Re: [PATCH bpf-next v3 3/4] selftests/bpf: integrate test_tc_tunnel.sh tests into test_progs

[Martin KaFai Lau <martin.lau@linux.dev>]

On 10/30/25 7:04 AM, Alexis Lothoré wrote:
>>> +	int family = cfg->ipproto == 6 ? AF_INET6 : AF_INET;
>>> +
>>> +	cfg->server_fd = start_reuseport_server(family, SOCK_STREAM,
>>> +						cfg->server_addr, TEST_PORT,
>>> +						TIMEOUT_MS, 1);
>>
>> Why reuseport is needed? Does it have issue in bind() to the same
>> ip/port in the later sub-test?
> 
> Yes, I observed that is I use the bare start_server, I systematically have
> the first test passing, an all the others failing on the server startup
> with errno 98 (Address already in use). I have been assuming that it is due
> to some TIME_WAIT state on the freshly closed socket, but I may be missing
> something ?

Thanks for confirming. You are right. It should be the TIME_WAIT. Using 
SO_REUSEPORT works but become confusing on what the test is trying to do 
by starting only 1 reuseport server. reuseport is usually used with >1 
server listening on the same address. A better thing to do is to always 
setsockopt(SO_REUSEADDR) in start_server_addr for TCP.