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

[Bob Liu <bob.liu@xxxxxxxxxx>]

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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