On 13/02/2020 15:53, Michael S. Tsirkin wrote:
On Thu, Feb 13, 2020 at 07:44:06AM -0800, Eric Dumazet wrote:
On 2/13/20 2:00 AM, Michael S. Tsirkin wrote:
On Wed, Feb 12, 2020 at 05:38:09PM +0000, Anton Ivanov wrote:
On 11/02/2020 10:37, Michael S. Tsirkin wrote:
On Tue, Feb 11, 2020 at 07:42:37AM +0000, Anton Ivanov wrote:
On 11/02/2020 02:51, Jason Wang wrote:
On 2020/2/11 上午12:55, Anton Ivanov wrote:
On 09/12/2019 10:48, anton.iva...@cambridgegreys.com wrote:
From: Anton Ivanov <anton.iva...@cambridgegreys.com>
Some of the frames marked as GSO which arrive at
virtio_net_hdr_from_skb() have no GSO_TYPE, no
fragments (data_len = 0) and length significantly shorter
than the MTU (752 in my experiments).
This is observed on raw sockets reading off vEth interfaces
in all 4.x and 5.x kernels I tested.
These frames are reported as invalid while they are in fact
gso-less frames.
This patch marks the vnet header as no-GSO for them instead
of reporting it as invalid.
Signed-off-by: Anton Ivanov <anton.iva...@cambridgegreys.com>
---
include/linux/virtio_net.h | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
index 0d1fe9297ac6..d90d5cff1b9a 100644
--- a/include/linux/virtio_net.h
+++ b/include/linux/virtio_net.h
@@ -112,8 +112,12 @@ static inline int
virtio_net_hdr_from_skb(const struct sk_buff *skb,
hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
else if (sinfo->gso_type & SKB_GSO_TCPV6)
hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
- else
- return -EINVAL;
+ else {
+ if (skb->data_len == 0)
+ hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
+ else
+ return -EINVAL;
+ }
if (sinfo->gso_type & SKB_GSO_TCP_ECN)
hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
} else
ping.
Do you mean gso_size is set but gso_type is not? Looks like a bug
elsewhere.
Thanks
Yes.
I could not trace it where it is coming from.
I see it when doing recvmmsg on raw sockets in the UML vector network
drivers.
I think we need to find the culprit and fix it there, lots of other things
can break otherwise.
Just printing out skb->dev->name should do the trick, no?
The printk in virtio_net_hdr_from_skb says NULL.
That is probably normal for a locally originated frame.
I cannot reproduce this with network traffic by the way - it happens only if
the traffic is locally originated on the host.
A,
OK so is it code in __tcp_transmit_skb that sets gso_size to non-null
when gso_type is 0?
Correct way to determine if a packet is a gso one is by looking at gso_size.
Then only it is legal looking at gso_type
static inline bool skb_is_gso(const struct sk_buff *skb)
{
return skb_shinfo(skb)->gso_size;
}
/* Note: Should be called only if skb_is_gso(skb) is true */
static inline bool skb_is_gso_v6(const struct sk_buff *skb)
...
There is absolutely no relation between GSO and skb->data_len, skb can be
linearized
for various orthogonal reasons.
The reported problem is that virtio gets a packet where gso_size
is !0 but gso_type is 0.
It currently drops these on the assumption that it's some type
of a gso packet it does not know how to handle.
So you are saying if skb_is_gso we can still have gso_type set to 0,
and that's an expected configuration?
So the patch should just be:
- if (skb_is_gso(skb)) {
+ if (skb_is_gso(skb) && sinfo->gso_type) {
Yes, provided that skb_is_gso(skb) and sinfo->gso_type == 0 is a valid state.
I agree with Jason, there may be something wrong going on here and we need to
find the source which creates these packets.
A.
?
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--
Anton R. Ivanov
Cambridgegreys Limited. Registered in England. Company Number 10273661
https://www.cambridgegreys.com/
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