diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index 08ae01b41c832d7144bdeceb70b976adaf281d4c..ba30a6d9fefabf225631b731a1ce0fc73ea7653d 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -136,12 +136,10 @@ struct xenvif {
char rx_irq_name[IFNAMSIZ+4]; /* DEVNAME-rx */
struct xen_netif_rx_back_ring rx;
struct sk_buff_head rx_queue;
-
- /* Allow xenvif_start_xmit() to peek ahead in the rx request
- * ring. This is a prediction of what rx_req_cons will be
- * once all queued skbs are put on the ring.
+ /* Set when the RX interrupt is triggered by the frontend.
+ * The worker thread may need to wake the queue.
*/
- RING_IDX rx_req_cons_peek;
+ bool rx_event;
/* Given MAX_BUFFER_OFFSET of 4096 the worst case is that each
* head/fragment page uses 2 copy operations because it
@@ -198,8 +196,6 @@ void xenvif_xenbus_fini(void);
int xenvif_schedulable(struct xenvif *vif);
-int xenvif_rx_ring_full(struct xenvif *vif);
-
int xenvif_must_stop_queue(struct xenvif *vif);
/* (Un)Map communication rings. */
@@ -211,21 +207,20 @@ int xenvif_map_frontend_rings(struct xenvif *vif,
/* Check for SKBs from frontend and schedule backend processing */
void xenvif_check_rx_xenvif(struct xenvif *vif);
-/* Queue an SKB for transmission to the frontend */
-void xenvif_queue_tx_skb(struct xenvif *vif, struct sk_buff *skb);
-/* Notify xenvif that ring now has space to send an skb to the frontend */
-void xenvif_notify_tx_completion(struct xenvif *vif);
-
/* Prevent the device from generating any further traffic. */
void xenvif_carrier_off(struct xenvif *vif);
-/* Returns number of ring slots required to send an skb to the frontend */
-unsigned int xenvif_count_skb_slots(struct xenvif *vif, struct sk_buff *skb);
-
int xenvif_tx_action(struct xenvif *vif, int budget);
-void xenvif_rx_action(struct xenvif *vif);
int xenvif_kthread(void *data);
+void xenvif_kick_thread(struct xenvif *vif);
+
+/* 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);
+
+void xenvif_stop_queue(struct xenvif *vif);
extern bool separate_tx_rx_irq;
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 870f1fa583702ee4bc61d9acab3e4925a4d984e0..1dcb9606e6e08f0ab1ac059d51d24b8833415a49 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -46,11 +46,6 @@ int xenvif_schedulable(struct xenvif *vif)
return netif_running(vif->dev) && netif_carrier_ok(vif->dev);
}
-static int xenvif_rx_schedulable(struct xenvif *vif)
-{
- return xenvif_schedulable(vif) && !xenvif_rx_ring_full(vif);
-}
-
static irqreturn_t xenvif_tx_interrupt(int irq, void *dev_id)
{
struct xenvif *vif = dev_id;
@@ -104,8 +99,8 @@ static irqreturn_t xenvif_rx_interrupt(int irq, void *dev_id)
{
struct xenvif *vif = dev_id;
- if (xenvif_rx_schedulable(vif))
- netif_wake_queue(vif->dev);
+ vif->rx_event = true;
+ xenvif_kick_thread(vif);
return IRQ_HANDLED;
}
@@ -121,24 +116,35 @@ static irqreturn_t xenvif_interrupt(int irq, void *dev_id)
static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct xenvif *vif = netdev_priv(dev);
+ int min_slots_needed;
BUG_ON(skb->dev != dev);
/* Drop the packet if vif is not ready */
- if (vif->task == NULL)
+ if (vif->task == NULL || !xenvif_schedulable(vif))
goto drop;
- /* Drop the packet if the target domain has no receive buffers. */
- if (!xenvif_rx_schedulable(vif))
- goto drop;
+ /* At best we'll need one slot for the header and one for each
+ * frag.
+ */
+ min_slots_needed = 1 + skb_shinfo(skb)->nr_frags;
- /* Reserve ring slots for the worst-case number of fragments. */
- vif->rx_req_cons_peek += xenvif_count_skb_slots(vif, skb);
+ /* If the skb is GSO then we'll also need an extra slot for the
+ * metadata.
+ */
+ if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4 ||
+ skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
+ min_slots_needed++;
- if (vif->can_queue && xenvif_must_stop_queue(vif))
- netif_stop_queue(dev);
+ /* If the skb can't possibly fit in the remaining slots
+ * then turn off the queue to give the ring a chance to
+ * drain.
+ */
+ if (!xenvif_rx_ring_slots_available(vif, min_slots_needed))
+ xenvif_stop_queue(vif);
- xenvif_queue_tx_skb(vif, skb);
+ skb_queue_tail(&vif->rx_queue, skb);
+ xenvif_kick_thread(vif);
return NETDEV_TX_OK;
@@ -148,12 +154,6 @@ static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev)
return NETDEV_TX_OK;
}
-void xenvif_notify_tx_completion(struct xenvif *vif)
-{
- if (netif_queue_stopped(vif->dev) && xenvif_rx_schedulable(vif))
- netif_wake_queue(vif->dev);
-}
-
static struct net_device_stats *xenvif_get_stats(struct net_device *dev)
{
struct xenvif *vif = netdev_priv(dev);
@@ -378,6 +378,8 @@ int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
if (err < 0)
goto err;
+ init_waitqueue_head(&vif->wq);
+
if (tx_evtchn == rx_evtchn) {
/* feature-split-event-channels == 0 */
err = bind_interdomain_evtchn_to_irqhandler(
@@ -410,7 +412,6 @@ int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
disable_irq(vif->rx_irq);
}
- init_waitqueue_head(&vif->wq);
task = kthread_create(xenvif_kthread,
(void *)vif, "%s", vif->dev->name);
if (IS_ERR(task)) {
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index acf13920e6d1804c94c672560f45154545ec9c54..43341b82649c2451a3ea7378714dc45599541ca9 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 @@ int xenvif_map_frontend_rings(struct xenvif *vif,
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;
}