On 11/20/18 11:14 AM, Jesper Dangaard Brouer wrote:
> On Tue, 20 Nov 2018 16:47:19 +0100
> Pavel Popa <pashinho1990@xxxxxxxxx> wrote:
>
>> Well, here's the output from the `ip link` cmd:
>> 3: eth3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 xdp qdisc mq state UP
>> link/ether 52:54:fc:47:e2:d3 brd ff:ff:ff:ff:ff:ff
>> prog/xdp id 1 tag 1cd982ef22273bda jited
>> 4: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 xdp qdisc mq state UP
>> link/ether 52:54:55:d3:50:ee brd ff:ff:ff:ff:ff:ff
>> prog/xdp id 1 tag 1cd982ef22273bda jited
>>
>> As you can see, there's the XDP program ID 1 executing on them.
>> However, there's definitely something interesting happening when
>> bpf_fib_lookup() returns BPF_FIB_LKUP_RET_NO_NEIGH, for which my XDP
>> program just returns XDP_PASS while the following line gets printed in
>> kern.log:
>> eth3: bad gso: type: 164, size: 256
>>
>> No idea what's wrong here.
>> Also, when bpf_fib_lookup() returns BPF_FIB_LKUP_RET_SUCCESS, for
>> which my XDP program executes bpf_redirect_map(&dev_map,
>> fib_params.ifindex, 0), the following gets printed in
>>
>> /sys/kernel/debug/tracing/trace_pipe:
>> xdp_redirect_map_err: prog_id=1 action=REDIRECT ifindex=3
>> to_ifindex=0 err=-14 map_id=0 map_index=4
>
> The err=-14 is -EFAULT.
>
> Notice "ifindex=3" but "to_ifindex=0", which is the problem. The
> "map_index=4" is correct, but "to_ifindex" does a lookup in the map for
> the net_device->ifindex stored in this map. It is fairly unlikely that
> you added device with ifindex=0 to map index 4, I presume?
>
> Then I was thinking, maybe the "map_index=4" doesn't contain anything,
> but reading the code, that will return err=-22 (#define EINVAL 22),
> which it not the case.
>
> Assuming that map_index=4 does contain a valid net_device. Following
> the code via __bpf_tx_xdp_map -> dev_map_enqueue, I simply cannot find
> an -EFAULT err return value.
>
Pavel:
Does the xdp_fwd sample work as is? you should be able to use it in your
setup with out changes to verify basic functionality.
>From there you can check the fib lookup:
perf record -e fib:* -a -- sleep 5
<run traffic during 5-second window>
perf script
Look at the FIB lookup result and egress device. Is it correct? The
fib_params.ifindex is set based on the egress device from the fib lookup.
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