1 files changed, 51 insertions, 12 deletions

diff --git a/kernel/kthread.c b/kernel/kthread.c
index c5f3c6613b6d..4f9c60ef95e8 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -45,6 +45,13 @@ struct kthread_stop_info
 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);
@@ -122,6 +129,25 @@ static void keventd_create_kthread(void *_create)
         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[],
@@ -156,6 +182,15 @@ struct task_struct *kthread_create(int (*threadfn)(void *data),
 }
 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);
@@ -166,14 +201,21 @@ void kthread_bind(struct task_struct *k, unsigned int cpu)
 }
 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)
 {
-        return kthread_stop_sem(k, NULL);
-}
-EXPORT_SYMBOL(kthread_stop);
-
-int kthread_stop_sem(struct task_struct *k, struct semaphore *s)
-{
         int ret;
 
         mutex_lock(&kthread_stop_lock);
@@ -187,10 +229,7 @@ int kthread_stop_sem(struct task_struct *k, struct semaphore *s)
 
         /* Now set kthread_should_stop() to true, and wake it up. */
         kthread_stop_info.k = k;
-        if (s)
-                up(s);
-        else
-                wake_up_process(k);
+        wake_up_process(k);
         put_task_struct(k);
 
         /* Once it dies, reset stop ptr, gather result and we're done. */
@@ -201,7 +240,7 @@ int kthread_stop_sem(struct task_struct *k, struct semaphore *s)
 
         return ret;
 }
-EXPORT_SYMBOL(kthread_stop_sem);
+EXPORT_SYMBOL(kthread_stop);
 
 static __init int helper_init(void)
 {
@@ -210,5 +249,5 @@ static __init int helper_init(void)
 
         return 0;
 }
-core_initcall(helper_init);
 
+core_initcall(helper_init);