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Date:   Fri, 14 May 2021 17:49:18 -0700
From:   Martin KaFai Lau <kafai@fb.com>
To:     Kuniyuki Iwashima <kuniyu@amazon.co.jp>
CC:     "David S . Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Eric Dumazet <edumazet@google.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Benjamin Herrenschmidt <benh@amazon.com>,
        Kuniyuki Iwashima <kuni1840@gmail.com>, <bpf@vger.kernel.org>,
        <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v5 bpf-next 02/11] tcp: Add num_closed_socks to struct
 sock_reuseport.
Message-ID: <20210515004918.rhtnsbvowtp6mudj@kafai-mbp>
References: <20210510034433.52818-1-kuniyu@amazon.co.jp>
 <20210510034433.52818-3-kuniyu@amazon.co.jp>
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On Mon, May 10, 2021 at 12:44:24PM +0900, Kuniyuki Iwashima wrote:
> As noted in the following commit, a closed listener has to hold the
> reference to the reuseport group for socket migration. This patch adds a
> field (num_closed_socks) to struct sock_reuseport to manage closed sockets
> within the same reuseport group. Moreover, this and the following commits
> introduce some helper functions to split socks[] into two sections and keep
> TCP_LISTEN and TCP_CLOSE sockets in each section. Like a double-ended
> queue, we will place TCP_LISTEN sockets from the front and TCP_CLOSE
> sockets from the end.
> 
>   TCP_LISTEN---------->       <-------TCP_CLOSE
>   +---+---+  ---  +---+  ---  +---+  ---  +---+
>   | 0 | 1 |  ...  | i |  ...  | j |  ...  | k |
>   +---+---+  ---  +---+  ---  +---+  ---  +---+
> 
>   i = num_socks - 1
>   j = max_socks - num_closed_socks
>   k = max_socks - 1
> 
> This patch also extends reuseport_add_sock() and reuseport_grow() to
> support num_closed_socks.
Acked-by: Martin KaFai Lau <kafai@fb.com>