[Xen-changelog] [xen master] Mini-OS: netfront: Fix rx ring starvation in network_rx

[patchbot@xxxxxxx]

commit eed8d774ce19dcae26e1cc077088397681ad65eb
Author:     Martin Lucina <martin@xxxxxxxxxx>
AuthorDate: Thu Dec 4 14:33:53 2014 +0100
Commit:     Ian Campbell <ian.campbell@xxxxxxxxxx>
CommitDate: Tue Jan 13 10:40:28 2015 +0000

    Mini-OS: netfront: Fix rx ring starvation in network_rx
    
    In network_rx() we must push the same amount of requests back onto the
    ring in the second loop that we consumed in the first loop. Otherwise
    the ring will eventually starve itself of free request slots and no
    packets will be delivered.
    
    Further, we make the HAVE_LIBC codepath clearer to follow by removing
    the "some" variable from the for loop initialisation and conditions.
    
    Signed-off-by: Martin Lucina <martin@xxxxxxxxxx>
    Acked-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>
---
 extras/mini-os/netfront.c |   36 +++++++++++++++++-------------------
 1 files changed, 17 insertions(+), 19 deletions(-)

diff --git a/extras/mini-os/netfront.c b/extras/mini-os/netfront.c
index 44c3995..42bb103 100644
--- a/extras/mini-os/netfront.c
+++ b/extras/mini-os/netfront.c
@@ -96,42 +96,35 @@ static inline int xennet_rxidx(RING_IDX idx)
 void network_rx(struct netfront_dev *dev)
 {
     RING_IDX rp,cons,req_prod;
-    struct netif_rx_response *rx;
-    int nr_consumed, some, more, i, notify;
-
+    int nr_consumed, more, i, notify;
+#ifdef HAVE_LIBC
+    int some;
+#endif
 
+    nr_consumed = 0;
 moretodo:
     rp = dev->rx.sring->rsp_prod;
     rmb(); /* Ensure we see queued responses up to 'rp'. */
-    cons = dev->rx.rsp_cons;
 
-    for (nr_consumed = 0, some = 0;
-         (cons != rp) && !some;
-         nr_consumed++, cons++)
+#ifdef HAVE_LIBC
+    some = 0;
+#endif
+    for (cons = dev->rx.rsp_cons; cons != rp; nr_consumed++, cons++)
     {
         struct net_buffer* buf;
         unsigned char* page;
         int id;
 
-        rx = RING_GET_RESPONSE(&dev->rx, cons);
-
-        if (rx->flags & NETRXF_extra_info)
-        {
-            printk("+++++++++++++++++++++ we have extras!\n");
-            continue;
-        }
-
-
-        if (rx->status == NETIF_RSP_NULL) continue;
+        struct netif_rx_response *rx = RING_GET_RESPONSE(&dev->rx, cons);
 
         id = rx->id;
-        BUG_ON(id >= NET_TX_RING_SIZE);
+        BUG_ON(id >= NET_RX_RING_SIZE);
 
         buf = &dev->rx_buffers[id];
         page = (unsigned char*)buf->page;
         gnttab_end_access(buf->gref);
 
-        if(rx->status>0)
+        if (rx->status > NETIF_RSP_NULL)
         {
 #ifdef HAVE_LIBC
            if (dev->netif_rx == NETIF_SELECT_RX) {
@@ -142,6 +135,7 @@ moretodo:
                memcpy(dev->data, page+rx->offset, len);
                dev->rlen = len;
                some = 1;
+                break;
            } else
 #endif
                dev->netif_rx(page+rx->offset,rx->status);
@@ -150,7 +144,11 @@ moretodo:
     dev->rx.rsp_cons=cons;
 
     RING_FINAL_CHECK_FOR_RESPONSES(&dev->rx,more);
+#ifdef HAVE_LIBC
     if(more && !some) goto moretodo;
+#else
+    if(more) goto moretodo;
+#endif
 
     req_prod = dev->rx.req_prod_pvt;
 
--
generated by git-patchbot for /home/xen/git/xen.git#master

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