[ClusterLabs] Antw: Re: Antw: Re: [Cluster-devel] DLM connection channel switch take too long time (> 5mins)

[Guoqing Jiang]

On 03/13/2018 03:09 PM, Ulrich Windl wrote:
>
>>>> Guoqing Jiang <gqjiang at suse.com> schrieb am 13.03.2018 um 05:00 in Nachricht
> <87a8e0e7-63f3-2329-6598-1fa80b1b12d5 at suse.com>:
>
>> On 03/08/2018 07:24 PM, Ulrich Windl wrote:
>>> Hi!
>>>
>>> What surprises me most is that a connect(...O_NONBLOCK) actually blocks:
>>>
>>> EINPROGRESS
>>>                 The  socket  is  non-blocking  and the connection cannot be
>> com-
>>>                 pleted immediately.
>>>
>> Maybe it is because that the socket is created by sock_create_kern, and
>> O_NONBLOCK flag is not worked  since __sctp_connect has the following
>> description.
>>
>>          /* in-kernel sockets don't generally have a file allocated to them
>>            * if all they do is call sock_create_kern().
>>            */
>>           if (sk->sk_socket->file)
>>                   f_flags = sk->sk_socket->file->f_flags;
>>
>>           timeo = sock_sndtimeo(sk, f_flags & O_NONBLOCK);
> But O_NONBLOCK is still passed to sock_sndtimeo() (unless the intention was "f_flags & ~O_NONBLOCK").
>

If I am not reading wrong, the O_NONBLOCK doesn't have effective above
since f_flags is still 0.

So, in this case, timeo is set to sk->sk_sndtimeo. In sctp_wait_for_connect
you also can see nonblock is only work when timeo is set to 0.

             if (!*timeo_p)
                         goto do_nonblock;


Thanks,
Guoqing