[Xen-changelog] [xen-unstable] [Mini-OS] Fix netfront xmit overflow

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

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1195910934 0
# Node ID 7eea09b188395a8e2d893bae4d5dab9b29f3ad71
# Parent  eac7ef8ba544989ea40f9beb9f1761ece595c5b3
[Mini-OS] Fix netfront xmit overflow

Fix xmit overflow by making netfront_xmit sleep until
network_tx_buf_gc() frees an xmit request.

Signed-off-by: Samuel Thibault <samuel.thibault@xxxxxxxxxx>
---
 extras/mini-os/netfront.c |   24 +++++++++++++++++-------
 1 files changed, 17 insertions(+), 7 deletions(-)

diff -r eac7ef8ba544 -r 7eea09b18839 extras/mini-os/netfront.c
--- a/extras/mini-os/netfront.c Sat Nov 24 13:28:27 2007 +0000
+++ b/extras/mini-os/netfront.c Sat Nov 24 13:28:54 2007 +0000
@@ -13,6 +13,7 @@
 #include <gnttab.h>
 #include <xmalloc.h>
 #include <time.h>
+#include <semaphore.h>
 
 void init_rx_buffers(void);
 
@@ -48,6 +49,7 @@ char* xenbus_printf(xenbus_transaction_t
 
 unsigned short rx_freelist[NET_RX_RING_SIZE];
 unsigned short tx_freelist[NET_TX_RING_SIZE];
+__DECLARE_SEMAPHORE_GENERIC(tx_sem, NET_TX_RING_SIZE);
 
 struct net_buffer {
     void* page;
@@ -188,6 +190,7 @@ void network_tx_buf_gc(void)
             buf->gref=GRANT_INVALID_REF;
 
             add_id_to_freelist(id,tx_freelist);
+            up(&tx_sem);
         }
 
         np->tx.rsp_cons = prod;
@@ -422,16 +425,23 @@ void netfront_xmit(unsigned char* data,i
 void netfront_xmit(unsigned char* data,int len)
 {
     int flags;
-    local_irq_save(flags);
-
     struct net_info* info = &net_info;
     struct netif_tx_request *tx;
-    RING_IDX i = info->tx.req_prod_pvt;
+    RING_IDX i;
     int notify;
-    int id = get_id_from_freelist(tx_freelist);
-    struct net_buffer* buf = &tx_buffers[id];
-    void* page = buf->page;
-
+    int id;
+    struct net_buffer* buf;
+    void* page;
+
+    down(&tx_sem);
+
+    local_irq_save(flags);
+
+    id = get_id_from_freelist(tx_freelist);
+    buf = &tx_buffers[id];
+    page = buf->page;
+
+    i = info->tx.req_prod_pvt;
     tx = RING_GET_REQUEST(&info->tx, i);
 
     memcpy(page,data,len);

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