Merge branch 'mptcp-endpoint-readd-fixes' into main

Matthieu Baerts says:

====================
mptcp: fix signal endpoint readd

Issue torvalds#501 [1] showed that the Netlink PM currently doesn't correctly
support removal and re-add of signal endpoints.

Patches 1 and 2 address the issue: the first one in the userspace path-
manager, introduced in v5.19 ; and the second one in the in-kernel path-
manager, introduced in v5.7.

Patch 3 introduces a related selftest. There is no 'Fixes' tag, because
it might be hard to backport it automatically, as missing helpers in
Bash will not be caught when compiling the kernel or the selftests.

The last two patches address two small issues in the MPTCP selftests,
one introduced in v6.6., and the other one in v5.17.

Link: multipath-tcp/mptcp_net-next#501 [1]
====================

Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/mptcp/pm_netlink.c

@@ -1401,6 +1401,7 @@ static bool mptcp_pm_remove_anno_addr(struct mptcp_sock *msk,
 	ret = remove_anno_list_by_saddr(msk, addr);
 	if (ret || force) {
 		spin_lock_bh(&msk->pm.lock);
+		msk->pm.add_addr_signaled -= ret;
 		mptcp_pm_remove_addr(msk, &list);
 		spin_unlock_bh(&msk->pm.lock);
 	}
@@ -1534,16 +1535,25 @@ 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;
+	int anno_nr = 0;
 
 	list_for_each_entry(entry, rm_list, list) {
-		if ((remove_anno_list_by_saddr(msk, &entry->addr) ||
-		     lookup_subflow_by_saddr(&msk->conn_list, &entry->addr)) &&
-		    alist.nr < MPTCP_RM_IDS_MAX)
-			alist.ids[alist.nr++] = entry->addr.id;
+		if (alist.nr >= MPTCP_RM_IDS_MAX)
+			break;
+
+		/* only delete if either announced or matching a subflow */
+		if (remove_anno_list_by_saddr(msk, &entry->addr))
+			anno_nr++;
+		else if (!lookup_subflow_by_saddr(&msk->conn_list,
+						  &entry->addr))
+			continue;
+
+		alist.ids[alist.nr++] = entry->addr.id;
 	}
 
 	if (alist.nr) {
 		spin_lock_bh(&msk->pm.lock);
+		msk->pm.add_addr_signaled -= anno_nr;
 		mptcp_pm_remove_addr(msk, &alist);
 		spin_unlock_bh(&msk->pm.lock);
 	}
@@ -1556,17 +1566,18 @@ static void mptcp_pm_remove_addrs_and_subflows(struct mptcp_sock *msk,
 	struct mptcp_pm_addr_entry *entry;
 
 	list_for_each_entry(entry, rm_list, list) {
-		if (lookup_subflow_by_saddr(&msk->conn_list, &entry->addr) &&
-		    slist.nr < MPTCP_RM_IDS_MAX)
+		if (slist.nr < MPTCP_RM_IDS_MAX &&
+		    lookup_subflow_by_saddr(&msk->conn_list, &entry->addr))
 			slist.ids[slist.nr++] = entry->addr.id;
 
-		if (remove_anno_list_by_saddr(msk, &entry->addr) &&
-		    alist.nr < MPTCP_RM_IDS_MAX)
+		if (alist.nr < MPTCP_RM_IDS_MAX &&
+		    remove_anno_list_by_saddr(msk, &entry->addr))
 			alist.ids[alist.nr++] = entry->addr.id;
 	}
 
 	if (alist.nr) {
 		spin_lock_bh(&msk->pm.lock);
+		msk->pm.add_addr_signaled -= alist.nr;
 		mptcp_pm_remove_addr(msk, &alist);
 		spin_unlock_bh(&msk->pm.lock);
 	}

tools/testing/selftests/net/mptcp/mptcp_connect.c

@@ -1115,11 +1115,11 @@ int main_loop_s(int listensock)
 		return 1;
 	}
 
-	if (--cfg_repeat > 0) {
-		if (cfg_input)
-			close(fd);
+	if (cfg_input)
+		close(fd);
+
+	if (--cfg_repeat > 0)
 		goto again;
-	}
 
 	return 0;
 }

tools/testing/selftests/net/mptcp/mptcp_join.sh

@@ -661,7 +661,7 @@ pm_nl_check_endpoint()
 	done
 
 	if [ -z "${id}" ]; then
-		test_fail "bad test - missing endpoint id"
+		fail_test "bad test - missing endpoint id"
 		return
 	fi
 
@@ -3526,6 +3526,35 @@ endpoint_tests()
 		chk_mptcp_info subflows 1 subflows 1
 		mptcp_lib_kill_wait $tests_pid
 	fi
+
+	# remove and re-add
+	if reset "delete re-add signal" &&
+	   mptcp_lib_kallsyms_has "subflow_rebuild_header$"; then
+		pm_nl_set_limits $ns1 1 1
+		pm_nl_set_limits $ns2 1 1
+		pm_nl_add_endpoint $ns1 10.0.2.1 id 1 flags signal
+		test_linkfail=4 speed=20 \
+			run_tests $ns1 $ns2 10.0.1.1 &
+		local tests_pid=$!
+
+		wait_mpj $ns2
+		pm_nl_check_endpoint "creation" \
+			$ns1 10.0.2.1 id 1 flags signal
+		chk_subflow_nr "before delete" 2
+		chk_mptcp_info subflows 1 subflows 1
+
+		pm_nl_del_endpoint $ns1 1 10.0.2.1
+		sleep 0.5
+		chk_subflow_nr "after delete" 1
+		chk_mptcp_info subflows 0 subflows 0
+
+		pm_nl_add_endpoint $ns1 10.0.2.1 flags signal
+		wait_mpj $ns2
+		chk_subflow_nr "after re-add" 2
+		chk_mptcp_info subflows 1 subflows 1
+		mptcp_lib_kill_wait $tests_pid
+	fi
+
 }
 
 # [$1: error message]