Testing of Kthread

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .1277-linux-2.6.1-rc2/kernel/kthread.c .1277-linux-2.6.1-rc2.updated/kernel/kthread.c
@@ -169,3 +169,90 @@ int kthread_stop(struct task_struct *k)
 	wait_for_completion(&stop.done);
 	return stop.result;
 }
+
+/* Test code */
+#include <linux/init.h>
+
+static int threadfn_count;
+
+static int threadfn(void *data)
+{
+	BUG_ON(strcmp(current->comm, "kthreadtest1") != 0);
+
+	if (data == do_exit)
+		do_exit(0);
+
+	while (!signal_pending(current)) {
+		threadfn_count++;
+		current->state = TASK_INTERRUPTIBLE;
+		schedule();
+	}
+
+	return PTR_ERR(data);
+}
+
+static int test_kthreads(void)
+{
+	struct task_struct *k;
+	int ret;
+
+	printk("kthread_create.\n");
+	threadfn_count = 0;
+	k = kthread_create(threadfn, NULL, "kthreadtest%i", 1);
+	BUG_ON(IS_ERR(k));
+	BUG_ON(threadfn_count);
+
+	printk("kthread_start.\n");
+	kthread_start(k);
+	current->state = TASK_INTERRUPTIBLE;
+	schedule_timeout(1);
+	BUG_ON(threadfn_count != 1);
+
+	printk("kthread threadfn.\n");
+	wake_up_process(k);
+	current->state = TASK_INTERRUPTIBLE;
+	schedule_timeout(1);
+	BUG_ON(threadfn_count != 2);
+
+	printk("kthread_stop.\n");
+	ret = kthread_stop(k);
+	BUG_ON(threadfn_count != 2);
+	BUG_ON(ret != 0);
+
+	printk("kthread: stopped before starting\n");
+	threadfn_count = 0;
+	k = kthread_create(threadfn, NULL, "kthreadtest%i", 1);
+	BUG_ON(IS_ERR(k));
+	BUG_ON(threadfn_count);
+	ret = kthread_stop(k);
+	printk("ret = %i\n", ret);
+	BUG_ON(ret != -EINTR);
+	BUG_ON(threadfn_count);
+
+	printk("kthread: threadfn returns error.\n");
+	threadfn_count = 0;
+	k = kthread_create(threadfn, ERR_PTR(-EINVAL), "kthreadtest%i", 1);
+	BUG_ON(IS_ERR(k));
+	kthread_start(k);
+	current->state = TASK_INTERRUPTIBLE;
+	schedule_timeout(1);
+	BUG_ON(threadfn_count != 1);
+	ret = kthread_stop(k);
+	BUG_ON(threadfn_count != 1);
+	BUG_ON(ret != -EINVAL);
+
+	printk("kthread: threadfn which exits.\n");
+	k = kthread_create(threadfn, do_exit, "kthreadtest%i", 1);
+	BUG_ON(IS_ERR(k));
+	get_task_struct(k);
+	kthread_start(k);
+	current->state = TASK_INTERRUPTIBLE;
+	schedule_timeout(1);
+	BUG_ON(!(k->state & (TASK_ZOMBIE|TASK_DEAD)));
+	put_task_struct(k);
+
+	printk("All kthread tests passed...\n");
+	return 0;
+}
+
+module_init(test_kthreads);