#include <linux/unistd.h>
#include <linux/file.h>
#include <linux/module.h>
+#include <linux/mutex.h>
#include <asm/semaphore.h>
+/*
+ * We dont want to execute off keventd since it might
+ * hold a semaphore our callers hold too:
+ */
+static struct workqueue_struct *helper_wq;
+
struct kthread_create_info
{
/* Information passed to kthread() from keventd. */
/* Thread stopping is done by setthing this var: lock serializes
* multiple kthread_stop calls. */
-static DECLARE_MUTEX(kthread_stop_lock);
+static DEFINE_MUTEX(kthread_stop_lock);
static struct kthread_stop_info kthread_stop_info;
+/**
+ * kthread_should_stop - should this kthread return now?
+ *
+ * When someone calls kthread_stop on your kthread, it will be woken
+ * 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)
{
return (kthread_stop_info.k == current);
create->result = ERR_PTR(pid);
} else {
wait_for_completion(&create->started);
- create->result = find_task_by_pid(pid);
+ read_lock(&tasklist_lock);
+ create->result = find_task_by_real_pid(pid);
+ read_unlock(&tasklist_lock);
}
complete(&create->done);
}
+/**
+ * kthread_create - create a kthread.
+ * @threadfn: the function to run until signal_pending(current).
+ * @data: data ptr for @threadfn.
+ * @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().
+ *
+ * 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
+ * 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[],
init_completion(&create.started);
init_completion(&create.done);
- /* If we're being called to start the first workqueue, we
- * can't use keventd. */
- if (!keventd_up())
+ /*
+ * The workqueue needs to start up first:
+ */
+ if (!helper_wq)
work.func(work.data);
else {
- schedule_work(&work);
+ queue_work(helper_wq, &work);
wait_for_completion(&create.done);
}
if (!IS_ERR(create.result)) {
}
EXPORT_SYMBOL(kthread_create);
+/**
+ * kthread_bind - bind a just-created kthread to a cpu.
+ * @k: 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)
{
BUG_ON(k->state != TASK_INTERRUPTIBLE);
}
EXPORT_SYMBOL(kthread_bind);
+/**
+ * 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().
+ *
+ * Returns the result of threadfn(), or %-EINTR if wake_up_process()
+ * was never called.
+ */
int kthread_stop(struct task_struct *k)
{
int ret;
- down(&kthread_stop_lock);
+ mutex_lock(&kthread_stop_lock);
/* It could exit after stop_info.k set, but before wake_up_process. */
get_task_struct(k);
/* Must init completion *before* thread sees kthread_stop_info.k */
init_completion(&kthread_stop_info.done);
- wmb();
+ smp_wmb();
/* Now set kthread_should_stop() to true, and wake it up. */
kthread_stop_info.k = k;
wait_for_completion(&kthread_stop_info.done);
kthread_stop_info.k = NULL;
ret = kthread_stop_info.err;
- up(&kthread_stop_lock);
+ mutex_unlock(&kthread_stop_lock);
return ret;
}
EXPORT_SYMBOL(kthread_stop);
+
+static __init int helper_init(void)
+{
+ helper_wq = create_singlethread_workqueue("kthread");
+ BUG_ON(!helper_wq);
+
+ return 0;
+}
+
+core_initcall(helper_init);
git://git.onelab.eu / linux-2.6.git / blobdiff