linux-kernel - Re: [PATCH bpf-next v2] selftests/bpf: fix incorrect fcntl call (test

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Date:   Mon, 26 Sep 2022 17:54:19 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     John Fastabend <john.fastabend@...il.com>,
        Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Qiao Ma <mqaio@...ux.alibaba.com>,
        Jakub Sitnicki <jakub@...udflare.com>,
        Andrii Nakryiko <andrii@...nel.org>,
        Shuah Khan <shuah@...nel.org>, Mykola Lysenko <mykolal@...com>,
        LKML <linux-kernel@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>
Subject: Re: [PATCH bpf-next v2] selftests/bpf: fix incorrect fcntl call
 (test_sockmap.c)

On 9/22/22 8:46 PM, John Fastabend wrote:
> Andrii Nakryiko wrote:
>> On Fri, Aug 26, 2022 at 9:24 AM John Fastabend <john.fastabend@...il.com> wrote:
>>> Alexei Starovoitov wrote:
>>>> On Wed, Aug 24, 2022 at 7:11 PM Qiao Ma <mqaio@...ux.alibaba.com> wrote:
>>>>>
>>>>> In test_sockmap.c, the testcase sets socket nonblock first, and then
>>>>> calls select() and recvmsg() to receive data.
>>>>> If some error occur, nonblock setting will make recvmsg() return
>>>>> immediately, rather than blocking forever.
>>>>>
>>>>> However, the way to call fcntl() to set nonblock is wrong.
>>>>> To set socket noblock, we need to use
>>>>>> fcntl(fd, F_SETFL, O_NONBLOCK);
>>>>> rather than:
>>>>>> fcntl(fd, O_NONBLOCK);
>>>>>
>>>>> Signed-off-by: Qiao Ma <mqaio@...ux.alibaba.com>
>>>>> ---
>>>>>   tools/testing/selftests/bpf/test_sockmap.c | 7 ++++++-
>>>>>   1 file changed, 6 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/tools/testing/selftests/bpf/test_sockmap.c b/tools/testing/selftests/bpf/test_sockmap.c
>>>>> index 0fbaccdc8861..abb4102f33b0 100644
>>>>> --- a/tools/testing/selftests/bpf/test_sockmap.c
>>>>> +++ b/tools/testing/selftests/bpf/test_sockmap.c
>>>>> @@ -598,7 +598,12 @@ static int msg_loop(int fd, int iov_count, int iov_length, int cnt,
>>>>>                  struct timeval timeout;
>>>>>                  fd_set w;
>>>>>
>>>>> -               fcntl(fd, fd_flags);
>>>>> +               err = fcntl(fd, F_SETFL, fd_flags);
>>>>> +               if (err < 0) {
>>>>> +                       perror("fcntl failed");
>>>>> +                       goto out_errno;
>>>>> +               }
>>>>> +
>>>>
>>>> John, Jakub,
>>>>
>>>> Please review this.
>>>> Unfortunately test_sockmap (and sockmap kernel) is broken
>>>> before and after this patch,
>>>> so I'm hesitant to apply it not to make thing harder to debug.
>>>> Here is what I see:
>>>> # ./test_sockmap
> 
> [...]
> 
>>>> and test_sockmap 'hangs' (or doing something for long time) after
>>>> #31/ 6 sockhash:ktls:txmsg test drop:OK
>>>
>>> Thanks for spotting I'll take a look.
>>
>> Friendly ping. John, did you get a chance to look at this? This patch
>> is still marked as "Needs ACK" in Patchworks.
> 
> Yep thanks. We are tracking a couple fixes internally around this so should
> have something pop out soon. I think we want the fix and test to go in at
> the same time.

Ok, I'll mark it as 'awaiting upstream' assuming that you carry this fix forward
together with your series then.

Thanks,
Daniel