Re: [Patch] rwsem: fix rwsem_is_locked() bug

[Amerigo Wang <amwang@redhat.com>]

David Howells wrote:
> 
> Your patch would probably be better as:
> 
> -	woken = 0;
> +	woken = ++sem->activity;
> 	while (waiter->flags & RWSEM_WAITING_FOR_READ) {
> 		struct list_head *next = waiter->list.next;
> 
> 		list_del(&waiter->list);
> 		tsk = waiter->task;
> 		smp_mb();
> 		waiter->task = NULL;
> 		wake_up_process(tsk);
> 		put_task_struct(tsk);
> 		woken++;
> 		if (list_empty(&sem->wait_list))
> 			break;
> 		waiter = list_entry(next, struct rwsem_waiter, list);
> 	}
> 
> -	sem->activity += woken;
> +	sem->activity = woken;

FYI, this seems wrong, probably even worse than what it is now.
I tried this change, it breaks portmap.