--- /dev/null
+#ifndef _LINUX_SMPBOOT_H
+#define _LINUX_SMPBOOT_H
+
+#include <linux/types.h>
+
+struct task_struct;
+/* Cookie handed to the thread_fn*/
+struct smpboot_thread_data;
+
+/**
+ * struct smp_hotplug_thread - CPU hotplug related thread descriptor
+ * @store: Pointer to per cpu storage for the task pointers
+ * @list: List head for core management
+ * @thread_should_run: Check whether the thread should run or not. Called with
+ * preemption disabled.
+ * @thread_fn: The associated thread function
+ * @setup: Optional setup function, called when the thread gets
+ * operational the first time
+ * @cleanup: Optional cleanup function, called when the thread
+ * should stop (module exit)
+ * @park: Optional park function, called when the thread is
+ * parked (cpu offline)
+ * @unpark: Optional unpark function, called when the thread is
+ * unparked (cpu online)
+ * @thread_comm: The base name of the thread
+ */
+struct smp_hotplug_thread {
+ struct task_struct __percpu **store;
+ struct list_head list;
+ int (*thread_should_run)(unsigned int cpu);
+ void (*thread_fn)(unsigned int cpu);
+ void (*setup)(unsigned int cpu);
+ void (*cleanup)(unsigned int cpu, bool online);
+ void (*park)(unsigned int cpu);
+ void (*unpark)(unsigned int cpu);
+ const char *thread_comm;
+};
+
+int smpboot_register_percpu_thread(struct smp_hotplug_thread *plug_thread);
+void smpboot_unregister_percpu_thread(struct smp_hotplug_thread *plug_thread);
+int smpboot_thread_schedule(void);
+
+#endif
/*
* Common SMP CPU bringup/teardown functions
*/
+#include <linux/cpu.h>
#include <linux/err.h>
#include <linux/smp.h>
#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/slab.h>
#include <linux/sched.h>
+#include <linux/export.h>
#include <linux/percpu.h>
+#include <linux/kthread.h>
+#include <linux/smpboot.h>
#include "smpboot.h"
}
}
#endif
+
+static LIST_HEAD(hotplug_threads);
+static DEFINE_MUTEX(smpboot_threads_lock);
+
+struct smpboot_thread_data {
+ unsigned int cpu;
+ unsigned int status;
+ struct smp_hotplug_thread *ht;
+};
+
+enum {
+ HP_THREAD_NONE = 0,
+ HP_THREAD_ACTIVE,
+ HP_THREAD_PARKED,
+};
+
+/**
+ * smpboot_thread_fn - percpu hotplug thread loop function
+ * @data: thread data pointer
+ *
+ * Checks for thread stop and park conditions. Calls the necessary
+ * setup, cleanup, park and unpark functions for the registered
+ * thread.
+ *
+ * Returns 1 when the thread should exit, 0 otherwise.
+ */
+static int smpboot_thread_fn(void *data)
+{
+ struct smpboot_thread_data *td = data;
+ struct smp_hotplug_thread *ht = td->ht;
+
+ while (1) {
+ set_current_state(TASK_INTERRUPTIBLE);
+ preempt_disable();
+ if (kthread_should_stop()) {
+ set_current_state(TASK_RUNNING);
+ preempt_enable();
+ if (ht->cleanup)
+ ht->cleanup(td->cpu, cpu_online(td->cpu));
+ kfree(td);
+ return 0;
+ }
+
+ if (kthread_should_park()) {
+ __set_current_state(TASK_RUNNING);
+ preempt_enable();
+ if (ht->park && td->status == HP_THREAD_ACTIVE) {
+ BUG_ON(td->cpu != smp_processor_id());
+ ht->park(td->cpu);
+ td->status = HP_THREAD_PARKED;
+ }
+ kthread_parkme();
+ /* We might have been woken for stop */
+ continue;
+ }
+
+ BUG_ON(td->cpu != smp_processor_id());
+
+ /* Check for state change setup */
+ switch (td->status) {
+ case HP_THREAD_NONE:
+ preempt_enable();
+ if (ht->setup)
+ ht->setup(td->cpu);
+ td->status = HP_THREAD_ACTIVE;
+ preempt_disable();
+ break;
+ case HP_THREAD_PARKED:
+ preempt_enable();
+ if (ht->unpark)
+ ht->unpark(td->cpu);
+ td->status = HP_THREAD_ACTIVE;
+ preempt_disable();
+ break;
+ }
+
+ if (!ht->thread_should_run(td->cpu)) {
+ preempt_enable();
+ schedule();
+ } else {
+ set_current_state(TASK_RUNNING);
+ preempt_enable();
+ ht->thread_fn(td->cpu);
+ }
+ }
+}
+
+static int
+__smpboot_create_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
+{
+ struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
+ struct smpboot_thread_data *td;
+
+ if (tsk)
+ return 0;
+
+ td = kzalloc_node(sizeof(*td), GFP_KERNEL, cpu_to_node(cpu));
+ if (!td)
+ return -ENOMEM;
+ td->cpu = cpu;
+ td->ht = ht;
+
+ tsk = kthread_create_on_cpu(smpboot_thread_fn, td, cpu,
+ ht->thread_comm);
+ if (IS_ERR(tsk)) {
+ kfree(td);
+ return PTR_ERR(tsk);
+ }
+
+ get_task_struct(tsk);
+ *per_cpu_ptr(ht->store, cpu) = tsk;
+ return 0;
+}
+
+int smpboot_create_threads(unsigned int cpu)
+{
+ struct smp_hotplug_thread *cur;
+ int ret = 0;
+
+ mutex_lock(&smpboot_threads_lock);
+ list_for_each_entry(cur, &hotplug_threads, list) {
+ ret = __smpboot_create_thread(cur, cpu);
+ if (ret)
+ break;
+ }
+ mutex_unlock(&smpboot_threads_lock);
+ return ret;
+}
+
+static void smpboot_unpark_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
+{
+ struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
+
+ kthread_unpark(tsk);
+}
+
+void smpboot_unpark_threads(unsigned int cpu)
+{
+ struct smp_hotplug_thread *cur;
+
+ mutex_lock(&smpboot_threads_lock);
+ list_for_each_entry(cur, &hotplug_threads, list)
+ smpboot_unpark_thread(cur, cpu);
+ mutex_unlock(&smpboot_threads_lock);
+}
+
+static void smpboot_park_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
+{
+ struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
+
+ if (tsk)
+ kthread_park(tsk);
+}
+
+void smpboot_park_threads(unsigned int cpu)
+{
+ struct smp_hotplug_thread *cur;
+
+ mutex_lock(&smpboot_threads_lock);
+ list_for_each_entry_reverse(cur, &hotplug_threads, list)
+ smpboot_park_thread(cur, cpu);
+ mutex_unlock(&smpboot_threads_lock);
+}
+
+static void smpboot_destroy_threads(struct smp_hotplug_thread *ht)
+{
+ unsigned int cpu;
+
+ /* We need to destroy also the parked threads of offline cpus */
+ for_each_possible_cpu(cpu) {
+ struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
+
+ if (tsk) {
+ kthread_stop(tsk);
+ put_task_struct(tsk);
+ *per_cpu_ptr(ht->store, cpu) = NULL;
+ }
+ }
+}
+
+/**
+ * smpboot_register_percpu_thread - Register a per_cpu thread related to hotplug
+ * @plug_thread: Hotplug thread descriptor
+ *
+ * Creates and starts the threads on all online cpus.
+ */
+int smpboot_register_percpu_thread(struct smp_hotplug_thread *plug_thread)
+{
+ unsigned int cpu;
+ int ret = 0;
+
+ mutex_lock(&smpboot_threads_lock);
+ for_each_online_cpu(cpu) {
+ ret = __smpboot_create_thread(plug_thread, cpu);
+ if (ret) {
+ smpboot_destroy_threads(plug_thread);
+ goto out;
+ }
+ smpboot_unpark_thread(plug_thread, cpu);
+ }
+ list_add(&plug_thread->list, &hotplug_threads);
+out:
+ mutex_unlock(&smpboot_threads_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(smpboot_register_percpu_thread);
+
+/**
+ * smpboot_unregister_percpu_thread - Unregister a per_cpu thread related to hotplug
+ * @plug_thread: Hotplug thread descriptor
+ *
+ * Stops all threads on all possible cpus.
+ */
+void smpboot_unregister_percpu_thread(struct smp_hotplug_thread *plug_thread)
+{
+ get_online_cpus();
+ mutex_lock(&smpboot_threads_lock);
+ list_del(&plug_thread->list);
+ smpboot_destroy_threads(plug_thread);
+ mutex_unlock(&smpboot_threads_lock);
+ put_online_cpus();
+}
+EXPORT_SYMBOL_GPL(smpboot_unregister_percpu_thread);
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