1 files changed, 71 insertions, 146 deletions

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index acf13920e6d..43341b82649 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -138,36 +138,26 @@ static inline pending_ring_idx_t nr_pending_reqs(struct xenvif *vif)
 		vif->pending_prod + vif->pending_cons;
 }
 
-static int max_required_rx_slots(struct xenvif *vif)
+bool xenvif_rx_ring_slots_available(struct xenvif *vif, int needed)
 {
-	int max = DIV_ROUND_UP(vif->dev->mtu, PAGE_SIZE);
+	RING_IDX prod, cons;
 
-	/* XXX FIXME: RX path dependent on MAX_SKB_FRAGS */
-	if (vif->can_sg || vif->gso_mask || vif->gso_prefix_mask)
-		max += MAX_SKB_FRAGS + 1; /* extra_info + frags */
-
-	return max;
-}
-
-int xenvif_rx_ring_full(struct xenvif *vif)
-{
-	RING_IDX peek   = vif->rx_req_cons_peek;
-	RING_IDX needed = max_required_rx_slots(vif);
+	do {
+		prod = vif->rx.sring->req_prod;
+		cons = vif->rx.req_cons;
 
-	return ((vif->rx.sring->req_prod - peek) < needed) ||
-	       ((vif->rx.rsp_prod_pvt + XEN_NETIF_RX_RING_SIZE - peek) < needed);
-}
+		if (prod - cons >= needed)
+			return true;
 
-int xenvif_must_stop_queue(struct xenvif *vif)
-{
-	if (!xenvif_rx_ring_full(vif))
-		return 0;
+		vif->rx.sring->req_event = prod + 1;
 
-	vif->rx.sring->req_event = vif->rx_req_cons_peek +
-		max_required_rx_slots(vif);
-	mb(); /* request notification /then/ check the queue */
+		/* Make sure event is visible before we check prod
+		 * again.
+		 */
+		mb();
+	} while (vif->rx.sring->req_prod != prod);
 
-	return xenvif_rx_ring_full(vif);
+	return false;
 }
 
 /*
@@ -210,93 +200,6 @@ static bool start_new_rx_buffer(int offset, unsigned long size, int head)
 	return false;
 }
 
-struct xenvif_count_slot_state {
-	unsigned long copy_off;
-	bool head;
-};
-
-unsigned int xenvif_count_frag_slots(struct xenvif *vif,
-				     unsigned long offset, unsigned long size,
-				     struct xenvif_count_slot_state *state)
-{
-	unsigned count = 0;
-
-	offset &= ~PAGE_MASK;
-
-	while (size > 0) {
-		unsigned long bytes;
-
-		bytes = PAGE_SIZE - offset;
-
-		if (bytes > size)
-			bytes = size;
-
-		if (start_new_rx_buffer(state->copy_off, bytes, state->head)) {
-			count++;
-			state->copy_off = 0;
-		}
-
-		if (state->copy_off + bytes > MAX_BUFFER_OFFSET)
-			bytes = MAX_BUFFER_OFFSET - state->copy_off;
-
-		state->copy_off += bytes;
-
-		offset += bytes;
-		size -= bytes;
-
-		if (offset == PAGE_SIZE)
-			offset = 0;
-
-		state->head = false;
-	}
-
-	return count;
-}
-
-/*
- * Figure out how many ring slots we're going to need to send @skb to
- * the guest. This function is essentially a dry run of
- * xenvif_gop_frag_copy.
- */
-unsigned int xenvif_count_skb_slots(struct xenvif *vif, struct sk_buff *skb)
-{
-	struct xenvif_count_slot_state state;
-	unsigned int count;
-	unsigned char *data;
-	unsigned i;
-
-	state.head = true;
-	state.copy_off = 0;
-
-	/* Slot for the first (partial) page of data. */
-	count = 1;
-
-	/* Need a slot for the GSO prefix for GSO extra data? */
-	if (skb_shinfo(skb)->gso_size)
-		count++;
-
-	data = skb->data;
-	while (data < skb_tail_pointer(skb)) {
-		unsigned long offset = offset_in_page(data);
-		unsigned long size = PAGE_SIZE - offset;
-
-		if (data + size > skb_tail_pointer(skb))
-			size = skb_tail_pointer(skb) - data;
-
-		count += xenvif_count_frag_slots(vif, offset, size, &state);
-
-		data += size;
-	}
-
-	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
-		unsigned long size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
-		unsigned long offset = skb_shinfo(skb)->frags[i].page_offset;
-
-		count += xenvif_count_frag_slots(vif, offset, size, &state);
-	}
-	return count;
-}
-
 struct netrx_pending_operations {
 	unsigned copy_prod, copy_cons;
 	unsigned meta_prod, meta_cons;
@@ -557,12 +460,12 @@ struct skb_cb_overlay {
 	int meta_slots_used;
 };
 
-static void xenvif_kick_thread(struct xenvif *vif)
+void xenvif_kick_thread(struct xenvif *vif)
 {
 	wake_up(&vif->wq);
 }
 
-void xenvif_rx_action(struct xenvif *vif)
+static void xenvif_rx_action(struct xenvif *vif)
 {
 	s8 status;
 	u16 flags;
@@ -571,8 +474,6 @@ void xenvif_rx_action(struct xenvif *vif)
 	struct sk_buff *skb;
 	LIST_HEAD(notify);
 	int ret;
-	int nr_frags;
-	int count;
 	unsigned long offset;
 	struct skb_cb_overlay *sco;
 	int need_to_notify = 0;
@@ -584,29 +485,44 @@ void xenvif_rx_action(struct xenvif *vif)
 
 	skb_queue_head_init(&rxq);
 
-	count = 0;
-
 	while ((skb = skb_dequeue(&vif->rx_queue)) != NULL) {
-		vif = netdev_priv(skb->dev);
-		nr_frags = skb_shinfo(skb)->nr_frags;
+		int max_slots_needed;
+		int i;
+
+		/* We need a cheap worse case estimate for the number of
+		 * slots we'll use.
+		 */
+
+		max_slots_needed = DIV_ROUND_UP(offset_in_page(skb->data) +
+						skb_headlen(skb),
+						PAGE_SIZE);
+		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+			unsigned int size;
+			size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
+			max_slots_needed += DIV_ROUND_UP(size, PAGE_SIZE);
+		}
+		if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4 ||
+		    skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
+			max_slots_needed++;
+
+		/* If the skb may not fit then bail out now */
+		if (!xenvif_rx_ring_slots_available(vif, max_slots_needed)) {
+			skb_queue_head(&vif->rx_queue, skb);
+			need_to_notify = 1;
+			break;
+		}
 
 		sco = (struct skb_cb_overlay *)skb->cb;
 		sco->meta_slots_used = xenvif_gop_skb(skb, &npo);
-
-		count += nr_frags + 1;
+		BUG_ON(sco->meta_slots_used > max_slots_needed);
 
 		__skb_queue_tail(&rxq, skb);
-
-		/* Filled the batch queue? */
-		/* XXX FIXME: RX path dependent on MAX_SKB_FRAGS */
-		if (count + MAX_SKB_FRAGS >= XEN_NETIF_RX_RING_SIZE)
-			break;
 	}
 
 	BUG_ON(npo.meta_prod > ARRAY_SIZE(vif->meta));
 
 	if (!npo.copy_prod)
-		return;
+		goto done;
 
 	BUG_ON(npo.copy_prod > ARRAY_SIZE(vif->grant_copy_op));
 	gnttab_batch_copy(vif->grant_copy_op, npo.copy_prod);
@@ -614,8 +530,6 @@ void xenvif_rx_action(struct xenvif *vif)
 	while ((skb = __skb_dequeue(&rxq)) != NULL) {
 		sco = (struct skb_cb_overlay *)skb->cb;
 
-		vif = netdev_priv(skb->dev);
-
 		if ((1 << vif->meta[npo.meta_cons].gso_type) &
 		    vif->gso_prefix_mask) {
 			resp = RING_GET_RESPONSE(&vif->rx,
@@ -681,25 +595,13 @@ void xenvif_rx_action(struct xenvif *vif)
 		if (ret)
 			need_to_notify = 1;
 
-		xenvif_notify_tx_completion(vif);
-
 		npo.meta_cons += sco->meta_slots_used;
 		dev_kfree_skb(skb);
 	}
 
+done:
 	if (need_to_notify)
 		notify_remote_via_irq(vif->rx_irq);
-
-	/* More work to do? */
-	if (!skb_queue_empty(&vif->rx_queue))
-		xenvif_kick_thread(vif);
-}
-
-void xenvif_queue_tx_skb(struct xenvif *vif, struct sk_buff *skb)
-{
-	skb_queue_tail(&vif->rx_queue, skb);
-
-	xenvif_kick_thread(vif);
 }
 
 void xenvif_check_rx_xenvif(struct xenvif *vif)
@@ -1804,7 +1706,7 @@ static struct xen_netif_rx_response *make_rx_response(struct xenvif *vif,
 
 static inline int rx_work_todo(struct xenvif *vif)
 {
-	return !skb_queue_empty(&vif->rx_queue);
+	return !skb_queue_empty(&vif->rx_queue) || vif->rx_event;
 }
 
 static inline int tx_work_todo(struct xenvif *vif)
@@ -1854,8 +1756,6 @@ int xenvif_map_frontend_rings(struct xenvif *vif,
 	rxs = (struct xen_netif_rx_sring *)addr;
 	BACK_RING_INIT(&vif->rx, rxs, PAGE_SIZE);
 
-	vif->rx_req_cons_peek = 0;
-
 	return 0;
 
 err:
@@ -1863,9 +1763,24 @@ err:
 	return err;
 }
 
+void xenvif_stop_queue(struct xenvif *vif)
+{
+	if (!vif->can_queue)
+		return;
+
+	netif_stop_queue(vif->dev);
+}
+
+static void xenvif_start_queue(struct xenvif *vif)
+{
+	if (xenvif_schedulable(vif))
+		netif_wake_queue(vif->dev);
+}
+
 int xenvif_kthread(void *data)
 {
 	struct xenvif *vif = data;
+	struct sk_buff *skb;
 
 	while (!kthread_should_stop()) {
 		wait_event_interruptible(vif->wq,
@@ -1874,12 +1789,22 @@ int xenvif_kthread(void *data)
 		if (kthread_should_stop())
 			break;
 
-		if (rx_work_todo(vif))
+		if (!skb_queue_empty(&vif->rx_queue))
 			xenvif_rx_action(vif);
 
+		vif->rx_event = false;
+
+		if (skb_queue_empty(&vif->rx_queue) &&
+		    netif_queue_stopped(vif->dev))
+			xenvif_start_queue(vif);
+
 		cond_resched();
 	}
 
+	/* Bin any remaining skbs */
+	while ((skb = skb_dequeue(&vif->rx_queue)) != NULL)
+		dev_kfree_skb(skb);
+
 	return 0;
 }