netdev - Re: [PATCH net] net/smc: fix cleanup for linkgroup setup failures

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Date:   Wed, 26 Feb 2020 20:18:43 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     kgraul@...ux.ibm.com
Cc:     netdev@...r.kernel.org, linux-s390@...r.kernel.org,
        heiko.carstens@...ibm.com, raspl@...ux.ibm.com,
        ubraun@...ux.ibm.com
Subject: Re: [PATCH net] net/smc: fix cleanup for linkgroup setup failures

From: Karsten Graul <kgraul@...ux.ibm.com>
Date: Tue, 25 Feb 2020 16:34:36 +0100

> From: Ursula Braun <ubraun@...ux.ibm.com>
> 
> If an SMC connection to a certain peer is setup the first time,
> a new linkgroup is created. In case of setup failures, such a
> linkgroup is unusable and should disappear. As a first step the
> linkgroup is removed from the linkgroup list in smc_lgr_forget().
> 
> There are 2 problems:
> smc_listen_decline() might be called before linkgroup creation
> resulting in a crash due to calling smc_lgr_forget() with
> parameter NULL.
> If a setup failure occurs after linkgroup creation, the connection
> is never unregistered from the linkgroup, preventing linkgroup
> freeing.
> 
> This patch introduces an enhanced smc_lgr_cleanup_early() function
> which
> * contains a linkgroup check for early smc_listen_decline()
>   invocations
> * invokes smc_conn_free() to guarantee unregistering of the
>   connection.
> * schedules fast linkgroup removal of the unusable linkgroup
> 
> And the unused function smcd_conn_free() is removed from smc_core.h.
> 
> Fixes: 3b2dec2603d5b ("net/smc: restructure client and server code in af_smc")
> Fixes: 2a0674fffb6bc ("net/smc: improve abnormal termination of link groups")
> Signed-off-by: Ursula Braun <ubraun@...ux.ibm.com>
> Signed-off-by: Karsten Graul <kgraul@...ux.ibm.com>

Applied and queued up for -stable, thanks.