Re: [PATCH 03/11] locking, rwsem: introduce basis for down_write_killable

[Michal Hocko]

On Wed 11-05-16 10:44:01, Peter Zijlstra wrote:
[...]
> @@ -504,6 +502,18 @@ __rwsem_down_write_failed_common(struct rw_semaphore *sem, int state)
>  	raw_spin_unlock_irq(&sem->wait_lock);
>  
>  	return ret;
> +
> +out_nolock:
> +	__set_current_state(TASK_RUNNING);
> +	raw_spin_lock_irq(&sem->wait_lock);
> +	list_del(&waiter.list);
> +	if (list_empty(&sem->wait_list))
> +		rwsem_atomic_update(-RWSEM_WAITING_BIAS, sem);
> +	else
> +		__rwsem_do_wake(sem, RWSEM_WAKE_READERS);
> +	raw_spin_unlock_irq(&sem->wait_lock);
> +
> +	return ERR_PTR(-EINTR);
>  }

Looks much better but don't we have to check the count for potentially
pending writers?

-- 
Michal Hocko
SUSE Labs