linux-kernel - Re: [PATCH v3 3/8] net/handshake: Ensure the request is destructed on completion

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Message-ID: <4f16296c-c1e1-43c2-8a73-36dabaa2ffd1@suse.de>
Date: Tue, 7 Oct 2025 07:20:42 +0200
From: Hannes Reinecke <hare@...e.de>
To: Alistair Francis <alistair23@...il.com>
Cc: chuck.lever@...cle.com, hare@...nel.org,
 kernel-tls-handshake@...ts.linux.dev, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
 linux-nvme@...ts.infradead.org, linux-nfs@...r.kernel.org,
 kbusch@...nel.org, axboe@...nel.dk, hch@....de, sagi@...mberg.me,
 kch@...dia.com, Alistair Francis <alistair.francis@....com>
Subject: Re: [PATCH v3 3/8] net/handshake: Ensure the request is destructed on
 completion

On 10/7/25 03:22, Alistair Francis wrote:
> On Mon, Oct 6, 2025 at 4:16 PM Hannes Reinecke <hare@...e.de> wrote:
>>
>> On 10/3/25 06:31, alistair23@...il.com wrote:
>>> From: Alistair Francis <alistair.francis@....com>
>>>
>>> To avoid future handshake_req_hash_add() calls failing with EEXIST when
>>> performing a KeyUpdate let's make sure the old request is destructed
>>> as part of the completion.
>>>
>>> Signed-off-by: Alistair Francis <alistair.francis@....com>
>>> ---
>>> v3:
>>>    - New patch
>>>
>>>    net/handshake/request.c | 2 ++
>>>    1 file changed, 2 insertions(+)
>>>
>>> diff --git a/net/handshake/request.c b/net/handshake/request.c
>>> index 0d1c91c80478..194725a8aaca 100644
>>> --- a/net/handshake/request.c
>>> +++ b/net/handshake/request.c
>>> @@ -311,6 +311,8 @@ void handshake_complete(struct handshake_req *req, unsigned int status,
>>>                /* Handshake request is no longer pending */
>>>                sock_put(sk);
>>>        }
>>> +
>>> +     handshake_sk_destruct_req(sk);
>>>    }
>>>    EXPORT_SYMBOL_IF_KUNIT(handshake_complete);
>>>
>> Curious.
>> Why do we need it now? We had been happily using the handshake mechanism
>> for quite some time now, so who had been destroying the request without
>> this patch?
> 
> Until now a handshake would only be destroyed on a failure or when a
> sock is freed (via the sk_destruct function pointer).
> handshake_complete() is only called on errors, not a successful
> handshake so it doesn't remove the request.
> 
> Note that destroying is mostly just removing the entry from the hash
> table with rhashtable_remove_fast(). Which is what we need to be able
> to submit it again.
> 

And we really should've done that in the first place.
Thanks for the explanation.

Reviewed-by: Hannes Reinecke <hare@...e.de>

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