xen-netback: split event channels support for Xen backend driver
Netback and netfront only use one event channel to do TX / RX notification,
which may cause unnecessary wake-up of processing routines. This patch adds a
new feature called feature-split-event-channels to netback, enabling it to
handle TX and RX events separately.
Netback will use tx_irq to notify guest for TX completion, rx_irq for RX
notification.
If frontend doesn't support this feature, tx_irq equals to rx_irq.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 82202c2..087d2db 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -60,21 +60,39 @@
return xenvif_schedulable(vif) && !xen_netbk_rx_ring_full(vif);
}
-static irqreturn_t xenvif_interrupt(int irq, void *dev_id)
+static irqreturn_t xenvif_tx_interrupt(int irq, void *dev_id)
{
struct xenvif *vif = dev_id;
if (vif->netbk == NULL)
- return IRQ_NONE;
+ return IRQ_HANDLED;
xen_netbk_schedule_xenvif(vif);
+ return IRQ_HANDLED;
+}
+
+static irqreturn_t xenvif_rx_interrupt(int irq, void *dev_id)
+{
+ struct xenvif *vif = dev_id;
+
+ if (vif->netbk == NULL)
+ return IRQ_HANDLED;
+
if (xenvif_rx_schedulable(vif))
netif_wake_queue(vif->dev);
return IRQ_HANDLED;
}
+static irqreturn_t xenvif_interrupt(int irq, void *dev_id)
+{
+ xenvif_tx_interrupt(irq, dev_id);
+ xenvif_rx_interrupt(irq, dev_id);
+
+ return IRQ_HANDLED;
+}
+
static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct xenvif *vif = netdev_priv(dev);
@@ -125,13 +143,17 @@
static void xenvif_up(struct xenvif *vif)
{
xen_netbk_add_xenvif(vif);
- enable_irq(vif->irq);
+ enable_irq(vif->tx_irq);
+ if (vif->tx_irq != vif->rx_irq)
+ enable_irq(vif->rx_irq);
xen_netbk_check_rx_xenvif(vif);
}
static void xenvif_down(struct xenvif *vif)
{
- disable_irq(vif->irq);
+ disable_irq(vif->tx_irq);
+ if (vif->tx_irq != vif->rx_irq)
+ disable_irq(vif->rx_irq);
del_timer_sync(&vif->credit_timeout);
xen_netbk_deschedule_xenvif(vif);
xen_netbk_remove_xenvif(vif);
@@ -308,12 +330,13 @@
}
int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
- unsigned long rx_ring_ref, unsigned int evtchn)
+ unsigned long rx_ring_ref, unsigned int tx_evtchn,
+ unsigned int rx_evtchn)
{
int err = -ENOMEM;
/* Already connected through? */
- if (vif->irq)
+ if (vif->tx_irq)
return 0;
__module_get(THIS_MODULE);
@@ -322,13 +345,37 @@
if (err < 0)
goto err;
- err = bind_interdomain_evtchn_to_irqhandler(
- vif->domid, evtchn, xenvif_interrupt, 0,
- vif->dev->name, vif);
- if (err < 0)
- goto err_unmap;
- vif->irq = err;
- disable_irq(vif->irq);
+ if (tx_evtchn == rx_evtchn) {
+ /* feature-split-event-channels == 0 */
+ err = bind_interdomain_evtchn_to_irqhandler(
+ vif->domid, tx_evtchn, xenvif_interrupt, 0,
+ vif->dev->name, vif);
+ if (err < 0)
+ goto err_unmap;
+ vif->tx_irq = vif->rx_irq = err;
+ disable_irq(vif->tx_irq);
+ } else {
+ /* feature-split-event-channels == 1 */
+ snprintf(vif->tx_irq_name, sizeof(vif->tx_irq_name),
+ "%s-tx", vif->dev->name);
+ err = bind_interdomain_evtchn_to_irqhandler(
+ vif->domid, tx_evtchn, xenvif_tx_interrupt, 0,
+ vif->tx_irq_name, vif);
+ if (err < 0)
+ goto err_unmap;
+ vif->tx_irq = err;
+ disable_irq(vif->tx_irq);
+
+ snprintf(vif->rx_irq_name, sizeof(vif->rx_irq_name),
+ "%s-rx", vif->dev->name);
+ err = bind_interdomain_evtchn_to_irqhandler(
+ vif->domid, rx_evtchn, xenvif_rx_interrupt, 0,
+ vif->rx_irq_name, vif);
+ if (err < 0)
+ goto err_tx_unbind;
+ vif->rx_irq = err;
+ disable_irq(vif->rx_irq);
+ }
xenvif_get(vif);
@@ -342,6 +389,9 @@
rtnl_unlock();
return 0;
+err_tx_unbind:
+ unbind_from_irqhandler(vif->tx_irq, vif);
+ vif->tx_irq = 0;
err_unmap:
xen_netbk_unmap_frontend_rings(vif);
err:
@@ -375,8 +425,13 @@
atomic_dec(&vif->refcnt);
wait_event(vif->waiting_to_free, atomic_read(&vif->refcnt) == 0);
- if (vif->irq) {
- unbind_from_irqhandler(vif->irq, vif);
+ if (vif->tx_irq) {
+ if (vif->tx_irq == vif->rx_irq)
+ unbind_from_irqhandler(vif->tx_irq, vif);
+ else {
+ unbind_from_irqhandler(vif->tx_irq, vif);
+ unbind_from_irqhandler(vif->rx_irq, vif);
+ }
/* vif->irq is valid, we had a module_get in
* xenvif_connect.
*/