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block: merge blk_invoke_request_fn() into __blk_run_queue() 

__blk_run_queue wraps blk_invoke_request_fn() such that it
additionally removes plug and bails out early if the queue is empty.
Both extra operations have their own pending mechanisms and don't
cause any harm correctness-wise when they are done superflously.

The only user of blk_invoke_request_fn() being blk_start_queue(),
there isn't much reason to keep both functions around.  Merge
blk_invoke_request_fn() into __blk_run_queue() and make
blk_start_queue() use __blk_run_queue() instead.

[ Impact: merge two subtly different internal functions ]

Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Tejun Heo 2009-04-23 11:05:17 +09:00 committed by Jens Axboe
parent db2dbb12dc
commit a538cd03be
1 changed files with 14 additions and 21 deletions
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35
block/blk-core.c
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@ -333,24 +333,6 @@ void blk_unplug(struct request_queue *q)
} }
EXPORT_SYMBOL(blk_unplug); EXPORT_SYMBOL(blk_unplug);
static void blk_invoke_request_fn(struct request_queue *q)
{
if (unlikely(blk_queue_stopped(q)))
return;
/*
* one level of recursion is ok and is much faster than kicking
* the unplug handling
*/
if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) {
q->request_fn(q);
queue_flag_clear(QUEUE_FLAG_REENTER, q);
} else {
queue_flag_set(QUEUE_FLAG_PLUGGED, q);
kblockd_schedule_work(q, &q->unplug_work);
}
}
/** /**
* blk_start_queue - restart a previously stopped queue * blk_start_queue - restart a previously stopped queue
* @q: The &struct request_queue in question * @q: The &struct request_queue in question
@ -365,7 +347,7 @@ void blk_start_queue(struct request_queue *q)
WARN_ON(!irqs_disabled()); WARN_ON(!irqs_disabled());
queue_flag_clear(QUEUE_FLAG_STOPPED, q); queue_flag_clear(QUEUE_FLAG_STOPPED, q);
blk_invoke_request_fn(q); __blk_run_queue(q);
} }
EXPORT_SYMBOL(blk_start_queue); EXPORT_SYMBOL(blk_start_queue);
@ -425,12 +407,23 @@ void __blk_run_queue(struct request_queue *q)
{ {
blk_remove_plug(q); blk_remove_plug(q);
if (unlikely(blk_queue_stopped(q)))
return;
if (elv_queue_empty(q))
return;
/* /*
* Only recurse once to avoid overrunning the stack, let the unplug * Only recurse once to avoid overrunning the stack, let the unplug
* handling reinvoke the handler shortly if we already got there. * handling reinvoke the handler shortly if we already got there.
*/ */
if (!elv_queue_empty(q)) if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) {
blk_invoke_request_fn(q); q->request_fn(q);
queue_flag_clear(QUEUE_FLAG_REENTER, q);
} else {
queue_flag_set(QUEUE_FLAG_PLUGGED, q);
kblockd_schedule_work(q, &q->unplug_work);
}
} }
EXPORT_SYMBOL(__blk_run_queue); EXPORT_SYMBOL(__blk_run_queue);