#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/mutex.h>
-
-#define KTHREAD_NICE_LEVEL (-5)
+#include <linux/slab.h>
+#include <linux/freezer.h>
+#include <trace/events/sched.h>
static DEFINE_SPINLOCK(kthread_create_lock);
static LIST_HEAD(kthread_create_list);
/* Information passed to kthread() from kthreadd. */
int (*threadfn)(void *data);
void *data;
- struct completion started;
/* 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 {
+ int should_stop;
+ void *data;
+ struct completion exited;
};
-/* 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(tsk) \
+ container_of((tsk)->vfork_done, struct kthread, exited)
/**
* kthread_should_stop - should this kthread return now?
*/
int kthread_should_stop(void)
{
- return (kthread_stop_info.k == current);
+ return to_kthread(current)->should_stop;
}
EXPORT_SYMBOL(kthread_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;
+}
+
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.should_stop = 0;
+ self.data = data;
+ init_completion(&self.exited);
+ current->vfork_done = &self.exited;
/* OK, tell user we're spawned, wait for stop or wakeup */
__set_current_state(TASK_UNINTERRUPTIBLE);
- complete(&create->started);
+ create->result = current;
+ complete(&create->done);
schedule();
- if (!kthread_should_stop())
+ ret = -EINTR;
+ if (!self.should_stop)
ret = threadfn(data);
- /* 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);
- }
- return 0;
+ /* we can't just return, we must preserve "self" on stack */
+ do_exit(ret);
}
static void create_kthread(struct kthread_create_info *create)
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);
- read_lock(&tasklist_lock);
- create->result = find_task_by_pid_ns(pid, &init_pid_ns);
- read_unlock(&tasklist_lock);
- /*
- * 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_MASK_ALL_PTR);
+ complete(&create->done);
}
- complete(&create->done);
}
/**
*
* 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().
*
* When woken, the thread will run @threadfn() with @data as its
* argument. @threadfn() can either call do_exit() directly if it is a
create.threadfn = threadfn;
create.data = data;
- init_completion(&create.started);
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;
}
/**
* 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)
{
- if (k->state != TASK_UNINTERRUPTIBLE) {
+ /* Must have done schedule() in kthread() before we set_task_cpu */
+ if (!wait_task_inactive(p, TASK_UNINTERRUPTIBLE)) {
WARN_ON(1);
return;
}
- /* Must have done schedule() in kthread() before we set_task_cpu */
- wait_task_inactive(k, 0);
- set_task_cpu(k, cpu);
- k->cpus_allowed = cpumask_of_cpu(cpu);
- k->rt.nr_cpus_allowed = 1;
- k->flags |= PF_THREAD_BOUND;
+
+ p->cpus_allowed = cpumask_of_cpu(cpu);
+ p->rt.nr_cpus_allowed = 1;
+ p->flags |= PF_THREAD_BOUND;
}
EXPORT_SYMBOL(kthread_bind);
* @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. */
+ trace_sched_kthread_stop(k);
get_task_struct(k);
- /* Must init completion *before* thread sees kthread_stop_info.k */
- init_completion(&kthread_stop_info.done);
- smp_wmb();
+ kthread = to_kthread(k);
+ barrier(); /* it might have exited */
+ if (k->vfork_done != NULL) {
+ kthread->should_stop = 1;
+ wake_up_process(k);
+ wait_for_completion(&kthread->exited);
+ }
+ ret = k->exit_code;
- /* Now set kthread_should_stop() to true, and wake it up. */
- kthread_stop_info.k = k;
- wake_up_process(k);
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;
}
/* 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_MASK_ALL_PTR);
+ set_cpus_allowed_ptr(tsk, cpu_all_mask);
+ set_mems_allowed(node_states[N_HIGH_MEMORY]);
current->flags |= PF_NOFREEZE | PF_FREEZER_NOSIG;
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);
+ }
+ spin_unlock_irq(&worker->lock);
+
+ if (work) {
+ __set_current_state(TASK_RUNNING);
+ work->func(work);
+ smp_wmb(); /* wmb worker-b0 paired with flush-b1 */
+ work->done_seq = work->queue_seq;
+ smp_mb(); /* mb worker-b1 paired with flush-b0 */
+ if (atomic_read(&work->flushing))
+ wake_up_all(&work->done);
+ } else if (!freezing(current))
+ schedule();
+
+ try_to_freeze();
+ goto repeat;
+}
+EXPORT_SYMBOL_GPL(kthread_worker_fn);
+
+/**
+ * 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)) {
+ list_add_tail(&work->node, &worker->work_list);
+ work->queue_seq++;
+ if (likely(worker->task))
+ wake_up_process(worker->task);
+ ret = true;
+ }
+ spin_unlock_irqrestore(&worker->lock, flags);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(queue_kthread_work);
+
+/**
+ * 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)
+{
+ int seq = work->queue_seq;
+
+ atomic_inc(&work->flushing);
+
+ /*
+ * mb flush-b0 paired with worker-b1, to make sure either
+ * worker sees the above increment or we see done_seq update.
+ */
+ smp_mb__after_atomic_inc();
+
+ /* A - B <= 0 tests whether B is in front of A regardless of overflow */
+ wait_event(work->done, seq - work->done_seq <= 0);
+ atomic_dec(&work->flushing);
+
+ /*
+ * rmb flush-b1 paired with worker-b0, to make sure our caller
+ * sees every change made by work->func().
+ */
+ smp_mb__after_atomic_dec();
+}
+EXPORT_SYMBOL_GPL(flush_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_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);
projects / linux-flexiantxendom0-natty.git / blobdiff