From: liuyacan@corp.netease.com
To: kgraul@linux.ibm.com
Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
liuyacan@corp.netease.com, netdev@vger.kernel.org,
pabeni@redhat.com, ubraun@linux.ibm.com
Subject: Re: [PATCH net] net/smc: fix listen processing for SMC-Rv2
Date: Mon, 23 May 2022 21:25:31 +0800 [thread overview]
Message-ID: <20220523132531.2419421-1-liuyacan@corp.netease.com> (raw)
In-Reply-To: <f35924c0-4691-3b11-c302-9d79f3e3c1c7@linux.ibm.com>
> >>> 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.
> >
> > I also have considered this way, one question is that do we need to do more roll
> > back work before V1 check?
> >
> > Specifically, In smc_find_rdma_v2_device_serv(), there are the following steps:
> >
> > 1. smc_listen_rdma_init()
> > 1.1 smc_conn_create()
> > 1.2 smc_buf_create() --> may fail
> > 2. smc_listen_rdma_reg() --> may fail
> >
> > When later steps fail, Do we need to roll back previous steps?
>
> That is a good question and I think that is a different problem for another patch.
> smc_listen_rdma_init() maybe should call smc_conn_abort() similar to what smc_listen_ism_init()
> does in this situation. And when smc_listen_rdma_reg() fails ... hmm we need to think about this.
>
> We will also discuss this here in our team.
Ok, I will revert this patch and resend a simpler one. Thank you.
prev parent reply other threads:[~2022-05-23 13:25 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-23 5:50 [PATCH net] net/smc: fix listen processing for SMC-Rv2 liuyacan
2022-05-23 9:10 ` patchwork-bot+netdevbpf
2022-05-23 11:19 ` Karsten Graul
2022-05-23 12:12 ` liuyacan
2022-05-23 12:37 ` Karsten Graul
2022-05-23 13:25 ` liuyacan [this message]
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