOFTIRQ);
+		local_irq_enable();
+	}
+}
+
+static void tasklet_hi_action(struct softirq_action *a)
+{
+	struct tasklet_struct *list;
+
+	local_irq_disable();
+	list = __get_cpu_var(tasklet_hi_vec).head;
+	__get_cpu_var(tasklet_hi_vec).head = NULL;
+	__get_cpu_var(tasklet_hi_vec).tail = &__get_cpu_var(tasklet_hi_vec).head;
+	local_irq_enable();
+
+	while (list) {
+		struct tasklet_struct *t = list;
+
+		list = list->next;
+
+		if (tasklet_trylock(t)) {
+			if (!atomic_read(&t->count)) {
+				if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state))
+					BUG();
+				t->func(t->data);
+				tasklet_unlock(t);
+				continue;
+			}
+			tasklet_unlock(t);
+		}
+
+		local_irq_disable();
+		t->next = NULL;
+		*__get_cpu_var(tasklet_hi_vec).tail = t;
+		__get_cpu_var(tasklet_hi_vec).tail = &(t->next);
+		__raise_softirq_irqoff(HI_SOFTIRQ);
+		local_irq_enable();
+	}
+}
+
+
+void tasklet_init(struct tasklet_struct *t,
+		  void (*func)(unsigned long), unsigned long data)
+{
+	t->next = NULL;
+	t->state = 0;
+	atomic_set(&t->count, 0);
+	t->func = func;
+	t->data = data;
+}
+
+EXPORT_SYMBOL(tasklet_init);
+
+void tasklet_kill(struct tasklet_struct *t)
+{
+	if (in_interrupt())
+		printk("Attempt to kill tasklet from interrupt\n");
+
+	while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) {
+		do
+			yield();
+		while (test_bit(TASKLET_STATE_SCHED, &t->state));
+	}
+	tasklet_unlock_wait(t);
+	clear_bit(TASKLET_STATE_SCHED, &t->state);
+}
+
+EXPORT_SYMBOL(tasklet_kill);
+
+DEFINE_PER_CPU(struct list_head [NR_SOFTIRQS], softirq_work_list);
+EXPORT_PER_CPU_SYMBOL(softirq_work_list);
+
+static void __local_trigger(struct call_single_data *cp, int softirq)
+{
+	struct list_head *head = &__get_cpu_var(softirq_work_list[softirq]);
+
+	list_add_tail(&cp->list, head);
+
+	/* Trigger the softirq only if the list was previously empty.  */
+	if (head->next == &cp->list)
+		raise_softirq_irqoff(softirq);
+}
+
+#ifdef CONFIG_USE_GENERIC_SMP_HELPERS
+static void remote_softirq_receive(void *data)
+{
+	struct call_single_data *cp = data;
+	unsigned long flags;
+	int softirq;
+
+	softirq = cp->priv;
+
+	local_irq_save(flags);
+	__local_trigger(cp, softirq);
+	local_irq_restore(flags);
+}
+
+static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq)
+{
+	if (cpu_online(cpu)) {
+		cp->func = remote_softirq_receive;
+		cp->info = cp;
+		cp->flags = 0;
+		cp->priv = softirq;
+
+		__smp_call_function_single(cpu, cp);
+		return 0;
+	}
+	return 1;
+}
+#else /* CONFIG_USE_GENERIC_SMP_HELPERS */
+static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq)
+{
+	return 1;
+}
+#endif
+
+/**
+ * __send_remote_softirq - try to schedule softirq work on a remote cpu
+ * @cp: private SMP call function data area
+ * @cpu: the remote cpu
+ * @this_cpu: the currently executing cpu
+ * @softirq: the softirq for the work
+ *
+ * Attempt to schedule softirq work on a remote cpu.  If this cannot be
+ * done, the work is instead queued up on the local cpu.
+ *
+ * Interrupts must be disabled.
+ */
+void __send_remote_softirq(struct call_single_data *cp, int cpu, int this_cpu, int softirq)
+{
+	if (cpu == this_cpu || __try_remote_softirq(cp, cpu, softirq))
+		__local_trigger(cp, softirq);
+}
+EXPORT_SYMBOL(__send_remote_softirq);
+
+/**
+ * send_remote_softirq - try to schedule softirq work on a remote cpu
+ * @cp: private SMP call function data area
+ * @cpu: the remote cpu
+ * @softirq: the softirq for the work
+ *
+ * Like __send_remote_softirq except that disabling interrupts and
+ * computing the current cpu is done for the caller.
+ */
+void send_remote_softirq(struct call_single_data *cp, int cpu, int softirq)
+{
+	unsigned long flags;
+	int this_cpu;
+
+	local_irq_save(flags);
+	this_cpu = smp_processor_id();
+	__send_remote_softirq(cp, cpu, this_cpu, softirq);
+	local_irq_restore(flags);
+}
+EXPORT_SYMBOL(send_remote_softirq);
+
+static int __cpuinit remote_softirq_cpu_notify(struct notifier_block *self,
+					       unsigned long action, void *hcpu)
+{
+	/*
+	 * If a CPU goes away, splice its entries to the current CPU
+	 * and trigger a run of the softirq
+	 */
+	if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
+		int cpu = (unsigned long) hcpu;
+		int i;
+
+		local_irq_disable();
+		for (i = 0; i < NR_SOFTIRQS; i++) {
+			struct list_head *head = &per_cpu(softirq_work_list[i], cpu);
+			struct list_head *local_head;
+
+			if (list_empty(head))
+				continue;
+
+			local_head = &__get_cpu_var(softirq_work_list[i]);
+			list_splice_init(head, local_head);
+			raise_softirq_irqoff(i);
+		}
+		local_irq_enable();
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block __cpuinitdata remote_softirq_cpu_notifier = {
+	.notifier_call	= remote_softirq_cpu_notify,
+};
+
+void __init softirq_init(void)
+{
+	int cpu;
+
+	for_each_possible_cpu(cpu) {
+		int i;
+
+		per_cpu(tasklet_vec, cpu).tail =
+			&per_cpu(tasklet_vec, cpu).head;
+		per_cpu(tasklet_hi_vec, cpu).tail =
+			&per_cpu(tasklet_hi_vec, cpu).head;
+		for (i = 0; i < NR_SOFTIRQS; i++)
+			INIT_LIST_HEAD(&per_cpu(softirq_work_list[i], cpu));
+	}
+
+	register_hotcpu_notifier(&remote_softirq_cpu_notifier);
+
+	open_softirq(TASKLET_SOFTIRQ, tasklet_action);
+	open_softirq(HI_SOFTIRQ, tasklet_hi_action);
+}
+
+static int ksoftirqd(void * __bind_cpu)
+{
+	set_current_state(TASK_INTERRUPTIBLE);
+
+	while (!kthread_should_stop()) {
+		preempt_disable();
+		if (!local_softirq_pending()) {
+			preempt_enable_no_resched();
+			schedule();
+			preempt_disable();
+		}
+
+		__set_current_state(TASK_RUNNING);
+
+		while (local_softirq_pending()) {
+			/* Preempt disable stops cpu going offline.
+			   If already offline, we'll be on wrong CPU:
+			   don't process */
+			if (cpu_is_offline((long)__bind_cpu))
+				goto wait_to_die;
+			do_softirq();
+			preempt_enable_no_resched();
+			cond_resched();
+			preempt_disable();
+		}
+		preempt_enable();
+		set_current_state(TASK_INTERRUPTIBLE);
+	}
+	__set_current_state(TASK_RUNNING);
+	return 0;
+
+wait_to_die:
+	preempt_enable();
+	/* Wait for kthread_stop */
+	set_current_state(TASK_INTERRUPTIBLE);
+	while (!kthread_should_stop()) {
+		schedule();
+		set_current_state(TASK_INTERRUPTIBLE);
+	}
+	__set_current_state(TASK_RUNNING);
+	return 0;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+/*
+ * tasklet_kill_immediate is called to remove a tasklet which can already be
+ * scheduled for execution on @cpu.
+ *
+ * Unlike tasklet_kill, this function removes the tasklet
+ * _immediately_, even if the tasklet is in TASKLET_STATE_SCHED state.
+ *
+ * When this function is called, @cpu must be in the CPU_DEAD state.
+ */
+void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu)
+{
+	struct tasklet_struct **i;
+
+	BUG_ON(cpu_online(cpu));
+	BUG_ON(test_bit(TASKLET_STATE_RUN, &t->state));
+
+	if (!test_bit(TASKLET_STATE_SCHED, &t->state))
+		return;
+
+	/* CPU is dead, so no lock needed. */
+	for (i = &per_cpu(tasklet_vec, cpu).head; *i; i = &(*i)->next) {
+		if (*i == t) {
+			*i = t->next;
+			/* If this was the tail element, move the tail ptr */
+			if (*i == NULL)
+				per_cpu(tasklet_vec, cpu).tail = i;
+			return;
+		}
+	}
+	BUG();
+}
+
+static void takeover_tasklets(unsigned int cpu)
+{
+	/* CPU is dead, so no lock needed. */
+	local_irq_disable();
+
+	/* Find end, append list for that CPU. */
+	if (&per_cpu(tasklet_vec, cpu).head != per_cpu(tasklet_vec, cpu).tail) {
+		*(__get_cpu_var(tasklet_vec).tail) = per_cpu(tasklet_vec, cpu).head;
+		__get_cpu_var(tasklet_vec).tail = per_cpu(tasklet_vec, cpu).tail;
+		per_cpu(tasklet_vec, cpu).head = NULL;
+		per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head;
+	}
+	raise_softirq_irqoff(TASKLET_SOFTIRQ);
+
+	if (&per_cpu(tasklet_hi_vec, cpu).head != per_cpu(tasklet_hi_vec, cpu).tail) {
+		*__get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).head;
+		__get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).tail;
+		per_cpu(tasklet_hi_vec, cpu).head = NULL;
+		per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head;
+	}
+	raise_softirq_irqoff(HI_SOFTIRQ);
+
+	local_irq_enable();
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
+static int __cpuinit cpu_callback(struct notifier_block *nfb,
+				  unsigned long action,
+				  void *hcpu)
+{
+	int hotcpu = (unsigned long)hcpu;
+	struct task_struct *p;
+
+	switch (action) {
+	case CPU_UP_PREPARE:
+	case CPU_UP_PREPARE_FROZEN:
+		p = kthread_create(ksoftirqd, hcpu, "ksoftirqd/%d", hotcpu);
+		if (IS_ERR(p)) {
+			printk("ksoftirqd for %i failed\n", hotcpu);
+			return NOTIFY_BAD;
+		}
+		kthread_bind(p, hotcpu);
+  		per_cpu(ksoftirqd, hotcpu) = p;
+ 		break;
+	case CPU_ONLINE:
+	case CPU_ONLINE_FROZEN:
+		wake_up_process(per_cpu(ksoftirqd, hotcpu));
+		break;
+#ifdef CONFIG_HOTPLUG_CPU
+	case CPU_UP_CANCELED:
+	case CPU_UP_CANCELED_FROZEN:
+		if (!per_cpu(ksoftirqd, hotcpu))
+			break;
+		/* Unbind so it can run.  Fall thru. */
+		kthread_bind(per_cpu(ksoftirqd, hotcpu),
+			     any_online_cpu(cpu_online_map));
+	case CPU_DEAD:
+	case CPU_DEAD_FROZEN: {
+		struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
+
+		p = per_cpu(ksoftirqd, hotcpu);
+		per_cpu(ksoftirqd, hotcpu) = NULL;
+		sched_setscheduler_nocheck(p, SCHED_FIFO, &param);
+		kthread_stop(p);
+		takeover_tasklets(hotcpu);
+		break;
+	}
+#endif /* CONFIG_HOTPLUG_CPU */
+ 	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block __cpuinitdata cpu_nfb = {
+	.notifier_call = cpu_callback
+};
+
+static __init int spawn_ksoftirqd(void)
+{
+	void *cpu = (void *)(long)smp_processor_id();
+	int err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
+
+	BUG_ON(err == NOTIFY_BAD);
+	cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
+	register_cpu_notifier(&cpu_nfb);
+	return 0;
+}
+early_initcall(spawn_ksoftirqd);
+
+#ifdef CONFIG_SMP
+/*
+ * Call a function on all processors
+ */
+int on_each_cpu(void (*func) (void *info), void *info, int wait)
+{
+	int ret = 0;
+
+	preempt_disable();
+	ret = smp_call_function(func, info, wait);
+	local_irq_disable();
+	func(info);
+	local_irq_enable();
+	preempt_enable();
+	return ret;
+}
+EXPORT_SYMBOL(on_each_cpu);
+#endif