diff mbox

[net-next,2/2] xen-netfront: split event channels feature support

Message ID 1369090931-27306-3-git-send-email-wei.liu2@citrix.com
State Changes Requested, archived
Delegated to: David Miller
Headers show

Commit Message

Wei Liu May 20, 2013, 11:02 p.m. UTC 
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>
---
 drivers/net/xen-netfront.c |  181 +++++++++++++++++++++++++++++++++++++-------
 1 file changed, 152 insertions(+), 29 deletions(-)

Comments

David Vrabel May 21, 2013, 1:39 p.m. UTC | #1 
On 21/05/13 00:02, Wei Liu wrote:
> 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.
[...]
> --- a/drivers/net/xen-netfront.c
> +++ b/drivers/net/xen-netfront.c
> @@ -1503,12 +1528,90 @@ 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);

This message is pointless chatter as the information is available
elsewhere.  Please remove.

> +	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);

Similarly.

Otherwise,

Reviewed-by: David Vrabel <david.vrabel@citrix.com>

David
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Wei Liu May 21, 2013, 1:41 p.m. UTC | #2 
On Tue, May 21, 2013 at 02:39:01PM +0100, David Vrabel wrote:
[...]
> > +	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);
> 
> This message is pointless chatter as the information is available
> elsewhere.  Please remove.
> 

Do you mean /proc/interrupt by "elsewhere"? Information there doesn't
give you irq<->evtchn mapping info.


Wei.
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Konrad Rzeszutek Wilk May 21, 2013, 4:28 p.m. UTC | #3 
On Tue, May 21, 2013 at 02:41:49PM +0100, Wei Liu wrote:
> On Tue, May 21, 2013 at 02:39:01PM +0100, David Vrabel wrote:
> [...]
> > > +	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);
> > 
> > This message is pointless chatter as the information is available
> > elsewhere.  Please remove.
> > 
> 
> Do you mean /proc/interrupt by "elsewhere"? Information there doesn't
> give you irq<->evtchn mapping info.

If you really want to, that should be implemented via an DebugFS entry that can
be driven from drivers/xen/events.c. As the events.c is the generic code that sets
up the Xen events, pirqs, ipis, <-> Linux IRQs.

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Wei Liu May 21, 2013, 5:07 p.m. UTC | #4 
On Tue, May 21, 2013 at 12:28:25PM -0400, Konrad Rzeszutek Wilk wrote:
> On Tue, May 21, 2013 at 02:41:49PM +0100, Wei Liu wrote:
> > On Tue, May 21, 2013 at 02:39:01PM +0100, David Vrabel wrote:
> > [...]
> > > > +	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);
> > > 
> > > This message is pointless chatter as the information is available
> > > elsewhere.  Please remove.
> > > 
> > 
> > Do you mean /proc/interrupt by "elsewhere"? Information there doesn't
> > give you irq<->evtchn mapping info.
> 
> If you really want to, that should be implemented via an DebugFS entry that can
> be driven from drivers/xen/events.c. As the events.c is the generic code that sets
> up the Xen events, pirqs, ipis, <-> Linux IRQs.

I mainly focus on upstreaming all necessary features for a new Xen
network baseline, so I would rather not touch other files.

I will delete these dev_info, they don't seem to be critical anyway.


Wei.
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David Vrabel May 22, 2013, 3:52 p.m. UTC | #5 
On 21/05/13 14:41, Wei Liu wrote:
> On Tue, May 21, 2013 at 02:39:01PM +0100, David Vrabel wrote:
> [...]
>>> +	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);
>>
>> This message is pointless chatter as the information is available
>> elsewhere.  Please remove.
>>
> 
> Do you mean /proc/interrupt by "elsewhere"? Information there doesn't
> give you irq<->evtchn mapping info.

A combination of /proc/interrupts and the xenstore keys.

David
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diff mbox

Patch

diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index 5770e3b..716b2bd 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 +1528,90 @@  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 < 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;
+
+	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;
 	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 +1619,12 @@  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 +1659,18 @@  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 +1715,27 @@  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 +1848,9 @@  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);