how to use chain in rtems?

[Chan Kim]

Hello, all,

To use chain, I added rtems_chain_control queue; in the host structure. 
Also, mrq has rtems_chain_node node; as the first element.

The method I used is 
to initialize : 
        rtems_chain_initialize_empty(&host->queue);
to append mrq to the queue : 
                rtems_chain_append(&host->queue, &mrq->node);
to get the first node : 
                mrq = (struct mmc_request *)host->queue.Chain.Head.fill;  (method 1)                
                mrq = (struct mmc_reequest *)rtems_chain_head(&host->queue);  (method 2)
                 
                rtems_chain_extract(&mrq->node);   (after method1 or method 2 I did this to distroy the node from the chain)

Is this correct method? I put WR mrq and when I was about to extract that, I enqueued RD mrq, then, when I read the first element,
it is RD mrq (using method 1) or some other value (using method 2).
Please someone tell me how to use it.

Thanks in advance.
Chan