On Fri, Nov 28, 2014 at 05:25:27PM -0200, Marcelo Ricardo Leitner wrote:

Hi,

I saw there are tun updates on Dave's queue but none seemed to handle this.

I can't use current net-next
(799d2fff1858004526ad75d66a5dd8a5cce6ad40) on a kvm hypervisor
because tun got clogged somehow. Bisected down to:

Umm...  In host, presumably?

And net/core/datagram.c, skb_copy_datagram_from_iter():
        if (copy > 0) {
                int ret;
                if (copy > len)
                        copy = len;
                ret = copy_from_iter(skb->data + offset, copy, from);
                if (ret != copy) {
                        pr_err("%d ret=%d copy=%d offset=%d
len=%d\n", __LINE__, ret, copy, offset, len);
                        goto fault;
                }


I get, for tun interfaces:
[   75.435552] 506 ret=80 copy=90 offset=0 len=90
[   75.435563] tun: 1124 0 -14           (null)
[   75.499528] 506 ret=80 copy=90 offset=0 len=90
[   75.499540] tun: 1124 0 -14           (null)

These were 1 drop on 1 interface each

And for tap interfaces:
[  301.982639] 506 ret=80 copy=90 offset=0 len=90
[  301.982649] tun: 1124 0 -14           (null)
[  301.988625] 506 ret=80 copy=90 offset=0 len=90
[  301.988635] tun: 1124 0 -14           (null)
[  301.994762] 506 ret=80 copy=90 offset=0 len=90
[  301.994773] tun: 1124 0 -14           (null)
[  302.229962] 506 ret=332 copy=342 offset=0 len=342
[  302.229972] tun: 1124 0 -14           (null)
[  302.230621] 506 ret=332 copy=342 offset=0 len=342
[  302.230627] tun: 1124 0 -14           (null)
[  302.239065] 506 ret=332 copy=342 offset=0 len=342
[  302.239071] tun: 1124 0 -14           (null)

It's returning 10 bytes less than the expected... ideas?

Could you print vnet_hdr_sz and sizeof(gso) right after that
copy_from_iter(&gso, ...)?