Re: [PATCH 2/6] xen-netfront: reduce gso_max_size to account for ethernet header
From: David Miller <davem@davemloft.net>
Date: 2013-03-25 16:18:12
From: David Miller <davem@davemloft.net>
Date: 2013-03-25 16:18:12
From: Wei Liu <redacted> Date: Mon, 25 Mar 2013 11:08:18 +0000
The maximum packet including ethernet header that can be handled by netfront / netback wire format is 65535. Reduce gso_max_size accordingly. Drop skb and print warning when skb->len > 65535. This can 1) save the effort to send malformed packet to netback, 2) help spotting misconfiguration of netfront in the future. Signed-off-by: Wei Liu <redacted>
This is effectively the default already, you don't need to change this
value explicitly.
->gso_max_size is set by default to 65536 and then TCP performs this
calculation:
xmit_size_goal = ((sk->sk_gso_max_size - 1) -
inet_csk(sk)->icsk_af_ops->net_header_len -
inet_csk(sk)->icsk_ext_hdr_len -
tp->tcp_header_len);
thereby making it adhere to your limits just fine.