[NET] front: Added feature-rx-notify

This patch adds support to the frontend for notifying the backend whenever
the rx ring is refilled.  This is required in order for the backend to
get a tx queue.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Modified to only send notification if req_event index is set
appropriately.

Signed-off-by: Keir Fraser <keir@xensource.com>

diff --git a/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c b/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
index 77921f081dcfc1ceb2db76d77618da577ad70815..2bfd63acd8d900815c908b802355d3bc4b026907 100644 (file)
--- a/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
+++ b/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
@@ -326,6 +326,12 @@ again:
                goto abort_transaction;
        }
 
+       err = xenbus_printf(xbt, dev->nodename, "feature-rx-notify", "%d", 1);
+       if (err) {
+               message = "writing feature-rx-notify";
+               goto abort_transaction;
+       }
+
        err = xenbus_transaction_end(xbt, 0);
        if (err) {
                if (err == -EAGAIN)
@@ -569,7 +575,7 @@ static void network_alloc_rx_buffers(struct net_device *dev)
        unsigned short id;
        struct netfront_info *np = netdev_priv(dev);
        struct sk_buff *skb;
-       int i, batch_target;
+       int i, batch_target, notify;
        RING_IDX req_prod = np->rx.req_prod_pvt;
        struct xen_memory_reservation reservation;
        grant_ref_t ref;
@@ -682,7 +688,9 @@ static void network_alloc_rx_buffers(struct net_device *dev)
        /* Above is a suitable barrier to ensure backend will see requests. */
        np->rx.req_prod_pvt = req_prod + i;
  push:
-       RING_PUSH_REQUESTS(&np->rx);
+       RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&np->rx, notify);
+       if (notify)
+               notify_remote_via_irq(np->irq);
 }
 
 static void xennet_make_frags(struct sk_buff *skb, struct net_device *dev,

diff --git a/xen/include/public/io/netif.h b/xen/include/public/io/netif.h
index 7b219b00a22bfd85f1b3a24606e65bea783b9f67..b551006034dfaad2cf019aaa169f1a1e64df81c5 100644 (file)
--- a/xen/include/public/io/netif.h
+++ b/xen/include/public/io/netif.h
@@ -13,10 +13,11 @@
 #include "../grant_table.h"
 
 /*
- * Note that there is *never* any need to notify the backend when
- * enqueuing receive requests (struct netif_rx_request). Notifications
- * after enqueuing any other type of message should be conditional on
+ * Notifications after enqueuing any type of message should be conditional on
  * the appropriate req_event or rsp_event field in the shared ring.
+ * If the client sends notification for rx requests then it should specify
+ * feature 'feature-rx-notify' via xenbus. Otherwise the backend will assume
+ * that it cannot safely queue packets (as it may not be kicked to send them).
  */
 
 /*