xen-netback: Factor queue-specific data into queue struct

In preparation for multi-queue support in xen-netback, move the
queue-specific data from struct xenvif into struct xenvif_queue, and
update the rest of the code to use this.

Also adds loops over queues where appropriate, even though only one is
configured at this point, and uses alloc_netdev_mq() and the
corresponding multi-queue netif wake/start/stop functions in preparation
for multiple active queues.

Finally, implements a trivial queue selection function suitable for
ndo_select_queue, which simply returns 0 for a single queue and uses
skb_get_hash() to compute the queue index otherwise.
Signed-off-by: Andrew J. Bennieston <andrew.bennieston@citrix.com>
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/xen-netback/common.h

@@ -99,22 +99,43 @@ struct xenvif_rx_meta {
  */
 #define XEN_NETBK_LEGACY_SLOTS_MAX XEN_NETIF_NR_SLOTS_MIN
 
-struct xenvif {
-	/* Unique identifier for this interface. */
-	domid_t          domid;
-	unsigned int     handle;
+/* Queue name is interface name with "-qNNN" appended */
+#define QUEUE_NAME_SIZE (IFNAMSIZ + 5)
 
-	/* Is this interface disabled? True when backend discovers
-	 * frontend is rogue.
+/* IRQ name is queue name with "-tx" or "-rx" appended */
+#define IRQ_NAME_SIZE (QUEUE_NAME_SIZE + 3)
+
+struct xenvif;
+
+struct xenvif_stats {
+	/* Stats fields to be updated per-queue.
+	 * A subset of struct net_device_stats that contains only the
+	 * fields that are updated in netback.c for each queue.
 	 */
-	bool disabled;
+	unsigned int rx_bytes;
+	unsigned int rx_packets;
+	unsigned int tx_bytes;
+	unsigned int tx_packets;
+
+	/* Additional stats used by xenvif */
+	unsigned long rx_gso_checksum_fixup;
+	unsigned long tx_zerocopy_sent;
+	unsigned long tx_zerocopy_success;
+	unsigned long tx_zerocopy_fail;
+	unsigned long tx_frag_overflow;
+};
+
+struct xenvif_queue { /* Per-queue data for xenvif */
+	unsigned int id; /* Queue ID, 0-based */
+	char name[QUEUE_NAME_SIZE]; /* DEVNAME-qN */
+	struct xenvif *vif; /* Parent VIF */
 
 	/* Use NAPI for guest TX */
 	struct napi_struct napi;
 	/* When feature-split-event-channels = 0, tx_irq = rx_irq. */
 	unsigned int tx_irq;
 	/* Only used when feature-split-event-channels = 1 */
-	char tx_irq_name[IFNAMSIZ+4]; /* DEVNAME-tx */
+	char tx_irq_name[IRQ_NAME_SIZE]; /* DEVNAME-qN-tx */
 	struct xen_netif_tx_back_ring tx;
 	struct sk_buff_head tx_queue;
 	struct page *mmap_pages[MAX_PENDING_REQS];
@@ -150,7 +171,7 @@ struct xenvif {
 	/* When feature-split-event-channels = 0, tx_irq = rx_irq. */
 	unsigned int rx_irq;
 	/* Only used when feature-split-event-channels = 1 */
-	char rx_irq_name[IFNAMSIZ+4]; /* DEVNAME-rx */
+	char rx_irq_name[IRQ_NAME_SIZE]; /* DEVNAME-qN-rx */
 	struct xen_netif_rx_back_ring rx;
 	struct sk_buff_head rx_queue;
 	RING_IDX rx_last_skb_slots;
@@ -165,6 +186,22 @@ struct xenvif {
 	 */
 	struct xenvif_rx_meta meta[XEN_NETIF_RX_RING_SIZE];
 
+	/* Transmit shaping: allow 'credit_bytes' every 'credit_usec'. */
+	unsigned long   credit_bytes;
+	unsigned long   credit_usec;
+	unsigned long   remaining_credit;
+	struct timer_list credit_timeout;
+	u64 credit_window_start;
+
+	/* Statistics */
+	struct xenvif_stats stats;
+};
+
+struct xenvif {
+	/* Unique identifier for this interface. */
+	domid_t          domid;
+	unsigned int     handle;
+
 	u8               fe_dev_addr[6];
 
 	/* Frontend feature information. */
@@ -178,19 +215,13 @@ struct xenvif {
 	/* Internal feature information. */
 	u8 can_queue:1;	    /* can queue packets for receiver? */
 
-	/* Transmit shaping: allow 'credit_bytes' every 'credit_usec'. */
-	unsigned long   credit_bytes;
-	unsigned long   credit_usec;
-	unsigned long   remaining_credit;
-	struct timer_list credit_timeout;
-	u64 credit_window_start;
+	/* Is this interface disabled? True when backend discovers
+	 * frontend is rogue.
+	 */
+	bool disabled;
 
-	/* Statistics */
-	unsigned long rx_gso_checksum_fixup;
-	unsigned long tx_zerocopy_sent;
-	unsigned long tx_zerocopy_success;
-	unsigned long tx_zerocopy_fail;
-	unsigned long tx_frag_overflow;
+	/* Queues */
+	struct xenvif_queue *queues;
 
 	/* Miscellaneous private stuff. */
 	struct net_device *dev;
@@ -205,7 +236,9 @@ struct xenvif *xenvif_alloc(struct device *parent,
 			    domid_t domid,
 			    unsigned int handle);
 
-int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
+int xenvif_init_queue(struct xenvif_queue *queue);
+
+int xenvif_connect(struct xenvif_queue *queue, unsigned long tx_ring_ref,
 		   unsigned long rx_ring_ref, unsigned int tx_evtchn,
 		   unsigned int rx_evtchn);
 void xenvif_disconnect(struct xenvif *vif);
@@ -216,44 +249,47 @@ void xenvif_xenbus_fini(void);
 
 int xenvif_schedulable(struct xenvif *vif);
 
-int xenvif_must_stop_queue(struct xenvif *vif);
+int xenvif_must_stop_queue(struct xenvif_queue *queue);
+
+int xenvif_queue_stopped(struct xenvif_queue *queue);
+void xenvif_wake_queue(struct xenvif_queue *queue);
 
 /* (Un)Map communication rings. */
-void xenvif_unmap_frontend_rings(struct xenvif *vif);
-int xenvif_map_frontend_rings(struct xenvif *vif,
+void xenvif_unmap_frontend_rings(struct xenvif_queue *queue);
+int xenvif_map_frontend_rings(struct xenvif_queue *queue,
 			      grant_ref_t tx_ring_ref,
 			      grant_ref_t rx_ring_ref);
 
 /* Check for SKBs from frontend and schedule backend processing */
-void xenvif_napi_schedule_or_enable_events(struct xenvif *vif);
+void xenvif_napi_schedule_or_enable_events(struct xenvif_queue *queue);
 
 /* Prevent the device from generating any further traffic. */
 void xenvif_carrier_off(struct xenvif *vif);
 
-int xenvif_tx_action(struct xenvif *vif, int budget);
+int xenvif_tx_action(struct xenvif_queue *queue, int budget);
 
 int xenvif_kthread_guest_rx(void *data);
-void xenvif_kick_thread(struct xenvif *vif);
+void xenvif_kick_thread(struct xenvif_queue *queue);
 
 int xenvif_dealloc_kthread(void *data);
 
 /* Determine whether the needed number of slots (req) are available,
  * and set req_event if not.
  */
-bool xenvif_rx_ring_slots_available(struct xenvif *vif, int needed);
+bool xenvif_rx_ring_slots_available(struct xenvif_queue *queue, int needed);
 
-void xenvif_stop_queue(struct xenvif *vif);
+void xenvif_carrier_on(struct xenvif *vif);
 
 /* Callback from stack when TX packet can be released */
 void xenvif_zerocopy_callback(struct ubuf_info *ubuf, bool zerocopy_success);
 
 /* Unmap a pending page and release it back to the guest */
-void xenvif_idx_unmap(struct xenvif *vif, u16 pending_idx);
+void xenvif_idx_unmap(struct xenvif_queue *queue, u16 pending_idx);
 
-static inline pending_ring_idx_t nr_pending_reqs(struct xenvif *vif)
+static inline pending_ring_idx_t nr_pending_reqs(struct xenvif_queue *queue)
 {
 	return MAX_PENDING_REQS -
-		vif->pending_prod + vif->pending_cons;
+		queue->pending_prod + queue->pending_cons;
 }
 
 /* Callback from stack when TX packet can be released */

drivers/net/xen-netback/xenbus.c

@@ -19,6 +19,8 @@
 */
 
 #include "common.h"
+#include <linux/vmalloc.h>
+#include <linux/rtnetlink.h>
 
 struct backend_info {
 	struct xenbus_device *dev;
@@ -34,8 +36,9 @@ struct backend_info {
 	u8 have_hotplug_status_watch:1;
 };
 
-static int connect_rings(struct backend_info *);
-static void connect(struct backend_info *);
+static int connect_rings(struct backend_info *be, struct xenvif_queue *queue);
+static void connect(struct backend_info *be);
+static int read_xenbus_vif_flags(struct backend_info *be);
 static void backend_create_xenvif(struct backend_info *be);
 static void unregister_hotplug_status_watch(struct backend_info *be);
 static void set_backend_state(struct backend_info *be,
@@ -485,10 +488,10 @@ static void connect(struct backend_info *be)
 {
 	int err;
 	struct xenbus_device *dev = be->dev;
-
-	err = connect_rings(be);
-	if (err)
-		return;
+	unsigned long credit_bytes, credit_usec;
+	unsigned int queue_index;
+	unsigned int requested_num_queues = 1;
+	struct xenvif_queue *queue;
 
 	err = xen_net_read_mac(dev, be->vif->fe_dev_addr);
 	if (err) {
@@ -496,9 +499,34 @@ static void connect(struct backend_info *be)
 		return;
 	}
 
-	xen_net_read_rate(dev, &be->vif->credit_bytes,
-			  &be->vif->credit_usec);
-	be->vif->remaining_credit = be->vif->credit_bytes;
+	xen_net_read_rate(dev, &credit_bytes, &credit_usec);
+	read_xenbus_vif_flags(be);
+
+	be->vif->queues = vzalloc(requested_num_queues *
+				  sizeof(struct xenvif_queue));
+	rtnl_lock();
+	netif_set_real_num_tx_queues(be->vif->dev, requested_num_queues);
+	rtnl_unlock();
+
+	for (queue_index = 0; queue_index < requested_num_queues; ++queue_index) {
+		queue = &be->vif->queues[queue_index];
+		queue->vif = be->vif;
+		queue->id = queue_index;
+		snprintf(queue->name, sizeof(queue->name), "%s-q%u",
+				be->vif->dev->name, queue->id);
+
+		err = xenvif_init_queue(queue);
+		if (err)
+			goto err;
+
+		queue->remaining_credit = credit_bytes;
+
+		err = connect_rings(be, queue);
+		if (err)
+			goto err;
+	}
+
+	xenvif_carrier_on(be->vif);
 
 	unregister_hotplug_status_watch(be);
 	err = xenbus_watch_pathfmt(dev, &be->hotplug_status_watch,
@@ -507,18 +535,26 @@ static void connect(struct backend_info *be)
 	if (!err)
 		be->have_hotplug_status_watch = 1;
 
-	netif_wake_queue(be->vif->dev);
+	netif_tx_wake_all_queues(be->vif->dev);
+
+	return;
+
+err:
+	vfree(be->vif->queues);
+	be->vif->queues = NULL;
+	rtnl_lock();
+	netif_set_real_num_tx_queues(be->vif->dev, 0);
+	rtnl_unlock();
+	return;
 }
 
 
-static int connect_rings(struct backend_info *be)
+static int connect_rings(struct backend_info *be, struct xenvif_queue *queue)
 {
-	struct xenvif *vif = be->vif;
 	struct xenbus_device *dev = be->dev;
 	unsigned long tx_ring_ref, rx_ring_ref;
-	unsigned int tx_evtchn, rx_evtchn, rx_copy;
+	unsigned int tx_evtchn, rx_evtchn;
 	int err;
-	int val;
 
 	err = xenbus_gather(XBT_NIL, dev->otherend,
 			    "tx-ring-ref", "%lu", &tx_ring_ref,
@@ -546,6 +582,27 @@ static int connect_rings(struct backend_info *be)
 		rx_evtchn = tx_evtchn;
 	}
 
+	/* Map the shared frame, irq etc. */
+	err = xenvif_connect(queue, tx_ring_ref, rx_ring_ref,
+			     tx_evtchn, rx_evtchn);
+	if (err) {
+		xenbus_dev_fatal(dev, err,
+				 "mapping shared-frames %lu/%lu port tx %u rx %u",
+				 tx_ring_ref, rx_ring_ref,
+				 tx_evtchn, rx_evtchn);
+		return err;
+	}
+
+	return 0;
+}
+
+static int read_xenbus_vif_flags(struct backend_info *be)
+{
+	struct xenvif *vif = be->vif;
+	struct xenbus_device *dev = be->dev;
+	unsigned int rx_copy;
+	int err, val;
+
 	err = xenbus_scanf(XBT_NIL, dev->otherend, "request-rx-copy", "%u",
 			   &rx_copy);
 	if (err == -ENOENT) {
@@ -621,16 +678,6 @@ static int connect_rings(struct backend_info *be)
 		val = 0;
 	vif->ipv6_csum = !!val;
 
-	/* Map the shared frame, irq etc. */
-	err = xenvif_connect(vif, tx_ring_ref, rx_ring_ref,
-			     tx_evtchn, rx_evtchn);
-	if (err) {
-		xenbus_dev_fatal(dev, err,
-				 "mapping shared-frames %lu/%lu port tx %u rx %u",
-				 tx_ring_ref, rx_ring_ref,
-				 tx_evtchn, rx_evtchn);
-		return err;
-	}
 	return 0;
 }