Re: [PATCH] add netconsole support for xen-netfront

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Wed, Jan 11, 2012 at 04:52:36PM +0800, Zhenzhong Duan wrote:
> add polling interface to xen-netfront device to support netconsole
> 

Ian, any thoughts on the spinlock changes?

> Signed-off-by: Tina.Yang <tina.yang@oracle.com>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Cc: Jeremy Fitzhardinge <jeremy@goop.org>
> Signed-off-by: Zhenzhong.Duan <zhenzhong.duan@oracle.com>
> Tested-by: gurudas.pai <gurudas.pai@oracle.com>
> ---
>  drivers/net/xen-netfront.c |   57 ++++++++++++++++++++++++++-----------------
>  1 files changed, 34 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
> index fa67905..db638b4 100644
> --- a/drivers/net/xen-netfront.c
> +++ b/drivers/net/xen-netfront.c
> @@ -489,6 +489,7 @@ static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
>  	int frags = skb_shinfo(skb)->nr_frags;
>  	unsigned int offset = offset_in_page(data);
>  	unsigned int len = skb_headlen(skb);
> +	unsigned long flags;
>  
>  	frags += DIV_ROUND_UP(offset + len, PAGE_SIZE);
>  	if (unlikely(frags > MAX_SKB_FRAGS + 1)) {
> @@ -498,12 +499,12 @@ static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
>  		goto drop;
>  	}
>  
> -	spin_lock_irq(&np->tx_lock);
> +	spin_lock_irqsave(&np->tx_lock, flags);
>  
>  	if (unlikely(!netif_carrier_ok(dev) ||
>  		     (frags > 1 && !xennet_can_sg(dev)) ||
>  		     netif_needs_gso(skb, netif_skb_features(skb)))) {
> -		spin_unlock_irq(&np->tx_lock);
> +		spin_unlock_irqrestore(&np->tx_lock, flags);
>  		goto drop;
>  	}
>  
> @@ -574,7 +575,7 @@ static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
>  	if (!netfront_tx_slot_available(np))
>  		netif_stop_queue(dev);
>  
> -	spin_unlock_irq(&np->tx_lock);
> +	spin_unlock_irqrestore(&np->tx_lock, flags);
>  
>  	return NETDEV_TX_OK;
>  
> @@ -1228,6 +1229,33 @@ static int xennet_set_features(struct net_device *dev,
>  	return 0;
>  }
>  
> +static irqreturn_t xennet_interrupt(int irq, void *dev_id)
> +{
> +	struct net_device *dev = dev_id;
> +	struct netfront_info *np = netdev_priv(dev);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&np->tx_lock, flags);
> +
> +	if (likely(netif_carrier_ok(dev))) {
> +		xennet_tx_buf_gc(dev);
> +		/* Under tx_lock: protects access to rx shared-ring indexes. */
> +		if (RING_HAS_UNCONSUMED_RESPONSES(&np->rx))
> +			napi_schedule(&np->napi);
> +	}
> +
> +	spin_unlock_irqrestore(&np->tx_lock, flags);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +#ifdef CONFIG_NET_POLL_CONTROLLER
> +static void xennet_poll_controller(struct net_device *dev)
> +{
> +	xennet_interrupt(0, dev);
> +}
> +#endif
> +
>  static const struct net_device_ops xennet_netdev_ops = {
>  	.ndo_open            = xennet_open,
>  	.ndo_uninit          = xennet_uninit,
> @@ -1239,6 +1267,9 @@ static const struct net_device_ops xennet_netdev_ops = {
>  	.ndo_validate_addr   = eth_validate_addr,
>  	.ndo_fix_features    = xennet_fix_features,
>  	.ndo_set_features    = xennet_set_features,
> +#ifdef CONFIG_NET_POLL_CONTROLLER
> +	.ndo_poll_controller = xennet_poll_controller,
> +#endif
>  };
>  
>  static struct net_device * __devinit xennet_create_dev(struct xenbus_device *dev)
> @@ -1448,26 +1479,6 @@ static int xen_net_read_mac(struct xenbus_device *dev, u8 mac[])
>  	return 0;
>  }
>  
> -static irqreturn_t xennet_interrupt(int irq, void *dev_id)
> -{
> -	struct net_device *dev = dev_id;
> -	struct netfront_info *np = netdev_priv(dev);
> -	unsigned long flags;
> -
> -	spin_lock_irqsave(&np->tx_lock, flags);
> -
> -	if (likely(netif_carrier_ok(dev))) {
> -		xennet_tx_buf_gc(dev);
> -		/* Under tx_lock: protects access to rx shared-ring indexes. */
> -		if (RING_HAS_UNCONSUMED_RESPONSES(&np->rx))
> -			napi_schedule(&np->napi);
> -	}
> -
> -	spin_unlock_irqrestore(&np->tx_lock, flags);
> -
> -	return IRQ_HANDLED;
> -}
> -
>  static int setup_netfront(struct xenbus_device *dev, struct netfront_info *info)
>  {
>  	struct xen_netif_tx_sring *txs;
> -- 
> 1.7.3