Re: [PATCH] mmc: queue: exclude asynchronous transfer for special request

[Konstantin Dorfman <kdorfman@codeaurora.org>]

On 12/21/2012 07:36 AM, Seungwon Jeon wrote:
> On Thursday, December 20, 2012, Konstantin Dorfman wrote:
>> Hello Jeon,
>>
>>
>> On 12/20/2012 12:27 PM, Seungwon Jeon wrote:
>>> Unlike normal r/w request, special requests(discard, flush)
>>> is finished with a one-time issue_fn. Request change to
>>> mqrq_prev makes unnecessary call.
>>>
>>> Signed-off-by: Seungwon Jeon <tgih.jun@samsung.com>
>>> ---
>>>    drivers/mmc/card/queue.c |    8 ++++++++
>>>    1 files changed, 8 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
>>> index fadf52e..a71db7a 100644
>>> --- a/drivers/mmc/card/queue.c
>>> +++ b/drivers/mmc/card/queue.c
>>> @@ -58,6 +58,7 @@ static int mmc_queue_thread(void *d)
>>>    	do {
>>>    		struct request *req = NULL;
>>>    		struct mmc_queue_req *tmp;
>>> +		unsigned int cmd_flags = 0;
>>>
>>>    		spin_lock_irq(q->queue_lock);
>>>    		set_current_state(TASK_INTERRUPTIBLE);
>>> @@ -67,12 +68,19 @@ static int mmc_queue_thread(void *d)
>>>
>>>    		if (req || mq->mqrq_prev->req) {
>>>    			set_current_state(TASK_RUNNING);
>>> +			cmd_flags = req ? req->cmd_flags : 0;
>>>    			mq->issue_fn(mq, req);
>>>
>>>    			/*
>>>    			 * Current request becomes previous request
>>>    			 * and vice versa.
>>> +			 * In case of special requests, current request
>>> +			 * has been finished. Do not remain it to previous
>>> +			 * request.
>>>    			 */
>>> +			if (cmd_flags & REQ_DISCARD || cmd_flags & REQ_FLUSH)
>>> +				mq->mqrq_cur->req = NULL;
>>> +
>>>    			mq->mqrq_prev->brq.mrq.data = NULL;
>>>    			mq->mqrq_prev->req = NULL;
>>>    			tmp = mq->mqrq_prev;
>>>
>> It is better to define control mask, REQ_CONTROL_MASK, which will
>> include all control/special requests.
> Agree, it's better.
>
>>
>> Then, when additional request will be added, there will be no need to
>> change here, only update the mask.
>>
>> Another option - to clean mq->mqrq_cur->req immediately after executing
>> a special request in mmc_blk_issue_rq().
> Yes, I also approached it with the same idea at the beginning.
> But it seems that 'queue.c' has a role of management of two requests,
> while 'block.c' just uses these request. It makes sense?
Sure, agree with you.

Thanks,

-- 
Konstantin Dorfman,
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