On Sun, Jul 24, 2016 at 6:26 AM, Ryan Moats <[email protected]> wrote:
> "dev" <[email protected]> wrote on 07/21/2016 05:36:13 AM: > > > From: nickcooper-zhangtonghao <[email protected]> > > To: [email protected] > > Cc: nickcooper-zhangtonghao <[email protected]> > > Date: 07/21/2016 05:36 AM > > Subject: [ovs-dev] [PATCH] ovn: remove the dead code. > > Sent by: "dev" <[email protected]> > > > > It is not necessary to assign 0 to ip_csum. > > > > Signed-off-by: nickcooper-zhangtonghao <nickcooper- > > [email protected]> > > --- > > ovn/controller/pinctrl.c | 1 - > > 1 file changed, 1 deletion(-) > > > > diff --git a/ovn/controller/pinctrl.c b/ovn/controller/pinctrl.c > > index 7893872..b35576a 100644 > > --- a/ovn/controller/pinctrl.c > > +++ b/ovn/controller/pinctrl.c > > @@ -349,7 +349,6 @@ pinctrl_handle_put_dhcp_opts( > > struct ip_header *out_ip = dp_packet_l3(&pkt_out); > > out_ip->ip_tot_len = htons(pkt_out.l4_ofs - pkt_out.l3_ofs + > > new_l4_size); > > udp->udp_csum = 0; > > - out_ip->ip_csum = 0; > This is not a dead code. It is required. The reason it is required is because the DHCPv4 response packet is constructed by copying the DHCPv4 request packet and then adding the dhcp options. So the ip_csum needs to be set to 0 before calling "csum", otherwise, csum() will calculate wrong checksum. because of which the VM will reject the DHCPv4 response packet. You can verify yourself by applying the ovn-northd DHCP patch [1]. [1] - https://patchwork.ozlabs.org/patch/651958/ > out_ip->ip_csum = csum(out_ip, sizeof *out_ip); > > > > pin->packet = dp_packet_data(&pkt_out); > > lgtm... > > Acked-by: Ryan Moats <[email protected]> > _______________________________________________ > dev mailing list > [email protected] > http://openvswitch.org/mailman/listinfo/dev > _______________________________________________ dev mailing list [email protected] http://openvswitch.org/mailman/listinfo/dev
