[MPTCP] Re: [MPTCP][PATCH v4 mptcp-next 3/5] mptcp: add the incoming RM_ADDR support

[MPTCP] Re: [MPTCP][PATCH v4 mptcp-next 3/5] mptcp: add the incoming RM_ADDR support

[Paolo Abeni]

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On Thu, 2020-07-30 at 19:06 +0800, Geliang Tang wrote:
> This patch added the RM_ADDR option parsing logic:
> 
> We parsed the incoming options to find if the rm_addr option is received,
> and called mptcp_pm_rm_addr_received to schedule PM work to a new status,
> named MPTCP_PM_RM_ADDR_RECEIVED.
> 
> PM work got this status, and called mptcp_pm_nl_rm_addr_received to handle
> it.
> 
> In mptcp_pm_nl_rm_addr_received, we closed the subflow matching the rm_id,
> and updated PM counter.
> 
> Suggested-by: Matthieu Baerts <matthieu.baerts(a)tessares.net>
> Suggested-by: Paolo Abeni <pabeni(a)redhat.com>
> Suggested-by: Mat Martineau <mathew.j.martineau(a)linux.intel.com>
> Signed-off-by: Geliang Tang <geliangtang(a)gmail.com>
> ---
>  net/mptcp/options.c    |  5 +++++
>  net/mptcp/pm.c         | 12 ++++++++++++
>  net/mptcp/pm_netlink.c | 33 ++++++++++++++++++++++++++++++++-
>  net/mptcp/protocol.c   | 12 ++++++++----
>  net/mptcp/protocol.h   |  7 +++++++
>  net/mptcp/subflow.c    |  1 +
>  6 files changed, 65 insertions(+), 5 deletions(-)
> 
> diff --git a/net/mptcp/options.c b/net/mptcp/options.c
> index bbc124876417..a52a05effac9 100644
> --- a/net/mptcp/options.c
> +++ b/net/mptcp/options.c
> @@ -888,6 +888,11 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
>  		mp_opt.add_addr = 0;
>  	}
>  
> +	if (mp_opt.rm_addr) {
> +		mptcp_pm_rm_addr_received(msk, mp_opt.rm_id);
> +		mp_opt.rm_addr = 0;
> +	}
> +
>  	if (!mp_opt.dss)
>  		return;
>  
> diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
> index 81b07ae213b9..558462d87eb3 100644
> --- a/net/mptcp/pm.c
> +++ b/net/mptcp/pm.c
> @@ -149,6 +149,18 @@ void mptcp_pm_add_addr_received(struct mptcp_sock *msk,
>  	spin_unlock_bh(&pm->lock);
>  }
>  
> +void mptcp_pm_rm_addr_received(struct mptcp_sock *msk, u8 rm_id)
> +{
> +	struct mptcp_pm_data *pm = &msk->pm;
> +
> +	pr_debug("msk=%p remote_id=%d", msk, rm_id);
> +
> +	spin_lock_bh(&pm->lock);
> +	mptcp_pm_schedule_work(msk, MPTCP_PM_RM_ADDR_RECEIVED);
> +	pm->rm_id = rm_id;
> +	spin_unlock_bh(&pm->lock);
> +}
> +
>  /* path manager helpers */
>  
>  bool mptcp_pm_add_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
> diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
> index c8820c4156e6..74a18e463c3d 100644
> --- a/net/mptcp/pm_netlink.c
> +++ b/net/mptcp/pm_netlink.c
> @@ -173,7 +173,7 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)
>  {
>  	struct sock *sk = (struct sock *)msk;
>  	struct mptcp_pm_addr_entry *local;
> -	struct mptcp_addr_info remote;
> +	struct mptcp_addr_info remote = { 0 };
>  	struct pm_nl_pernet *pernet;
>  
>  	pernet = net_generic(sock_net((struct sock *)msk), pm_nl_pernet_id);
> @@ -261,6 +261,37 @@ void mptcp_pm_nl_add_addr_received(struct mptcp_sock *msk)
>  	spin_lock_bh(&msk->pm.lock);
>  }
>  
> +void mptcp_pm_nl_rm_addr_received(struct mptcp_sock *msk)
> +{
> +	struct mptcp_subflow_context *subflow, *tmp;
> +	struct sock *sk = (struct sock *)msk;
> +
> +	pr_debug("rm_id %d", msk->pm.rm_id);
> +
> +	if (!msk->pm.rm_id)
> +		return;
> +
> +	if (list_empty(&msk->conn_list))
> +		return;
> +
> +	msk->pm.add_addr_accepted--;
> +	msk->pm.subflows--;
> +	WRITE_ONCE(msk->pm.accept_addr, true);
> +
> +	list_for_each_entry_safe(subflow, tmp, &msk->conn_list, node) {
> +		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
> +		int how = RCV_SHUTDOWN | SEND_SHUTDOWN;
> +		long timeout = 0;
> +
> +		if (msk->pm.rm_id == subflow->remote_id) {
> +			spin_unlock_bh(&msk->pm.lock);
> +			mptcp_subflow_shutdown(sk, ssk, how);
> +			__mptcp_close_ssk(sk, ssk, subflow, timeout);
> +			spin_lock_bh(&msk->pm.lock);
> +		}

You can reduce the indentation level checking the opposite condition:

		if (msk->pm.rm_id != subflow->remote_id)
			continue;

		// shutdown and close
		break; // no other subflow to process

/P