Re: [PATCH] virtio_ring: remove unnecessary to_vvq call

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On Mon, Jun 06, 2022 at 08:59:51PM -0400, Bo Liu wrote:
> In many functions, the parameter passed in is "_vq", which still call
> to_vvq() to get 'vq'. It can avoid unnecessary call of to_vvq() by directly
> passing in the parameter "vq".
> 
> Signed-off-by: Bo Liu <liubo03@xxxxxxxxxx>

What does the patch accomplish? Is the generated binary faster? smaller?

> ---
>  drivers/virtio/virtio_ring.c | 100 ++++++++++++++---------------------
>  1 file changed, 41 insertions(+), 59 deletions(-)
> 
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 13a7348cedff..f82db59fdbdc 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -648,9 +648,8 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
>  	return -ENOMEM;
>  }
>  
> -static bool virtqueue_kick_prepare_split(struct virtqueue *_vq)
> +static bool virtqueue_kick_prepare_split(struct vring_virtqueue *vq)
>  {
> -	struct vring_virtqueue *vq = to_vvq(_vq);
>  	u16 new, old;
>  	bool needs_kick;
>  
> @@ -667,12 +666,12 @@ static bool virtqueue_kick_prepare_split(struct virtqueue *_vq)
>  	LAST_ADD_TIME_INVALID(vq);
>  
>  	if (vq->event) {
> -		needs_kick = vring_need_event(virtio16_to_cpu(_vq->vdev,
> +		needs_kick = vring_need_event(virtio16_to_cpu(vq->vq.vdev,
>  					vring_avail_event(&vq->split.vring)),
>  					      new, old);
>  	} else {
>  		needs_kick = !(vq->split.vring.used->flags &
> -					cpu_to_virtio16(_vq->vdev,
> +					cpu_to_virtio16(vq->vq.vdev,
>  						VRING_USED_F_NO_NOTIFY));
>  	}
>  	END_USE(vq);
> @@ -735,11 +734,10 @@ static inline bool more_used_split(const struct vring_virtqueue *vq)
>  			vq->split.vring.used->idx);
>  }
>  
> -static void *virtqueue_get_buf_ctx_split(struct virtqueue *_vq,
> +static void *virtqueue_get_buf_ctx_split(struct vring_virtqueue *vq,
>  					 unsigned int *len,
>  					 void **ctx)
>  {
> -	struct vring_virtqueue *vq = to_vvq(_vq);
>  	void *ret;
>  	unsigned int i;
>  	u16 last_used;
> @@ -761,9 +759,9 @@ static void *virtqueue_get_buf_ctx_split(struct virtqueue *_vq,
>  	virtio_rmb(vq->weak_barriers);
>  
>  	last_used = (vq->last_used_idx & (vq->split.vring.num - 1));
> -	i = virtio32_to_cpu(_vq->vdev,
> +	i = virtio32_to_cpu(vq->vq.vdev,
>  			vq->split.vring.used->ring[last_used].id);
> -	*len = virtio32_to_cpu(_vq->vdev,
> +	*len = virtio32_to_cpu(vq->vq.vdev,
>  			vq->split.vring.used->ring[last_used].len);
>  
>  	if (unlikely(i >= vq->split.vring.num)) {
> @@ -785,7 +783,7 @@ static void *virtqueue_get_buf_ctx_split(struct virtqueue *_vq,
>  	if (!(vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT))
>  		virtio_store_mb(vq->weak_barriers,
>  				&vring_used_event(&vq->split.vring),
> -				cpu_to_virtio16(_vq->vdev, vq->last_used_idx));
> +				cpu_to_virtio16(vq->vq.vdev, vq->last_used_idx));
>  
>  	LAST_ADD_TIME_INVALID(vq);
>  
> @@ -793,10 +791,8 @@ static void *virtqueue_get_buf_ctx_split(struct virtqueue *_vq,
>  	return ret;
>  }
>  
> -static void virtqueue_disable_cb_split(struct virtqueue *_vq)
> +static void virtqueue_disable_cb_split(struct vring_virtqueue *vq)
>  {
> -	struct vring_virtqueue *vq = to_vvq(_vq);
> -
>  	if (!(vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) {
>  		vq->split.avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
>  		if (vq->event)
> @@ -804,14 +800,13 @@ static void virtqueue_disable_cb_split(struct virtqueue *_vq)
>  			vring_used_event(&vq->split.vring) = 0x0;
>  		else
>  			vq->split.vring.avail->flags =
> -				cpu_to_virtio16(_vq->vdev,
> +				cpu_to_virtio16(vq->vq.vdev,
>  						vq->split.avail_flags_shadow);
>  	}
>  }
>  
> -static unsigned int virtqueue_enable_cb_prepare_split(struct virtqueue *_vq)
> +static unsigned int virtqueue_enable_cb_prepare_split(struct vring_virtqueue *vq)
>  {
> -	struct vring_virtqueue *vq = to_vvq(_vq);
>  	u16 last_used_idx;
>  
>  	START_USE(vq);
> @@ -825,26 +820,23 @@ static unsigned int virtqueue_enable_cb_prepare_split(struct virtqueue *_vq)
>  		vq->split.avail_flags_shadow &= ~VRING_AVAIL_F_NO_INTERRUPT;
>  		if (!vq->event)
>  			vq->split.vring.avail->flags =
> -				cpu_to_virtio16(_vq->vdev,
> +				cpu_to_virtio16(vq->vq.vdev,
>  						vq->split.avail_flags_shadow);
>  	}
> -	vring_used_event(&vq->split.vring) = cpu_to_virtio16(_vq->vdev,
> +	vring_used_event(&vq->split.vring) = cpu_to_virtio16(vq->vq.vdev,
>  			last_used_idx = vq->last_used_idx);
>  	END_USE(vq);
>  	return last_used_idx;
>  }
>  
> -static bool virtqueue_poll_split(struct virtqueue *_vq, unsigned int last_used_idx)
> +static bool virtqueue_poll_split(struct vring_virtqueue *vq, unsigned int last_used_idx)
>  {
> -	struct vring_virtqueue *vq = to_vvq(_vq);
> -
> -	return (u16)last_used_idx != virtio16_to_cpu(_vq->vdev,
> +	return (u16)last_used_idx != virtio16_to_cpu(vq->vq.vdev,
>  			vq->split.vring.used->idx);
>  }
>  
> -static bool virtqueue_enable_cb_delayed_split(struct virtqueue *_vq)
> +static bool virtqueue_enable_cb_delayed_split(struct vring_virtqueue *vq)
>  {
> -	struct vring_virtqueue *vq = to_vvq(_vq);
>  	u16 bufs;
>  
>  	START_USE(vq);
> @@ -858,7 +850,7 @@ static bool virtqueue_enable_cb_delayed_split(struct virtqueue *_vq)
>  		vq->split.avail_flags_shadow &= ~VRING_AVAIL_F_NO_INTERRUPT;
>  		if (!vq->event)
>  			vq->split.vring.avail->flags =
> -				cpu_to_virtio16(_vq->vdev,
> +				cpu_to_virtio16(vq->vq.vdev,
>  						vq->split.avail_flags_shadow);
>  	}
>  	/* TODO: tune this threshold */
> @@ -866,9 +858,9 @@ static bool virtqueue_enable_cb_delayed_split(struct virtqueue *_vq)
>  
>  	virtio_store_mb(vq->weak_barriers,
>  			&vring_used_event(&vq->split.vring),
> -			cpu_to_virtio16(_vq->vdev, vq->last_used_idx + bufs));
> +			cpu_to_virtio16(vq->vq.vdev, vq->last_used_idx + bufs));
>  
> -	if (unlikely((u16)(virtio16_to_cpu(_vq->vdev, vq->split.vring.used->idx)
> +	if (unlikely((u16)(virtio16_to_cpu(vq->vq.vdev, vq->split.vring.used->idx)
>  					- vq->last_used_idx) > bufs)) {
>  		END_USE(vq);
>  		return false;
> @@ -878,9 +870,8 @@ static bool virtqueue_enable_cb_delayed_split(struct virtqueue *_vq)
>  	return true;
>  }
>  
> -static void *virtqueue_detach_unused_buf_split(struct virtqueue *_vq)
> +static void *virtqueue_detach_unused_buf_split(struct vring_virtqueue *vq)
>  {
> -	struct vring_virtqueue *vq = to_vvq(_vq);
>  	unsigned int i;
>  	void *buf;
>  
> @@ -893,7 +884,7 @@ static void *virtqueue_detach_unused_buf_split(struct virtqueue *_vq)
>  		buf = vq->split.desc_state[i].data;
>  		detach_buf_split(vq, i, NULL);
>  		vq->split.avail_idx_shadow--;
> -		vq->split.vring.avail->idx = cpu_to_virtio16(_vq->vdev,
> +		vq->split.vring.avail->idx = cpu_to_virtio16(vq->vq.vdev,
>  				vq->split.avail_idx_shadow);
>  		END_USE(vq);
>  		return buf;
> @@ -1296,9 +1287,8 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
>  	return -EIO;
>  }
>  
> -static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq)
> +static bool virtqueue_kick_prepare_packed(struct vring_virtqueue *vq)
>  {
> -	struct vring_virtqueue *vq = to_vvq(_vq);
>  	u16 new, old, off_wrap, flags, wrap_counter, event_idx;
>  	bool needs_kick;
>  	union {
> @@ -1410,11 +1400,10 @@ static inline bool more_used_packed(const struct vring_virtqueue *vq)
>  			vq->packed.used_wrap_counter);
>  }
>  
> -static void *virtqueue_get_buf_ctx_packed(struct virtqueue *_vq,
> +static void *virtqueue_get_buf_ctx_packed(struct vring_virtqueue *vq,
>  					  unsigned int *len,
>  					  void **ctx)
>  {
> -	struct vring_virtqueue *vq = to_vvq(_vq);
>  	u16 last_used, id;
>  	void *ret;
>  
> @@ -1475,10 +1464,8 @@ static void *virtqueue_get_buf_ctx_packed(struct virtqueue *_vq,
>  	return ret;
>  }
>  
> -static void virtqueue_disable_cb_packed(struct virtqueue *_vq)
> +static void virtqueue_disable_cb_packed(struct vring_virtqueue *vq)
>  {
> -	struct vring_virtqueue *vq = to_vvq(_vq);
> -
>  	if (vq->packed.event_flags_shadow != VRING_PACKED_EVENT_FLAG_DISABLE) {
>  		vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE;
>  		vq->packed.vring.driver->flags =
> @@ -1486,10 +1473,8 @@ static void virtqueue_disable_cb_packed(struct virtqueue *_vq)
>  	}
>  }
>  
> -static unsigned int virtqueue_enable_cb_prepare_packed(struct virtqueue *_vq)
> +static unsigned int virtqueue_enable_cb_prepare_packed(struct vring_virtqueue *vq)
>  {
> -	struct vring_virtqueue *vq = to_vvq(_vq);
> -
>  	START_USE(vq);
>  
>  	/*
> @@ -1522,9 +1507,8 @@ static unsigned int virtqueue_enable_cb_prepare_packed(struct virtqueue *_vq)
>  			VRING_PACKED_EVENT_F_WRAP_CTR);
>  }
>  
> -static bool virtqueue_poll_packed(struct virtqueue *_vq, u16 off_wrap)
> +static bool virtqueue_poll_packed(struct vring_virtqueue *vq, u16 off_wrap)
>  {
> -	struct vring_virtqueue *vq = to_vvq(_vq);
>  	bool wrap_counter;
>  	u16 used_idx;
>  
> @@ -1534,9 +1518,8 @@ static bool virtqueue_poll_packed(struct virtqueue *_vq, u16 off_wrap)
>  	return is_used_desc_packed(vq, used_idx, wrap_counter);
>  }
>  
> -static bool virtqueue_enable_cb_delayed_packed(struct virtqueue *_vq)
> +static bool virtqueue_enable_cb_delayed_packed(struct vring_virtqueue *vq)
>  {
> -	struct vring_virtqueue *vq = to_vvq(_vq);
>  	u16 used_idx, wrap_counter;
>  	u16 bufs;
>  
> @@ -1593,9 +1576,8 @@ static bool virtqueue_enable_cb_delayed_packed(struct virtqueue *_vq)
>  	return true;
>  }
>  
> -static void *virtqueue_detach_unused_buf_packed(struct virtqueue *_vq)
> +static void *virtqueue_detach_unused_buf_packed(struct vring_virtqueue *vq)
>  {
> -	struct vring_virtqueue *vq = to_vvq(_vq);
>  	unsigned int i;
>  	void *buf;
>  
> @@ -1906,8 +1888,8 @@ bool virtqueue_kick_prepare(struct virtqueue *_vq)
>  {
>  	struct vring_virtqueue *vq = to_vvq(_vq);
>  
> -	return vq->packed_ring ? virtqueue_kick_prepare_packed(_vq) :
> -				 virtqueue_kick_prepare_split(_vq);
> +	return vq->packed_ring ? virtqueue_kick_prepare_packed(vq) :
> +				 virtqueue_kick_prepare_split(vq);
>  }
>  EXPORT_SYMBOL_GPL(virtqueue_kick_prepare);
>  
> @@ -1977,8 +1959,8 @@ void *virtqueue_get_buf_ctx(struct virtqueue *_vq, unsigned int *len,
>  {
>  	struct vring_virtqueue *vq = to_vvq(_vq);
>  
> -	return vq->packed_ring ? virtqueue_get_buf_ctx_packed(_vq, len, ctx) :
> -				 virtqueue_get_buf_ctx_split(_vq, len, ctx);
> +	return vq->packed_ring ? virtqueue_get_buf_ctx_packed(vq, len, ctx) :
> +				 virtqueue_get_buf_ctx_split(vq, len, ctx);
>  }
>  EXPORT_SYMBOL_GPL(virtqueue_get_buf_ctx);
>  
> @@ -2007,9 +1989,9 @@ void virtqueue_disable_cb(struct virtqueue *_vq)
>  		return;
>  
>  	if (vq->packed_ring)
> -		virtqueue_disable_cb_packed(_vq);
> +		virtqueue_disable_cb_packed(vq);
>  	else
> -		virtqueue_disable_cb_split(_vq);
> +		virtqueue_disable_cb_split(vq);
>  }
>  EXPORT_SYMBOL_GPL(virtqueue_disable_cb);
>  
> @@ -2032,8 +2014,8 @@ unsigned int virtqueue_enable_cb_prepare(struct virtqueue *_vq)
>  	if (vq->event_triggered)
>  		vq->event_triggered = false;
>  
> -	return vq->packed_ring ? virtqueue_enable_cb_prepare_packed(_vq) :
> -				 virtqueue_enable_cb_prepare_split(_vq);
> +	return vq->packed_ring ? virtqueue_enable_cb_prepare_packed(vq) :
> +				 virtqueue_enable_cb_prepare_split(vq);
>  }
>  EXPORT_SYMBOL_GPL(virtqueue_enable_cb_prepare);
>  
> @@ -2054,8 +2036,8 @@ bool virtqueue_poll(struct virtqueue *_vq, unsigned int last_used_idx)
>  		return false;
>  
>  	virtio_mb(vq->weak_barriers);
> -	return vq->packed_ring ? virtqueue_poll_packed(_vq, last_used_idx) :
> -				 virtqueue_poll_split(_vq, last_used_idx);
> +	return vq->packed_ring ? virtqueue_poll_packed(vq, last_used_idx) :
> +				 virtqueue_poll_split(vq, last_used_idx);
>  }
>  EXPORT_SYMBOL_GPL(virtqueue_poll);
>  
> @@ -2098,8 +2080,8 @@ bool virtqueue_enable_cb_delayed(struct virtqueue *_vq)
>  	if (vq->event_triggered)
>  		vq->event_triggered = false;
>  
> -	return vq->packed_ring ? virtqueue_enable_cb_delayed_packed(_vq) :
> -				 virtqueue_enable_cb_delayed_split(_vq);
> +	return vq->packed_ring ? virtqueue_enable_cb_delayed_packed(vq) :
> +				 virtqueue_enable_cb_delayed_split(vq);
>  }
>  EXPORT_SYMBOL_GPL(virtqueue_enable_cb_delayed);
>  
> @@ -2115,8 +2097,8 @@ void *virtqueue_detach_unused_buf(struct virtqueue *_vq)
>  {
>  	struct vring_virtqueue *vq = to_vvq(_vq);
>  
> -	return vq->packed_ring ? virtqueue_detach_unused_buf_packed(_vq) :
> -				 virtqueue_detach_unused_buf_split(_vq);
> +	return vq->packed_ring ? virtqueue_detach_unused_buf_packed(vq) :
> +				 virtqueue_detach_unused_buf_split(vq);
>  }
>  EXPORT_SYMBOL_GPL(virtqueue_detach_unused_buf);
>  
> -- 
> 2.27.0

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