[T106][ZXW-22]7520V3SCV2.01.01.02P42U09_VEC_V0.8_AP_VEC origin source commit
Change-Id: Ic6e05d89ecd62fc34f82b23dcf306c93764aec4b
diff --git a/ap/os/linux/linux-3.4.x/kernel/stop_machine.c b/ap/os/linux/linux-3.4.x/kernel/stop_machine.c
new file mode 100644
index 0000000..e98c70b
--- /dev/null
+++ b/ap/os/linux/linux-3.4.x/kernel/stop_machine.c
@@ -0,0 +1,620 @@
+/*
+ * kernel/stop_machine.c
+ *
+ * Copyright (C) 2008, 2005 IBM Corporation.
+ * Copyright (C) 2008, 2005 Rusty Russell rusty@rustcorp.com.au
+ * Copyright (C) 2010 SUSE Linux Products GmbH
+ * Copyright (C) 2010 Tejun Heo <tj@kernel.org>
+ *
+ * This file is released under the GPLv2 and any later version.
+ */
+#include <linux/completion.h>
+#include <linux/cpu.h>
+#include <linux/init.h>
+#include <linux/kthread.h>
+#include <linux/export.h>
+#include <linux/percpu.h>
+#include <linux/sched.h>
+#include <linux/stop_machine.h>
+#include <linux/interrupt.h>
+#include <linux/kallsyms.h>
+
+#include <linux/atomic.h>
+
+/*
+ * Structure to determine completion condition and record errors. May
+ * be shared by works on different cpus.
+ */
+struct cpu_stop_done {
+ atomic_t nr_todo; /* nr left to execute */
+ bool executed; /* actually executed? */
+ int ret; /* collected return value */
+ struct task_struct *waiter; /* woken when nr_todo reaches 0 */
+};
+
+/* the actual stopper, one per every possible cpu, enabled on online cpus */
+struct cpu_stopper {
+ raw_spinlock_t lock;
+ bool enabled; /* is this stopper enabled? */
+ struct list_head works; /* list of pending works */
+ struct task_struct *thread; /* stopper thread */
+};
+
+static DEFINE_PER_CPU(struct cpu_stopper, cpu_stopper);
+static bool stop_machine_initialized = false;
+
+static void cpu_stop_init_done(struct cpu_stop_done *done, unsigned int nr_todo)
+{
+ memset(done, 0, sizeof(*done));
+ atomic_set(&done->nr_todo, nr_todo);
+ done->waiter = current;
+}
+
+/* signal completion unless @done is NULL */
+static void cpu_stop_signal_done(struct cpu_stop_done *done, bool executed)
+{
+ if (done) {
+ if (executed)
+ done->executed = true;
+ if (atomic_dec_and_test(&done->nr_todo)) {
+ wake_up_process(done->waiter);
+ done->waiter = NULL;
+ }
+ }
+}
+
+/* queue @work to @stopper. if offline, @work is completed immediately */
+static void cpu_stop_queue_work(struct cpu_stopper *stopper,
+ struct cpu_stop_work *work)
+{
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&stopper->lock, flags);
+
+ if (stopper->enabled) {
+ list_add_tail(&work->list, &stopper->works);
+ wake_up_process(stopper->thread);
+ } else
+ cpu_stop_signal_done(work->done, false);
+
+ raw_spin_unlock_irqrestore(&stopper->lock, flags);
+}
+
+static void wait_for_stop_done(struct cpu_stop_done *done)
+{
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ while (atomic_read(&done->nr_todo)) {
+ schedule();
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ }
+ /*
+ * We need to wait until cpu_stop_signal_done() has cleared
+ * done->waiter.
+ */
+ while (done->waiter)
+ cpu_relax();
+ set_current_state(TASK_RUNNING);
+}
+
+/**
+ * stop_one_cpu - stop a cpu
+ * @cpu: cpu to stop
+ * @fn: function to execute
+ * @arg: argument to @fn
+ *
+ * Execute @fn(@arg) on @cpu. @fn is run in a process context with
+ * the highest priority preempting any task on the cpu and
+ * monopolizing it. This function returns after the execution is
+ * complete.
+ *
+ * This function doesn't guarantee @cpu stays online till @fn
+ * completes. If @cpu goes down in the middle, execution may happen
+ * partially or fully on different cpus. @fn should either be ready
+ * for that or the caller should ensure that @cpu stays online until
+ * this function completes.
+ *
+ * CONTEXT:
+ * Might sleep.
+ *
+ * RETURNS:
+ * -ENOENT if @fn(@arg) was not executed because @cpu was offline;
+ * otherwise, the return value of @fn.
+ */
+int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
+{
+ struct cpu_stop_done done;
+ struct cpu_stop_work work = { .fn = fn, .arg = arg, .done = &done };
+
+ cpu_stop_init_done(&done, 1);
+ cpu_stop_queue_work(&per_cpu(cpu_stopper, cpu), &work);
+ wait_for_stop_done(&done);
+ return done.executed ? done.ret : -ENOENT;
+}
+
+/**
+ * stop_one_cpu_nowait - stop a cpu but don't wait for completion
+ * @cpu: cpu to stop
+ * @fn: function to execute
+ * @arg: argument to @fn
+ *
+ * Similar to stop_one_cpu() but doesn't wait for completion. The
+ * caller is responsible for ensuring @work_buf is currently unused
+ * and will remain untouched until stopper starts executing @fn.
+ *
+ * CONTEXT:
+ * Don't care.
+ */
+void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
+ struct cpu_stop_work *work_buf)
+{
+ *work_buf = (struct cpu_stop_work){ .fn = fn, .arg = arg, };
+ cpu_stop_queue_work(&per_cpu(cpu_stopper, cpu), work_buf);
+}
+
+/* static data for stop_cpus */
+static DEFINE_MUTEX(stop_cpus_mutex);
+static DEFINE_MUTEX(stopper_lock);
+static DEFINE_PER_CPU(struct cpu_stop_work, stop_cpus_work);
+
+static void queue_stop_cpus_work(const struct cpumask *cpumask,
+ cpu_stop_fn_t fn, void *arg,
+ struct cpu_stop_done *done, bool inactive)
+{
+ struct cpu_stop_work *work;
+ unsigned int cpu;
+
+ /* initialize works and done */
+ for_each_cpu(cpu, cpumask) {
+ work = &per_cpu(stop_cpus_work, cpu);
+ work->fn = fn;
+ work->arg = arg;
+ work->done = done;
+ }
+
+ /*
+ * Make sure that all work is queued on all cpus before we
+ * any of the cpus can execute it.
+ */
+ if (!inactive) {
+ mutex_lock(&stopper_lock);
+ } else {
+ while (!mutex_trylock(&stopper_lock))
+ cpu_relax();
+ }
+ for_each_cpu(cpu, cpumask)
+ cpu_stop_queue_work(&per_cpu(cpu_stopper, cpu),
+ &per_cpu(stop_cpus_work, cpu));
+ mutex_unlock(&stopper_lock);
+}
+
+static int __stop_cpus(const struct cpumask *cpumask,
+ cpu_stop_fn_t fn, void *arg)
+{
+ struct cpu_stop_done done;
+
+ cpu_stop_init_done(&done, cpumask_weight(cpumask));
+ queue_stop_cpus_work(cpumask, fn, arg, &done, false);
+ wait_for_stop_done(&done);
+ return done.executed ? done.ret : -ENOENT;
+}
+
+/**
+ * stop_cpus - stop multiple cpus
+ * @cpumask: cpus to stop
+ * @fn: function to execute
+ * @arg: argument to @fn
+ *
+ * Execute @fn(@arg) on online cpus in @cpumask. On each target cpu,
+ * @fn is run in a process context with the highest priority
+ * preempting any task on the cpu and monopolizing it. This function
+ * returns after all executions are complete.
+ *
+ * This function doesn't guarantee the cpus in @cpumask stay online
+ * till @fn completes. If some cpus go down in the middle, execution
+ * on the cpu may happen partially or fully on different cpus. @fn
+ * should either be ready for that or the caller should ensure that
+ * the cpus stay online until this function completes.
+ *
+ * All stop_cpus() calls are serialized making it safe for @fn to wait
+ * for all cpus to start executing it.
+ *
+ * CONTEXT:
+ * Might sleep.
+ *
+ * RETURNS:
+ * -ENOENT if @fn(@arg) was not executed at all because all cpus in
+ * @cpumask were offline; otherwise, 0 if all executions of @fn
+ * returned 0, any non zero return value if any returned non zero.
+ */
+int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg)
+{
+ int ret;
+
+ /* static works are used, process one request at a time */
+ mutex_lock(&stop_cpus_mutex);
+ ret = __stop_cpus(cpumask, fn, arg);
+ mutex_unlock(&stop_cpus_mutex);
+ return ret;
+}
+
+/**
+ * try_stop_cpus - try to stop multiple cpus
+ * @cpumask: cpus to stop
+ * @fn: function to execute
+ * @arg: argument to @fn
+ *
+ * Identical to stop_cpus() except that it fails with -EAGAIN if
+ * someone else is already using the facility.
+ *
+ * CONTEXT:
+ * Might sleep.
+ *
+ * RETURNS:
+ * -EAGAIN if someone else is already stopping cpus, -ENOENT if
+ * @fn(@arg) was not executed at all because all cpus in @cpumask were
+ * offline; otherwise, 0 if all executions of @fn returned 0, any non
+ * zero return value if any returned non zero.
+ */
+int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg)
+{
+ int ret;
+
+ /* static works are used, process one request at a time */
+ if (!mutex_trylock(&stop_cpus_mutex))
+ return -EAGAIN;
+ ret = __stop_cpus(cpumask, fn, arg);
+ mutex_unlock(&stop_cpus_mutex);
+ return ret;
+}
+
+static int cpu_stopper_thread(void *data)
+{
+ struct cpu_stopper *stopper = data;
+ struct cpu_stop_work *work;
+ int ret;
+
+repeat:
+ set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */
+
+ if (kthread_should_stop()) {
+ __set_current_state(TASK_RUNNING);
+ return 0;
+ }
+
+ work = NULL;
+ raw_spin_lock_irq(&stopper->lock);
+ if (!list_empty(&stopper->works)) {
+ work = list_first_entry(&stopper->works,
+ struct cpu_stop_work, list);
+ list_del_init(&work->list);
+ }
+ raw_spin_unlock_irq(&stopper->lock);
+
+ if (work) {
+ cpu_stop_fn_t fn = work->fn;
+ void *arg = work->arg;
+ struct cpu_stop_done *done = work->done;
+ char ksym_buf[KSYM_NAME_LEN] __maybe_unused;
+
+ __set_current_state(TASK_RUNNING);
+
+ /*
+ * Wait until the stopper finished scheduling on all
+ * cpus
+ */
+ mutex_lock(&stopper_lock);
+ /*
+ * Let other cpu threads continue as well
+ */
+ mutex_unlock(&stopper_lock);
+
+ /* cpu stop callbacks are not allowed to sleep */
+ preempt_disable();
+
+ ret = fn(arg);
+ if (ret)
+ done->ret = ret;
+
+ /* restore preemption and check it's still balanced */
+ preempt_enable();
+ WARN_ONCE(preempt_count(),
+ "cpu_stop: %s(%p) leaked preempt count\n",
+ kallsyms_lookup((unsigned long)fn, NULL, NULL, NULL,
+ ksym_buf), arg);
+
+ /*
+ * Make sure that the wakeup and setting done->waiter
+ * to NULL is atomic.
+ */
+ local_irq_disable();
+ cpu_stop_signal_done(done, true);
+ local_irq_enable();
+ } else
+ schedule();
+
+ goto repeat;
+}
+
+extern void sched_set_stop_task(int cpu, struct task_struct *stop);
+
+/* manage stopper for a cpu, mostly lifted from sched migration thread mgmt */
+static int __cpuinit cpu_stop_cpu_callback(struct notifier_block *nfb,
+ unsigned long action, void *hcpu)
+{
+ unsigned int cpu = (unsigned long)hcpu;
+ struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
+ struct task_struct *p;
+
+ switch (action & ~CPU_TASKS_FROZEN) {
+ case CPU_UP_PREPARE:
+ BUG_ON(stopper->thread || stopper->enabled ||
+ !list_empty(&stopper->works));
+ p = kthread_create_on_node(cpu_stopper_thread,
+ stopper,
+ cpu_to_node(cpu),
+ "migration/%d", cpu);
+ if (IS_ERR(p))
+ return notifier_from_errno(PTR_ERR(p));
+ get_task_struct(p);
+ p->flags |= PF_STOMPER;
+ kthread_bind(p, cpu);
+ sched_set_stop_task(cpu, p);
+ stopper->thread = p;
+ break;
+
+ case CPU_ONLINE:
+ /* strictly unnecessary, as first user will wake it */
+ wake_up_process(stopper->thread);
+ /* mark enabled */
+ raw_spin_lock_irq(&stopper->lock);
+ stopper->enabled = true;
+ raw_spin_unlock_irq(&stopper->lock);
+ break;
+
+#ifdef CONFIG_HOTPLUG_CPU
+ case CPU_UP_CANCELED:
+ case CPU_POST_DEAD:
+ {
+ struct cpu_stop_work *work;
+
+ sched_set_stop_task(cpu, NULL);
+ /* kill the stopper */
+ kthread_stop(stopper->thread);
+ /* drain remaining works */
+ raw_spin_lock_irq(&stopper->lock);
+ list_for_each_entry(work, &stopper->works, list)
+ cpu_stop_signal_done(work->done, false);
+ stopper->enabled = false;
+ raw_spin_unlock_irq(&stopper->lock);
+ /* release the stopper */
+ put_task_struct(stopper->thread);
+ stopper->thread = NULL;
+ break;
+ }
+#endif
+ }
+
+ return NOTIFY_OK;
+}
+
+/*
+ * Give it a higher priority so that cpu stopper is available to other
+ * cpu notifiers. It currently shares the same priority as sched
+ * migration_notifier.
+ */
+static struct notifier_block __cpuinitdata cpu_stop_cpu_notifier = {
+ .notifier_call = cpu_stop_cpu_callback,
+ .priority = 10,
+};
+
+static int __init cpu_stop_init(void)
+{
+ void *bcpu = (void *)(long)smp_processor_id();
+ unsigned int cpu;
+ int err;
+
+ for_each_possible_cpu(cpu) {
+ struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
+
+ raw_spin_lock_init(&stopper->lock);
+ INIT_LIST_HEAD(&stopper->works);
+ }
+
+ /* start one for the boot cpu */
+ err = cpu_stop_cpu_callback(&cpu_stop_cpu_notifier, CPU_UP_PREPARE,
+ bcpu);
+ BUG_ON(err != NOTIFY_OK);
+ cpu_stop_cpu_callback(&cpu_stop_cpu_notifier, CPU_ONLINE, bcpu);
+ register_cpu_notifier(&cpu_stop_cpu_notifier);
+
+ stop_machine_initialized = true;
+
+ return 0;
+}
+early_initcall(cpu_stop_init);
+
+#ifdef CONFIG_STOP_MACHINE
+
+/* This controls the threads on each CPU. */
+enum stopmachine_state {
+ /* Dummy starting state for thread. */
+ STOPMACHINE_NONE,
+ /* Awaiting everyone to be scheduled. */
+ STOPMACHINE_PREPARE,
+ /* Disable interrupts. */
+ STOPMACHINE_DISABLE_IRQ,
+ /* Run the function */
+ STOPMACHINE_RUN,
+ /* Exit */
+ STOPMACHINE_EXIT,
+};
+
+struct stop_machine_data {
+ int (*fn)(void *);
+ void *data;
+ /* Like num_online_cpus(), but hotplug cpu uses us, so we need this. */
+ unsigned int num_threads;
+ const struct cpumask *active_cpus;
+
+ enum stopmachine_state state;
+ atomic_t thread_ack;
+};
+
+static void set_state(struct stop_machine_data *smdata,
+ enum stopmachine_state newstate)
+{
+ /* Reset ack counter. */
+ atomic_set(&smdata->thread_ack, smdata->num_threads);
+ smp_wmb();
+ smdata->state = newstate;
+}
+
+/* Last one to ack a state moves to the next state. */
+static void ack_state(struct stop_machine_data *smdata)
+{
+ if (atomic_dec_and_test(&smdata->thread_ack))
+ set_state(smdata, smdata->state + 1);
+}
+
+/* This is the cpu_stop function which stops the CPU. */
+static int stop_machine_cpu_stop(void *data)
+{
+ struct stop_machine_data *smdata = data;
+ enum stopmachine_state curstate = STOPMACHINE_NONE;
+ int cpu = smp_processor_id(), err = 0;
+ unsigned long flags;
+ bool is_active;
+
+ /*
+ * When called from stop_machine_from_inactive_cpu(), irq might
+ * already be disabled. Save the state and restore it on exit.
+ */
+ local_save_flags(flags);
+
+ if (!smdata->active_cpus)
+ is_active = cpu == cpumask_first(cpu_online_mask);
+ else
+ is_active = cpumask_test_cpu(cpu, smdata->active_cpus);
+
+ /* Simple state machine */
+ do {
+ /* Chill out and ensure we re-read stopmachine_state. */
+ cpu_relax();
+ if (smdata->state != curstate) {
+ curstate = smdata->state;
+ switch (curstate) {
+ case STOPMACHINE_DISABLE_IRQ:
+ local_irq_disable();
+ hard_irq_disable();
+ break;
+ case STOPMACHINE_RUN:
+ if (is_active)
+ err = smdata->fn(smdata->data);
+ break;
+ default:
+ break;
+ }
+ ack_state(smdata);
+ }
+ } while (curstate != STOPMACHINE_EXIT);
+
+ local_irq_restore(flags);
+ return err;
+}
+
+int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus)
+{
+ struct stop_machine_data smdata = { .fn = fn, .data = data,
+ .num_threads = num_online_cpus(),
+ .active_cpus = cpus };
+
+ if (!stop_machine_initialized) {
+ /*
+ * Handle the case where stop_machine() is called
+ * early in boot before stop_machine() has been
+ * initialized.
+ */
+ unsigned long flags;
+ int ret;
+
+ WARN_ON_ONCE(smdata.num_threads != 1);
+
+ local_irq_save(flags);
+ hard_irq_disable();
+ ret = (*fn)(data);
+ local_irq_restore(flags);
+
+ return ret;
+ }
+
+ /* Set the initial state and stop all online cpus. */
+ set_state(&smdata, STOPMACHINE_PREPARE);
+ return stop_cpus(cpu_online_mask, stop_machine_cpu_stop, &smdata);
+}
+
+int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus)
+{
+ int ret;
+
+ /* No CPUs can come up or down during this. */
+ get_online_cpus();
+ ret = __stop_machine(fn, data, cpus);
+ put_online_cpus();
+ return ret;
+}
+EXPORT_SYMBOL_GPL(stop_machine);
+
+/**
+ * stop_machine_from_inactive_cpu - stop_machine() from inactive CPU
+ * @fn: the function to run
+ * @data: the data ptr for the @fn()
+ * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
+ *
+ * This is identical to stop_machine() but can be called from a CPU which
+ * is not active. The local CPU is in the process of hotplug (so no other
+ * CPU hotplug can start) and not marked active and doesn't have enough
+ * context to sleep.
+ *
+ * This function provides stop_machine() functionality for such state by
+ * using busy-wait for synchronization and executing @fn directly for local
+ * CPU.
+ *
+ * CONTEXT:
+ * Local CPU is inactive. Temporarily stops all active CPUs.
+ *
+ * RETURNS:
+ * 0 if all executions of @fn returned 0, any non zero return value if any
+ * returned non zero.
+ */
+int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
+ const struct cpumask *cpus)
+{
+ struct stop_machine_data smdata = { .fn = fn, .data = data,
+ .active_cpus = cpus };
+ struct cpu_stop_done done;
+ int ret;
+
+ /* Local CPU must be inactive and CPU hotplug in progress. */
+ BUG_ON(cpu_active(raw_smp_processor_id()));
+ smdata.num_threads = num_active_cpus() + 1; /* +1 for local */
+
+ /* No proper task established and can't sleep - busy wait for lock. */
+ while (!mutex_trylock(&stop_cpus_mutex))
+ cpu_relax();
+
+ /* Schedule work on other CPUs and execute directly for local CPU */
+ set_state(&smdata, STOPMACHINE_PREPARE);
+ cpu_stop_init_done(&done, num_active_cpus());
+ queue_stop_cpus_work(cpu_active_mask, stop_machine_cpu_stop, &smdata,
+ &done, true);
+ ret = stop_machine_cpu_stop(&smdata);
+
+ /* Busy wait for completion. */
+ while (atomic_read(&done.nr_todo))
+ cpu_relax();
+
+ mutex_unlock(&stop_cpus_mutex);
+ return ret ?: done.ret;
+}
+
+#endif /* CONFIG_STOP_MACHINE */