1BLK_INIT_QUEUE(9)                Block Devices               BLK_INIT_QUEUE(9)
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NAME

6       blk_init_queue - prepare a request queue for use with a block device
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SYNOPSIS

9       struct request_queue * blk_init_queue(request_fn_proc * rfn,
10                                             spinlock_t * lock);
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ARGUMENTS

13       rfn
14           The function to be called to process requests that have been placed
15           on the queue.
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17       lock
18           Request queue spin lock
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DESCRIPTION

21       If a block device wishes to use the standard request handling
22       procedures, which sorts requests and coalesces adjacent requests, then
23       it must call blk_init_queue. The function rfn will be called when there
24       are requests on the queue that need to be processed. If the device
25       supports plugging, then rfn may not be called immediately when requests
26       are available on the queue, but may be called at some time later
27       instead. Plugged queues are generally unplugged when a buffer belonging
28       to one of the requests on the queue is needed, or due to memory
29       pressure.
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31       rfn is not required, or even expected, to remove all requests off the
32       queue, but only as many as it can handle at a time. If it does leave
33       requests on the queue, it is responsible for arranging that the
34       requests get dealt with eventually.
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36       The queue spin lock must be held while manipulating the requests on the
37       request queue; this lock will be taken also from interrupt context, so
38       irq disabling is needed for it.
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40       Function returns a pointer to the initialized request queue, or NULL if
41       it didn't succeed.
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NOTE

44       blk_init_queue must be paired with a blk_cleanup_queue call when the
45       block device is deactivated (such as at module unload).
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48Kernel Hackers Manual 2.6.       November 2011               BLK_INIT_QUEUE(9)
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