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Message-ID: <e0b64b80-90e1-5aed-1ca4-f6d20ebac6b7@linux.ibm.com>
Date:   Mon, 23 May 2022 16:44:57 +0200
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Subject: Re: [PATCH v2 net] net/smc: postpone sk_refcnt increment in connect()
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To:     liuyacan@corp.netease.com
Cc:     davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
        linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
        netdev@vger.kernel.org, pabeni@redhat.com, ubraun@linux.ibm.com
References: <5ce801b7-d446-ee28-86ec-968b7c172a80@linux.ibm.com>
 <20220523141905.2791310-1-liuyacan@corp.netease.com>
From:   Karsten Graul <kgraul@linux.ibm.com>
Organization: IBM Deutschland Research & Development GmbH
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On 23/05/2022 16:19, liuyacan@corp.netease.com wrote:
>> This is a rather unusual problem that can come up when fallback=true BEFORE smc_connect()
>> is called. But nevertheless, it is a problem.
>>
>> Right now I am not sure if it is okay when we NOT hold a ref to smc->sk during all fallback
>> processing. This change also conflicts with a patch that is already on net-next (3aba1030).
> 
> Do you mean put the ref to smc->sk during all fallback processing unconditionally and remove 
> the fallback branch sock_put() in __smc_release()?

What I had in mind was to eventually call sock_put() in __smc_release() even if sk->sk_state == SMC_INIT
(currently the extra check in the if() for sk->sk_state != SMC_INIT prevents the sock_put()), but only
when it is sure that we actually reached the sock_hold() in smc_connect() before.

But maybe we find out that the sock_hold() is not needed for fallback sockets, I don't know...