On 01/03/2014 04:47 PM, ext Daniel Borkmann wrote:
> On 01/03/2014 04:33 PM, Matija Glavinic Pecotic wrote:
>> Hello sctp folks,
>>
>> sctp regression suite is currently broken due to test_1_to_1_sockopt.
>>
>> Problem is following:
>>
>> TEST17 sets SO_SNDBUF to 2048
>>
>> TEST18 gets SO_SNDBUF, expected is 2x2048, but obtained value is 4480
>>
>>> test_1_to_1_sockopt.c 17 PASS : setsockopt() SO_SNDBUF - SUCCESS
>>> test_1_to_1_sockopt.c 18 PASS : getsockopt() SO_SNDBUF - SUCCESS
>>> test_1_to_1_sockopt.c 19 BROK : Comparison failed:Set value and got value differs Set Value=4096 Get Value=4480
>>
>> reason lies is net/core/sock.c
>>
>>> case SO_SNDBUF:
>>> /* Don't error on this BSD doesn't and if you think
>>> * about it this is right. Otherwise apps have to
>>> * play 'guess the biggest size' games. RCVBUF/SNDBUF
>>> * are treated in BSD as hints
>>> */
>>> val = min_t(u32, val, sysctl_wmem_max);
>>> set_sndbuf:
>>> sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
>>> sk->sk_sndbuf = max_t(u32, val * 2, SOCK_MIN_SNDBUF);
>>
>> since SOCK_MIN_SNDBUF is defined as:
>>
>> include/net/sock.h
>>> /* Since sk_{r,w}mem_alloc sums skb->truesize, even a small frame might
>>> * need sizeof(sk_buff) + MTU + padding, unless net driver perform copybreak.
>>> * Note: for send buffers, TCP works better if we can build two skbs at
>>> * minimum.
>>> */
>>> #define TCP_SKB_MIN_TRUESIZE (2048 + SKB_DATA_ALIGN(sizeof(struct sk_buff)))
>>>
>>> #define SOCK_MIN_SNDBUF (TCP_SKB_MIN_TRUESIZE * 2)
>>> #define SOCK_MIN_RCVBUF TCP_SKB_MIN_TRUESIZE
>>
>> we can observe that value for which we set SO_SNDBUF in TEST17 in test_1_to_1_sockopt.c needs to be increased
>>
>> Version is visible in subject, 1.0.15, I hope http://sourceforge.net/projects/lksctp/files/ is still valid place to get it.
>
> Already fixed in the current git tree (see lksctp.org) under
> b7ad1afc16cb0c5 ("tests: fix test_1_to_1_sockopt sock buff test
> case".) Will do a release some time next week.
I see, thanks, I will check it next time before reporting.
>> Best regards,
>>
>> Matija
>>
>> PS: happy new year!
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