linux-kernel - Re: [PATCH 2/9] virtio-blk: reorganize virtblk_add

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Date:	Sun, 17 Feb 2013 14:38:45 +0800
From:	Asias He <asias@...hat.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
CC:	linux-kernel@...r.kernel.org,
	Wanlong Gao <gaowanlong@...fujitsu.com>, mst@...hat.com,
	Rusty Russell <rusty@...tcorp.com.au>, kvm@...r.kernel.org,
	virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH 2/9] virtio-blk: reorganize virtblk_add_req

On 02/12/2013 08:23 PM, Paolo Bonzini wrote:
> Right now, both virtblk_add_req and virtblk_add_req_wait call
> virtqueue_add_buf.  To prepare for the next patches, abstract the call
> to virtqueue_add_buf into a new function __virtblk_add_req, and include
> the waiting logic directly in virtblk_add_req.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>

Reviewed-by: Asias He <asias@...hat.com>

> ---
>  drivers/block/virtio_blk.c |   55 ++++++++++++++++----------------------------
>  1 files changed, 20 insertions(+), 35 deletions(-)
> 
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index 8ad21a2..fd8a689 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -100,50 +100,39 @@ static inline struct virtblk_req *virtblk_alloc_req(struct virtio_blk *vblk,
>  	return vbr;
>  }
>  
> -static void virtblk_add_buf_wait(struct virtio_blk *vblk,
> -				 struct virtblk_req *vbr,
> -				 unsigned long out,
> -				 unsigned long in)
> +static inline int __virtblk_add_req(struct virtqueue *vq,
> +			     struct virtblk_req *vbr,
> +			     unsigned long out,
> +			     unsigned long in)
>  {
> +	return virtqueue_add_buf(vq, vbr->sg, out, in, vbr, GFP_ATOMIC);
> +}
> +
> +static void virtblk_add_req(struct virtblk_req *vbr,
> +			    unsigned int out, unsigned int in)
> +{
> +	struct virtio_blk *vblk = vbr->vblk;
>  	DEFINE_WAIT(wait);
> +	int ret;
>  
> -	for (;;) {
> +	spin_lock_irq(vblk->disk->queue->queue_lock);
> +	while (unlikely((ret = __virtblk_add_req(vblk->vq, vbr,
> +						 out, in)) < 0)) {
>  		prepare_to_wait_exclusive(&vblk->queue_wait, &wait,
>  					  TASK_UNINTERRUPTIBLE);
>  
> +		spin_unlock_irq(vblk->disk->queue->queue_lock);
> +		io_schedule();
>  		spin_lock_irq(vblk->disk->queue->queue_lock);
> -		if (virtqueue_add_buf(vblk->vq, vbr->sg, out, in, vbr,
> -				      GFP_ATOMIC) < 0) {
> -			spin_unlock_irq(vblk->disk->queue->queue_lock);
> -			io_schedule();
> -		} else {
> -			virtqueue_kick(vblk->vq);
> -			spin_unlock_irq(vblk->disk->queue->queue_lock);
> -			break;
> -		}
>  
> +		finish_wait(&vblk->queue_wait, &wait);
>  	}
>  
> -	finish_wait(&vblk->queue_wait, &wait);
> -}
> -
> -static inline void virtblk_add_req(struct virtblk_req *vbr,
> -				   unsigned int out, unsigned int in)
> -{
> -	struct virtio_blk *vblk = vbr->vblk;
> -
> -	spin_lock_irq(vblk->disk->queue->queue_lock);
> -	if (unlikely(virtqueue_add_buf(vblk->vq, vbr->sg, out, in, vbr,
> -					GFP_ATOMIC) < 0)) {
> -		spin_unlock_irq(vblk->disk->queue->queue_lock);
> -		virtblk_add_buf_wait(vblk, vbr, out, in);
> -		return;
> -	}
>  	virtqueue_kick(vblk->vq);
>  	spin_unlock_irq(vblk->disk->queue->queue_lock);
>  }
>  
> -static int virtblk_bio_send_flush(struct virtblk_req *vbr)
> +static void virtblk_bio_send_flush(struct virtblk_req *vbr)
>  {
>  	unsigned int out = 0, in = 0;
>  
> @@ -155,11 +144,9 @@ static int virtblk_bio_send_flush(struct virtblk_req *vbr)
>  	sg_set_buf(&vbr->sg[out + in++], &vbr->status, sizeof(vbr->status));
>  
>  	virtblk_add_req(vbr, out, in);
> -
> -	return 0;
>  }
>  
> -static int virtblk_bio_send_data(struct virtblk_req *vbr)
> +static void virtblk_bio_send_data(struct virtblk_req *vbr)
>  {
>  	struct virtio_blk *vblk = vbr->vblk;
>  	unsigned int num, out = 0, in = 0;
> @@ -188,8 +175,6 @@ static int virtblk_bio_send_data(struct virtblk_req *vbr)
>  	}
>  
>  	virtblk_add_req(vbr, out, in);
> -
> -	return 0;
>  }
>  
>  static void virtblk_bio_send_data_work(struct work_struct *work)
> 


-- 
Asias
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