rwsem: simplify __rwsem_do_wake

	waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list);

	if (!wakewrite) {

		if (waiter->type == RWSEM_WAITING_FOR_WRITE)

			goto out;

		goto dont_wake_writers;

	}

	/*

	 * as we support write lock stealing, we can't set sem->activity

	 * to -1 here to indicate we get the lock. Instead, we wake it up

	 * to let it go get it again.

	 */

	if (waiter->type == RWSEM_WAITING_FOR_WRITE) {

		if (wakewrite)

			/* Wake up a writer. Note that we do not grant it the

			 * lock - it will have to acquire it when it runs. */

			wake_up_process(waiter->task);

		goto out;

	}

	/* grant an infinite number of read locks to the front of the queue */

 dont_wake_writers:

	woken = 0;

	while (waiter->type == RWSEM_WAITING_FOR_READ) {

	do {

		struct list_head *next = waiter->list.next;

		list_del(&waiter->list);

		wake_up_process(tsk);

		put_task_struct(tsk);

		woken++;

		if (list_empty(&sem->wait_list))

		if (next == &sem->wait_list)

			break;

		waiter = list_entry(next, struct rwsem_waiter, list);

	}

	} while (waiter->type != RWSEM_WAITING_FOR_WRITE);

	sem->activity += woken;

	signed long woken, loop, adjustment;

	waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list);

	if (waiter->type != RWSEM_WAITING_FOR_WRITE)

		goto readers_only;

	if (wake_type == RWSEM_WAKE_READ_OWNED)

		/* Another active reader was observed, so wakeup is not

		 * likely to succeed. Save the atomic op.

	if (waiter->type == RWSEM_WAITING_FOR_WRITE) {

		if (wake_type != RWSEM_WAKE_READ_OWNED)

			/* Wake writer at the front of the queue, but do not

			 * grant it the lock yet as we want other writers

			 * to be able to steal it.  Readers, on the other hand,

			 * will block as they will notice the queued writer.

			 */

		goto out;

	/* Wake up the writing waiter and let the task grab the sem: */

			wake_up_process(waiter->task);

		goto out;

	}

 readers_only:

	/* If we come here from up_xxxx(), another thread might have reached

	 * rwsem_down_failed_common() before we acquired the spinlock and

	 * woken up a waiter, making it now active.  We prefer to check for

	rwsem_atomic_add(adjustment, sem);

	next = sem->wait_list.next;

	for (loop = woken; loop > 0; loop--) {

	loop = woken;

	do {

		waiter = list_entry(next, struct rwsem_waiter, list);

		next = waiter->list.next;

		tsk = waiter->task;

		waiter->task = NULL;

		wake_up_process(tsk);

		put_task_struct(tsk);

	}

	} while (--loop);

	sem->wait_list.next = next;

	next->prev = &sem->wait_list;