Subject: Re: [PATCH 3/4] net: xen-netback: use API provided by xenbus module to map rings

From: Konrad Rzeszutek Wilk <[email-masked]>
Date: Thu, 20 Oct 2011 17:00:53 -0400

On Thu, Oct 20, 2011 at 11:45:18AM +0100, David Vrabel wrote:
> The xenbus module provides xenbus_map_ring_valloc() and
> xenbus_map_ring_vfree().  Use these to map the Tx and Rx ring pages
> granted by the frontend.
> 
> Signed-off-by: David Vrabel <[email-masked]>
> Acked-by: Ian Campbell <[email-masked]>

Acked-by: Konrad Rzeszutek Wilk <[email-masked]>

> Dave, this is a standalone patch and can be applied independently of
> the rest of the series.

.. or Dave, if you would like I can carry these patches.

> 
>  drivers/net/xen-netback/common.h  |   11 ++---
>  drivers/net/xen-netback/netback.c |   80 ++++++++-----------------------------
>  2 files changed, 22 insertions(+), 69 deletions(-)
> 
> diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
> index 161f207..94b79c3 100644
> --- a/drivers/net/xen-netback/common.h
> +++ b/drivers/net/xen-netback/common.h
> @@ -58,10 +58,6 @@ struct xenvif {
>  	u8               fe_dev_addr[6];
>  
>  	/* Physical parameters of the comms window. */
> -	grant_handle_t   tx_shmem_handle;
> -	grant_ref_t      tx_shmem_ref;
> -	grant_handle_t   rx_shmem_handle;
> -	grant_ref_t      rx_shmem_ref;
>  	unsigned int     irq;
>  
>  	/* List of frontends to notify after a batch of frames sent. */
> @@ -70,8 +66,6 @@ struct xenvif {
>  	/* The shared rings and indexes. */
>  	struct xen_netif_tx_back_ring tx;
>  	struct xen_netif_rx_back_ring rx;
> -	struct vm_struct *tx_comms_area;
> -	struct vm_struct *rx_comms_area;
>  
>  	/* Frontend feature information. */
>  	u8 can_sg:1;
> @@ -106,6 +100,11 @@ struct xenvif {
>  	wait_queue_head_t waiting_to_free;
>  };
>  
> +static inline struct xenbus_device *xenvif_to_xenbus_device(struct xenvif *vif)
> +{
> +	return to_xenbus_device(vif->dev->dev.parent);
> +}
> +
>  #define XEN_NETIF_TX_RING_SIZE __CONST_RING_SIZE(xen_netif_tx, PAGE_SIZE)
>  #define XEN_NETIF_RX_RING_SIZE __CONST_RING_SIZE(xen_netif_rx, PAGE_SIZE)
>  
> diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
> index fd00f25..3af2924 100644
> --- a/drivers/net/xen-netback/netback.c
> +++ b/drivers/net/xen-netback/netback.c
> @@ -1577,88 +1577,42 @@ static int xen_netbk_kthread(void *data)
>  
>  void xen_netbk_unmap_frontend_rings(struct xenvif *vif)
>  {
> -	struct gnttab_unmap_grant_ref op;
> -
> -	if (vif->tx.sring) {
> -		gnttab_set_unmap_op(&op, (unsigned long)vif->tx_comms_area->addr,
> -				    GNTMAP_host_map, vif->tx_shmem_handle);
> -
> -		if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
> -			BUG();
> -	}
> -
> -	if (vif->rx.sring) {
> -		gnttab_set_unmap_op(&op, (unsigned long)vif->rx_comms_area->addr,
> -				    GNTMAP_host_map, vif->rx_shmem_handle);
> -
> -		if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
> -			BUG();
> -	}
> -	if (vif->rx_comms_area)
> -		free_vm_area(vif->rx_comms_area);
> -	if (vif->tx_comms_area)
> -		free_vm_area(vif->tx_comms_area);
> +	if (vif->tx.sring)
> +		xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(vif),
> +					vif->tx.sring);
> +	if (vif->rx.sring)
> +		xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(vif),
> +					vif->rx.sring);
>  }
>  
>  int xen_netbk_map_frontend_rings(struct xenvif *vif,
>  				 grant_ref_t tx_ring_ref,
>  				 grant_ref_t rx_ring_ref)
>  {
> -	struct gnttab_map_grant_ref op;
> +	void *addr;
>  	struct xen_netif_tx_sring *txs;
>  	struct xen_netif_rx_sring *rxs;
>  
>  	int err = -ENOMEM;
>  
> -	vif->tx_comms_area = alloc_vm_area(PAGE_SIZE);
> -	if (vif->tx_comms_area == NULL)
> +	err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(vif),
> +				     tx_ring_ref, &addr);
> +	if (err)
>  		goto err;
>  
> -	vif->rx_comms_area = alloc_vm_area(PAGE_SIZE);
> -	if (vif->rx_comms_area == NULL)
> -		goto err;
> -
> -	gnttab_set_map_op(&op, (unsigned long)vif->tx_comms_area->addr,
> -			  GNTMAP_host_map, tx_ring_ref, vif->domid);
> -
> -	if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
> -		BUG();
> -
> -	if (op.status) {
> -		netdev_warn(vif->dev,
> -			    "failed to map tx ring. err=%d status=%d\n",
> -			    err, op.status);
> -		err = op.status;
> -		goto err;
> -	}
> -
> -	vif->tx_shmem_ref    = tx_ring_ref;
> -	vif->tx_shmem_handle = op.handle;
> -
> -	txs = (struct xen_netif_tx_sring *)vif->tx_comms_area->addr;
> +	txs = (struct xen_netif_tx_sring *)addr;
>  	BACK_RING_INIT(&vif->tx, txs, PAGE_SIZE);
>  
> -	gnttab_set_map_op(&op, (unsigned long)vif->rx_comms_area->addr,
> -			  GNTMAP_host_map, rx_ring_ref, vif->domid);
> -
> -	if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
> -		BUG();
> -
> -	if (op.status) {
> -		netdev_warn(vif->dev,
> -			    "failed to map rx ring. err=%d status=%d\n",
> -			    err, op.status);
> -		err = op.status;
> +	err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(vif),
> +				     rx_ring_ref, &addr);
> +	if (err)
>  		goto err;
> -	}
> -
> -	vif->rx_shmem_ref     = rx_ring_ref;
> -	vif->rx_shmem_handle  = op.handle;
> -	vif->rx_req_cons_peek = 0;
>  
> -	rxs = (struct xen_netif_rx_sring *)vif->rx_comms_area->addr;
> +	rxs = (struct xen_netif_rx_sring *)addr;
>  	BACK_RING_INIT(&vif->rx, rxs, PAGE_SIZE);
>  
> +	vif->rx_req_cons_peek = 0;
> +
>  	return 0;
>  
>  err:
> -- 
> 1.7.2.5
> 
> --
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