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Date: Fri, 14 Jun 2024 12:54:41 +0200
From: Florian Westphal <fw@strlen.de>
To: luoxuanqiang <luoxuanqiang@kylinos.cn>
Cc: edumazet@google.com, davem@davemloft.net, dsahern@kernel.org,
	fw@strlen.de, kuba@kernel.org, linux-kernel@vger.kernel.org,
	netdev@vger.kernel.org, pabeni@redhat.com, kuniyu@amazon.com,
	dccp@vger.kernel.org
Subject: Re: [PATCH net v2] Fix race for duplicate reqsk on identical SYN
Message-ID: <20240614105441.GA24596@breakpoint.cc>
References: <20240614102628.446642-1-luoxuanqiang@kylinos.cn>
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luoxuanqiang <luoxuanqiang@kylinos.cn> wrote:
>  include/net/inet_connection_sock.h |  2 +-
>  net/dccp/ipv4.c                    |  2 +-
>  net/dccp/ipv6.c                    |  2 +-
>  net/ipv4/inet_connection_sock.c    | 15 +++++++++++----
>  net/ipv4/tcp_input.c               | 11 ++++++++++-
>  5 files changed, 24 insertions(+), 8 deletions(-)
> 
> diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
> index 7d6b1254c92d..8773d161d184 100644
> --- a/include/net/inet_connection_sock.h
> +++ b/include/net/inet_connection_sock.h
> @@ -264,7 +264,7 @@ struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
>  				      struct request_sock *req,
>  				      struct sock *child);
>  void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
> -				   unsigned long timeout);
> +				   unsigned long timeout, bool *found_dup_sk);

Nit:

I think it would be preferrable to change retval to bool rather than
bool *found_dup_sk extra arg, so one can do

bool inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
  				   unsigned long timeout)
{
	if (!reqsk_queue_hash_req(req, timeout))
		return false;

i.e. let retval indicate wheter reqsk was inserted or not.

Patch looks good to me otherwise.