Marek Marczykowski
12 years ago
parent
e929164e52
commit
0ebad7661f
@ -1,60 +1,42 @@
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Subject: [Xen-devel] [PATCH] xen/netback: calculate correctly the SKB slots.
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Date: Mon, 21 May 2012 13:36:33 -0400
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From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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To: xen-devel@lists.xensource.com, ian.campbell@citrix.com,
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netdev@vger.kernel.org, davem@davemloft.net, linux-kernel@vger.kernel.org
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CC: Adnan Misherfi <adnan.misherfi@oracle.com>, Konrad Rzeszutek Wilk
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<konrad.wilk@oracle.com>
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From: Adnan Misherfi <adnan.misherfi@oracle.com>
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A programming error cause the calculation of receive SKB slots to be
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wrong, which caused the RX ring to be erroneously declared full,
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and the receive queue to be stopped. The problem shows up when two
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guest running on the same server tries to communicates using large
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MTUs. Each guest is connected to a bridge with VLAN over bond
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interface, so traffic from one guest leaves the server on one bridge
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and comes back to the second guest on the second bridge. This can be
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reproduces using ping, and one guest as follow:
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- Create active-back bond (bond0)
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- Set up VLAN 5 on bond0 (bond0.5)
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- Create a bridge (br1)
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- Add bond0.5 to a bridge (br1)
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- Start a guest and connect it to br1
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- Set MTU of 9000 across the link
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Ping the guest from an external host using packet sizes of 3991, and
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4054; ping -s 3991 -c 128 "Guest-IP-Address"
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At the beginning ping works fine, but after a while ping packets do
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not reach the guest because the RX ring becomes full, and the queue
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get stopped. Once the problem accrued, the only way to get out of it
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is to reboot the guest, or use xm network-detach/network-attach.
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ping works for packets sizes 3990,3992, and many other sizes including
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4000,5000,9000, and 1500 ..etc. MTU size of 3991,4054 are the sizes
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that quickly reproduce this problem.
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Signed-off-by: Adnan Misherfi <adnan.misherfi@oracle.com>
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Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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From: Simon Graham <simon.graham@citrix.com>
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To: Ian Campbell <Ian.Campbell@citrix.com>, "konrad.wilk@oracle.com"
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<konrad.wilk@oracle.com>, "xen-devel@lists.xensource.com"
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<xen-devel@lists.xensource.com>, "netdev@vger.kernel.org"
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<netdev@vger.kernel.org>
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Date: Thu, 24 May 2012 12:26:07 -0400
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Cc: "bhutchings@solarflare.com" <bhutchings@solarflare.com>,
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Simon Graham <simon.graham@citrix.com>,
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"davem@davemloft.net" <davem@davemloft.net>,
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"adnan.misherfi@oracle.com" <adnan.misherfi@oracle.com>
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Subject: [Xen-devel] [PATCH] xen/netback: Calculate the number of SKB slots
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required correctly
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When calculating the number of slots required for a packet header, the code
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was reserving too many slots if the header crossed a page boundary. Since
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netbk_gop_skb copies the header to the start of the page, the count of
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slots required for the header should be based solely on the header size.
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This problem is easy to reproduce if a VIF is bridged to a USB 3G modem
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device as the skb->data value always starts near the end of the first page.
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Signed-off-by: Simon Graham <simon.graham@citrix.com>
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---
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drivers/net/xen-netback/netback.c | 2 +-
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1 files changed, 1 insertions(+), 1 deletions(-)
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drivers/net/xen-netback/netback.c | 3 +--
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1 files changed, 1 insertions(+), 2 deletions(-)
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diff --git a/drivers/net/xen-netback/netback.c
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b/drivers/net/xen-netback/netback.c
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index 957cf9d..e382e5b 100644
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diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
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index 2596401..f4a6fca 100644
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--- a/drivers/net/xen-netback/netback.c
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+++ b/drivers/net/xen-netback/netback.c
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@@ -212,7 +212,7 @@ unsigned int xenvif_count_skb_slots(struct xenvif *vif, struct sk_buff *skb)
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@@ -325,8 +325,7 @@ unsigned int xen_netbk_count_skb_slots(struct xenvif *vif, struct sk_buff *skb)
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unsigned int count;
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int i, copy_off;
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count = DIV_ROUND_UP(
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- count = DIV_ROUND_UP(
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- offset_in_page(skb->data)+skb_headlen(skb), PAGE_SIZE);
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+ offset_in_page(skb->data + skb_headlen(skb)), PAGE_SIZE);
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+ count = DIV_ROUND_UP(skb_headlen(skb), PAGE_SIZE);
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copy_off = skb_headlen(skb) % PAGE_SIZE;
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--
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1.7.7.5
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1.7.9.1
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