Merge to Fedora kernel-2.6.18-1.2224_FC5 patched with stable patch-2.6.18.1-vs2.0...

[linux-2.6.git] / drivers / xen / netback / interface.c

diff --git a/drivers/xen/netback/interface.c b/drivers/xen/netback/interface.c
index d60b23b..d70955f 100644 (file)
--- a/drivers/xen/netback/interface.c
+++ b/drivers/xen/netback/interface.c
@@ -34,6 +34,24 @@
 #include <linux/ethtool.h>
 #include <linux/rtnetlink.h>
 
+/*
+ * Module parameter 'queue_length':
+ * 
+ * Enables queuing in the network stack when a client has run out of receive
+ * descriptors. Although this feature can improve receive bandwidth by avoiding
+ * packet loss, it can also result in packets sitting in the 'tx_queue' for
+ * unbounded time. This is bad if those packets hold onto foreign resources.
+ * For example, consider a packet that holds onto resources belonging to the
+ * guest for which it is queued (e.g., packet received on vif1.0, destined for
+ * vif1.1 which is not activated in the guest): in this situation the guest
+ * will never be destroyed, unless vif1.1 is taken down (which flushes the
+ * 'tx_queue').
+ * 
+ * Only set this parameter to non-zero value if you know what you are doing!
+ */
+static unsigned long netbk_queue_length = 0;
+module_param_named(queue_length, netbk_queue_length, ulong, 0);
+
 static void __netif_up(netif_t *netif)
 {
        enable_irq(netif->irq);
@@ -44,6 +62,7 @@ static void __netif_down(netif_t *netif)
 {
        disable_irq(netif->irq);
        netif_deschedule_work(netif);
+       del_timer_sync(&netif->credit_timeout);
 }
 
 static int net_open(struct net_device *dev)
@@ -134,6 +153,7 @@ netif_t *netif_alloc(domid_t domid, unsigned int handle, u8 be_mac[ETH_ALEN])
        netif->credit_bytes = netif->remaining_credit = ~0UL;
        netif->credit_usec  = 0UL;
        init_timer(&netif->credit_timeout);
+       netif->credit_timeout.expires = jiffies;
 
        dev->hard_start_xmit = netif_be_start_xmit;
        dev->get_stats       = netif_be_get_stats;
@@ -144,11 +164,10 @@ netif_t *netif_alloc(domid_t domid, unsigned int handle, u8 be_mac[ETH_ALEN])
 
        SET_ETHTOOL_OPS(dev, &network_ethtool_ops);
 
-       /*
-        * Reduce default TX queuelen so that each guest interface only
-        * allows it to eat around 6.4MB of host memory.
-        */
-       dev->tx_queue_len = 100;
+       dev->tx_queue_len = netbk_queue_length;
+       if (dev->tx_queue_len != 0)
+               printk(KERN_WARNING "netbk: WARNING: device '%s' has non-zero "
+                      "queue length (%lu)!\n", dev->name, dev->tx_queue_len);
 
        for (i = 0; i < ETH_ALEN; i++)
                if (be_mac[i] != 0)