[NETLINK]: Extend netlink messaging interface

[pandora-kernel.git] / kernel / kthread.c

diff --git a/kernel/kthread.c b/kernel/kthread.c
index f50f174..4f9c60e 100644 (file)
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -12,6 +12,7 @@
 #include <linux/unistd.h>
 #include <linux/file.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 #include <asm/semaphore.h>
 
 /*
@@ -41,9 +42,16 @@ struct kthread_stop_info
 
 /* 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);
@@ -114,11 +122,32 @@ static void keventd_create_kthread(void *_create)
                create->result = ERR_PTR(pid);
        } else {
                wait_for_completion(&create->started);
+               read_lock(&tasklist_lock);
                create->result = find_task_by_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[],
@@ -153,6 +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);
@@ -163,11 +201,24 @@ 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)
 {
        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);
@@ -185,7 +236,7 @@ int kthread_stop(struct task_struct *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;
 }
@@ -198,5 +249,5 @@ static __init int helper_init(void)
 
        return 0;
 }
-core_initcall(helper_init);
 
+core_initcall(helper_init);