#include <linux/kthread.h>
#include <linux/completion.h>
#include <linux/err.h>
+#include <linux/cpuset.h>
#include <linux/unistd.h>
#include <linux/file.h>
-#include <linux/module.h>
+#include <linux/export.h>
#include <linux/mutex.h>
-#include <trace/sched.h>
-
-#define KTHREAD_NICE_LEVEL (-5)
+#include <linux/slab.h>
+#include <linux/freezer.h>
+#include <linux/ptrace.h>
+#include <linux/uaccess.h>
+#include <trace/events/sched.h>
static DEFINE_SPINLOCK(kthread_create_lock);
static LIST_HEAD(kthread_create_list);
struct task_struct *kthreadd_task;
-DEFINE_TRACE(sched_kthread_stop);
-DEFINE_TRACE(sched_kthread_stop_ret);
-
struct kthread_create_info
{
/* Information passed to kthread() from kthreadd. */
int (*threadfn)(void *data);
void *data;
- struct completion started;
+ int node;
/* Result passed back to kthread_create() from kthreadd. */
struct task_struct *result;
struct list_head list;
};
-struct kthread_stop_info
-{
- struct task_struct *k;
- int err;
- struct completion done;
+struct kthread {
+ unsigned long flags;
+ unsigned int cpu;
+ void *data;
+ struct completion parked;
+ struct completion exited;
+};
+
+enum KTHREAD_BITS {
+ KTHREAD_IS_PER_CPU = 0,
+ KTHREAD_SHOULD_STOP,
+ KTHREAD_SHOULD_PARK,
+ KTHREAD_IS_PARKED,
};
-/* Thread stopping is done by setthing this var: lock serializes
- * multiple kthread_stop calls. */
-static DEFINE_MUTEX(kthread_stop_lock);
-static struct kthread_stop_info kthread_stop_info;
+#define __to_kthread(vfork) \
+ container_of(vfork, struct kthread, exited)
+
+static inline struct kthread *to_kthread(struct task_struct *k)
+{
+ return __to_kthread(k->vfork_done);
+}
+
+static struct kthread *to_live_kthread(struct task_struct *k)
+{
+ struct completion *vfork = ACCESS_ONCE(k->vfork_done);
+ if (likely(vfork))
+ return __to_kthread(vfork);
+ return NULL;
+}
/**
* kthread_should_stop - should this kthread return now?
* and this will return true. You should then return, and your return
* value will be passed through to kthread_stop().
*/
-int kthread_should_stop(void)
+bool kthread_should_stop(void)
{
- return (kthread_stop_info.k == current);
+ return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags);
}
EXPORT_SYMBOL(kthread_should_stop);
+/**
+ * kthread_should_park - should this kthread park now?
+ *
+ * When someone calls kthread_park() on your kthread, it will be woken
+ * and this will return true. You should then do the necessary
+ * cleanup and call kthread_parkme()
+ *
+ * Similar to kthread_should_stop(), but this keeps the thread alive
+ * and in a park position. kthread_unpark() "restarts" the thread and
+ * calls the thread function again.
+ */
+bool kthread_should_park(void)
+{
+ return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(current)->flags);
+}
+
+/**
+ * kthread_freezable_should_stop - should this freezable kthread return now?
+ * @was_frozen: optional out parameter, indicates whether %current was frozen
+ *
+ * kthread_should_stop() for freezable kthreads, which will enter
+ * refrigerator if necessary. This function is safe from kthread_stop() /
+ * freezer deadlock and freezable kthreads should use this function instead
+ * of calling try_to_freeze() directly.
+ */
+bool kthread_freezable_should_stop(bool *was_frozen)
+{
+ bool frozen = false;
+
+ might_sleep();
+
+ if (unlikely(freezing(current)))
+ frozen = __refrigerator(true);
+
+ if (was_frozen)
+ *was_frozen = frozen;
+
+ return kthread_should_stop();
+}
+EXPORT_SYMBOL_GPL(kthread_freezable_should_stop);
+
+/**
+ * kthread_data - return data value specified on kthread creation
+ * @task: kthread task in question
+ *
+ * Return the data value specified when kthread @task was created.
+ * The caller is responsible for ensuring the validity of @task when
+ * calling this function.
+ */
+void *kthread_data(struct task_struct *task)
+{
+ return to_kthread(task)->data;
+}
+
+/**
+ * probe_kthread_data - speculative version of kthread_data()
+ * @task: possible kthread task in question
+ *
+ * @task could be a kthread task. Return the data value specified when it
+ * was created if accessible. If @task isn't a kthread task or its data is
+ * inaccessible for any reason, %NULL is returned. This function requires
+ * that @task itself is safe to dereference.
+ */
+void *probe_kthread_data(struct task_struct *task)
+{
+ struct kthread *kthread = to_kthread(task);
+ void *data = NULL;
+
+ probe_kernel_read(&data, &kthread->data, sizeof(data));
+ return data;
+}
+
+static void __kthread_parkme(struct kthread *self)
+{
+ __set_current_state(TASK_PARKED);
+ while (test_bit(KTHREAD_SHOULD_PARK, &self->flags)) {
+ if (!test_and_set_bit(KTHREAD_IS_PARKED, &self->flags))
+ complete(&self->parked);
+ schedule();
+ __set_current_state(TASK_PARKED);
+ }
+ clear_bit(KTHREAD_IS_PARKED, &self->flags);
+ __set_current_state(TASK_RUNNING);
+}
+
+void kthread_parkme(void)
+{
+ __kthread_parkme(to_kthread(current));
+}
+
static int kthread(void *_create)
{
+ /* Copy data: it's on kthread's stack */
struct kthread_create_info *create = _create;
- int (*threadfn)(void *data);
- void *data;
- int ret = -EINTR;
+ int (*threadfn)(void *data) = create->threadfn;
+ void *data = create->data;
+ struct kthread self;
+ int ret;
- /* Copy data: it's on kthread's stack */
- threadfn = create->threadfn;
- data = create->data;
+ self.flags = 0;
+ self.data = data;
+ init_completion(&self.exited);
+ init_completion(&self.parked);
+ current->vfork_done = &self.exited;
/* OK, tell user we're spawned, wait for stop or wakeup */
__set_current_state(TASK_UNINTERRUPTIBLE);
create->result = current;
- complete(&create->started);
+ complete(&create->done);
schedule();
- if (!kthread_should_stop())
- ret = threadfn(data);
+ ret = -EINTR;
- /* It might have exited on its own, w/o kthread_stop. Check. */
- if (kthread_should_stop()) {
- kthread_stop_info.err = ret;
- complete(&kthread_stop_info.done);
+ if (!test_bit(KTHREAD_SHOULD_STOP, &self.flags)) {
+ __kthread_parkme(&self);
+ ret = threadfn(data);
}
- return 0;
+ /* we can't just return, we must preserve "self" on stack */
+ do_exit(ret);
+}
+
+/* called from do_fork() to get node information for about to be created task */
+int tsk_fork_get_node(struct task_struct *tsk)
+{
+#ifdef CONFIG_NUMA
+ if (tsk == kthreadd_task)
+ return tsk->pref_node_fork;
+#endif
+ return numa_node_id();
}
static void create_kthread(struct kthread_create_info *create)
{
int pid;
+#ifdef CONFIG_NUMA
+ current->pref_node_fork = create->node;
+#endif
/* We want our own signal handler (we take no signals by default). */
pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD);
if (pid < 0) {
create->result = ERR_PTR(pid);
- } else {
- struct sched_param param = { .sched_priority = 0 };
- wait_for_completion(&create->started);
- /*
- * root may have changed our (kthreadd's) priority or CPU mask.
- * The kernel thread should not inherit these properties.
- */
- sched_setscheduler(create->result, SCHED_NORMAL, ¶m);
- set_user_nice(create->result, KTHREAD_NICE_LEVEL);
- set_cpus_allowed_ptr(create->result, cpu_all_mask);
+ complete(&create->done);
}
- complete(&create->done);
}
/**
- * kthread_create - create a kthread.
+ * kthread_create_on_node - create a kthread.
* @threadfn: the function to run until signal_pending(current).
* @data: data ptr for @threadfn.
+ * @node: memory node number.
* @namefmt: printf-style name for the thread.
*
* Description: This helper function creates and names a kernel
* thread. The thread will be stopped: use wake_up_process() to start
- * it. See also kthread_run(), kthread_create_on_cpu().
+ * it. See also kthread_run().
*
+ * If thread is going to be bound on a particular cpu, give its node
+ * in @node, to get NUMA affinity for kthread stack, or else give -1.
* When woken, the thread will run @threadfn() with @data as its
* argument. @threadfn() can either call do_exit() directly if it is a
- * standalone thread for which noone will call kthread_stop(), or
+ * standalone thread for which no one will call kthread_stop(), or
* return when 'kthread_should_stop()' is true (which means
* kthread_stop() has been called). The return value should be zero
* or a negative error number; it will be passed to kthread_stop().
*
* Returns a task_struct or ERR_PTR(-ENOMEM).
*/
-struct task_struct *kthread_create(int (*threadfn)(void *data),
- void *data,
- const char namefmt[],
- ...)
+struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
+ void *data, int node,
+ const char namefmt[],
+ ...)
{
struct kthread_create_info create;
create.threadfn = threadfn;
create.data = data;
- init_completion(&create.started);
+ create.node = node;
init_completion(&create.done);
spin_lock(&kthread_create_lock);
wait_for_completion(&create.done);
if (!IS_ERR(create.result)) {
+ static const struct sched_param param = { .sched_priority = 0 };
va_list args;
+
va_start(args, namefmt);
vsnprintf(create.result->comm, sizeof(create.result->comm),
namefmt, args);
va_end(args);
+ /*
+ * root may have changed our (kthreadd's) priority or CPU mask.
+ * The kernel thread should not inherit these properties.
+ */
+ sched_setscheduler_nocheck(create.result, SCHED_NORMAL, ¶m);
+ set_cpus_allowed_ptr(create.result, cpu_all_mask);
}
return create.result;
}
-EXPORT_SYMBOL(kthread_create);
+EXPORT_SYMBOL(kthread_create_on_node);
+
+static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state)
+{
+ /* Must have done schedule() in kthread() before we set_task_cpu */
+ if (!wait_task_inactive(p, state)) {
+ WARN_ON(1);
+ return;
+ }
+ /* It's safe because the task is inactive. */
+ do_set_cpus_allowed(p, cpumask_of(cpu));
+ p->flags |= PF_NO_SETAFFINITY;
+}
/**
* kthread_bind - bind a just-created kthread to a cpu.
- * @k: thread created by kthread_create().
+ * @p: thread created by kthread_create().
* @cpu: cpu (might not be online, must be possible) for @k to run on.
*
* Description: This function is equivalent to set_cpus_allowed(),
* except that @cpu doesn't need to be online, and the thread must be
* stopped (i.e., just returned from kthread_create()).
*/
-void kthread_bind(struct task_struct *k, unsigned int cpu)
+void kthread_bind(struct task_struct *p, unsigned int cpu)
{
- /* Must have done schedule() in kthread() before we set_task_cpu */
- if (!wait_task_inactive(k, TASK_UNINTERRUPTIBLE)) {
- WARN_ON(1);
- return;
- }
- set_task_cpu(k, cpu);
- k->cpus_allowed = cpumask_of_cpu(cpu);
- k->rt.nr_cpus_allowed = 1;
- k->flags |= PF_THREAD_BOUND;
+ __kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE);
}
EXPORT_SYMBOL(kthread_bind);
+/**
+ * kthread_create_on_cpu - Create a cpu bound kthread
+ * @threadfn: the function to run until signal_pending(current).
+ * @data: data ptr for @threadfn.
+ * @cpu: The cpu on which the thread should be bound,
+ * @namefmt: printf-style name for the thread. Format is restricted
+ * to "name.*%u". Code fills in cpu number.
+ *
+ * Description: This helper function creates and names a kernel thread
+ * The thread will be woken and put into park mode.
+ */
+struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data),
+ void *data, unsigned int cpu,
+ const char *namefmt)
+{
+ struct task_struct *p;
+
+ p = kthread_create_on_node(threadfn, data, cpu_to_node(cpu), namefmt,
+ cpu);
+ if (IS_ERR(p))
+ return p;
+ set_bit(KTHREAD_IS_PER_CPU, &to_kthread(p)->flags);
+ to_kthread(p)->cpu = cpu;
+ /* Park the thread to get it out of TASK_UNINTERRUPTIBLE state */
+ kthread_park(p);
+ return p;
+}
+
+static void __kthread_unpark(struct task_struct *k, struct kthread *kthread)
+{
+ clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
+ /*
+ * We clear the IS_PARKED bit here as we don't wait
+ * until the task has left the park code. So if we'd
+ * park before that happens we'd see the IS_PARKED bit
+ * which might be about to be cleared.
+ */
+ if (test_and_clear_bit(KTHREAD_IS_PARKED, &kthread->flags)) {
+ if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags))
+ __kthread_bind(k, kthread->cpu, TASK_PARKED);
+ wake_up_state(k, TASK_PARKED);
+ }
+}
+
+/**
+ * kthread_unpark - unpark a thread created by kthread_create().
+ * @k: thread created by kthread_create().
+ *
+ * Sets kthread_should_park() for @k to return false, wakes it, and
+ * waits for it to return. If the thread is marked percpu then its
+ * bound to the cpu again.
+ */
+void kthread_unpark(struct task_struct *k)
+{
+ struct kthread *kthread = to_live_kthread(k);
+
+ if (kthread)
+ __kthread_unpark(k, kthread);
+}
+
+/**
+ * kthread_park - park a thread created by kthread_create().
+ * @k: thread created by kthread_create().
+ *
+ * Sets kthread_should_park() for @k to return true, wakes it, and
+ * waits for it to return. This can also be called after kthread_create()
+ * instead of calling wake_up_process(): the thread will park without
+ * calling threadfn().
+ *
+ * Returns 0 if the thread is parked, -ENOSYS if the thread exited.
+ * If called by the kthread itself just the park bit is set.
+ */
+int kthread_park(struct task_struct *k)
+{
+ struct kthread *kthread = to_live_kthread(k);
+ int ret = -ENOSYS;
+
+ if (kthread) {
+ if (!test_bit(KTHREAD_IS_PARKED, &kthread->flags)) {
+ set_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
+ if (k != current) {
+ wake_up_process(k);
+ wait_for_completion(&kthread->parked);
+ }
+ }
+ ret = 0;
+ }
+ return ret;
+}
+
/**
* kthread_stop - stop a thread created by kthread_create().
* @k: thread created by kthread_create().
*
* Sets kthread_should_stop() for @k to return true, wakes it, and
- * waits for it to exit. Your threadfn() must not call do_exit()
- * itself if you use this function! This can also be called after
- * kthread_create() instead of calling wake_up_process(): the thread
- * will exit without calling threadfn().
+ * waits for it to exit. This can also be called after kthread_create()
+ * instead of calling wake_up_process(): the thread will exit without
+ * calling threadfn().
+ *
+ * If threadfn() may call do_exit() itself, the caller must ensure
+ * task_struct can't go away.
*
* Returns the result of threadfn(), or %-EINTR if wake_up_process()
* was never called.
*/
int kthread_stop(struct task_struct *k)
{
+ struct kthread *kthread;
int ret;
- mutex_lock(&kthread_stop_lock);
-
- /* It could exit after stop_info.k set, but before wake_up_process. */
- get_task_struct(k);
-
trace_sched_kthread_stop(k);
- /* Must init completion *before* thread sees kthread_stop_info.k */
- init_completion(&kthread_stop_info.done);
- smp_wmb();
-
- /* Now set kthread_should_stop() to true, and wake it up. */
- kthread_stop_info.k = k;
- wake_up_process(k);
+ get_task_struct(k);
+ kthread = to_live_kthread(k);
+ if (kthread) {
+ set_bit(KTHREAD_SHOULD_STOP, &kthread->flags);
+ __kthread_unpark(k, kthread);
+ wake_up_process(k);
+ wait_for_completion(&kthread->exited);
+ }
+ ret = k->exit_code;
put_task_struct(k);
- /* Once it dies, reset stop ptr, gather result and we're done. */
- wait_for_completion(&kthread_stop_info.done);
- kthread_stop_info.k = NULL;
- ret = kthread_stop_info.err;
- mutex_unlock(&kthread_stop_lock);
-
trace_sched_kthread_stop_ret(ret);
-
return ret;
}
EXPORT_SYMBOL(kthread_stop);
/* Setup a clean context for our children to inherit. */
set_task_comm(tsk, "kthreadd");
ignore_signals(tsk);
- set_user_nice(tsk, KTHREAD_NICE_LEVEL);
set_cpus_allowed_ptr(tsk, cpu_all_mask);
+ set_mems_allowed(node_states[N_MEMORY]);
- current->flags |= PF_NOFREEZE | PF_FREEZER_NOSIG;
+ current->flags |= PF_NOFREEZE;
for (;;) {
set_current_state(TASK_INTERRUPTIBLE);
return 0;
}
+
+void __init_kthread_worker(struct kthread_worker *worker,
+ const char *name,
+ struct lock_class_key *key)
+{
+ spin_lock_init(&worker->lock);
+ lockdep_set_class_and_name(&worker->lock, key, name);
+ INIT_LIST_HEAD(&worker->work_list);
+ worker->task = NULL;
+}
+EXPORT_SYMBOL_GPL(__init_kthread_worker);
+
+/**
+ * kthread_worker_fn - kthread function to process kthread_worker
+ * @worker_ptr: pointer to initialized kthread_worker
+ *
+ * This function can be used as @threadfn to kthread_create() or
+ * kthread_run() with @worker_ptr argument pointing to an initialized
+ * kthread_worker. The started kthread will process work_list until
+ * the it is stopped with kthread_stop(). A kthread can also call
+ * this function directly after extra initialization.
+ *
+ * Different kthreads can be used for the same kthread_worker as long
+ * as there's only one kthread attached to it at any given time. A
+ * kthread_worker without an attached kthread simply collects queued
+ * kthread_works.
+ */
+int kthread_worker_fn(void *worker_ptr)
+{
+ struct kthread_worker *worker = worker_ptr;
+ struct kthread_work *work;
+
+ WARN_ON(worker->task);
+ worker->task = current;
+repeat:
+ set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */
+
+ if (kthread_should_stop()) {
+ __set_current_state(TASK_RUNNING);
+ spin_lock_irq(&worker->lock);
+ worker->task = NULL;
+ spin_unlock_irq(&worker->lock);
+ return 0;
+ }
+
+ work = NULL;
+ spin_lock_irq(&worker->lock);
+ if (!list_empty(&worker->work_list)) {
+ work = list_first_entry(&worker->work_list,
+ struct kthread_work, node);
+ list_del_init(&work->node);
+ }
+ worker->current_work = work;
+ spin_unlock_irq(&worker->lock);
+
+ if (work) {
+ __set_current_state(TASK_RUNNING);
+ work->func(work);
+ } else if (!freezing(current))
+ schedule();
+
+ try_to_freeze();
+ goto repeat;
+}
+EXPORT_SYMBOL_GPL(kthread_worker_fn);
+
+/* insert @work before @pos in @worker */
+static void insert_kthread_work(struct kthread_worker *worker,
+ struct kthread_work *work,
+ struct list_head *pos)
+{
+ lockdep_assert_held(&worker->lock);
+
+ list_add_tail(&work->node, pos);
+ work->worker = worker;
+ if (likely(worker->task))
+ wake_up_process(worker->task);
+}
+
+/**
+ * queue_kthread_work - queue a kthread_work
+ * @worker: target kthread_worker
+ * @work: kthread_work to queue
+ *
+ * Queue @work to work processor @task for async execution. @task
+ * must have been created with kthread_worker_create(). Returns %true
+ * if @work was successfully queued, %false if it was already pending.
+ */
+bool queue_kthread_work(struct kthread_worker *worker,
+ struct kthread_work *work)
+{
+ bool ret = false;
+ unsigned long flags;
+
+ spin_lock_irqsave(&worker->lock, flags);
+ if (list_empty(&work->node)) {
+ insert_kthread_work(worker, work, &worker->work_list);
+ ret = true;
+ }
+ spin_unlock_irqrestore(&worker->lock, flags);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(queue_kthread_work);
+
+struct kthread_flush_work {
+ struct kthread_work work;
+ struct completion done;
+};
+
+static void kthread_flush_work_fn(struct kthread_work *work)
+{
+ struct kthread_flush_work *fwork =
+ container_of(work, struct kthread_flush_work, work);
+ complete(&fwork->done);
+}
+
+/**
+ * flush_kthread_work - flush a kthread_work
+ * @work: work to flush
+ *
+ * If @work is queued or executing, wait for it to finish execution.
+ */
+void flush_kthread_work(struct kthread_work *work)
+{
+ struct kthread_flush_work fwork = {
+ KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn),
+ COMPLETION_INITIALIZER_ONSTACK(fwork.done),
+ };
+ struct kthread_worker *worker;
+ bool noop = false;
+
+retry:
+ worker = work->worker;
+ if (!worker)
+ return;
+
+ spin_lock_irq(&worker->lock);
+ if (work->worker != worker) {
+ spin_unlock_irq(&worker->lock);
+ goto retry;
+ }
+
+ if (!list_empty(&work->node))
+ insert_kthread_work(worker, &fwork.work, work->node.next);
+ else if (worker->current_work == work)
+ insert_kthread_work(worker, &fwork.work, worker->work_list.next);
+ else
+ noop = true;
+
+ spin_unlock_irq(&worker->lock);
+
+ if (!noop)
+ wait_for_completion(&fwork.done);
+}
+EXPORT_SYMBOL_GPL(flush_kthread_work);
+
+/**
+ * flush_kthread_worker - flush all current works on a kthread_worker
+ * @worker: worker to flush
+ *
+ * Wait until all currently executing or pending works on @worker are
+ * finished.
+ */
+void flush_kthread_worker(struct kthread_worker *worker)
+{
+ struct kthread_flush_work fwork = {
+ KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn),
+ COMPLETION_INITIALIZER_ONSTACK(fwork.done),
+ };
+
+ queue_kthread_work(worker, &fwork.work);
+ wait_for_completion(&fwork.done);
+}
+EXPORT_SYMBOL_GPL(flush_kthread_worker);
Code Review / linux-3.10.git / blobdiff