[PATCH v6 mptcp-next 0/7] mptcp: improve subflow creation on errors

[PATCH v6 mptcp-next 0/7] mptcp: improve subflow creation on errors

[Paolo Abeni]

This iteration tries to add address the feedback on v5, namely
test counter update and locking in write_options. The latter
required quite significant changes in patch 5/7.

Additionally the series now includes the pending cleanup, as
they depends on the previous patches. No changes there WRT the
previous iteration.

Currently when a subflow connection fails - either the TCP
connection is reset by the peer, or the MPJ handshake never
completes - the in kernel PM don't perform any further action.
Notably no additional subflow creation is attempted.

This series is aimed at improving the in-kernel path manager
behavior in the above scenario:
- each endpoint is used only once per connection (patch 2/4)
- on failure we try to move to the next subflow, if any
  (patch 3/4)

The first patch is minor cleanup, and the last patch adds
specific self-tests.

This should address/close:
https://github.com/multipath-tcp/mptcp_net-next/issues/235
https://github.com/multipath-tcp/mptcp_net-next/issues/242

Paolo Abeni (7):
  mptcp: fix per socket endpoint accounting.
  mptcp: clean-up MPJ option writing.
  mptcp: keep track of local endpoint still available for each msk
  mptcp: do not block subflows creation on errors
  selftests: mptcp: add tests for subflow creation failure
  mptcp: cleanup MPJ subflow list handling
  mptcp: avoid atomic bit manipulation when possible

 net/mptcp/options.c                           |  44 ++--
 net/mptcp/pm.c                                |  24 ++-
 net/mptcp/pm_netlink.c                        | 188 +++++++++++-------
 net/mptcp/protocol.c                          | 158 +++++++--------
 net/mptcp/protocol.h                          |  46 +++--
 net/mptcp/sockopt.c                           |  24 +--
 net/mptcp/subflow.c                           |   9 +-
 tools/testing/selftests/net/mptcp/config      |   1 +
 .../testing/selftests/net/mptcp/mptcp_join.sh |  83 +++++++-
 9 files changed, 350 insertions(+), 227 deletions(-)

-- 
2.33.1

[PATCH v6 mptcp-next 1/7] mptcp: fix per socket endpoint accounting.

[Paolo Abeni]

Since full-mesh endpoint support, the reception of a single ADD_ADDR
option can cause multiple subflows creation. When such option is
accepted we increment 'add_addr_accepted' by one. When we received
a paired RM_ADDR option, we deleted all the relevant subflows,
decrementing 'add_addr_accepted' by one for each of them.

We have a similar issue for 'local_addr_used'

Fix them moving the pm endpoint accounting outside the subflow
traversal.

Fixes: 1a0d6136c5f0 ("mptcp: local addresses fullmesh")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
 net/mptcp/pm_netlink.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index 3186d33b5208..d18b13e3e74c 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -710,6 +710,8 @@ static void mptcp_pm_nl_rm_addr_or_subflow(struct mptcp_sock *msk,
 		return;
 
 	for (i = 0; i < rm_list->nr; i++) {
+		bool removed = false;
+
 		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;
@@ -729,15 +731,19 @@ static void mptcp_pm_nl_rm_addr_or_subflow(struct mptcp_sock *msk,
 			mptcp_close_ssk(sk, ssk, subflow);
 			spin_lock_bh(&msk->pm.lock);
 
-			if (rm_type == MPTCP_MIB_RMADDR) {
-				msk->pm.add_addr_accepted--;
-				WRITE_ONCE(msk->pm.accept_addr, true);
-			} else if (rm_type == MPTCP_MIB_RMSUBFLOW) {
-				msk->pm.local_addr_used--;
-			}
+			removed = true;
 			msk->pm.subflows--;
 			__MPTCP_INC_STATS(sock_net(sk), rm_type);
 		}
+		if (!removed)
+			continue;
+
+		if (rm_type == MPTCP_MIB_RMADDR) {
+			msk->pm.add_addr_accepted--;
+			WRITE_ONCE(msk->pm.accept_addr, true);
+		} else if (rm_type == MPTCP_MIB_RMSUBFLOW) {
+			msk->pm.local_addr_used--;
+		}
 	}
 }
 
-- 
2.33.1

[PATCH v6 mptcp-next 2/7] mptcp: clean-up MPJ option writing.

[Paolo Abeni]

Check for all MPJ variant at once, this reduces the number
of conditionals traversed on average and will simplify the
next patch.

No functional change intended.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
 net/mptcp/options.c | 44 +++++++++++++++++++++++---------------------
 1 file changed, 23 insertions(+), 21 deletions(-)

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 8a1020e4285c..7a6a39b71633 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -1381,27 +1381,29 @@ void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
 
 		/* MPC is additionally mutually exclusive with MP_PRIO */
 		goto mp_capable_done;
-	} else if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) {
-		*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
-				      TCPOLEN_MPTCP_MPJ_SYN,
-				      opts->backup, opts->join_id);
-		put_unaligned_be32(opts->token, ptr);
-		ptr += 1;
-		put_unaligned_be32(opts->nonce, ptr);
-		ptr += 1;
-	} else if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) {
-		*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
-				      TCPOLEN_MPTCP_MPJ_SYNACK,
-				      opts->backup, opts->join_id);
-		put_unaligned_be64(opts->thmac, ptr);
-		ptr += 2;
-		put_unaligned_be32(opts->nonce, ptr);
-		ptr += 1;
-	} else if (OPTION_MPTCP_MPJ_ACK & opts->suboptions) {
-		*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
-				      TCPOLEN_MPTCP_MPJ_ACK, 0, 0);
-		memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN);
-		ptr += 5;
+	} else if (OPTIONS_MPTCP_MPJ & opts->suboptions) {
+		if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) {
+			*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
+					      TCPOLEN_MPTCP_MPJ_SYN,
+					      opts->backup, opts->join_id);
+			put_unaligned_be32(opts->token, ptr);
+			ptr += 1;
+			put_unaligned_be32(opts->nonce, ptr);
+			ptr += 1;
+		} else if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) {
+			*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
+					      TCPOLEN_MPTCP_MPJ_SYNACK,
+					      opts->backup, opts->join_id);
+			put_unaligned_be64(opts->thmac, ptr);
+			ptr += 2;
+			put_unaligned_be32(opts->nonce, ptr);
+			ptr += 1;
+		} else {
+			*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
+					      TCPOLEN_MPTCP_MPJ_ACK, 0, 0);
+			memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN);
+			ptr += 5;
+		}
 	} else if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) {
 		u8 len = TCPOLEN_MPTCP_ADD_ADDR_BASE;
 		u8 echo = MPTCP_ADDR_ECHO;
-- 
2.33.1

[PATCH v6 mptcp-next 3/7] mptcp: keep track of local endpoint still available for each msk

[Paolo Abeni]

Include into the path manager status a bitmap tracking the list
of local endpoints still available - not yet used - for the
relavant mptcp socket.
Keep such map updated at endpoint creation/deleteion time, so
that we can easily skip already used endpoint at local address
selection time.
The endpoint used by the initial subflow is lazyly accounted at
subflow creation time: the usage bitmap is be up2date before
endpoint selection and we avoid such unneeded task in some relevant
scenarions - e.g. busy servers accepting incoming subflows but
not creating any additional ones nor annuncing additional addresses.

Overall this allows for fair local endpoints usage in case of
subflow failure.

As a side effect, this patch also enforces that each endpoint
is used at most once for each mptcp connection.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
v4 -> v5:
 - track MPC subflow, too
 - update self-tests accordingly

v3 -> v4:
 - track the available (not yet used) id instead of the used ones
 - track both
 - cleanup duplication with id_bitmap
---
 net/mptcp/pm.c                                |   1 +
 net/mptcp/pm_netlink.c                        | 116 +++++++++++-------
 net/mptcp/protocol.c                          |   3 +-
 net/mptcp/protocol.h                          |  11 +-
 .../testing/selftests/net/mptcp/mptcp_join.sh |   5 +-
 5 files changed, 86 insertions(+), 50 deletions(-)

diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index 761995a34124..d6d22f18c418 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -376,6 +376,7 @@ void mptcp_pm_data_reset(struct mptcp_sock *msk)
 	WRITE_ONCE(msk->pm.accept_subflow, false);
 	WRITE_ONCE(msk->pm.remote_deny_join_id0, false);
 	msk->pm.status = 0;
+	bitmap_fill(msk->pm.id_avail_bitmap, MAX_ADDR_ID + 1);
 
 	mptcp_pm_nl_data_init(msk);
 }
diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index d18b13e3e74c..1be7f92e9fc8 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -38,9 +38,6 @@ struct mptcp_pm_add_entry {
 	u8			retrans_times;
 };
 
-#define MAX_ADDR_ID		255
-#define BITMAP_SZ DIV_ROUND_UP(MAX_ADDR_ID + 1, BITS_PER_LONG)
-
 struct pm_nl_pernet {
 	/* protects pernet updates */
 	spinlock_t		lock;
@@ -52,14 +49,14 @@ struct pm_nl_pernet {
 	unsigned int		local_addr_max;
 	unsigned int		subflows_max;
 	unsigned int		next_id;
-	unsigned long		id_bitmap[BITMAP_SZ];
+	DECLARE_BITMAP(id_bitmap, MAX_ADDR_ID + 1);
 };
 
 #define MPTCP_PM_ADDR_MAX	8
 #define ADD_ADDR_RETRANS_MAX	3
 
 static bool addresses_equal(const struct mptcp_addr_info *a,
-			    struct mptcp_addr_info *b, bool use_port)
+			    const struct mptcp_addr_info *b, bool use_port)
 {
 	bool addr_equals = false;
 
@@ -173,6 +170,9 @@ select_local_address(const struct pm_nl_pernet *pernet,
 		if (!(entry->flags & MPTCP_PM_ADDR_FLAG_SUBFLOW))
 			continue;
 
+		if (!test_bit(entry->addr.id, msk->pm.id_avail_bitmap))
+			continue;
+
 		if (entry->addr.family != sk->sk_family) {
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 			if ((entry->addr.family == AF_INET &&
@@ -183,23 +183,17 @@ select_local_address(const struct pm_nl_pernet *pernet,
 				continue;
 		}
 
-		/* avoid any address already in use by subflows and
-		 * pending join
-		 */
-		if (!lookup_subflow_by_saddr(&msk->conn_list, &entry->addr)) {
-			ret = entry;
-			break;
-		}
+		ret = entry;
+		break;
 	}
 	rcu_read_unlock();
 	return ret;
 }
 
 static struct mptcp_pm_addr_entry *
-select_signal_address(struct pm_nl_pernet *pernet, unsigned int pos)
+select_signal_address(struct pm_nl_pernet *pernet, struct mptcp_sock *msk)
 {
 	struct mptcp_pm_addr_entry *entry, *ret = NULL;
-	int i = 0;
 
 	rcu_read_lock();
 	/* do not keep any additional per socket state, just signal
@@ -208,12 +202,14 @@ select_signal_address(struct pm_nl_pernet *pernet, unsigned int pos)
 	 * can lead to additional addresses not being announced.
 	 */
 	list_for_each_entry_rcu(entry, &pernet->local_addr_list, list) {
+		if (!test_bit(entry->addr.id, msk->pm.id_avail_bitmap))
+			continue;
+
 		if (!(entry->flags & MPTCP_PM_ADDR_FLAG_SIGNAL))
 			continue;
-		if (i++ == pos) {
-			ret = entry;
-			break;
-		}
+
+		ret = entry;
+		break;
 	}
 	rcu_read_unlock();
 	return ret;
@@ -257,9 +253,11 @@ EXPORT_SYMBOL_GPL(mptcp_pm_get_local_addr_max);
 
 static void check_work_pending(struct mptcp_sock *msk)
 {
-	if (msk->pm.add_addr_signaled == mptcp_pm_get_add_addr_signal_max(msk) &&
-	    (msk->pm.local_addr_used == mptcp_pm_get_local_addr_max(msk) ||
-	     msk->pm.subflows == mptcp_pm_get_subflows_max(msk)))
+	struct pm_nl_pernet *pernet = net_generic(sock_net((struct sock *)msk), pm_nl_pernet_id);
+
+	if (msk->pm.subflows == mptcp_pm_get_subflows_max(msk) ||
+	    (find_next_and_bit(pernet->id_bitmap, msk->pm.id_avail_bitmap, MAX_ADDR_ID + 1, 0) ==
+	     MAX_ADDR_ID + 1))
 		WRITE_ONCE(msk->pm.work_pending, false);
 }
 
@@ -459,6 +457,35 @@ static unsigned int fill_remote_addresses_vec(struct mptcp_sock *msk, bool fullm
 	return i;
 }
 
+static struct mptcp_pm_addr_entry *
+__lookup_addr_by_id(struct pm_nl_pernet *pernet, unsigned int id)
+{
+	struct mptcp_pm_addr_entry *entry;
+
+	list_for_each_entry(entry, &pernet->local_addr_list, list) {
+		if (entry->addr.id == id)
+			return entry;
+	}
+	return NULL;
+}
+
+static int
+lookup_id_by_addr(struct pm_nl_pernet *pernet, const struct mptcp_addr_info *addr)
+{
+	struct mptcp_pm_addr_entry *entry;
+	int ret = -1;
+
+	rcu_read_lock();
+	list_for_each_entry(entry, &pernet->local_addr_list, list) {
+		if (addresses_equal(&entry->addr, addr, entry->addr.port)) {
+			ret = entry->addr.id;
+			break;
+		}
+	}
+	rcu_read_unlock();
+	return ret;
+}
+
 static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)
 {
 	struct sock *sk = (struct sock *)msk;
@@ -474,6 +501,19 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)
 	local_addr_max = mptcp_pm_get_local_addr_max(msk);
 	subflows_max = mptcp_pm_get_subflows_max(msk);
 
+	/* do lazy endpoint usage accounting for the MPC subflows */
+	if (unlikely(!(msk->pm.status & BIT(MPTCP_PM_MPC_ENDPOINT_ACCOUNTED))) && msk->first) {
+		struct mptcp_addr_info local;
+		int mpc_id;
+
+		local_address((struct sock_common *)msk->first, &local);
+		mpc_id = lookup_id_by_addr(pernet, &local);
+		if (mpc_id < 0)
+			__clear_bit(mpc_id, msk->pm.id_avail_bitmap);
+
+		msk->pm.status |= BIT(MPTCP_PM_MPC_ENDPOINT_ACCOUNTED);
+	}
+
 	pr_debug("local %d:%d signal %d:%d subflows %d:%d\n",
 		 msk->pm.local_addr_used, local_addr_max,
 		 msk->pm.add_addr_signaled, add_addr_signal_max,
@@ -481,21 +521,16 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)
 
 	/* check first for announce */
 	if (msk->pm.add_addr_signaled < add_addr_signal_max) {
-		local = select_signal_address(pernet,
-					      msk->pm.add_addr_signaled);
+		local = select_signal_address(pernet, msk);
 
 		if (local) {
 			if (mptcp_pm_alloc_anno_list(msk, local)) {
+				__clear_bit(local->addr.id, msk->pm.id_avail_bitmap);
 				msk->pm.add_addr_signaled++;
 				mptcp_pm_announce_addr(msk, &local->addr, false);
 				mptcp_pm_nl_addr_send_ack(msk);
 			}
-		} else {
-			/* pick failed, avoid fourther attempts later */
-			msk->pm.local_addr_used = add_addr_signal_max;
 		}
-
-		check_work_pending(msk);
 	}
 
 	/* check if should create a new subflow */
@@ -509,19 +544,16 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)
 			int i, nr;
 
 			msk->pm.local_addr_used++;
-			check_work_pending(msk);
 			nr = fill_remote_addresses_vec(msk, fullmesh, addrs);
+			if (nr)
+				__clear_bit(local->addr.id, msk->pm.id_avail_bitmap);
 			spin_unlock_bh(&msk->pm.lock);
 			for (i = 0; i < nr; i++)
 				__mptcp_subflow_connect(sk, &local->addr, &addrs[i]);
 			spin_lock_bh(&msk->pm.lock);
-			return;
 		}
-
-		/* lookup failed, avoid fourther attempts later */
-		msk->pm.local_addr_used = local_addr_max;
-		check_work_pending(msk);
 	}
+	check_work_pending(msk);
 }
 
 static void mptcp_pm_nl_fully_established(struct mptcp_sock *msk)
@@ -735,6 +767,7 @@ static void mptcp_pm_nl_rm_addr_or_subflow(struct mptcp_sock *msk,
 			msk->pm.subflows--;
 			__MPTCP_INC_STATS(sock_net(sk), rm_type);
 		}
+		__set_bit(rm_list->ids[1], msk->pm.id_avail_bitmap);
 		if (!removed)
 			continue;
 
@@ -764,6 +797,9 @@ void mptcp_pm_nl_work(struct mptcp_sock *msk)
 
 	msk_owned_by_me(msk);
 
+	if (!(pm->status & MPTCP_PM_WORK_MASK))
+		return;
+
 	spin_lock_bh(&msk->pm.lock);
 
 	pr_debug("msk=%p status=%x", msk, pm->status);
@@ -1197,18 +1233,6 @@ static int mptcp_nl_cmd_add_addr(struct sk_buff *skb, struct genl_info *info)
 	return 0;
 }
 
-static struct mptcp_pm_addr_entry *
-__lookup_addr_by_id(struct pm_nl_pernet *pernet, unsigned int id)
-{
-	struct mptcp_pm_addr_entry *entry;
-
-	list_for_each_entry(entry, &pernet->local_addr_list, list) {
-		if (entry->addr.id == id)
-			return entry;
-	}
-	return NULL;
-}
-
 int mptcp_pm_get_flags_and_ifindex_by_id(struct net *net, unsigned int id,
 					 u8 *flags, int *ifindex)
 {
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 4a8f2476cc75..63602c68f03d 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2508,8 +2508,7 @@ static void mptcp_worker(struct work_struct *work)
 
 	mptcp_check_fastclose(msk);
 
-	if (msk->pm.status)
-		mptcp_pm_nl_work(msk);
+	mptcp_pm_nl_work(msk);
 
 	if (test_and_clear_bit(MPTCP_WORK_EOF, &msk->flags))
 		mptcp_check_for_eof(msk);
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 47d24478763c..e63fe60f70b8 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -173,16 +173,24 @@ enum mptcp_pm_status {
 	MPTCP_PM_ADD_ADDR_SEND_ACK,
 	MPTCP_PM_RM_ADDR_RECEIVED,
 	MPTCP_PM_ESTABLISHED,
-	MPTCP_PM_ALREADY_ESTABLISHED,	/* persistent status, set after ESTABLISHED event */
 	MPTCP_PM_SUBFLOW_ESTABLISHED,
+	MPTCP_PM_ALREADY_ESTABLISHED,	/* persistent status, set after ESTABLISHED event */
+	MPTCP_PM_MPC_ENDPOINT_ACCOUNTED /* persistent status, set after MPC local address is
+					 * accounted int id_avail_bitmap
+					 */
 };
 
+/* Status bits below MPTCP_PM_ALREADY_ESTABLISHED need pm worker actions */
+#define MPTCP_PM_WORK_MASK ((1 << MPTCP_PM_ALREADY_ESTABLISHED) - 1)
+
 enum mptcp_addr_signal_status {
 	MPTCP_ADD_ADDR_SIGNAL,
 	MPTCP_ADD_ADDR_ECHO,
 	MPTCP_RM_ADDR_SIGNAL,
 };
 
+#define MAX_ADDR_ID		255
+
 struct mptcp_pm_data {
 	struct mptcp_addr_info local;
 	struct mptcp_addr_info remote;
@@ -201,6 +209,7 @@ struct mptcp_pm_data {
 	u8		local_addr_used;
 	u8		subflows;
 	u8		status;
+	DECLARE_BITMAP(id_avail_bitmap, MAX_ADDR_ID + 1);
 	struct mptcp_rm_list rm_list_tx;
 	struct mptcp_rm_list rm_list_rx;
 };
diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index 2684ef9c0d42..526b05771d08 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -1109,7 +1109,10 @@ signal_address_tests()
 	ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 flags signal
 	ip netns exec $ns2 ./pm_nl_ctl add 10.0.4.2 flags signal
 	run_tests $ns1 $ns2 10.0.1.1
-	chk_add_nr 4 4
+
+	# the server will not signal the address teminating
+	# the MPC subflow
+	chk_add_nr 3 3
 }
 
 link_failure_tests()
-- 
2.33.1

[PATCH v6 mptcp-next 4/7] mptcp: do not block subflows creation on errors

[Paolo Abeni]

If the MPTCP configuration allows for multiple subflows
creation, and the first additional subflows never reach
the fully established status - e.g. due to packets drop or
reset - the in kernel path manager do not move to the
next subflow.

This patch introduces a new PM helper to cope with MPJ
subflow creation failure and delay and hook it where appropriate.

Such helper triggers additional subflow creation, as needed
and updates the PM subflow counter, if the current one is
closing.

Additionally start all the needed additional subflows
as soon as the MPTCP socket is fully established, so we don't
have to cope with slow MPJ handshake blocking the next subflow
creation.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
v5 -> v6:
 - start all the subflows at once.

v3 -> v4:
 - fix 'subflows' underflow

v2 -> v3:
 - fix compile warning (CI)

v1 -> v2:
 - explicitly hook on subflow close instead of error notification
 - fix checkpatch issue (Mat)
 - introduce and use a new pm helper to cope with subflow close
 - update pm subflow counters on close
---
 net/mptcp/pm.c         | 23 ++++++++++++--
 net/mptcp/pm_netlink.c | 69 +++++++++++++++++++++++++-----------------
 net/mptcp/protocol.c   |  6 ++++
 net/mptcp/protocol.h   |  4 ++-
 4 files changed, 71 insertions(+), 31 deletions(-)

diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index d6d22f18c418..fac02ac195c7 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -172,9 +172,28 @@ void mptcp_pm_subflow_established(struct mptcp_sock *msk)
 	spin_unlock_bh(&pm->lock);
 }
 
-void mptcp_pm_subflow_closed(struct mptcp_sock *msk, u8 id)
+void mptcp_pm_subflow_check_next(struct mptcp_sock *msk, const struct sock *ssk,
+				 const struct mptcp_subflow_context *subflow)
 {
-	pr_debug("msk=%p", msk);
+	struct mptcp_pm_data *pm = &msk->pm;
+	bool update_subflows;
+
+	update_subflows = (ssk->sk_state == TCP_CLOSE) &&
+			  (subflow->request_join || subflow->mp_join);
+	if (!READ_ONCE(pm->work_pending) && !update_subflows)
+		return;
+
+	spin_lock_bh(&pm->lock);
+	if (update_subflows)
+		pm->subflows--;
+
+	/* Even if this subflow is not really established, tell the PM to try
+	 * to pick the next ones, if possible.
+	 */
+	if (mptcp_pm_nl_check_work_pending(msk))
+		mptcp_pm_schedule_work(msk, MPTCP_PM_SUBFLOW_ESTABLISHED);
+
+	spin_unlock_bh(&pm->lock);
 }
 
 void mptcp_pm_add_addr_received(struct mptcp_sock *msk,
diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index 1be7f92e9fc8..33af358129cc 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -251,14 +251,17 @@ unsigned int mptcp_pm_get_local_addr_max(struct mptcp_sock *msk)
 }
 EXPORT_SYMBOL_GPL(mptcp_pm_get_local_addr_max);
 
-static void check_work_pending(struct mptcp_sock *msk)
+bool mptcp_pm_nl_check_work_pending(struct mptcp_sock *msk)
 {
 	struct pm_nl_pernet *pernet = net_generic(sock_net((struct sock *)msk), pm_nl_pernet_id);
 
 	if (msk->pm.subflows == mptcp_pm_get_subflows_max(msk) ||
 	    (find_next_and_bit(pernet->id_bitmap, msk->pm.id_avail_bitmap, MAX_ADDR_ID + 1, 0) ==
-	     MAX_ADDR_ID + 1))
+	     MAX_ADDR_ID + 1)) {
 		WRITE_ONCE(msk->pm.work_pending, false);
+		return false;
+	}
+	return true;
 }
 
 struct mptcp_pm_add_entry *
@@ -427,6 +430,7 @@ static bool lookup_address_in_vec(struct mptcp_addr_info *addrs, unsigned int nr
 static unsigned int fill_remote_addresses_vec(struct mptcp_sock *msk, bool fullmesh,
 					      struct mptcp_addr_info *addrs)
 {
+	bool deny_id0 = READ_ONCE(msk->pm.remote_deny_join_id0);
 	struct sock *sk = (struct sock *)msk, *ssk;
 	struct mptcp_subflow_context *subflow;
 	struct mptcp_addr_info remote = { 0 };
@@ -434,22 +438,28 @@ static unsigned int fill_remote_addresses_vec(struct mptcp_sock *msk, bool fullm
 	int i = 0;
 
 	subflows_max = mptcp_pm_get_subflows_max(msk);
+	remote_address((struct sock_common *)sk, &remote);
 
 	/* Non-fullmesh endpoint, fill in the single entry
 	 * corresponding to the primary MPC subflow remote address
 	 */
 	if (!fullmesh) {
-		remote_address((struct sock_common *)sk, &remote);
+		if (deny_id0)
+			return 0;
+
 		msk->pm.subflows++;
 		addrs[i++] = remote;
 	} else {
 		mptcp_for_each_subflow(msk, subflow) {
 			ssk = mptcp_subflow_tcp_sock(subflow);
-			remote_address((struct sock_common *)ssk, &remote);
-			if (!lookup_address_in_vec(addrs, i, &remote) &&
+			remote_address((struct sock_common *)ssk, &addrs[i]);
+			if (deny_id0 && addresses_equal(&addrs[i], &remote, false))
+				continue;
+
+			if (!lookup_address_in_vec(addrs, i, &addrs[i]) &&
 			    msk->pm.subflows < subflows_max) {
 				msk->pm.subflows++;
-				addrs[i++] = remote;
+				i++;
 			}
 		}
 	}
@@ -503,12 +513,12 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)
 
 	/* do lazy endpoint usage accounting for the MPC subflows */
 	if (unlikely(!(msk->pm.status & BIT(MPTCP_PM_MPC_ENDPOINT_ACCOUNTED))) && msk->first) {
-		struct mptcp_addr_info local;
+		struct mptcp_addr_info mpc_addr;
 		int mpc_id;
 
-		local_address((struct sock_common *)msk->first, &local);
-		mpc_id = lookup_id_by_addr(pernet, &local);
-		if (mpc_id < 0)
+		local_address((struct sock_common *)msk->first, &mpc_addr);
+		mpc_id = lookup_id_by_addr(pernet, &mpc_addr);
+		if (mpc_id >= 0)
 			__clear_bit(mpc_id, msk->pm.id_avail_bitmap);
 
 		msk->pm.status |= BIT(MPTCP_PM_MPC_ENDPOINT_ACCOUNTED);
@@ -534,26 +544,28 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)
 	}
 
 	/* check if should create a new subflow */
-	if (msk->pm.local_addr_used < local_addr_max &&
-	    msk->pm.subflows < subflows_max &&
-	    !READ_ONCE(msk->pm.remote_deny_join_id0)) {
+	while (msk->pm.local_addr_used < local_addr_max &&
+	       msk->pm.subflows < subflows_max) {
+		struct mptcp_addr_info addrs[MPTCP_PM_ADDR_MAX];
+		bool fullmesh;
+		int i, nr;
+
 		local = select_local_address(pernet, msk);
-		if (local) {
-			bool fullmesh = !!(local->flags & MPTCP_PM_ADDR_FLAG_FULLMESH);
-			struct mptcp_addr_info addrs[MPTCP_PM_ADDR_MAX];
-			int i, nr;
+		if (!local)
+			break;
 
-			msk->pm.local_addr_used++;
-			nr = fill_remote_addresses_vec(msk, fullmesh, addrs);
-			if (nr)
-				__clear_bit(local->addr.id, msk->pm.id_avail_bitmap);
-			spin_unlock_bh(&msk->pm.lock);
-			for (i = 0; i < nr; i++)
-				__mptcp_subflow_connect(sk, &local->addr, &addrs[i]);
-			spin_lock_bh(&msk->pm.lock);
-		}
+		fullmesh = !!(local->flags & MPTCP_PM_ADDR_FLAG_FULLMESH);
+
+		msk->pm.local_addr_used++;
+		nr = fill_remote_addresses_vec(msk, fullmesh, addrs);
+		if (nr)
+			__clear_bit(local->addr.id, msk->pm.id_avail_bitmap);
+		spin_unlock_bh(&msk->pm.lock);
+		for (i = 0; i < nr; i++)
+			__mptcp_subflow_connect(sk, &local->addr, &addrs[i]);
+		spin_lock_bh(&msk->pm.lock);
 	}
-	check_work_pending(msk);
+	mptcp_pm_nl_check_work_pending(msk);
 }
 
 static void mptcp_pm_nl_fully_established(struct mptcp_sock *msk)
@@ -760,11 +772,12 @@ static void mptcp_pm_nl_rm_addr_or_subflow(struct mptcp_sock *msk,
 				 i, rm_list->ids[i], subflow->local_id, subflow->remote_id);
 			spin_unlock_bh(&msk->pm.lock);
 			mptcp_subflow_shutdown(sk, ssk, how);
+
+			/* the following takes care of updating the subflows counter */
 			mptcp_close_ssk(sk, ssk, subflow);
 			spin_lock_bh(&msk->pm.lock);
 
 			removed = true;
-			msk->pm.subflows--;
 			__MPTCP_INC_STATS(sock_net(sk), rm_type);
 		}
 		__set_bit(rm_list->ids[1], msk->pm.id_avail_bitmap);
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 63602c68f03d..aa0a1fe749d9 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2351,6 +2351,12 @@ void mptcp_close_ssk(struct sock *sk, struct sock *ssk,
 {
 	if (sk->sk_state == TCP_ESTABLISHED)
 		mptcp_event(MPTCP_EVENT_SUB_CLOSED, mptcp_sk(sk), ssk, GFP_KERNEL);
+
+	/* subflow aborted before reaching the fully_established status
+	 * attempt the creation of the next subflow
+	 */
+	mptcp_pm_subflow_check_next(mptcp_sk(sk), ssk, subflow);
+
 	__mptcp_close_ssk(sk, ssk, subflow, MPTCP_CF_PUSH);
 }
 
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index e63fe60f70b8..f38c93c7805c 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -744,7 +744,9 @@ void mptcp_pm_fully_established(struct mptcp_sock *msk, const struct sock *ssk,
 bool mptcp_pm_allow_new_subflow(struct mptcp_sock *msk);
 void mptcp_pm_connection_closed(struct mptcp_sock *msk);
 void mptcp_pm_subflow_established(struct mptcp_sock *msk);
-void mptcp_pm_subflow_closed(struct mptcp_sock *msk, u8 id);
+bool mptcp_pm_nl_check_work_pending(struct mptcp_sock *msk);
+void mptcp_pm_subflow_check_next(struct mptcp_sock *msk, const struct sock *ssk,
+				 const struct mptcp_subflow_context *subflow);
 void mptcp_pm_add_addr_received(struct mptcp_sock *msk,
 				const struct mptcp_addr_info *addr);
 void mptcp_pm_add_addr_echoed(struct mptcp_sock *msk,
-- 
2.33.1

[PATCH v6 mptcp-next 5/7] selftests: mptcp: add tests for subflow creation failure

[Paolo Abeni]

Verify that, when multiple endpoints are available, subflows
creation proceed even when the first additional subflow creation
fails - due to packet drop on the relevant link

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
v5 -> v6:
 - fix test cnt update

v4 -> v5:
 - new test checking for wrong MPC reuse

v3 -> v4:
 - use $() where applicable - Matt
 - fix typo in help() - Matt

v1 -> v2:
 - add missing NF kconfig
 - add more test-cases (drop, later subflow creation)
---
 tools/testing/selftests/net/mptcp/config      |  1 +
 .../testing/selftests/net/mptcp/mptcp_join.sh | 78 ++++++++++++++++++-
 2 files changed, 78 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/mptcp/config b/tools/testing/selftests/net/mptcp/config
index 419e71560fd1..41e94e004bdc 100644
--- a/tools/testing/selftests/net/mptcp/config
+++ b/tools/testing/selftests/net/mptcp/config
@@ -18,4 +18,5 @@ CONFIG_NFT_TPROXY=m
 CONFIG_NFT_SOCKET=m
 CONFIG_IP_ADVANCED_ROUTER=y
 CONFIG_IP_MULTIPLE_TABLES=y
+CONFIG_IP_NF_TARGET_REJECT=m
 CONFIG_IPV6_MULTIPLE_TABLES=y
diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index 526b05771d08..56fcc8b412fc 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -975,6 +975,22 @@ chk_link_usage()
 	fi
 }
 
+wait_for_tw()
+{
+	local timeout_ms=$((timeout_poll * 1000))
+	local time=0
+	local ns=$1
+
+	while [ $time -lt $timeout_ms ]; do
+		local cnt=$(ip netns exec $ns ss -t state time-wait |wc -l)
+
+		[ "$cnt" = 1 ] && return 1
+		time=$((time + 100))
+		sleep 0.1
+	done
+	return 1
+}
+
 subflows_tests()
 {
 	reset
@@ -1032,6 +1048,61 @@ subflows_tests()
 	chk_join_nr "single subflow, dev" 1 1 1
 }
 
+subflows_error_tests()
+{
+	# If a single subflow is configured, and matches the MPC src
+	# address, no additional subflow should be created
+	reset
+	ip netns exec $ns1 ./pm_nl_ctl limits 0 1
+	ip netns exec $ns2 ./pm_nl_ctl limits 0 1
+	ip netns exec $ns2 ./pm_nl_ctl add 10.0.1.2 flags subflow
+	run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow
+	chk_join_nr "no MPC address reuse with single endpoint" 0 0 0
+
+	# multiple subflows, with subflow creation error
+	reset
+	ip netns exec $ns1 ./pm_nl_ctl limits 0 2
+	ip netns exec $ns2 ./pm_nl_ctl limits 0 2
+	ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 flags subflow
+	ip netns exec $ns2 ./pm_nl_ctl add 10.0.2.2 flags subflow
+	ip netns exec $ns1 iptables -A INPUT -s 10.0.3.2 -p tcp -j REJECT
+	run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow
+	chk_join_nr "multiple subflows, with failing subflow" 1 1 1
+
+	# multiple subflows, with subflow timeout on MPJ
+	reset
+	ip netns exec $ns1 ./pm_nl_ctl limits 0 2
+	ip netns exec $ns2 ./pm_nl_ctl limits 0 2
+	ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 flags subflow
+	ip netns exec $ns2 ./pm_nl_ctl add 10.0.2.2 flags subflow
+	ip netns exec $ns1 iptables -A INPUT -s 10.0.3.2 -p tcp -j DROP
+	run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow
+	chk_join_nr "multiple subflows, with subflow timeout" 1 1 1
+
+	# multiple subflows, check that the endpoint corresponding to
+	# closed subflow (due to reset) is not reused if additional
+	# subflows are added later
+	reset
+	ip netns exec $ns1 ./pm_nl_ctl limits 0 1
+	ip netns exec $ns2 ./pm_nl_ctl limits 0 1
+	ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 flags subflow
+	ip netns exec $ns1 iptables -A INPUT -s 10.0.3.2 -p tcp -j REJECT
+	run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow &
+
+	# updates in the child shell do not have any effect here, we
+	# need to bump the test counter for the above case
+	TEST_COUNT=$((TEST_COUNT))
+
+	# mpj subflow will be in TW after the reset
+	wait_for_tw $ns2
+	ip netns exec $ns2 ./pm_nl_ctl add 10.0.2.2 flags subflow
+	wait
+
+	# additional subflow could be created only if the PM select
+	# the later endpoint, skipping the already used one
+	chk_join_nr "multiple subflows, fair usage on close" 1 1 1
+}
+
 signal_address_tests()
 {
 	# add_address, unused
@@ -1843,6 +1914,7 @@ fullmesh_tests()
 all_tests()
 {
 	subflows_tests
+	subflows_error_tests
 	signal_address_tests
 	link_failure_tests
 	add_addr_timeout_tests
@@ -1862,6 +1934,7 @@ usage()
 {
 	echo "mptcp_join usage:"
 	echo "  -f subflows_tests"
+	echo "  -e subflows_error_tests"
 	echo "  -s signal_address_tests"
 	echo "  -l link_failure_tests"
 	echo "  -t add_addr_timeout_tests"
@@ -1910,11 +1983,14 @@ if [ $do_all_tests -eq 1 ]; then
 	exit $ret
 fi
 
-while getopts 'fsltra64bpkdmchCS' opt; do
+while getopts 'fesltra64bpkdmchCS' opt; do
 	case $opt in
 		f)
 			subflows_tests
 			;;
+		e)
+			subflows_error_tests
+			;;
 		s)
 			signal_address_tests
 			;;
-- 
2.33.1

Re: [PATCH v6 mptcp-next 5/7] selftests: mptcp: add tests for subflow creation failure

[Mat Martineau]

On Tue, 14 Dec 2021, Paolo Abeni wrote:

> Verify that, when multiple endpoints are available, subflows
> creation proceed even when the first additional subflow creation
> fails - due to packet drop on the relevant link
>
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> ---
> v5 -> v6:
> - fix test cnt update
>
> v4 -> v5:
> - new test checking for wrong MPC reuse
>
> v3 -> v4:
> - use $() where applicable - Matt
> - fix typo in help() - Matt
>
> v1 -> v2:
> - add missing NF kconfig
> - add more test-cases (drop, later subflow creation)
> ---
> tools/testing/selftests/net/mptcp/config      |  1 +
> .../testing/selftests/net/mptcp/mptcp_join.sh | 78 ++++++++++++++++++-
> 2 files changed, 78 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/net/mptcp/config b/tools/testing/selftests/net/mptcp/config
> index 419e71560fd1..41e94e004bdc 100644
> --- a/tools/testing/selftests/net/mptcp/config
> +++ b/tools/testing/selftests/net/mptcp/config
> @@ -18,4 +18,5 @@ CONFIG_NFT_TPROXY=m
> CONFIG_NFT_SOCKET=m
> CONFIG_IP_ADVANCED_ROUTER=y
> CONFIG_IP_MULTIPLE_TABLES=y
> +CONFIG_IP_NF_TARGET_REJECT=m
> CONFIG_IPV6_MULTIPLE_TABLES=y
> diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
> index 526b05771d08..56fcc8b412fc 100755
> --- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
> +++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
> @@ -975,6 +975,22 @@ chk_link_usage()
> 	fi
> }
>
> +wait_for_tw()
> +{
> +	local timeout_ms=$((timeout_poll * 1000))
> +	local time=0
> +	local ns=$1
> +
> +	while [ $time -lt $timeout_ms ]; do
> +		local cnt=$(ip netns exec $ns ss -t state time-wait |wc -l)
> +
> +		[ "$cnt" = 1 ] && return 1
> +		time=$((time + 100))
> +		sleep 0.1
> +	done
> +	return 1
> +}
> +
> subflows_tests()
> {
> 	reset
> @@ -1032,6 +1048,61 @@ subflows_tests()
> 	chk_join_nr "single subflow, dev" 1 1 1
> }
>
> +subflows_error_tests()
> +{
> +	# If a single subflow is configured, and matches the MPC src
> +	# address, no additional subflow should be created
> +	reset
> +	ip netns exec $ns1 ./pm_nl_ctl limits 0 1
> +	ip netns exec $ns2 ./pm_nl_ctl limits 0 1
> +	ip netns exec $ns2 ./pm_nl_ctl add 10.0.1.2 flags subflow
> +	run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow
> +	chk_join_nr "no MPC address reuse with single endpoint" 0 0 0
> +
> +	# multiple subflows, with subflow creation error
> +	reset
> +	ip netns exec $ns1 ./pm_nl_ctl limits 0 2
> +	ip netns exec $ns2 ./pm_nl_ctl limits 0 2
> +	ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 flags subflow
> +	ip netns exec $ns2 ./pm_nl_ctl add 10.0.2.2 flags subflow
> +	ip netns exec $ns1 iptables -A INPUT -s 10.0.3.2 -p tcp -j REJECT
> +	run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow
> +	chk_join_nr "multiple subflows, with failing subflow" 1 1 1
> +
> +	# multiple subflows, with subflow timeout on MPJ
> +	reset
> +	ip netns exec $ns1 ./pm_nl_ctl limits 0 2
> +	ip netns exec $ns2 ./pm_nl_ctl limits 0 2
> +	ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 flags subflow
> +	ip netns exec $ns2 ./pm_nl_ctl add 10.0.2.2 flags subflow
> +	ip netns exec $ns1 iptables -A INPUT -s 10.0.3.2 -p tcp -j DROP
> +	run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow
> +	chk_join_nr "multiple subflows, with subflow timeout" 1 1 1
> +
> +	# multiple subflows, check that the endpoint corresponding to
> +	# closed subflow (due to reset) is not reused if additional
> +	# subflows are added later
> +	reset
> +	ip netns exec $ns1 ./pm_nl_ctl limits 0 1
> +	ip netns exec $ns2 ./pm_nl_ctl limits 0 1
> +	ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 flags subflow
> +	ip netns exec $ns1 iptables -A INPUT -s 10.0.3.2 -p tcp -j REJECT
> +	run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow &
> +
> +	# updates in the child shell do not have any effect here, we
> +	# need to bump the test counter for the above case
> +	TEST_COUNT=$((TEST_COUNT))

Missing the "+1"... maybe Matthieu can adjust when applying?


-Mat

> +
> +	# mpj subflow will be in TW after the reset
> +	wait_for_tw $ns2
> +	ip netns exec $ns2 ./pm_nl_ctl add 10.0.2.2 flags subflow
> +	wait
> +
> +	# additional subflow could be created only if the PM select
> +	# the later endpoint, skipping the already used one
> +	chk_join_nr "multiple subflows, fair usage on close" 1 1 1
> +}
> +
> signal_address_tests()
> {
> 	# add_address, unused
> @@ -1843,6 +1914,7 @@ fullmesh_tests()
> all_tests()
> {
> 	subflows_tests
> +	subflows_error_tests
> 	signal_address_tests
> 	link_failure_tests
> 	add_addr_timeout_tests
> @@ -1862,6 +1934,7 @@ usage()
> {
> 	echo "mptcp_join usage:"
> 	echo "  -f subflows_tests"
> +	echo "  -e subflows_error_tests"
> 	echo "  -s signal_address_tests"
> 	echo "  -l link_failure_tests"
> 	echo "  -t add_addr_timeout_tests"
> @@ -1910,11 +1983,14 @@ if [ $do_all_tests -eq 1 ]; then
> 	exit $ret
> fi
>
> -while getopts 'fsltra64bpkdmchCS' opt; do
> +while getopts 'fesltra64bpkdmchCS' opt; do
> 	case $opt in
> 		f)
> 			subflows_tests
> 			;;
> +		e)
> +			subflows_error_tests
> +			;;
> 		s)
> 			signal_address_tests
> 			;;
> -- 
> 2.33.1
>
>
>

--
Mat Martineau
Intel

[PATCH v6 mptcp-next 6/7] mptcp: cleanup MPJ subflow list handling

[Paolo Abeni]

We can simplify the join list handling leveraging the
mptcp_release_cb(): if we can acquire the msk socket
lock ad mptcp_finish_join time, move the new subflow
directly into the conn_list, othewise place it on join_list and
let the release_cb process such list.

Since pending MPJ connection are now always processed
in a timely way, we can avoid flushing the join list
every time we have to process all the current subflows.

Additionally we can now use the mptcp data lock to protect
the join_list, removing the additional spin lock.

Finally, the MPJ handshake is now always finalized under the
msk socket lock, we can drop the additional synchronization
between mptcp_finish_join() and mptcp_close().

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
rfc -> v1:
 - fix list corruption in __mptcp_flush_join_list()
 - fix label name typo (Mat)
---
 net/mptcp/pm_netlink.c |   3 --
 net/mptcp/protocol.c   | 109 +++++++++++++++++------------------------
 net/mptcp/protocol.h   |  15 +-----
 net/mptcp/sockopt.c    |  24 +++------
 net/mptcp/subflow.c    |   5 +-
 5 files changed, 56 insertions(+), 100 deletions(-)

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index 33af358129cc..139c33171397 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -165,7 +165,6 @@ select_local_address(const struct pm_nl_pernet *pernet,
 	msk_owned_by_me(msk);
 
 	rcu_read_lock();
-	__mptcp_flush_join_list(msk);
 	list_for_each_entry_rcu(entry, &pernet->local_addr_list, list) {
 		if (!(entry->flags & MPTCP_PM_ADDR_FLAG_SUBFLOW))
 			continue;
@@ -595,7 +594,6 @@ static unsigned int fill_local_addresses_vec(struct mptcp_sock *msk,
 	subflows_max = mptcp_pm_get_subflows_max(msk);
 
 	rcu_read_lock();
-	__mptcp_flush_join_list(msk);
 	list_for_each_entry_rcu(entry, &pernet->local_addr_list, list) {
 		if (!(entry->flags & MPTCP_PM_ADDR_FLAG_FULLMESH))
 			continue;
@@ -684,7 +682,6 @@ void mptcp_pm_nl_addr_send_ack(struct mptcp_sock *msk)
 	    !mptcp_pm_should_rm_signal(msk))
 		return;
 
-	__mptcp_flush_join_list(msk);
 	subflow = list_first_entry_or_null(&msk->conn_list, typeof(*subflow), node);
 	if (subflow) {
 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index aa0a1fe749d9..e81fd46a43c4 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -808,47 +808,31 @@ void mptcp_data_ready(struct sock *sk, struct sock *ssk)
 	mptcp_data_unlock(sk);
 }
 
-static bool mptcp_do_flush_join_list(struct mptcp_sock *msk)
+static bool __mptcp_finish_join(struct mptcp_sock *msk, struct sock *ssk)
 {
-	struct mptcp_subflow_context *subflow;
-	bool ret = false;
-
-	if (likely(list_empty(&msk->join_list)))
+	if (((struct sock *)msk)->sk_state != TCP_ESTABLISHED)
 		return false;
 
-	spin_lock_bh(&msk->join_list_lock);
-	list_for_each_entry(subflow, &msk->join_list, node) {
-		u32 sseq = READ_ONCE(subflow->setsockopt_seq);
-
-		mptcp_propagate_sndbuf((struct sock *)msk, mptcp_subflow_tcp_sock(subflow));
-		if (READ_ONCE(msk->setsockopt_seq) != sseq)
-			ret = true;
-	}
-	list_splice_tail_init(&msk->join_list, &msk->conn_list);
-	spin_unlock_bh(&msk->join_list_lock);
-
-	return ret;
-}
-
-void __mptcp_flush_join_list(struct mptcp_sock *msk)
-{
-	if (likely(!mptcp_do_flush_join_list(msk)))
-		return;
-
-	if (!test_and_set_bit(MPTCP_WORK_SYNC_SETSOCKOPT, &msk->flags))
-		mptcp_schedule_work((struct sock *)msk);
+	mptcp_propagate_sndbuf((struct sock *)msk, ssk);
+	mptcp_sockopt_sync_locked(msk, ssk);
+	WRITE_ONCE(msk->allow_infinite_fallback, false);
+	return true;
 }
 
-static void mptcp_flush_join_list(struct mptcp_sock *msk)
+static void __mptcp_flush_join_list(struct sock *sk)
 {
-	bool sync_needed = test_and_clear_bit(MPTCP_WORK_SYNC_SETSOCKOPT, &msk->flags);
-
-	might_sleep();
+	struct mptcp_subflow_context *tmp, *subflow;
+	struct mptcp_sock *msk = mptcp_sk(sk);
 
-	if (!mptcp_do_flush_join_list(msk) && !sync_needed)
-		return;
+	list_for_each_entry_safe(subflow, tmp, &msk->join_list, node) {
+		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+		bool slow = lock_sock_fast(ssk);
 
-	mptcp_sockopt_sync_all(msk);
+		list_move_tail(&subflow->node, &msk->conn_list);
+		if (!__mptcp_finish_join(msk, ssk))
+			mptcp_subflow_reset(ssk);
+		unlock_sock_fast(ssk, slow);
+	}
 }
 
 static bool mptcp_timer_pending(struct sock *sk)
@@ -1568,7 +1552,6 @@ void __mptcp_push_pending(struct sock *sk, unsigned int flags)
 			int ret = 0;
 
 			prev_ssk = ssk;
-			__mptcp_flush_join_list(msk);
 			ssk = mptcp_subflow_get_send(msk);
 
 			/* First check. If the ssk has changed since
@@ -1973,7 +1956,6 @@ static bool __mptcp_move_skbs(struct mptcp_sock *msk)
 	unsigned int moved = 0;
 	bool ret, done;
 
-	mptcp_flush_join_list(msk);
 	do {
 		struct sock *ssk = mptcp_subflow_recv_lookup(msk);
 		bool slowpath;
@@ -2510,7 +2492,6 @@ static void mptcp_worker(struct work_struct *work)
 		goto unlock;
 
 	mptcp_check_data_fin_ack(sk);
-	mptcp_flush_join_list(msk);
 
 	mptcp_check_fastclose(msk);
 
@@ -2548,8 +2529,6 @@ static int __mptcp_init_sock(struct sock *sk)
 {
 	struct mptcp_sock *msk = mptcp_sk(sk);
 
-	spin_lock_init(&msk->join_list_lock);
-
 	INIT_LIST_HEAD(&msk->conn_list);
 	INIT_LIST_HEAD(&msk->join_list);
 	INIT_LIST_HEAD(&msk->rtx_queue);
@@ -2728,7 +2707,6 @@ static void __mptcp_check_send_data_fin(struct sock *sk)
 		}
 	}
 
-	mptcp_flush_join_list(msk);
 	mptcp_for_each_subflow(msk, subflow) {
 		struct sock *tcp_sk = mptcp_subflow_tcp_sock(subflow);
 
@@ -2761,12 +2739,7 @@ static void __mptcp_destroy_sock(struct sock *sk)
 
 	might_sleep();
 
-	/* be sure to always acquire the join list lock, to sync vs
-	 * mptcp_finish_join().
-	 */
-	spin_lock_bh(&msk->join_list_lock);
-	list_splice_tail_init(&msk->join_list, &msk->conn_list);
-	spin_unlock_bh(&msk->join_list_lock);
+	/* join list will be eventually flushed (with rst) at sock lock release time*/
 	list_splice_init(&msk->conn_list, &conn_list);
 
 	sk_stop_timer(sk, &msk->sk.icsk_retransmit_timer);
@@ -2869,8 +2842,6 @@ static int mptcp_disconnect(struct sock *sk, int flags)
 	struct mptcp_subflow_context *subflow;
 	struct mptcp_sock *msk = mptcp_sk(sk);
 
-	mptcp_do_flush_join_list(msk);
-
 	inet_sk_state_store(sk, TCP_CLOSE);
 
 	mptcp_for_each_subflow(msk, subflow) {
@@ -3103,6 +3074,8 @@ static void mptcp_release_cb(struct sock *sk)
 			flags |= BIT(MPTCP_PUSH_PENDING);
 		if (test_and_clear_bit(MPTCP_RETRANSMIT, &mptcp_sk(sk)->flags))
 			flags |= BIT(MPTCP_RETRANSMIT);
+		if (test_and_clear_bit(MPTCP_FLUSH_JOIN_LIST, &mptcp_sk(sk)->flags))
+			flags |= BIT(MPTCP_FLUSH_JOIN_LIST);
 		if (!flags)
 			break;
 
@@ -3115,6 +3088,8 @@ static void mptcp_release_cb(struct sock *sk)
 		 */
 
 		spin_unlock_bh(&sk->sk_lock.slock);
+		if (flags & BIT(MPTCP_FLUSH_JOIN_LIST))
+			__mptcp_flush_join_list(sk);
 		if (flags & BIT(MPTCP_PUSH_PENDING))
 			__mptcp_push_pending(sk, 0);
 		if (flags & BIT(MPTCP_RETRANSMIT))
@@ -3260,7 +3235,7 @@ bool mptcp_finish_join(struct sock *ssk)
 	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 	struct sock *parent = (void *)msk;
 	struct socket *parent_sock;
-	bool ret;
+	bool ret = true;
 
 	pr_debug("msk=%p, subflow=%p", msk, subflow);
 
@@ -3273,24 +3248,32 @@ bool mptcp_finish_join(struct sock *ssk)
 	if (!msk->pm.server_side)
 		goto out;
 
-	if (!mptcp_pm_allow_new_subflow(msk)) {
-		subflow->reset_reason = MPTCP_RST_EPROHIBIT;
-		return false;
-	}
+	if (!mptcp_pm_allow_new_subflow(msk))
+		goto err_prohibited;
 
-	/* active connections are already on conn_list, and we can't acquire
-	 * msk lock here.
-	 * use the join list lock as synchronization point and double-check
-	 * msk status to avoid racing with __mptcp_destroy_sock()
+	if (WARN_ON_ONCE(!list_empty(&subflow->node)))
+		goto err_prohibited;
+
+	/* active connections are already on conn_list.
+	 * If we can't acquire msk socket lock here, let the release callback
+	 * handle it
 	 */
-	spin_lock_bh(&msk->join_list_lock);
-	ret = inet_sk_state_load(parent) == TCP_ESTABLISHED;
-	if (ret && !WARN_ON_ONCE(!list_empty(&subflow->node))) {
-		list_add_tail(&subflow->node, &msk->join_list);
+	mptcp_data_lock(parent);
+	if (!sock_owned_by_user(parent)) {
+		ret = __mptcp_finish_join(msk, ssk);
+		if (ret) {
+			sock_hold(ssk);
+			list_add_tail(&subflow->node, &msk->conn_list);
+		}
+	} else {
 		sock_hold(ssk);
+		list_add_tail(&subflow->node, &msk->join_list);
+		set_bit(MPTCP_FLUSH_JOIN_LIST, &msk->flags);
 	}
-	spin_unlock_bh(&msk->join_list_lock);
+	mptcp_data_unlock(parent);
+
 	if (!ret) {
+err_prohibited:
 		subflow->reset_reason = MPTCP_RST_EPROHIBIT;
 		return false;
 	}
@@ -3301,8 +3284,9 @@ bool mptcp_finish_join(struct sock *ssk)
 	parent_sock = READ_ONCE(parent->sk_socket);
 	if (parent_sock && !ssk->sk_socket)
 		mptcp_sock_graft(ssk, parent_sock);
+
 	subflow->map_seq = READ_ONCE(msk->ack_seq);
-	WRITE_ONCE(msk->allow_infinite_fallback, false);
+
 out:
 	mptcp_event(MPTCP_EVENT_SUB_ESTABLISHED, msk, ssk, GFP_ATOMIC);
 	return true;
@@ -3567,7 +3551,6 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
 		/* set ssk->sk_socket of accept()ed flows to mptcp socket.
 		 * This is needed so NOSPACE flag can be set from tcp stack.
 		 */
-		mptcp_flush_join_list(msk);
 		mptcp_for_each_subflow(msk, subflow) {
 			struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
 
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index f38c93c7805c..27a510b20996 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -120,7 +120,7 @@
 #define MPTCP_CLEAN_UNA		7
 #define MPTCP_ERROR_REPORT	8
 #define MPTCP_RETRANSMIT	9
-#define MPTCP_WORK_SYNC_SETSOCKOPT 10
+#define MPTCP_FLUSH_JOIN_LIST	10
 #define MPTCP_CONNECTED		11
 
 static inline bool before64(__u64 seq1, __u64 seq2)
@@ -261,7 +261,6 @@ struct mptcp_sock {
 	u8		recvmsg_inq:1,
 			cork:1,
 			nodelay:1;
-	spinlock_t	join_list_lock;
 	struct work_struct work;
 	struct sk_buff  *ooo_last_skb;
 	struct rb_root  out_of_order_queue;
@@ -510,15 +509,6 @@ mptcp_subflow_get_mapped_dsn(const struct mptcp_subflow_context *subflow)
 	return subflow->map_seq + mptcp_subflow_get_map_offset(subflow);
 }
 
-static inline void mptcp_add_pending_subflow(struct mptcp_sock *msk,
-					     struct mptcp_subflow_context *subflow)
-{
-	sock_hold(mptcp_subflow_tcp_sock(subflow));
-	spin_lock_bh(&msk->join_list_lock);
-	list_add_tail(&subflow->node, &msk->join_list);
-	spin_unlock_bh(&msk->join_list_lock);
-}
-
 void mptcp_subflow_process_delegated(struct sock *ssk);
 
 static inline void mptcp_subflow_delegate(struct mptcp_subflow_context *subflow, int action)
@@ -683,7 +673,6 @@ void __mptcp_data_acked(struct sock *sk);
 void __mptcp_error_report(struct sock *sk);
 void mptcp_subflow_eof(struct sock *sk);
 bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq, bool use_64bit);
-void __mptcp_flush_join_list(struct mptcp_sock *msk);
 static inline bool mptcp_data_fin_enabled(const struct mptcp_sock *msk)
 {
 	return READ_ONCE(msk->snd_data_fin_enable) &&
@@ -843,7 +832,7 @@ unsigned int mptcp_pm_get_subflows_max(struct mptcp_sock *msk);
 unsigned int mptcp_pm_get_local_addr_max(struct mptcp_sock *msk);
 
 void mptcp_sockopt_sync(struct mptcp_sock *msk, struct sock *ssk);
-void mptcp_sockopt_sync_all(struct mptcp_sock *msk);
+void mptcp_sockopt_sync_locked(struct mptcp_sock *msk, struct sock *ssk);
 
 static inline struct mptcp_ext *mptcp_get_ext(const struct sk_buff *skb)
 {
diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index aa3fcd86dbe2..dacf3cee0027 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -1285,27 +1285,15 @@ void mptcp_sockopt_sync(struct mptcp_sock *msk, struct sock *ssk)
 	}
 }
 
-void mptcp_sockopt_sync_all(struct mptcp_sock *msk)
+void mptcp_sockopt_sync_locked(struct mptcp_sock *msk, struct sock *ssk)
 {
-	struct mptcp_subflow_context *subflow;
-	struct sock *sk = (struct sock *)msk;
-	u32 seq;
-
-	seq = sockopt_seq_reset(sk);
+	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 
-	mptcp_for_each_subflow(msk, subflow) {
-		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
-		u32 sseq = READ_ONCE(subflow->setsockopt_seq);
+	msk_owned_by_me(msk);
 
-		if (sseq != msk->setsockopt_seq) {
-			__mptcp_sockopt_sync(msk, ssk);
-			WRITE_ONCE(subflow->setsockopt_seq, seq);
-		} else if (sseq != seq) {
-			WRITE_ONCE(subflow->setsockopt_seq, seq);
-		}
+	if (READ_ONCE(subflow->setsockopt_seq) != msk->setsockopt_seq) {
+		sync_socket_options(msk, ssk);
 
-		cond_resched();
+		subflow->setsockopt_seq = msk->setsockopt_seq;
 	}
-
-	msk->setsockopt_seq = seq;
 }
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 0f90bd61de01..8716b9cb8040 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -1446,7 +1446,8 @@ int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
 	subflow->request_bkup = !!(flags & MPTCP_PM_ADDR_FLAG_BACKUP);
 	mptcp_info2sockaddr(remote, &addr, ssk->sk_family);
 
-	mptcp_add_pending_subflow(msk, subflow);
+	sock_hold(ssk);
+	list_add_tail(&subflow->node, &msk->conn_list);
 	err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK);
 	if (err && err != -EINPROGRESS)
 		goto failed_unlink;
@@ -1458,9 +1459,7 @@ int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
 	return err;
 
 failed_unlink:
-	spin_lock_bh(&msk->join_list_lock);
 	list_del(&subflow->node);
-	spin_unlock_bh(&msk->join_list_lock);
 	sock_put(mptcp_subflow_tcp_sock(subflow));
 
 failed:
-- 
2.33.1

[PATCH v6 mptcp-next 7/7] mptcp: avoid atomic bit manipulation when possible

[Paolo Abeni]

Currently the msk->flags bitmask carries both state for the
mptcp_release_cb() - mostly touched under the mptcp data lock
- and others state info touched even outside such lock scope.

As a consequence, msk->flags is always manipulated with
atomic operations.

This change splits such bitmask in two separate fields, so
that we use plain bit oper operations when touching the
cb-related info.

The MPTCP_PUSH_PENDING bit needs additional care, as it is the
only CB related field currently accessed either under the mptcp
data lock or the mptcp socket lock.
Let's add another mask just for such bit's sake.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
 net/mptcp/protocol.c | 46 +++++++++++++++++++++++---------------------
 net/mptcp/protocol.h | 18 ++++++++++-------
 net/mptcp/subflow.c  |  4 ++--
 3 files changed, 37 insertions(+), 31 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index e81fd46a43c4..334abea4be9c 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -763,7 +763,7 @@ static bool move_skbs_to_msk(struct mptcp_sock *msk, struct sock *ssk)
 		if (!sock_owned_by_user(sk))
 			__mptcp_error_report(sk);
 		else
-			set_bit(MPTCP_ERROR_REPORT,  &msk->flags);
+			__set_bit(MPTCP_ERROR_REPORT,  &msk->cb_flags);
 	}
 
 	/* If the moves have caught up with the DATA_FIN sequence number
@@ -1529,9 +1529,8 @@ static void mptcp_update_post_push(struct mptcp_sock *msk,
 
 void mptcp_check_and_set_pending(struct sock *sk)
 {
-	if (mptcp_send_head(sk) &&
-	    !test_bit(MPTCP_PUSH_PENDING, &mptcp_sk(sk)->flags))
-		set_bit(MPTCP_PUSH_PENDING, &mptcp_sk(sk)->flags);
+	if (mptcp_send_head(sk))
+		mptcp_sk(sk)->push_pending |= MPTCP_PUSH_PENDING;
 }
 
 void __mptcp_push_pending(struct sock *sk, unsigned int flags)
@@ -2146,7 +2145,7 @@ static void mptcp_retransmit_timer(struct timer_list *t)
 			mptcp_schedule_work(sk);
 	} else {
 		/* delegate our work to tcp_release_cb() */
-		set_bit(MPTCP_RETRANSMIT, &msk->flags);
+		__set_bit(MPTCP_RETRANSMIT, &msk->cb_flags);
 	}
 	bh_unlock_sock(sk);
 	sock_put(sk);
@@ -2858,7 +2857,9 @@ static int mptcp_disconnect(struct sock *sk, int flags)
 
 	mptcp_destroy_common(msk);
 	msk->last_snd = NULL;
-	msk->flags = 0;
+	WRITE_ONCE(msk->flags, 0);
+	msk->cb_flags = 0;
+	msk->push_pending = 0;
 	msk->recovery = false;
 	msk->can_ack = false;
 	msk->fully_established = false;
@@ -3041,7 +3042,7 @@ void __mptcp_data_acked(struct sock *sk)
 	if (!sock_owned_by_user(sk))
 		__mptcp_clean_una(sk);
 	else
-		set_bit(MPTCP_CLEAN_UNA, &mptcp_sk(sk)->flags);
+		__set_bit(MPTCP_CLEAN_UNA, &mptcp_sk(sk)->cb_flags);
 
 	if (mptcp_pending_data_fin_ack(sk))
 		mptcp_schedule_work(sk);
@@ -3060,22 +3061,22 @@ void __mptcp_check_push(struct sock *sk, struct sock *ssk)
 		else if (xmit_ssk)
 			mptcp_subflow_delegate(mptcp_subflow_ctx(xmit_ssk), MPTCP_DELEGATE_SEND);
 	} else {
-		set_bit(MPTCP_PUSH_PENDING, &mptcp_sk(sk)->flags);
+		__set_bit(MPTCP_PUSH_PENDING, &mptcp_sk(sk)->cb_flags);
 	}
 }
 
+#define MPTCP_FLAGS_PROCESS_CTX_NEED (MPTCP_PUSH_PENDING | \
+				      MPTCP_RETRANSMIT | \
+				      MPTCP_FLUSH_JOIN_LIST)
+
 /* processes deferred events and flush wmem */
 static void mptcp_release_cb(struct sock *sk)
 {
+	struct mptcp_sock *msk = mptcp_sk(sk);
+
 	for (;;) {
-		unsigned long flags = 0;
-
-		if (test_and_clear_bit(MPTCP_PUSH_PENDING, &mptcp_sk(sk)->flags))
-			flags |= BIT(MPTCP_PUSH_PENDING);
-		if (test_and_clear_bit(MPTCP_RETRANSMIT, &mptcp_sk(sk)->flags))
-			flags |= BIT(MPTCP_RETRANSMIT);
-		if (test_and_clear_bit(MPTCP_FLUSH_JOIN_LIST, &mptcp_sk(sk)->flags))
-			flags |= BIT(MPTCP_FLUSH_JOIN_LIST);
+		unsigned long flags = (msk->cb_flags & MPTCP_FLAGS_PROCESS_CTX_NEED) |
+				      msk->push_pending;
 		if (!flags)
 			break;
 
@@ -3086,7 +3087,8 @@ static void mptcp_release_cb(struct sock *sk)
 		 *    datapath acquires the msk socket spinlock while helding
 		 *    the subflow socket lock
 		 */
-
+		msk->push_pending = 0;
+		msk->cb_flags &= ~flags;
 		spin_unlock_bh(&sk->sk_lock.slock);
 		if (flags & BIT(MPTCP_FLUSH_JOIN_LIST))
 			__mptcp_flush_join_list(sk);
@@ -3102,11 +3104,11 @@ static void mptcp_release_cb(struct sock *sk)
 	/* be sure to set the current sk state before tacking actions
 	 * depending on sk_state
 	 */
-	if (test_and_clear_bit(MPTCP_CONNECTED, &mptcp_sk(sk)->flags))
+	if (__test_and_clear_bit(MPTCP_CONNECTED, &msk->cb_flags))
 		__mptcp_set_connected(sk);
-	if (test_and_clear_bit(MPTCP_CLEAN_UNA, &mptcp_sk(sk)->flags))
+	if (__test_and_clear_bit(MPTCP_CLEAN_UNA, &msk->cb_flags))
 		__mptcp_clean_una_wakeup(sk);
-	if (test_and_clear_bit(MPTCP_ERROR_REPORT, &mptcp_sk(sk)->flags))
+	if (__test_and_clear_bit(MPTCP_ERROR_REPORT, &msk->cb_flags))
 		__mptcp_error_report(sk);
 
 	__mptcp_update_rmem(sk);
@@ -3148,7 +3150,7 @@ void mptcp_subflow_process_delegated(struct sock *ssk)
 		if (!sock_owned_by_user(sk))
 			__mptcp_subflow_push_pending(sk, ssk);
 		else
-			set_bit(MPTCP_PUSH_PENDING, &mptcp_sk(sk)->flags);
+			__set_bit(MPTCP_PUSH_PENDING, &mptcp_sk(sk)->cb_flags);
 		mptcp_data_unlock(sk);
 		mptcp_subflow_delegated_done(subflow, MPTCP_DELEGATE_SEND);
 	}
@@ -3268,7 +3270,7 @@ bool mptcp_finish_join(struct sock *ssk)
 	} else {
 		sock_hold(ssk);
 		list_add_tail(&subflow->node, &msk->join_list);
-		set_bit(MPTCP_FLUSH_JOIN_LIST, &msk->flags);
+		__set_bit(MPTCP_FLUSH_JOIN_LIST, &msk->cb_flags);
 	}
 	mptcp_data_unlock(parent);
 
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 27a510b20996..0459f164dc0b 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -110,18 +110,20 @@
 /* MPTCP TCPRST flags */
 #define MPTCP_RST_TRANSIENT	BIT(0)
 
-/* MPTCP socket flags */
+/* MPTCP socket atomic flags */
 #define MPTCP_NOSPACE		1
 #define MPTCP_WORK_RTX		2
 #define MPTCP_WORK_EOF		3
 #define MPTCP_FALLBACK_DONE	4
 #define MPTCP_WORK_CLOSE_SUBFLOW 5
-#define MPTCP_PUSH_PENDING	6
-#define MPTCP_CLEAN_UNA		7
-#define MPTCP_ERROR_REPORT	8
-#define MPTCP_RETRANSMIT	9
-#define MPTCP_FLUSH_JOIN_LIST	10
-#define MPTCP_CONNECTED		11
+
+/* MPTCP socket release cb flags */
+#define MPTCP_PUSH_PENDING	1
+#define MPTCP_CLEAN_UNA		2
+#define MPTCP_ERROR_REPORT	3
+#define MPTCP_RETRANSMIT	4
+#define MPTCP_FLUSH_JOIN_LIST	5
+#define MPTCP_CONNECTED		6
 
 static inline bool before64(__u64 seq1, __u64 seq2)
 {
@@ -249,6 +251,8 @@ struct mptcp_sock {
 	u32		token;
 	int		rmem_released;
 	unsigned long	flags;
+	unsigned long	cb_flags;
+	unsigned long	push_pending;
 	bool		recovery;		/* closing subflow write queue reinjected */
 	bool		can_ack;
 	bool		fully_established;
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 8716b9cb8040..557ef71309b0 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -388,7 +388,7 @@ static void mptcp_set_connected(struct sock *sk)
 	if (!sock_owned_by_user(sk))
 		__mptcp_set_connected(sk);
 	else
-		set_bit(MPTCP_CONNECTED, &mptcp_sk(sk)->flags);
+		__set_bit(MPTCP_CONNECTED, &mptcp_sk(sk)->cb_flags);
 	mptcp_data_unlock(sk);
 }
 
@@ -1279,7 +1279,7 @@ static void subflow_error_report(struct sock *ssk)
 	if (!sock_owned_by_user(sk))
 		__mptcp_error_report(sk);
 	else
-		set_bit(MPTCP_ERROR_REPORT,  &mptcp_sk(sk)->flags);
+		__set_bit(MPTCP_ERROR_REPORT,  &mptcp_sk(sk)->cb_flags);
 	mptcp_data_unlock(sk);
 }
 
-- 
2.33.1

Re: [PATCH v6 mptcp-next 7/7] mptcp: avoid atomic bit manipulation when possible

[Paolo Abeni]

On Tue, 2021-12-14 at 17:58 +0100, Paolo Abeni wrote:
> Currently the msk->flags bitmask carries both state for the
> mptcp_release_cb() - mostly touched under the mptcp data lock
> - and others state info touched even outside such lock scope.
> 
> As a consequence, msk->flags is always manipulated with
> atomic operations.
> 
> This change splits such bitmask in two separate fields, so
> that we use plain bit oper operations when touching the
> cb-related info.
> 
> The MPTCP_PUSH_PENDING bit needs additional care, as it is the
> only CB related field currently accessed either under the mptcp
> data lock or the mptcp socket lock.
> Let's add another mask just for such bit's sake.
> 
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>

This patch has still a few issues - basically it lacks a bunch of
BIT(). @Matt: could you please apply patches 1-6 (with modification on
patch 5) and leave this alone? I'll try to send a new version soon.

Otherwise I'll re-send the whole series.

Thanks!

Paolo

Re: [PATCH v6 mptcp-next 7/7] mptcp: avoid atomic bit manipulation when possible

[Matthieu Baerts]

Hi Paolo, Mat,

On 15/12/2021 16:10, Paolo Abeni wrote:
> On Tue, 2021-12-14 at 17:58 +0100, Paolo Abeni wrote:
>> Currently the msk->flags bitmask carries both state for the
>> mptcp_release_cb() - mostly touched under the mptcp data lock
>> - and others state info touched even outside such lock scope.
>>
>> As a consequence, msk->flags is always manipulated with
>> atomic operations.
>>
>> This change splits such bitmask in two separate fields, so
>> that we use plain bit oper operations when touching the
>> cb-related info.
>>
>> The MPTCP_PUSH_PENDING bit needs additional care, as it is the
>> only CB related field currently accessed either under the mptcp
>> data lock or the mptcp socket lock.
>> Let's add another mask just for such bit's sake.
>>
>> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> 
> This patch has still a few issues - basically it lacks a bunch of
> BIT(). @Matt: could you please apply patches 1-6 (with modification on
> patch 5) and leave this alone? I'll try to send a new version soon.

Thank you for the patches, the reviews and the notes.

These patches except the last one 7/7/ have just been applied in our
tree (features for net-next) with Mat's RvB tags, without a few spelling
typo spot by "checkpatch --codespell" and a typo spot by Mat in patch 5/7

- 7dff646b6956: mptcp: fix per socket endpoint accounting
- b3b313667f76: mptcp: clean-up MPJ option writing
- 93ddc71f0055: mptcp: keep track of local endpoint still available for
each msk
  - I had a small conflict and while at it, I added MPTCP_PM_ prefix to
MAX_ADDR_ID: https://paste.opendev.org/show/811700/
- b3adca806c71: mptcp: do not block subflows creation on errors
- 0f4945b51e44: selftests: mptcp: add tests for subflow creation failure
  - 07368dde952a: selftests: mptcp: apply Mat's comment
- 1d0e64a63ddc: mptcp: cleanup MPJ subflow list handling
- Results: 8c25dcd7cdf7..c94ca039d4f9

Builds and tests are now in progress:



https://cirrus-ci.com/github/multipath-tcp/mptcp_net-next/export/20211215T155626

https://github.com/multipath-tcp/mptcp_net-next/actions/workflows/build-validation.yml?query=branch:export

Cheers,
Matt
-- 
Tessares | Belgium | Hybrid Access Solutions
www.tessares.net

Re: [PATCH v6 mptcp-next 0/7] mptcp: improve subflow creation on errors

[Mat Martineau]

On Tue, 14 Dec 2021, Paolo Abeni wrote:

> This iteration tries to add address the feedback on v5, namely
> test counter update and locking in write_options. The latter
> required quite significant changes in patch 5/7.
>
> Additionally the series now includes the pending cleanup, as
> they depends on the previous patches. No changes there WRT the
> previous iteration.
>
> Currently when a subflow connection fails - either the TCP
> connection is reset by the peer, or the MPJ handshake never
> completes - the in kernel PM don't perform any further action.
> Notably no additional subflow creation is attempted.
>
> This series is aimed at improving the in-kernel path manager
> behavior in the above scenario:
> - each endpoint is used only once per connection (patch 2/4)
> - on failure we try to move to the next subflow, if any
>  (patch 3/4)
>
> The first patch is minor cleanup, and the last patch adds
> specific self-tests.
>
> This should address/close:
> https://github.com/multipath-tcp/mptcp_net-next/issues/235
> https://github.com/multipath-tcp/mptcp_net-next/issues/242
>

Hi Paolo -

Thanks for the changes, I think the "start all the subflows in a loop" 
works out better.

Looks good for wider testing on the export branch, with the one selftest 
fix noted in patch 5 (Matthieu, let us know how you prefer to proceed on 
that).

Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>


> Paolo Abeni (7):
>  mptcp: fix per socket endpoint accounting.
>  mptcp: clean-up MPJ option writing.
>  mptcp: keep track of local endpoint still available for each msk
>  mptcp: do not block subflows creation on errors
>  selftests: mptcp: add tests for subflow creation failure
>  mptcp: cleanup MPJ subflow list handling
>  mptcp: avoid atomic bit manipulation when possible
>
> net/mptcp/options.c                           |  44 ++--
> net/mptcp/pm.c                                |  24 ++-
> net/mptcp/pm_netlink.c                        | 188 +++++++++++-------
> net/mptcp/protocol.c                          | 158 +++++++--------
> net/mptcp/protocol.h                          |  46 +++--
> net/mptcp/sockopt.c                           |  24 +--
> net/mptcp/subflow.c                           |   9 +-
> tools/testing/selftests/net/mptcp/config      |   1 +
> .../testing/selftests/net/mptcp/mptcp_join.sh |  83 +++++++-
> 9 files changed, 350 insertions(+), 227 deletions(-)
>
> -- 
> 2.33.1
>
>
>

--
Mat Martineau
Intel

Re: [PATCH v6 mptcp-next 0/7] mptcp: improve subflow creation on errors

[Matthieu Baerts]

Hi Paolo,

On 14/12/2021 17:58, Paolo Abeni wrote:
> This iteration tries to add address the feedback on v5, namely
> test counter update and locking in write_options. The latter
> required quite significant changes in patch 5/7.
> 
> Additionally the series now includes the pending cleanup, as
> they depends on the previous patches. No changes there WRT the
> previous iteration.
> 
> Currently when a subflow connection fails - either the TCP
> connection is reset by the peer, or the MPJ handshake never
> completes - the in kernel PM don't perform any further action.
> Notably no additional subflow creation is attempted.
> 
> This series is aimed at improving the in-kernel path manager
> behavior in the above scenario:
> - each endpoint is used only once per connection (patch 2/4)
> - on failure we try to move to the next subflow, if any
>   (patch 3/4)
> 
> The first patch is minor cleanup, and the last patch adds
> specific self-tests.
> 
> This should address/close:
> https://github.com/multipath-tcp/mptcp_net-next/issues/235
> https://github.com/multipath-tcp/mptcp_net-next/issues/242

Is it OK to close these two issues now or do you prefer to do that when
patch 7/7 will be applied?

Cheers,
Matt
-- 
Tessares | Belgium | Hybrid Access Solutions
www.tessares.net