mptcp: only send RM_ADDR in nl_cmd_remove

The specifications from [1] about the "REMOVE" command say:

    Announce that an address has been lost to the peer

It was then only supposed to send a RM_ADDR and not trying to delete
associated subflows.

A new helper mptcp_pm_remove_addrs() is then introduced to do just
that, compared to mptcp_pm_remove_addrs_and_subflows() also removing
subflows.

To delete a subflow, the userspace daemon can use the "SUB_DESTROY"
command, see mptcp_nl_cmd_sf_destroy().

Fixes: d9a4594 ("mptcp: netlink: Add MPTCP_PM_CMD_REMOVE")
Link: https://github.com/multipath-tcp/mptcp/blob/mptcp_v0.96/include/uapi/linux/mptcp.h [1]
Cc: [email protected]
Reviewed-by: Matthieu Baerts <[email protected]>
Signed-off-by: Geliang Tang <[email protected]>
Signed-off-by: Mat Martineau <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

net/mptcp/pm_netlink.c

@@ -1558,6 +1558,24 @@ static int mptcp_nl_cmd_del_addr(struct sk_buff *skb, struct genl_info *info)
 	return ret;
 }
 
+void mptcp_pm_remove_addrs(struct mptcp_sock *msk, struct list_head *rm_list)
+{
+	struct mptcp_rm_list alist = { .nr = 0 };
+	struct mptcp_pm_addr_entry *entry;
+
+	list_for_each_entry(entry, rm_list, list) {
+		remove_anno_list_by_saddr(msk, &entry->addr);
+		if (alist.nr < MPTCP_RM_IDS_MAX)
+			alist.ids[alist.nr++] = entry->addr.id;
+	}
+
+	if (alist.nr) {
+		spin_lock_bh(&msk->pm.lock);
+		mptcp_pm_remove_addr(msk, &alist);
+		spin_unlock_bh(&msk->pm.lock);
+	}
+}
+
 void mptcp_pm_remove_addrs_and_subflows(struct mptcp_sock *msk,
 					struct list_head *rm_list)
 {

net/mptcp/pm_userspace.c

@@ -232,7 +232,7 @@ int mptcp_nl_cmd_remove(struct sk_buff *skb, struct genl_info *info)
 
 	list_move(&match->list, &free_list);
 
-	mptcp_pm_remove_addrs_and_subflows(msk, &free_list);
+	mptcp_pm_remove_addrs(msk, &free_list);
 
 	release_sock((struct sock *)msk);
 

net/mptcp/protocol.h

@@ -832,6 +832,7 @@ int mptcp_pm_announce_addr(struct mptcp_sock *msk,
 			   bool echo);
 int mptcp_pm_remove_addr(struct mptcp_sock *msk, const struct mptcp_rm_list *rm_list);
 int mptcp_pm_remove_subflow(struct mptcp_sock *msk, const struct mptcp_rm_list *rm_list);
+void mptcp_pm_remove_addrs(struct mptcp_sock *msk, struct list_head *rm_list);
 void mptcp_pm_remove_addrs_and_subflows(struct mptcp_sock *msk,
 					struct list_head *rm_list);