Revert 337f13046ff0 ("futex: Allow FUTEX_CLOCK_REALTIME with FUTEX_WAIT op")

[linux-2.6-microblaze.git] / kernel / kthread.c

diff --git a/kernel/kthread.c b/kernel/kthread.c
index 1578973..fe3f2a4 100644 (file)
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -84,6 +84,25 @@ static inline struct kthread *to_kthread(struct task_struct *k)
        return (__force void *)k->set_child_tid;
 }
 
+/*
+ * Variant of to_kthread() that doesn't assume @p is a kthread.
+ *
+ * Per construction; when:
+ *
+ *   (p->flags & PF_KTHREAD) && p->set_child_tid
+ *
+ * the task is both a kthread and struct kthread is persistent. However
+ * PF_KTHREAD on it's own is not, kernel_thread() can exec() (See umh.c and
+ * begin_new_exec()).
+ */
+static inline struct kthread *__to_kthread(struct task_struct *p)
+{
+       void *kthread = (__force void *)p->set_child_tid;
+       if (kthread && !(p->flags & PF_KTHREAD))
+               kthread = NULL;
+       return kthread;
+}
+
 void free_kthread_struct(struct task_struct *k)
 {
        struct kthread *kthread;
@@ -168,8 +187,9 @@ EXPORT_SYMBOL_GPL(kthread_freezable_should_stop);
  */
 void *kthread_func(struct task_struct *task)
 {
-       if (task->flags & PF_KTHREAD)
-               return to_kthread(task)->threadfn;
+       struct kthread *kthread = __to_kthread(task);
+       if (kthread)
+               return kthread->threadfn;
        return NULL;
 }
 EXPORT_SYMBOL_GPL(kthread_func);
@@ -199,10 +219,11 @@ EXPORT_SYMBOL_GPL(kthread_data);
  */
 void *kthread_probe_data(struct task_struct *task)
 {
-       struct kthread *kthread = to_kthread(task);
+       struct kthread *kthread = __to_kthread(task);
        void *data = NULL;
 
-       copy_from_kernel_nofault(&data, &kthread->data, sizeof(data));
+       if (kthread)
+               copy_from_kernel_nofault(&data, &kthread->data, sizeof(data));
        return data;
 }
 
@@ -514,9 +535,9 @@ void kthread_set_per_cpu(struct task_struct *k, int cpu)
        set_bit(KTHREAD_IS_PER_CPU, &kthread->flags);
 }
 
-bool kthread_is_per_cpu(struct task_struct *k)
+bool kthread_is_per_cpu(struct task_struct *p)
 {
-       struct kthread *kthread = to_kthread(k);
+       struct kthread *kthread = __to_kthread(p);
        if (!kthread)
                return false;
 
@@ -963,7 +984,8 @@ static void __kthread_queue_delayed_work(struct kthread_worker *worker,
        struct timer_list *timer = &dwork->timer;
        struct kthread_work *work = &dwork->work;
 
-       WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn);
+       WARN_ON_FUNCTION_MISMATCH(timer->function,
+                                 kthread_delayed_work_timer_fn);
 
        /*
         * If @delay is 0, queue @dwork->work immediately.  This is for