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Message-ID: <20130304212416.GI16762@phenom.dumpdata.com>
Date: Mon, 4 Mar 2013 16:24:16 -0500
From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To: Wei Liu <wei.liu2@...rix.com>
Cc: xen-devel@...ts.xen.org, netdev@...r.kernel.org,
ian.campbell@...rix.com, annie.li@...cle.com
Subject: Re: [PATCH 8/8] netfront: split event channels support
On Fri, Feb 15, 2013 at 04:00:09PM +0000, Wei Liu wrote:
> If this feature is not activated, rx_irq = tx_irq. See corresponding netback
> change log for details.
To make it easier for people that use 'git log --grep' one usually says:
"See xen/netfront: Use .. " for the frontend implementation. That way
you can just copy-n-paste the title of the patch in the search functionality.
You should also include in this patch the description of the protocol.
And explain how it benefits the networking subsystem?
>
> Signed-off-by: Wei Liu <wei.liu2@...rix.com>
> ---
> drivers/net/xen-netfront.c | 184 ++++++++++++++++++++++++++++++++++++--------
> 1 file changed, 152 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
> index de73a71..ea9b656 100644
> --- a/drivers/net/xen-netfront.c
> +++ b/drivers/net/xen-netfront.c
> @@ -100,7 +100,12 @@ struct netfront_info {
>
> struct napi_struct napi;
>
> - unsigned int evtchn;
> + /*
> + * Split event channels support, tx_* == rx_* when using
> + * single event channel.
> + */
> + unsigned int tx_evtchn, rx_evtchn;
> + unsigned int tx_irq, rx_irq;
> struct xenbus_device *xbdev;
>
> spinlock_t tx_lock;
> @@ -344,7 +349,7 @@ no_skb:
> push:
> RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&np->rx, notify);
> if (notify)
> - notify_remote_via_irq(np->netdev->irq);
> + notify_remote_via_irq(np->rx_irq);
> }
>
> static int xennet_open(struct net_device *dev)
> @@ -633,7 +638,7 @@ static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
>
> RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&np->tx, notify);
> if (notify)
> - notify_remote_via_irq(np->netdev->irq);
> + notify_remote_via_irq(np->tx_irq);
>
> u64_stats_update_begin(&stats->syncp);
> stats->tx_bytes += skb->len;
> @@ -1263,26 +1268,41 @@ static int xennet_set_features(struct net_device *dev,
> return 0;
> }
>
> -static irqreturn_t xennet_interrupt(int irq, void *dev_id)
> +/* Used for tx completion */
> +static irqreturn_t xennet_tx_interrupt(int tx_irq, void *dev_id)
> {
> - struct net_device *dev = dev_id;
> - struct netfront_info *np = netdev_priv(dev);
> + struct netfront_info *np = dev_id;
> + struct net_device *dev = np->netdev;
> unsigned long flags;
>
> spin_lock_irqsave(&np->tx_lock, flags);
> + xennet_tx_buf_gc(dev);
> + spin_unlock_irqrestore(&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);
> - }
> + return IRQ_HANDLED;
> +}
>
> - spin_unlock_irqrestore(&np->tx_lock, flags);
> +/* Used for rx */
> +static irqreturn_t xennet_rx_interrupt(int rx_irq, void *dev_id)
> +{
> + struct netfront_info *np = dev_id;
> + struct net_device *dev = np->netdev;
> +
> + if (likely(netif_carrier_ok(dev) &&
> + RING_HAS_UNCONSUMED_RESPONSES(&np->rx)))
> + napi_schedule(&np->napi);
>
> return IRQ_HANDLED;
> }
>
> +/* Used for single event channel configuration */
> +static irqreturn_t xennet_interrupt(int irq, void *dev_id)
> +{
> + xennet_tx_interrupt(irq, dev_id);
> + xennet_rx_interrupt(irq, dev_id);
> + return IRQ_HANDLED;
> +}
> +
> #ifdef CONFIG_NET_POLL_CONTROLLER
> static void xennet_poll_controller(struct net_device *dev)
> {
> @@ -1451,9 +1471,14 @@ static void xennet_disconnect_backend(struct netfront_info *info)
> spin_unlock_irq(&info->tx_lock);
> spin_unlock_bh(&info->rx_lock);
>
> - if (info->netdev->irq)
> - unbind_from_irqhandler(info->netdev->irq, info->netdev);
> - info->evtchn = info->netdev->irq = 0;
> + if (info->tx_irq && (info->tx_irq == info->rx_irq))
> + unbind_from_irqhandler(info->tx_irq, info);
> + if (info->tx_irq && (info->tx_irq != info->rx_irq)) {
> + unbind_from_irqhandler(info->tx_irq, info);
> + unbind_from_irqhandler(info->rx_irq, info);
> + }
> + info->tx_evtchn = info->rx_evtchn = 0;
> + info->tx_irq = info->rx_irq = 0;
>
> xenbus_unmap_ring_vfree(info->xbdev, (void *)info->tx.sring);
> free_pages((unsigned long)info->tx.sring, info->tx_ring_page_order);
> @@ -1503,11 +1528,86 @@ static int xen_net_read_mac(struct xenbus_device *dev, u8 mac[])
> return 0;
> }
>
> +static int setup_netfront_single(struct netfront_info *info)
> +{
> + int err;
> +
> + err = xenbus_alloc_evtchn(info->xbdev, &info->tx_evtchn);
> + if (err < 0)
> + goto fail;
> +
> + err = bind_evtchn_to_irqhandler(info->tx_evtchn,
> + xennet_interrupt,
> + 0, info->netdev->name, info);
> + if (err < 0)
> + goto bind_fail;
> + info->rx_evtchn = info->tx_evtchn;
> + info->rx_irq = info->tx_irq = err;
> + dev_info(&info->xbdev->dev,
> + "single event channel, evtchn = %d, irq = %d\n",
> + info->tx_evtchn, info->tx_irq);
> +
> + return 0;
> +
> +bind_fail:
> + xenbus_free_evtchn(info->xbdev, info->tx_evtchn);
> + info->tx_evtchn = 0;
> +fail:
> + return err;
> +}
> +
> +static int setup_netfront_split(struct netfront_info *info)
> +{
> + int err;
> +
> + err = xenbus_alloc_evtchn(info->xbdev, &info->tx_evtchn);
> + if (err)
> + goto fail;
> + err = xenbus_alloc_evtchn(info->xbdev, &info->rx_evtchn);
> + if (err)
> + goto alloc_rx_evtchn_fail;
> +
> + err = bind_evtchn_to_irqhandler(info->tx_evtchn,
> + xennet_tx_interrupt,
> + 0, info->netdev->name, info);
> + if (err < 0)
> + goto bind_tx_fail;
> + info->tx_irq = err;
> +
> + err = bind_evtchn_to_irqhandler(info->rx_evtchn,
> + xennet_rx_interrupt,
> + 0, info->netdev->name, info);
> + if (err < 0)
> + goto bind_rx_fail;
> +
> + info->rx_irq = err;
> +
> + dev_info(&info->xbdev->dev,
> + "split event channels, tx_evtchn/irq = %d/%d, rx_evtchn/irq = %d/%d",
> + info->tx_evtchn, info->tx_irq,
> + info->rx_evtchn, info->rx_irq);
> +
> + return 0;
> +
> +bind_rx_fail:
> + unbind_from_irqhandler(info->tx_irq, info);
> + info->tx_irq = 0;
> +bind_tx_fail:
> + xenbus_free_evtchn(info->xbdev, info->rx_evtchn);
> + info->rx_evtchn = 0;
> +alloc_rx_evtchn_fail:
> + xenbus_free_evtchn(info->xbdev, info->tx_evtchn);
> + info->tx_evtchn = 0;
> +fail:
> + return err;
> +}
> +
> static int setup_netfront(struct xenbus_device *dev, struct netfront_info *info)
> {
> struct xen_netif_tx_sring *txs;
> struct xen_netif_rx_sring *rxs;
> int err;
> + unsigned int feature_split_evtchn;
> struct net_device *netdev = info->netdev;
> unsigned int max_tx_ring_page_order, max_rx_ring_page_order;
> int i;
> @@ -1527,6 +1627,12 @@ static int setup_netfront(struct xenbus_device *dev, struct netfront_info *info)
> }
>
> err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
> + "feature-split-event-channels", "%u",
> + &feature_split_evtchn);
> + if (err < 0)
> + feature_split_evtchn = 0;
> +
> + err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
> "max-tx-ring-page-order", "%u",
> &max_tx_ring_page_order);
> if (err < 0) {
> @@ -1598,20 +1704,17 @@ static int setup_netfront(struct xenbus_device *dev, struct netfront_info *info)
> if (err < 0)
> goto grant_rx_ring_fail;
>
> - err = xenbus_alloc_evtchn(dev, &info->evtchn);
> + if (feature_split_evtchn)
> + err = setup_netfront_split(info);
> + else
> + err = setup_netfront_single(info);
> +
> if (err)
> - goto alloc_evtchn_fail;
> + goto setup_evtchn_fail;
>
> - err = bind_evtchn_to_irqhandler(info->evtchn, xennet_interrupt,
> - 0, netdev->name, netdev);
> - if (err < 0)
> - goto bind_fail;
> - netdev->irq = err;
> return 0;
>
> -bind_fail:
> - xenbus_free_evtchn(dev, info->evtchn);
> -alloc_evtchn_fail:
> +setup_evtchn_fail:
> xenbus_unmap_ring_vfree(info->xbdev, (void *)info->rx.sring);
> grant_rx_ring_fail:
> free_pages((unsigned long)info->rx.sring, info->rx_ring_page_order);
> @@ -1696,11 +1799,26 @@ again:
> }
> }
>
> - err = xenbus_printf(xbt, dev->nodename,
> - "event-channel", "%u", info->evtchn);
> - if (err) {
> - message = "writing event-channel";
> - goto abort_transaction;
> + if (info->tx_evtchn == info->rx_evtchn) {
> + err = xenbus_printf(xbt, dev->nodename,
> + "event-channel", "%u", info->tx_evtchn);
> + if (err) {
> + message = "writing event-channel";
> + goto abort_transaction;
> + }
> + } else {
> + err = xenbus_printf(xbt, dev->nodename,
> + "event-channel-tx", "%u", info->tx_evtchn);
> + if (err) {
> + message = "writing event-channel-tx";
> + goto abort_transaction;
> + }
> + err = xenbus_printf(xbt, dev->nodename,
> + "event-channel-rx", "%u", info->rx_evtchn);
> + if (err) {
> + message = "writing event-channel-rx";
> + goto abort_transaction;
> + }
> }
>
> err = xenbus_printf(xbt, dev->nodename, "request-rx-copy", "%u",
> @@ -1814,7 +1932,9 @@ static int xennet_connect(struct net_device *dev)
> * packets.
> */
> netif_carrier_on(np->netdev);
> - notify_remote_via_irq(np->netdev->irq);
> + notify_remote_via_irq(np->tx_irq);
> + if (np->tx_irq != np->rx_irq)
> + notify_remote_via_irq(np->rx_irq);
> xennet_tx_buf_gc(dev);
> xennet_alloc_rx_buffers(dev);
>
> --
> 1.7.10.4
>
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