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xen-netback: split event channels support for Xen backend driver

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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>
This commit is contained in:
Wei Liu
2013-05-22 06:34:45 +00:00
committed by David S. Miller
parent 8892475386
commit e1f00a69ec
4 changed files with 124 additions and 29 deletions
Download Patch File Download Diff File Expand all files Collapse all files

85
drivers/net/xen-netback/interface.c
View File

@@ -60,21 +60,39 @@ static int xenvif_rx_schedulable(struct xenvif *vif)
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 struct net_device_stats *xenvif_get_stats(struct net_device *dev)
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 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
}
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 @@ int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
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 @@ int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
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 @@ void xenvif_disconnect(struct xenvif *vif)
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.
*/