Wei Liu
2013-May-21 18:35 UTC
[PATCH net-next V2 2/2] xen-netfront: split event channels support for Xen frontend driver
This patch adds a new feature called feature-split-event-channels for
netfront, enabling it to handle TX and RX events separately.
If netback does not support this feature, it falls back to use single event
channel.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
---
drivers/net/xen-netfront.c | 173 ++++++++++++++++++++++++++++++++++++--------
1 file changed, 144 insertions(+), 29 deletions(-)
diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index 5770e3b..1fb2bfb4 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -85,7 +85,15 @@ 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;
+ /* Only used when split event channels support is enabled */
+ char tx_irq_name[IFNAMSIZ+4]; /* DEVNAME-tx */
+ char rx_irq_name[IFNAMSIZ+4]; /* DEVNAME-rx */
+
struct xenbus_device *xbdev;
spinlock_t tx_lock;
@@ -330,7 +338,7 @@ 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)
@@ -623,7 +631,7 @@ 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;
@@ -1254,23 +1262,35 @@ static int xennet_set_features(struct net_device *dev,
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))
+ return IRQ_HANDLED;
+}
+
+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);
- }
- spin_unlock_irqrestore(&np->tx_lock, flags);
+ return IRQ_HANDLED;
+}
+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;
}
@@ -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;
/* End access and free the pages */
xennet_end_access(info->tx_ring_ref, info->tx.sring);
@@ -1503,12 +1528,82 @@ 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;
+
+ 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 < 0)
+ goto fail;
+ err = xenbus_alloc_evtchn(info->xbdev, &info->rx_evtchn);
+ if (err < 0)
+ goto alloc_rx_evtchn_fail;
+
+ snprintf(info->tx_irq_name, sizeof(info->tx_irq_name),
+ "%s-tx", info->netdev->name);
+ err = bind_evtchn_to_irqhandler(info->tx_evtchn,
+ xennet_tx_interrupt,
+ 0, info->tx_irq_name, info);
+ if (err < 0)
+ goto bind_tx_fail;
+ info->tx_irq = err;
+
+ snprintf(info->rx_irq_name, sizeof(info->rx_irq_name),
+ "%s-rx", info->netdev->name);
+ err = bind_evtchn_to_irqhandler(info->rx_evtchn,
+ xennet_rx_interrupt,
+ 0, info->rx_irq_name, info);
+ if (err < 0)
+ goto bind_rx_fail;
+ info->rx_irq = err;
+
+ 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;
struct net_device *netdev = info->netdev;
+ unsigned int feature_split_evtchn;
info->tx_ring_ref = GRANT_INVALID_REF;
info->rx_ring_ref = GRANT_INVALID_REF;
@@ -1516,6 +1611,12 @@ static int setup_netfront(struct xenbus_device *dev,
struct netfront_info *info)
info->tx.sring = NULL;
netdev->irq = 0;
+ err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
+ "feature-split-event-channels", "%u",
+ &feature_split_evtchn);
+ if (err < 0)
+ feature_split_evtchn = 0;
+
err = xen_net_read_mac(dev, netdev->dev_addr);
if (err) {
xenbus_dev_fatal(dev, err, "parsing %s/mac", dev->nodename);
@@ -1550,22 +1651,18 @@ static int setup_netfront(struct xenbus_device *dev,
struct netfront_info *info)
goto grant_rx_ring_fail;
info->rx_ring_ref = err;
- 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;
- err = bind_evtchn_to_irqhandler(info->evtchn, xennet_interrupt,
- 0, netdev->name, netdev);
- if (err < 0)
- goto bind_fail;
- netdev->irq = err;
return 0;
/* If we fail to setup netfront, it is safe to just revoke access to
* granted pages because backend is not accessing it at this point.
*/
-bind_fail:
- xenbus_free_evtchn(dev, info->evtchn);
alloc_evtchn_fail:
gnttab_end_foreign_access_ref(info->rx_ring_ref, 0);
grant_rx_ring_fail:
@@ -1610,11 +1707,27 @@ again:
message = "writing rx ring-ref";
goto abort_transaction;
}
- 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",
@@ -1727,7 +1840,9 @@ 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
Jan Beulich
2013-May-22 08:13 UTC
Re: [PATCH net-next V2 2/2] xen-netfront: split event channels support for Xen frontend driver
>>> On 21.05.13 at 20:35, Wei Liu <wei.liu2@citrix.com> wrote: > @@ -1550,22 +1651,18 @@ static int setup_netfront(struct xenbus_device *dev, struct netfront_info *info) > goto grant_rx_ring_fail; > info->rx_ring_ref = err; > > - 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;You could easily fall back to single event channel mode here if split setup fails. Jan