From: Tony Lu <tonylu@linux.alibaba.com>
To: Guangguan Wang <guangguan.wang@linux.alibaba.com>
Cc: kgraul@linux.ibm.com, davem@davemloft.net, kuba@kernel.org,
linux-s390@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH net 2/2] net/smc: align the connect behaviour with TCP
Date: Wed, 11 May 2022 21:32:13 +0800 [thread overview]
Message-ID: <Ynu63ZIz433CYBtb@TonyMac-Alibaba> (raw)
In-Reply-To: <b380e302-5b16-2de0-eca0-9805359daaaa@linux.alibaba.com>
On Tue, May 10, 2022 at 08:58:38PM +0800, Guangguan Wang wrote:
>
>
> On 2022/5/10 17:30, Tony Lu wrote:
> > On Mon, May 09, 2022 at 07:58:37PM +0800, Guangguan Wang wrote:
> >> Connect with O_NONBLOCK will not be completed immediately
> >> and returns -EINPROGRESS. It is possible to use selector/poll
> >> for completion by selecting the socket for writing. After select
> >> indicates writability, a second connect function call will return
> >> 0 to indicate connected successfully as TCP does, but smc returns
> >
> > If the connection is established successfully, the following up call of
> > connect() returns -EISCONN (SS_CONNECTED), which is expected and SMC
> > does it, same as TCP.
> >
> > In case of misunderstanding, could you append more detailed information?
> >
> > Thanks,
> > Tony Lu
> >
>
> io_uring uses nonblocking connect as follow steps:
> 1) call connect with nonblocking
> 2) wait for selector/poll to indicate writability
> 3) call connect to confirm connection's state
>
> In the third step, tcp changes the socket state from SS_CONNECTING to
> SS_CONNECTED and returns 0 if the connection is established successfully,
> but smc returns -EISCONN.
Based on the steps you list, I am wondering if it is finished in the
step #1, the call of connect() in step #3 would return -EISCONN. Should
we check 0 and -EISCONN in step #3?
To fix this issue, I think we should be careful about adding and
handling sock state, maybe we could push it to net-next and take
advantage of sock state. And I will test this patch later in our test
cases.
Thanks,
Tony Lu
next prev parent reply other threads:[~2022-05-11 13:32 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-09 11:58 [PATCH net 0/2] net/smc: two fixes for using smc with io_uring Guangguan Wang
2022-05-09 11:58 ` [PATCH net 1/2] net/smc: non blocking recvmsg() return -EAGAIN when no data and signal_pending Guangguan Wang
2022-05-10 3:23 ` Tony Lu
2022-05-09 11:58 ` [PATCH net 2/2] net/smc: align the connect behaviour with TCP Guangguan Wang
2022-05-10 9:30 ` Tony Lu
2022-05-10 12:58 ` Guangguan Wang
2022-05-11 13:32 ` Tony Lu [this message]
2022-05-10 11:05 ` Paolo Abeni
2022-05-10 13:03 ` Guangguan Wang
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