Merge branch 'xen-netback-rx-refactor'

Paul Durrant says:

====================
xen-netback: guest rx side refactor

This series refactors the guest rx side of xen-netback:

- The code is moved into its own source module.

- The prefix variant of GSO handling is retired (since it is no longer
  in common use, and alternatives exist).

- The code is then simplified and modifications made to improve
  performance.

v2:
- Rebased onto refreshed net-next
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/xen-netback/Makefile

 obj-$(CONFIG_XEN_NETDEV_BACKEND) := xen-netback.o
 
-xen-netback-y := netback.o xenbus.o interface.o hash.o
+xen-netback-y := netback.o xenbus.o interface.o hash.o rx.o

drivers/net/xen-netback/common.h

@@ -91,13 +91,6 @@ struct xenvif_rx_meta {
  */
 #define MAX_XEN_SKB_FRAGS (65536 / XEN_PAGE_SIZE + 1)
 
-/* It's possible for an skb to have a maximal number of frags
- * but still be less than MAX_BUFFER_OFFSET in size. Thus the
- * worst-case number of copy operations is MAX_XEN_SKB_FRAGS per
- * ring slot.
- */
-#define MAX_GRANT_COPY_OPS (MAX_XEN_SKB_FRAGS * XEN_NETIF_RX_RING_SIZE)
-
 #define NETBACK_INVALID_HANDLE -1
 
 /* To avoid confusion, we define XEN_NETBK_LEGACY_SLOTS_MAX indicating
@@ -133,6 +126,15 @@ struct xenvif_stats {
 	unsigned long tx_frag_overflow;
 };
 
+#define COPY_BATCH_SIZE 64
+
+struct xenvif_copy_state {
+	struct gnttab_copy op[COPY_BATCH_SIZE];
+	RING_IDX idx[COPY_BATCH_SIZE];
+	unsigned int num;
+	struct sk_buff_head *completed;
+};
+
 struct xenvif_queue { /* Per-queue data for xenvif */
 	unsigned int id; /* Queue ID, 0-based */
 	char name[QUEUE_NAME_SIZE]; /* DEVNAME-qN */
@@ -189,12 +191,7 @@ struct xenvif_queue { /* Per-queue data for xenvif */
 	unsigned long last_rx_time;
 	bool stalled;
 
-	struct gnttab_copy grant_copy_op[MAX_GRANT_COPY_OPS];
-
-	/* We create one meta structure per ring request we consume, so
-	 * the maximum number is the same as the ring size.
-	 */
-	struct xenvif_rx_meta meta[XEN_NETIF_RX_RING_SIZE];
+	struct xenvif_copy_state rx_copy;
 
 	/* Transmit shaping: allow 'credit_bytes' every 'credit_usec'. */
 	unsigned long   credit_bytes;
@@ -260,7 +257,6 @@ struct xenvif {
 
 	/* Frontend feature information. */
 	int gso_mask;
-	int gso_prefix_mask;
 
 	u8 can_sg:1;
 	u8 ip_csum:1;
@@ -359,6 +355,7 @@ int xenvif_dealloc_kthread(void *data);
 
 irqreturn_t xenvif_ctrl_irq_fn(int irq, void *data);
 
+void xenvif_rx_action(struct xenvif_queue *queue);
 void xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff *skb);
 
 void xenvif_carrier_on(struct xenvif *vif);

drivers/net/xen-netback/interface.c

@@ -319,9 +319,9 @@ static netdev_features_t xenvif_fix_features(struct net_device *dev,
 
 	if (!vif->can_sg)
 		features &= ~NETIF_F_SG;
-	if (~(vif->gso_mask | vif->gso_prefix_mask) & GSO_BIT(TCPV4))
+	if (~(vif->gso_mask) & GSO_BIT(TCPV4))
 		features &= ~NETIF_F_TSO;
-	if (~(vif->gso_mask | vif->gso_prefix_mask) & GSO_BIT(TCPV6))
+	if (~(vif->gso_mask) & GSO_BIT(TCPV6))
 		features &= ~NETIF_F_TSO6;
 	if (!vif->ip_csum)
 		features &= ~NETIF_F_IP_CSUM;
@@ -467,7 +467,7 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
 	dev->netdev_ops	= &xenvif_netdev_ops;
 	dev->hw_features = NETIF_F_SG |
 		NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM |
-		NETIF_F_TSO | NETIF_F_TSO6;
+		NETIF_F_TSO | NETIF_F_TSO6 | NETIF_F_FRAGLIST;
 	dev->features = dev->hw_features | NETIF_F_RXCSUM;
 	dev->ethtool_ops = &xenvif_ethtool_ops;
 

drivers/net/xen-netback/xenbus.c

@@ -1135,7 +1135,6 @@ static int read_xenbus_vif_flags(struct backend_info *be)
 	vif->can_sg = !!val;
 
 	vif->gso_mask = 0;
-	vif->gso_prefix_mask = 0;
 
 	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4",
 			 "%d", &val) < 0)
@@ -1143,32 +1142,12 @@ static int read_xenbus_vif_flags(struct backend_info *be)
 	if (val)
 		vif->gso_mask |= GSO_BIT(TCPV4);
 
-	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4-prefix",
-			 "%d", &val) < 0)
-		val = 0;
-	if (val)
-		vif->gso_prefix_mask |= GSO_BIT(TCPV4);
-
 	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv6",
 			 "%d", &val) < 0)
 		val = 0;
 	if (val)
 		vif->gso_mask |= GSO_BIT(TCPV6);
 
-	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv6-prefix",
-			 "%d", &val) < 0)
-		val = 0;
-	if (val)
-		vif->gso_prefix_mask |= GSO_BIT(TCPV6);
-
-	if (vif->gso_mask & vif->gso_prefix_mask) {
-		xenbus_dev_fatal(dev, err,
-				 "%s: gso and gso prefix flags are not "
-				 "mutually exclusive",
-				 dev->otherend);
-		return -EOPNOTSUPP;
-	}
-
 	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-no-csum-offload",
 			 "%d", &val) < 0)
 		val = 0;