netdev - Re: [PATCH net-next] net/smc: init conn.tx_work & conn.send

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Date:   Thu, 17 May 2018 18:30:38 +0200
From:   Ursula Braun <ubraun@...ux.ibm.com>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     David Miller <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Eric Dumazet <eric.dumazet@...il.com>,
        linux-s390@...r.kernel.org
Subject: Re: [PATCH net-next] net/smc: init conn.tx_work & conn.send_lock
 sooner



On 05/17/2018 05:28 PM, Eric Dumazet wrote:
> On Thu, May 17, 2018 at 6:58 AM Ursula Braun <ubraun@...ux.ibm.com> wrote:
> 
> 
> 
>> On 05/17/2018 02:20 PM, Eric Dumazet wrote:
>>> On Thu, May 17, 2018 at 5:13 AM Ursula Braun <ubraun@...ux.ibm.com>
> wrote:
>>>
>>>> This problem should no longer show up with yesterday's net-next commit
>>>> 569bc6436568 ("net/smc: no tx work trigger for fallback sockets").
>>>
>>> It definitely triggers on latest net-next, which includes 569bc6436568
>>>
>>> Thanks.
>>>
> 
>> Sorry, my fault.
> 
>> Your proposed patch solves the problem. On the other hand the purpose of
>> smc_tx_init() has been to cover tx-related socket initializations needed
> for
>> connection sockets only. tx_work is something that should be scheduled
> only
>> for active connection sockets in non-fallback mode.
>> Thus I prefer this alternate patch to solve the problem:
> 
>> ---
>>   net/smc/af_smc.c |    8 ++++++--
>>   1 file changed, 6 insertions(+), 2 deletions(-)
> 
>> --- a/net/smc/af_smc.c
>> +++ b/net/smc/af_smc.c
>> @@ -1362,14 +1362,18 @@ static int smc_setsockopt(struct socket
>>                  }
>>                  break;
>>          case TCP_NODELAY:
>> -               if (sk->sk_state != SMC_INIT && sk->sk_state !=
> SMC_LISTEN) {
>> +               if (sk->sk_state != SMC_INIT &&
>> +                   sk->sk_state != SMC_LISTEN &&
>> +                   sk->sk_state != SMC_CLOSED) {
>>                          if (val && !smc->use_fallback)
>>                                  mod_delayed_work(system_wq,
> &smc->conn.tx_work,
>>                                                   0);
>>                  }
>>                  break;
>>          case TCP_CORK:
>> -               if (sk->sk_state != SMC_INIT && sk->sk_state !=
> SMC_LISTEN) {
>> +               if (sk->sk_state != SMC_INIT &&
>> +                   sk->sk_state != SMC_LISTEN &&
>> +                   sk->sk_state != SMC_CLOSED) {
>>                          if (!val && !smc->use_fallback)
>>                                  mod_delayed_work(system_wq,
> &smc->conn.tx_work,
>>                                                   0);
> 
>> What do you think?
> 
> I think my patch is cleaner.
> 
> Deferring spinlock and workqueues setup is a recipe for disaster.
> 

If your solution is preferred, I agree. In this case my today's net/smc patch
   net/smc: initialize tx_work before llc initial handshake
for the net-tree is obsolete.