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[Xen-devel] [RFC PATCH V3 16/16] netfront: split event channels support.



If this feature is not activated, rx_irq = tx_irq. See corresponding
netback change log for details.

Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 drivers/net/xen-netfront.c |  147 ++++++++++++++++++++++++++++++++++----------
 1 files changed, 115 insertions(+), 32 deletions(-)

diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index 32ec212..72c0429 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -98,7 +98,9 @@ struct netfront_info {
 
        unsigned long rx_gso_checksum_fixup;
 
-       unsigned int evtchn;
+       unsigned int split_evtchn;
+       unsigned int tx_evtchn, rx_evtchn;
+       unsigned int tx_irq, rx_irq;
        struct xenbus_device *xbdev;
 
        spinlock_t   tx_lock;
@@ -344,7 +346,7 @@ 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)
@@ -577,7 +579,7 @@ 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;
@@ -1242,22 +1244,35 @@ static int xennet_set_features(struct net_device *dev, 
u32 features)
        return 0;
 }
 
-static irqreturn_t xennet_interrupt(int irq, void *dev_id)
+static irqreturn_t xennet_tx_interrupt(int 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);
+static irqreturn_t xennet_rx_interrupt(int 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;
+}
+static irqreturn_t xennet_interrupt(int irq, void *dev_id)
+{
+       xennet_tx_interrupt(0, dev_id);
+
+       xennet_rx_interrupt(0, dev_id);
 
        return IRQ_HANDLED;
 }
@@ -1436,9 +1451,14 @@ 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->tx_irq = 0;
+       info->rx_evtchn = info->rx_irq = 0;
 
        for (i = 0; i < info->tx_ring_pages; i++) {
                int ref = info->tx_ring_ref[i];
@@ -1507,6 +1527,7 @@ static int setup_netfront(struct xenbus_device *dev, 
struct netfront_info *info)
        int err;
        struct net_device *netdev = info->netdev;
        unsigned int max_tx_ring_page_order, max_rx_ring_page_order;
+       unsigned int split_evtchn;
        int i, j;
 
        for (i = 0; i < XENNET_MAX_RING_PAGES; i++) {
@@ -1515,7 +1536,6 @@ static int setup_netfront(struct xenbus_device *dev, 
struct netfront_info *info)
        }
        info->rx.sring = NULL;
        info->tx.sring = NULL;
-       netdev->irq = 0;
 
        err = xen_net_read_mac(dev, netdev->dev_addr);
        if (err) {
@@ -1524,6 +1544,12 @@ static int setup_netfront(struct xenbus_device *dev, 
struct netfront_info *info)
        }
 
        err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
+                          "split-event-channels", "%u",
+                          &split_evtchn);
+       if (err < 0)
+               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) {
@@ -1589,20 +1615,59 @@ static int setup_netfront(struct xenbus_device *dev, 
struct netfront_info *info)
                info->rx_ring_ref[j] = err;
        }
 
-       err = xenbus_alloc_evtchn(dev, &info->evtchn);
-       if (err)
-               goto alloc_evtchn_fail;
+       if (!split_evtchn) {
+               err = xenbus_alloc_evtchn(dev, &info->tx_evtchn);
+               if (err)
+                       goto alloc_evtchn_fail;
 
-       err = bind_evtchn_to_irqhandler(info->evtchn, xennet_interrupt,
-                                       0, netdev->name, netdev);
-       if (err < 0)
-               goto bind_fail;
-       netdev->irq = err;
+               err = bind_evtchn_to_irqhandler(info->tx_evtchn,
+                                               xennet_interrupt,
+                                               0, netdev->name, info);
+               if (err < 0)
+                       goto bind_fail;
+               info->rx_evtchn = info->tx_evtchn;
+               info->tx_irq = info->rx_irq = err;
+               info->split_evtchn = 0;
+               dev_info(&dev->dev, "single event channel, irq = %d\n",
+                        info->tx_irq);
+       } else {
+               err = xenbus_alloc_evtchn(dev, &info->tx_evtchn);
+               if (err)
+                       goto alloc_evtchn_fail;
+               err = xenbus_alloc_evtchn(dev, &info->rx_evtchn);
+               if (err) {
+                       xenbus_free_evtchn(dev, info->tx_evtchn);
+                       goto alloc_evtchn_fail;
+               }
+               err = bind_evtchn_to_irqhandler(info->tx_evtchn,
+                                               xennet_tx_interrupt,
+                                               0, netdev->name, info);
+               if (err < 0)
+                       goto bind_fail;
+               info->tx_irq = err;
+               err = bind_evtchn_to_irqhandler(info->rx_evtchn,
+                                               xennet_rx_interrupt,
+                                               0, netdev->name, info);
+               if (err < 0) {
+                       unbind_from_irqhandler(info->tx_irq, info);
+                       goto bind_fail;
+               }
+               info->rx_irq = err;
+               info->split_evtchn = 1;
+               dev_info(&dev->dev, "split event channels,"
+                        " tx_irq = %d, rx_irq = %d\n",
+                        info->tx_irq, info->rx_irq);
+       }
 
        return 0;
 
 bind_fail:
-       xenbus_free_evtchn(dev, info->evtchn);
+       if (!split_evtchn)
+               xenbus_free_evtchn(dev, info->tx_evtchn);
+       else {
+               xenbus_free_evtchn(dev, info->tx_evtchn);
+               xenbus_free_evtchn(dev, info->rx_evtchn);
+       }
 alloc_evtchn_fail:
        for (; j >= 0; j--) {
                int ref = info->rx_ring_ref[j];
@@ -1690,11 +1755,27 @@ again:
                }
        }
 
-       err = xenbus_printf(xbt, dev->nodename,
-                           "event-channel", "%u", info->evtchn);
-       if (err) {
-               message = "writing event-channel";
-               goto abort_transaction;
+
+       if (!info->split_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",
@@ -1808,7 +1889,9 @@ 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->split_evtchn)
+               notify_remote_via_irq(np->rx_irq);
        xennet_tx_buf_gc(dev);
        xennet_alloc_rx_buffers(dev);
 
-- 
1.7.2.5


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