linux-kernel - Re: [PATCH] nvme/tcp: handle tls partially sent records in write

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Message-ID: <8e5a3ff3-d17a-488f-97fb-3904684edb47@suse.de>
Date: Tue, 7 Oct 2025 11:51:31 +0200
From: Hannes Reinecke <hare@...e.de>
To: Wilfred Mallawa <wilfred.opensource@...il.com>,
 linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org,
 netdev@...r.kernel.org
Cc: Keith Busch <kbusch@...nel.org>, Jens Axboe <axboe@...nel.dk>,
 Christoph Hellwig <hch@....de>, Sagi Grimberg <sagi@...mberg.me>,
 John Fastabend <john.fastabend@...il.com>, Jakub Kicinski <kuba@...nel.org>,
 Sabrina Dubroca <sd@...asysnail.net>, "David S . Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>
Subject: Re: [PATCH] nvme/tcp: handle tls partially sent records in
 write_space()

On 10/7/25 11:24, Wilfred Mallawa wrote:
> On Tue, 2025-10-07 at 07:19 +0200, Hannes Reinecke wrote:
>> On 10/7/25 02:46, Wilfred Mallawa wrote:
>>> From: Wilfred Mallawa <wilfred.mallawa@....com>
>>>
>>
> [...]
>> I wonder: Do we really need to check for a partially assembled
>> record,
>> or wouldn't it be easier to call queue->write_space() every time
>> here?
>> We sure would end up with executing the callback more often, but if
>> no
>> data is present it shouldn't do any harm.
>>
>> IE just use
>>
>> if (nvme_tcp_queue_tls(queue)
>>       queue->write_space(sk);
> 
> Hey Hannes,
> 
> This was my initial approach, but I figured using
> tls_is_partially_sent_record() might be slightly more efficient. But if
> we think that's negligible, happy to go with this approach (omitting
> the partial record check).
> 
Please do.
Performance testing on NVMe-TCP is notoriously tricky, so for now we
really should not assume anything here.
And it's making the patch _vastly_ simpler, _and_ we don't have to
involve the networking folks here.
We have a similar patch for the data_ready() function in nvmet_tcp(),
and that seemed to work, too.
Nit: we don't unset the 'NOSPACE' flag there. Can you check if that's
really required? And, if it is, fixup nvmet_tcp() to unset it?
Or, if not, modify your patch to not clear it?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@...e.de                                +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich