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Message-ID: <76eeb1b0-6e4f-986b-c32f-e7e4de3426a7@linux.ibm.com>
Date:   Mon, 23 May 2022 13:19:04 +0200
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Subject: Re: [PATCH net] net/smc: fix listen processing for SMC-Rv2
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To:     liuyacan@corp.netease.com, davem@davemloft.net,
        edumazet@google.com, kuba@kernel.org, pabeni@redhat.com
Cc:     linux-s390@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, ubraun@linux.ibm.com
References: <20220523055056.2078994-1-liuyacan@corp.netease.com>
From:   Karsten Graul <kgraul@linux.ibm.com>
Organization: IBM Deutschland Research & Development GmbH
In-Reply-To: <20220523055056.2078994-1-liuyacan@corp.netease.com>
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On 23/05/2022 07:50, liuyacan@corp.netease.com wrote:
> From: liuyacan <liuyacan@corp.netease.com>
> 
> In the process of checking whether RDMAv2 is available, the current
> implementation first sets ini->smcrv2.ib_dev_v2, and then allocates
> smc buf desc, but the latter may fail. Unfortunately, the caller
> will only check the former. In this case, a NULL pointer reference
> will occur in smc_clc_send_confirm_accept() when accessing
> conn->rmb_desc.
> 
> This patch does two things:
> 1. Use the return code to determine whether V2 is available.
> 2. If the return code is NODEV, continue to check whether V1 is
> available.
> 
> Fixes: e49300a6bf62 ("net/smc: add listen processing for SMC-Rv2")
> Signed-off-by: liuyacan <liuyacan@corp.netease.com>
> ---

I am not happy with this patch. You are right that this is a problem,
but the fix should be much simpler: set ini->smcrv2.ib_dev_v2 = NULL in
smc_find_rdma_v2_device_serv() after the not_found label, just like it is
done in a similar way for the ISM device in smc_find_ism_v1_device_serv().

Your patch changes many more things, and beside that you eliminated the calls 
to smc_find_ism_store_rc() completely, which is not correct.

Since your patch was already applied (btw. 3:20 hours after you submitted it),
please revert it and resend. Thank you.