BLK_INIT_QUEUE(9)                         Block Devices                         BLK_INIT_QUEUE(9)



NAME
       blk_init_queue - prepare a request queue for use with a block device

SYNOPSIS
       struct request_queue * blk_init_queue(request_fn_proc * rfn, spinlock_t * lock);

ARGUMENTS
       rfn
           The function to be called to process requests that have been placed on the queue.

       lock
           Request queue spin lock

DESCRIPTION
       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 memory pressure.

       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.

       The queue spin lock must be held while manipulating the requests on the request queue;
       this lock will be taken also from interrupt context, so irq disabling is needed for it.

       Function returns a pointer to the initialized request queue, or NULL if it didn't succeed.

NOTE
       blk_init_queue must be paired with a blk_cleanup_queue call when the block device is
       deactivated (such as at module unload).

COPYRIGHT
Kernel Hackers Manual 4.8.                 January 2017                         BLK_INIT_QUEUE(9)