netdev - Re: [PATCHv6 0/5] net/tls: fixes for NVMe-over-TLS

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Message-ID: <173e27fe-18bb-6194-2af3-1743bc0f8f61@grimberg.me>
Date: Mon, 3 Jul 2023 16:42:02 +0300
From: Sagi Grimberg <sagi@...mberg.me>
To: Hannes Reinecke <hare@...e.de>, David Howells <dhowells@...hat.com>
Cc: Keith Busch <kbusch@...nel.org>, Christoph Hellwig <hch@....de>,
 linux-nvme@...ts.infradead.org, Jakub Kicinski <kuba@...nel.org>,
 Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
 netdev@...r.kernel.org
Subject: Re: [PATCHv6 0/5] net/tls: fixes for NVMe-over-TLS


>>> Hannes Reinecke <hare@...e.de> wrote:
>>>
>>>>> 'discover' and 'connect' works, but when I'm trying to transfer data
>>>>> (eg by doing a 'mkfs.xfs') the whole thing crashes horribly in
>>>>> sock_sendmsg() as it's trying to access invalid pages :-(
>>>
>>> Can you be more specific about the crash?
>>
>> Hannes,
>>
>> See:
>> [PATCH net] nvme-tcp: Fix comma-related oops
> 
> Ah, right. That solves _that_ issue.
> 
> But now I'm deadlocking on the tls_rx_reader_lock() (patched as to your 
> suggestion). Investigating.

Are you sure it is a deadlock? or maybe you returned EAGAIN and nvme-tcp
does not interpret this as a transient status and simply returns from
io_work?

> But it brought up yet another can of worms: what _exactly_ is the return 
> value of ->read_sock()?
> 
> There are currently two conflicting use-cases:
> -> Ignore the return value, and assume errors etc are signalled
>     via 'desc.error'.
>     net/strparser/strparser.c
>     drivers/infiniband/sw/siw
>     drivers/scsi/iscsi_tcp.c
> -> use the return value of ->read_sock(), ignoring 'desc.error':
>     drivers/nvme/host/tcp.c
>     net/ipv4/tcp.c
> So which one is it?
> Needless to say, implementations following the second style do not
> set 'desc.error', causing any errors there to be ignored for callers
> from the first style...

I don't think ignoring the return value of read_sock makes sense because
it can fail outside of the recv_actor failures.

But to be on the safe side, perhaps you can both return an error and set
desc.error?

> Jakub?
> 
> Cheers,
> 
> Hannes
> 
>