epoll: don't use current in irq context

 */

struct nested_call_node {

	struct list_head llink;

	struct task_struct *task;

	void *cookie;

	int cpu;

};

/*

{

	int error, call_nests = 0;

	unsigned long flags;

	struct task_struct *this_task = current;

	int this_cpu = get_cpu();

	struct list_head *lsthead = &ncalls->tasks_call_list;

	struct nested_call_node *tncur;

	struct nested_call_node tnode;

	 * very much limited.

	 */

	list_for_each_entry(tncur, lsthead, llink) {

		if (tncur->task == this_task &&

		if (tncur->cpu == this_cpu &&

		    (tncur->cookie == cookie || ++call_nests > max_nests)) {

			/*

			 * Ops ... loop detected or maximum nest level reached.

			 * We abort this wake by breaking the cycle itself.

			 */

			spin_unlock_irqrestore(&ncalls->lock, flags);

			return -1;

			error = -1;

			goto out_unlock;

		}

	}

	/* Add the current task and cookie to the list */

	tnode.task = this_task;

	tnode.cpu = this_cpu;

	tnode.cookie = cookie;

	list_add(&tnode.llink, lsthead);

	/* Remove the current task from the list */

	spin_lock_irqsave(&ncalls->lock, flags);

	list_del(&tnode.llink);

 out_unlock:

	spin_unlock_irqrestore(&ncalls->lock, flags);

	put_cpu();

	return error;

}