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([2620:15c:2c1:200:55c7:81e6:c7d8:94b]) by smtp.gmail.com with ESMTPSA id 70-v6sm3440866pfz.27.2018.10.03.08.41.13 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 03 Oct 2018 08:41:14 -0700 (PDT) Subject: Re: [PATCH net-next] inet: do not set backlog if listen fails To: Yafang Shao , edumazet@google.com, davem@davemloft.net Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <1538579279-11614-1-git-send-email-laoar.shao@gmail.com> From: Eric Dumazet Message-ID: <9863d8b1-7249-e5ec-0400-4007798e69e2@gmail.com> Date: Wed, 3 Oct 2018 08:41:13 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <1538579279-11614-1-git-send-email-laoar.shao@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/03/2018 08:07 AM, Yafang Shao wrote: > These two backlog members are not necessary set in inet_csk_listen_start(). > Regarding sk_max_ack_backlog, it will be set in the caller inet_listen > and dccp_listen_start. > Regraing sk_ack_backlog, it is better to put it together with > sk_max_ack_backlog in the same function and only set on success. > > Signed-off-by: Yafang Shao > --- > net/dccp/proto.c | 1 + > net/ipv4/af_inet.c | 1 + > net/ipv4/inet_connection_sock.c | 3 --- > 3 files changed, 2 insertions(+), 3 deletions(-) > > diff --git a/net/dccp/proto.c b/net/dccp/proto.c > index 875858c..34d48cd 100644 > --- a/net/dccp/proto.c > +++ b/net/dccp/proto.c > @@ -959,6 +959,7 @@ int inet_dccp_listen(struct socket *sock, int backlog) > err = dccp_listen_start(sk, backlog); > if (err) > goto out; > + sk->sk_ack_backlog = 0; This is racy, remember that dccp and tcp have lockless listeners. Do not change sk_ack_backlog after a TCP/DCCP socket is ready to accept new flows.