Provided by: kernel-doc-2.4.27_2.4.27-12_all
blk_init_queue - prepare a request queue for use with a block device
void blk_init_queue (request_queue_t *q, request_fn_proc *rfn);
q The request_queue_t to be initialised
rfn The function to be called to process requests that have
been placed on the queue.
If a block device wishes to use the standard request handling
procedures, which sorts requests and coalesces adjacent requests, then
it must call blk_init_queue. The function rfn will be called when
there are requests on the queue that need to be processed. If the
device supports plugging, then rfn may not be called immediately when
requests are available on the queue, but may be called at some time
later instead. Plugged queues are generally unplugged when a buffer
belonging to one of the requests on the queue is needed, or due to
rfn is not required, or even expected, to remove all requests off the
queue, but only as many as it can handle at a time. If it does leave
requests on the queue, it is responsible for arranging that the
requests get dealt with eventually.
A global spin lock $io_request_lock must be held while manipulating the
requests on the request queue.
The request on the head of the queue is by default assumed to be
potentially active, and it is not considered for re-ordering or merging
whenever the given queue is unplugged. This behaviour can be changed
blk_init_queue must be paired with a blk_cleanup_queue call when the
block device is deactivated (such as at module unload).