On Mon, 2016-11-28 at 08:53 -0800, Eric Dumazet wrote:
> On Mon, 2016-11-28 at 11:47 -0500, David Miller wrote:
> > From: Stephen Rothwell <s...@canb.auug.org.au>
> > Date: Sun, 27 Nov 2016 13:04:00 +1100
> >
> > > [Just for Dave's information]
> > >
> > > On Fri, 25 Nov 2016 13:50:17 +0800 Eli Cooper <elicoo...@gmx.com> wrote:
> > >>
> > >> Similar to commit ae148b085876
> > >> ("ip6_tunnel: Update skb->protocol to ETH_P_IPV6 in ip6_tnl_xmit()"),
> > >> sit tunnels also need to update skb->protocol; otherwise, TSO/GSO packets
> > >> might not be properly segmented, which causes the packets being dropped.
> > >>
> > >> Reported-by: Stephen Rothwell <s...@canb.auug.org.au>
> > >> Tested-by: Eli Cooper <elicoo...@gmx.com>
> > >> Cc: sta...@vger.kernel.org
> > >> Signed-off-by: Eli Cooper <elicoo...@gmx.com>
> > >
> > > I tested this patch and it does *not* solve my problem.
> >
> > I'm torn on this patch, because it looked exactly like it would solve the
> > kind of problem Stephen is running into.
> >
> > Even though it doesn't fix his case, it seems correct to me.
> >
> > I was wondering if it was also important to set the skb->protocol
> > before the call to ip_tunnel_encap() but I couldn't find a dependency.
> >
> > In any event I'd like to see some other people review this change
> > before I apply it.
> >
> > My only other guess for Stephen's problem is somehow the SKB headers
> > aren't set up properly for what the GSO engine expects.
>
> Well, mlx4 just works, and uses GSO engine just fine.
>
> So my guess is this is a bug in Intel IGB driver.
About Eli patch : I do not believe it is needed.
Here is the path followed by SIT packet being GSO at the device layer :
We can see that ip_output() was called, and ip_output() already does :
skb->protocol = htons(ETH_P_IP);
[ 71.209437] sit: skb->protocol = dd86
[ 71.215387] skb_mac_gso_segment type 8
[ 71.219176] ------------[ cut here ]------------
[ 71.219180] WARNING: CPU: 25 PID: 12087 at net/core/dev.c:2642
skb_mac_gso_segment+0x166/0x170
[ 71.219200] CPU: 25 PID: 12087 Comm: netperf Not tainted 4.9.0-smp-DEV #362
[ 71.219203] ffffc90019d4b4d8 ffffffff813ca25b 0000000000000009
0000000000000000
[ 71.219204] ffffc90019d4b518 ffffffff810d0c13 00000a5219d4b4f0
0000000000000008
[ 71.219205] ffff881ff2524ae8 0000000000000001 0000000000000001
ffff881fe1107a9c
[ 71.219205] Call Trace:
[ 71.219209] [<ffffffff813ca25b>] dump_stack+0x4d/0x72
[ 71.219213] [<ffffffff810d0c13>] __warn+0xd3/0xf0
[ 71.219214] [<ffffffff810d0cfe>] warn_slowpath_null+0x1e/0x20
[ 71.219215] [<ffffffff8167b656>] skb_mac_gso_segment+0x166/0x170
[ 71.219216] [<ffffffff8167b719>] __skb_gso_segment+0xb9/0x140
[ 71.219218] [<ffffffff8167bb26>] validate_xmit_skb+0x136/0x2d0
[ 71.219219] [<ffffffff8167bd03>] validate_xmit_skb_list+0x43/0x70
[ 71.219221] [<ffffffff816a4817>] sch_direct_xmit+0x147/0x1a0
[ 71.219223] [<ffffffff8167c431>] __dev_queue_xmit+0x421/0x620
[ 71.219224] [<ffffffff8167c640>] dev_queue_xmit+0x10/0x20
[ 71.219226] [<ffffffff816db2d4>] ip_finish_output2+0x254/0x330
[ 71.219227] [<ffffffff816dcaa6>] ip_finish_output+0x136/0x1d0
[ 71.219228] [<ffffffff816dd4db>] ip_output+0xab/0xc0
[ 71.219230] [<ffffffff816dc970>] ? ip_fragment.constprop.58+0x80/0x80
[ 71.219231] [<ffffffff816dccb5>] ip_local_out+0x35/0x40
[ 71.219233] [<ffffffff81725aec>] iptunnel_xmit+0x14c/0x1c0
[ 71.219235] [<ffffffff8178f77a>] sit_tunnel_xmit+0x50a/0x860
[ 71.219236] [<ffffffff8167bde0>] dev_hard_start_xmit+0xb0/0x200
[ 71.219238] [<ffffffff8167c592>] __dev_queue_xmit+0x582/0x620
[ 71.219239] [<ffffffff8167c640>] dev_queue_xmit+0x10/0x20
[ 71.219241] [<ffffffff81684fb1>] neigh_direct_output+0x11/0x20
[ 71.219243] [<ffffffff81750e91>] ip6_finish_output2+0x181/0x460
[ 71.219245] [<ffffffff8178d00b>] ? ip6table_mangle_hook+0x3b/0x130
[ 71.219246] [<ffffffff81750ea4>] ? ip6_finish_output2+0x194/0x460
[ 71.219247] [<ffffffff8178d00b>] ? ip6table_mangle_hook+0x3b/0x130
[ 71.219249] [<ffffffff81752436>] ip6_finish_output+0xa6/0x110
[ 71.219250] [<ffffffff81752535>] ip6_output+0x95/0xe0
[ 71.219251] [<ffffffff81752390>] ? ip6_fragment+0x9e0/0x9e0
[ 71.219252] [<ffffffff8174edaf>] dst_output+0xf/0x20
[ 71.219254] [<ffffffff8174f347>] NF_HOOK.constprop.45+0x77/0x90
[ 71.219255] [<ffffffff8174eda0>] ? ac6_proc_exit+0x20/0x20
[ 71.219256] [<ffffffff817505b8>] ip6_xmit+0x268/0x4d0
[ 71.219257] [<ffffffff8174eda0>] ? ac6_proc_exit+0x20/0x20
[ 71.219258] [<ffffffff817505b8>] ? ip6_xmit+0x268/0x4d0
[ 71.219260] [<ffffffff817834b0>] ? inet6_csk_route_socket+0x120/0x1d0
[ 71.219262] [<ffffffff8122f771>] ? __kmalloc_node_track_caller+0x31/0x40
[ 71.219264] [<ffffffff8178363e>] inet6_csk_xmit+0x7e/0xc0
[ 71.219265] [<ffffffff8122f771>] ? __kmalloc_node_track_caller+0x31/0x40
[ 71.219267] [<ffffffff816f62e7>] tcp_transmit_skb+0x547/0x910
[ 71.219268] [<ffffffff816f6a6d>] tcp_write_xmit+0x3bd/0xf70
[ 71.219270] [<ffffffff813d0580>] ? __radix_tree_create+0x2d0/0x360
[ 71.219271] [<ffffffff816f7734>] tcp_push_one+0x34/0x40
[ 71.219272] [<ffffffff816e9141>] tcp_sendmsg+0x511/0xbc0
[ 71.219275] [<ffffffff81716375>] inet_sendmsg+0x65/0xa0
[ 71.219277] [<ffffffff81659188>] sock_sendmsg+0x38/0x50
[ 71.219278] [<ffffffff8165a8d6>] SYSC_sendto+0x106/0x170
[ 71.219281] [<ffffffff81139c06>] ? do_setitimer+0x1f6/0x250
[ 71.219282] [<ffffffff81139ca1>] ? alarm_setitimer+0x41/0x70
[ 71.219283] [<ffffffff8165b55e>] SyS_sendto+0xe/0x10
[ 71.219286] [<ffffffff817b5720>] entry_SYSCALL_64_fastpath+0x13/0x94
