[Xen-changelog] [xen-unstable] [NET] front: Added feature-rx-notify

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Node ID 23c37bc942da6cffaa9936784af7913a0a091675
# Parent  2e91ad1a89ce35c522e8989593cd2d4e83f04755
[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@xxxxxxxxxxxxxxxxxxx>

Modified to only send notification if req_event index is set
appropriately.

Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
 linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c |   12 ++++++++++--
 xen/include/public/io/netif.h                        |    7 ++++---
 2 files changed, 14 insertions(+), 5 deletions(-)

diff -r 2e91ad1a89ce -r 23c37bc942da 
linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
--- a/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c      Fri Jul 28 
17:04:55 2006 +0100
+++ b/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c      Fri Jul 28 
17:13:08 2006 +0100
@@ -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(str
        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(str
        /* 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 -r 2e91ad1a89ce -r 23c37bc942da xen/include/public/io/netif.h
--- a/xen/include/public/io/netif.h     Fri Jul 28 17:04:55 2006 +0100
+++ b/xen/include/public/io/netif.h     Fri Jul 28 17:13:08 2006 +0100
@@ -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).
  */
 
 /*

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