pvops: include patch for netback SKB slots calculation

patches.xen/pvops-netback-calculate-correctly-the-SKB-slots.patch

@@ -0,0 +1,60 @@
+Subject: [Xen-devel] [PATCH] xen/netback: calculate correctly the SKB slots.
+Date: Mon, 21 May 2012 13:36:33 -0400
+From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
+To: xen-devel@lists.xensource.com, ian.campbell@citrix.com,
+netdev@vger.kernel.org, davem@davemloft.net, linux-kernel@vger.kernel.org
+CC: Adnan Misherfi <adnan.misherfi@oracle.com>, Konrad Rzeszutek Wilk
+<konrad.wilk@oracle.com>
+
+From: Adnan Misherfi <adnan.misherfi@oracle.com>
+
+A programming error cause the calculation of receive SKB slots to be
+wrong, which caused the RX ring to be erroneously declared full,
+and the receive queue to be stopped. The problem shows up when two
+guest running on the same server tries to communicates using large
+MTUs. Each guest is connected to a bridge with VLAN over bond
+interface, so traffic from one guest leaves the server on one bridge
+and comes back to the second guest on the second bridge. This can be
+reproduces using ping, and one guest as follow:
+
+- Create active-back bond (bond0)
+- Set up VLAN 5 on bond0 (bond0.5)
+- Create a bridge (br1)
+- Add bond0.5 to a bridge (br1)
+- Start a guest and connect it to br1
+- Set MTU of 9000 across the link
+
+Ping the guest from an external host using packet sizes of 3991, and
+4054; ping -s 3991 -c 128 "Guest-IP-Address"
+
+At the beginning ping works fine, but after a while ping packets do
+not reach the guest because the RX ring becomes full, and the queue
+get stopped. Once the problem accrued, the only way to get out of it
+is to reboot the guest, or use xm network-detach/network-attach.
+
+ping works for packets sizes 3990,3992, and many other sizes including
+4000,5000,9000, and 1500 ..etc. MTU size of 3991,4054 are the sizes
+that quickly reproduce this problem.
+
+Signed-off-by: Adnan Misherfi <adnan.misherfi@oracle.com>
+Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
+---
+ drivers/net/xen-netback/netback.c |    2 +-
+ 1 files changed, 1 insertions(+), 1 deletions(-)
+
+diff --git a/drivers/net/xen-netback/netback.c
+b/drivers/net/xen-netback/netback.c
+index 957cf9d..e382e5b 100644
+--- a/drivers/net/xen-netback/netback.c
++++ b/drivers/net/xen-netback/netback.c
+@@ -212,7 +212,7 @@ unsigned int xenvif_count_skb_slots(struct xenvif *vif, struct sk_buff *skb)
+ 	int i, copy_off;
+
+ 	count = DIV_ROUND_UP(
+-			offset_in_page(skb->data)+skb_headlen(skb), PAGE_SIZE);
++			offset_in_page(skb->data + skb_headlen(skb)), PAGE_SIZE);
+
+ 	copy_off = skb_headlen(skb) % PAGE_SIZE;
+
+-- 
+1.7.7.5

series-pvops.conf

@@ -10,3 +10,4 @@ patches.xen/pvops-0009-xen-enlighten-Expose-MWAIT-and-MWAIT_LEAF-if-hypervi.patc
 patches.xen/pvops-0010-CPUFREQ-xen-governor-for-Xen-hypervisor-frequency-sc.patch
 patches.xen/pvops-0011-x86-PCI-Expand-the-x86_msi_ops-to-have-a-restore-MSI.patch
 patches.xen/pvops-enable-netfront-in-dom0.patch
+patches.xen/pvops-netback-calculate-correctly-the-SKB-slots.patch