From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5234519441 for ; Tue, 10 Oct 2023 12:49:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="u4S/+Fo2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0F6E1C433C7; Tue, 10 Oct 2023 12:49:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1696942150; bh=XBBfUW/SVpUppenEkZ/gYftoOYPvXJgJoeQwgghtOao=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=u4S/+Fo2oOPge7PaXND/JNDT3YdESnOBCspS+8mqVpv8W33MKhNCLzKuo43iyVkVc JzTI92U6q+IRO2k3CFeSw6Ly41omZ3u8F+f9FJcXAFVr+/LffGxr035PcAwdAWqtZr NIeQa9U66hN9A9TcW6wgk9fg6GTZ7roDZuHFHEu7FKW9nuhQWeNCOOLznuM7mHy6yR ijXxKJPHnlp5OE0Y3/K5J9Ut5wpWnTslgVIua+RuX9Kzd5YYvFYx77FGHLmZ3sFi5P aHQ6s//pU+2BwdBcqRafPSVHRjLrT9sIjwJloFXi/m5GbHLp+vEH8lc81BZJmEMOoW uNtJddgkGiB6A== Message-ID: <3158efd3-ba52-4b84-9d3a-4fea9ca3bc93@kernel.org> Date: Tue, 10 Oct 2023 14:49:08 +0200 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH mptcp-next v12 1/5] mptcp: avoid resetting when another subflow available Content-Language: en-GB, fr-BE To: Geliang Tang Cc: mptcp@lists.linux.dev References: <2b69fa22510db02a12eb101c3e8173dda76f8133.1696831239.git.geliang.tang@suse.com> <76f31a37-16b4-4e3a-8b00-fdb2c1eabfb4@kernel.org> <20231010061320.GB6593@localhost.localdomain> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Geliang, On 10/10/2023 08:13, Geliang Tang wrote: > On Mon, Oct 09, 2023 at 06:13:19PM +0200, Matthieu Baerts wrote: >> Hi Geliang, >> >> On 09/10/2023 08:02, Geliang Tang wrote: >>> When closing the msk->first socket in __mptcp_close_ssk(), if there's >>> another subflow available, it's better to avoid resetting it. >>> >>> Signed-off-by: Geliang Tang >>> --- >>> net/mptcp/protocol.c | 4 ++-- >>> 1 file changed, 2 insertions(+), 2 deletions(-) >>> >>> diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c >>> index 30e0c29ae0a4..6346a164ed66 100644 >>> --- a/net/mptcp/protocol.c >>> +++ b/net/mptcp/protocol.c >>> @@ -2396,7 +2396,7 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk, >>> goto out_release; >>> } >>> >>> - dispose_it = msk->free_first || ssk != msk->first; >>> + dispose_it = msk->free_first || ssk != msk->first || !list_is_singular(&msk->conn_list); >>> if (dispose_it) >>> list_del(&subflow->node); >>> >>> @@ -2446,7 +2446,7 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk, >>> >>> sock_put(ssk); >>> >>> - if (ssk == msk->first) >>> + if (ssk == msk->first && list_is_singular(&msk->conn_list)) >>> WRITE_ONCE(msk->first, NULL); >> >> I don't think we should 'dispose it' nor set 'msk->first' to NULL but > > That's what this patch dose. Dispose it, not set msk->first to NULL. Sorry, I meant: we should not 'dispose it' and we should not set 'msk->first' to NULL if we are not closing the whole MPTCP connection. >> instead, we should not call tcp_disconnect() directly: if the connection > > But this patch lacks the code to handle: > > ssk == msk->first && !list_is_singular(&msk->conn_list) > > Is my understanding correct? > > How about dropping list_is_singular() in the next block, something like: > > * For established sockets, allow an additional timeout before closing, > * as the protocol can still create more subflows. > */ > - if (list_is_singular(&msk->conn_list) && msk->first && > - inet_sk_state_load(msk->first) == TCP_CLOSE) { > + if (msk->first && inet_sk_state_load(msk->first) == TCP_CLOSE) { > if (sk->sk_state != TCP_ESTABLISHED || > msk->in_accept_queue || sock_flag(sk, SOCK_DEAD)) { > inet_sk_state_store(sk, TCP_CLOSE); I cannot tell like that, but what is important first is not to call 'tcp_disconnect()' on a non already closed socket. So we need something else before the 'disconnect()'. Cheers, Matt -- Tessares | Belgium | Hybrid Access Solutions www.tessares.net