netdev - Re: [PATCH net] net/smc: Send out the remaining data in sndbuf before close

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Date:   Mon, 28 Mar 2022 12:02:14 +0200
From:   Karsten Graul <kgraul@...ux.ibm.com>
To:     Wen Gu <guwen@...ux.alibaba.com>, davem@...emloft.net,
        kuba@...nel.org, dust.li@...ux.alibaba.com
Cc:     linux-s390@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net] net/smc: Send out the remaining data in sndbuf before
 close

On 28/03/2022 08:10, Wen Gu wrote:
> The current autocork algorithms will delay the data transmission
> in BH context to smc_release_cb() when sock_lock is hold by user.
> 
> So there is a possibility that when connection is being actively
> closed (sock_lock is hold by user now), some corked data still
> remains in sndbuf, waiting to be sent by smc_release_cb(). This
> will cause:
> 
> - smc_close_stream_wait(), which is called under the sock_lock,
>   has a high probability of timeout because data transmission is
>   delayed until sock_lock is released.
> 
> - Unexpected data sends may happen after connction closed and use
>   the rtoken which has been deleted by remote peer through
>   LLC_DELETE_RKEY messages.
> 
> So this patch will try to send out the remaining corked data in
> sndbuf before active close process, to ensure data integrity and
> avoid unexpected data transmission after close.
> 
> Reported-by: Guangguan Wang <guangguan.wang@...ux.alibaba.com>
> Fixes: 6b88af839d20 ("net/smc: don't send in the BH context if sock_owned_by_user")
> Signed-off-by: Wen Gu <guwen@...ux.alibaba.com>
> ---

Thank you,

Acked-by: Karsten Graul <kgraul@...ux.ibm.com>