Re: [PATCH 03/10] xen/blkfront: reorg info->io_lock after using blk-mq API

From: Bob Liu
Date: Wed Feb 18 2015 - 21:08:29 EST



On 02/19/2015 01:05 AM, Christoph Hellwig wrote:
> On Sun, Feb 15, 2015 at 04:18:58PM +0800, Bob Liu wrote:
>> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
>> index 3589436..5a90a51 100644
>> --- a/drivers/block/xen-blkfront.c
>> +++ b/drivers/block/xen-blkfront.c
>> @@ -614,25 +614,28 @@ static int blk_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
>> blk_mq_start_request(qd->rq);
>> spin_lock_irq(&info->io_lock);
>> if (RING_FULL(&info->ring)) {
>> + spin_unlock_irq(&info->io_lock);
>> blk_mq_stop_hw_queue(hctx);
>> ret = BLK_MQ_RQ_QUEUE_BUSY;
>> goto out;
>> }
>>
>> if (blkif_request_flush_invalid(qd->rq, info)) {
>> + spin_unlock_irq(&info->io_lock);
>> ret = BLK_MQ_RQ_QUEUE_ERROR;
>> goto out;
>> }
>>
>> if (blkif_queue_request(qd->rq)) {
>> + spin_unlock_irq(&info->io_lock);
>> blk_mq_stop_hw_queue(hctx);
>> ret = BLK_MQ_RQ_QUEUE_BUSY;
>> goto out;
>> }
>>
>> flush_requests(info);
>> -out:
>> spin_unlock_irq(&info->io_lock);
>> +out:
>> return ret;
>> }
>
> I'd rather write the function something like:
>
> spin_lock_irq(&info->io_lock);
> if (RING_FULL(&info->ring))
> goto out_busy;
> if (blkif_request_flush_invalid(qd->rq, info))
> goto out_error;
>
> if (blkif_queue_request(qd->rq))
> goto out_busy;
>
> flush_requests(info);
> spin_unlock_irq(&info->io_lock);
> return BLK_MQ_RQ_QUEUE_OK;
> out_error:
> spin_unlock_irq(&info->io_lock);
> return BLK_MQ_RQ_QUEUE_ERROR;
> out_busy:
> spin_unlock_irq(&info->io_lock);
> blk_mq_stop_hw_queue(hctx);
> return BLK_MQ_RQ_QUEUE_BUSY;
> }
>

Thank you! Will be updated.

> Also this really should be merged into the first patch.
>

I thought it would be easier for people to review by split into three
patches.
Anyway, I can merge them into the first one.

--
Regards,
-Bob
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