Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted

Pull networking updates from Jakub Kicinski:
 "Core:

   - Add dedicated kmem_cache for typical/small skb->head, avoid having
     to access struct page at kfree time, and improve memory use.

   - Introduce sysctl to set default RPS configuration for new netdevs.

   - Define Netlink protocol specification format which can be used to
     describe messages used by each family and auto-generate parsers.
     Add tools for generating kernel data structures and uAPI headers.

   - Expose all net/core sysctls inside netns.

   - Remove 4s sleep in netpoll if carrier is instantly detected on
     boot.

   - Add configurable limit of MDB entries per port, and port-vlan.

   - Continue populating drop reasons throughout the stack.

   - Retire a handful of legacy Qdiscs and classifiers.

  Protocols:

   - Support IPv4 big TCP (TSO frames larger than 64kB).

   - Add IP_LOCAL_PORT_RANGE socket option, to control local port range
     on socket by socket basis.

   - Track and report in procfs number of MPTCP sockets used.

   - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
     manager.

   - IPv6: don't check net.ipv6.route.max_size and rely on garbage
     collection to free memory (similarly to IPv4).

   - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).

   - ICMP: add per-rate limit counters.

   - Add support for user scanning requests in ieee802154.

   - Remove static WEP support.

   - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
     reporting.

   - WiFi 7 EHT channel puncturing support (client & AP).

  BPF:

   - Add a rbtree data structure following the "next-gen data structure"
     precedent set by recently added linked list, that is, by using
     kfunc + kptr instead of adding a new BPF map type.

   - Expose XDP hints via kfuncs with initial support for RX hash and
     timestamp metadata.

   - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
     better support decap on GRE tunnel devices not operating in collect
     metadata.

   - Improve x86 JIT's codegen for PROBE_MEM runtime error checks.

   - Remove the need for trace_printk_lock for bpf_trace_printk and
     bpf_trace_vprintk helpers.

   - Extend libbpf's bpf_tracing.h support for tracing arguments of
     kprobes/uprobes and syscall as a special case.

   - Significantly reduce the search time for module symbols by
     livepatch and BPF.

   - Enable cpumasks to be used as kptrs, which is useful for tracing
     programs tracking which tasks end up running on which CPUs in
     different time intervals.

   - Add support for BPF trampoline on s390x and riscv64.

   - Add capability to export the XDP features supported by the NIC.

   - Add __bpf_kfunc tag for marking kernel functions as kfuncs.

   - Add cgroup.memory=nobpf kernel parameter option to disable BPF
     memory accounting for container environments.

  Netfilter:

   - Remove the CLUSTERIP target. It has been marked as obsolete for
     years, and we still have WARN splats wrt races of the out-of-band
     /proc interface installed by this target.

   - Add 'destroy' commands to nf_tables. They are identical to the
     existing 'delete' commands, but do not return an error if the
     referenced object (set, chain, rule...) did not exist.

  Driver API:

   - Improve cpumask_local_spread() locality to help NICs set the right
     IRQ affinity on AMD platforms.

   - Separate C22 and C45 MDIO bus transactions more clearly.

   - Introduce new DCB table to control DSCP rewrite on egress.

   - Support configuration of Physical Layer Collision Avoidance (PLCA)
     Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
     shared medium Ethernet.

   - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
     preemption of low priority frames by high priority frames.

   - Add support for controlling MACSec offload using netlink SET.

   - Rework devlink instance refcounts to allow registration and
     de-registration under the instance lock. Split the code into
     multiple files, drop some of the unnecessarily granular locks and
     factor out common parts of netlink operation handling.

   - Add TX frame aggregation parameters (for USB drivers).

   - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
     messages with notifications for debug.

   - Allow offloading of UDP NEW connections via act_ct.

   - Add support for per action HW stats in TC.

   - Support hardware miss to TC action (continue processing in SW from
     a specific point in the action chain).

   - Warn if old Wireless Extension user space interface is used with
     modern cfg80211/mac80211 drivers. Do not support Wireless
     Extensions for Wi-Fi 7 devices at all. Everyone should switch to
     using nl80211 interface instead.

   - Improve the CAN bit timing configuration. Use extack to return
     error messages directly to user space, update the SJW handling,
     including the definition of a new default value that will benefit
     CAN-FD controllers, by increasing their oscillator tolerance.

  New hardware / drivers:

   - Ethernet:
      - nVidia BlueField-3 support (control traffic driver)
      - Ethernet support for imx93 SoCs
      - Motorcomm yt8531 gigabit Ethernet PHY
      - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
      - Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
      - Amlogic gxl MDIO mux

   - WiFi:
      - RealTek RTL8188EU (rtl8xxxu)
      - Qualcomm Wi-Fi 7 devices (ath12k)

   - CAN:
      - Renesas R-Car V4H

  Drivers:

   - Bluetooth:
      - Set Per Platform Antenna Gain (PPAG) for Intel controllers.

   - Ethernet NICs:
      - Intel (1G, igc):
         - support TSN / Qbv / packet scheduling features of i226 model
      - Intel (100G, ice):
         - use GNSS subsystem instead of TTY
         - multi-buffer XDP support
         - extend support for GPIO pins to E823 devices
      - nVidia/Mellanox:
         - update the shared buffer configuration on PFC commands
         - implement PTP adjphase function for HW offset control
         - TC support for Geneve and GRE with VF tunnel offload
         - more efficient crypto key management method
         - multi-port eswitch support
      - Netronome/Corigine:
         - add DCB IEEE support
         - support IPsec offloading for NFP3800
      - Freescale/NXP (enetc):
         - support XDP_REDIRECT for XDP non-linear buffers
         - improve reconfig, avoid link flap and waiting for idle
         - support MAC Merge layer
      - Other NICs:
         - sfc/ef100: add basic devlink support for ef100
         - ionic: rx_push mode operation (writing descriptors via MMIO)
         - bnxt: use the auxiliary bus abstraction for RDMA
         - r8169: disable ASPM and reset bus in case of tx timeout
         - cpsw: support QSGMII mode for J721e CPSW9G
         - cpts: support pulse-per-second output
         - ngbe: add an mdio bus driver
         - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
         - r8152: handle devices with FW with NCM support
         - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
         - virtio-net: support multi buffer XDP
         - virtio/vsock: replace virtio_vsock_pkt with sk_buff
         - tsnep: XDP support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add support for latency TLV (in FW control messages)
      - Microchip (sparx5):
         - separate explicit and implicit traffic forwarding rules, make
           the implicit rules always active
         - add support for egress DSCP rewrite
         - IS0 VCAP support (Ingress Classification)
         - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
           etc.)
         - ES2 VCAP support (Egress Access Control)
         - support for Per-Stream Filtering and Policing (802.1Q,
           8.6.5.1)

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - add MAB (port auth) offload support
         - enable PTP receive for mv88e6390
      - NXP (ocelot):
         - support MAC Merge layer
         - support for the the vsc7512 internal copper phys
      - Microchip:
         - lan9303: convert to PHYLINK
         - lan966x: support TC flower filter statistics
         - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
         - lan937x: support Credit Based Shaper configuration
         - ksz9477: support Energy Efficient Ethernet
      - other:
         - qca8k: convert to regmap read/write API, use bulk operations
         - rswitch: Improve TX timestamp accuracy

   - Intel WiFi (iwlwifi):
      - EHT (Wi-Fi 7) rate reporting
      - STEP equalizer support: transfer some STEP (connection to radio
        on platforms with integrated wifi) related parameters from the
        BIOS to the firmware.

   - Qualcomm 802.11ax WiFi (ath11k):
      - IPQ5018 support
      - Fine Timing Measurement (FTM) responder role support
      - channel 177 support

   - MediaTek WiFi (mt76):
      - per-PHY LED support
      - mt7996: EHT (Wi-Fi 7) support
      - Wireless Ethernet Dispatch (WED) reset support
      - switch to using page pool allocator

   - RealTek WiFi (rtw89):
      - support new version of Bluetooth co-existance

   - Mobile:
      - rmnet: support TX aggregation"

* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
  page_pool: add a comment explaining the fragment counter usage
  net: ethtool: fix __ethtool_dev_mm_supported() implementation
  ethtool: pse-pd: Fix double word in comments
  xsk: add linux/vmalloc.h to xsk.c
  sefltests: netdevsim: wait for devlink instance after netns removal
  selftest: fib_tests: Always cleanup before exit
  net/mlx5e: Align IPsec ASO result memory to be as required by hardware
  net/mlx5e: TC, Set CT miss to the specific ct action instance
  net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
  net/mlx5: Refactor tc miss handling to a single function
  net/mlx5: Kconfig: Make tc offload depend on tc skb extension
  net/sched: flower: Support hardware miss to tc action
  net/sched: flower: Move filter handle initialization earlier
  net/sched: cls_api: Support hardware miss to tc action
  net/sched: Rename user cookie and act cookie
  sfc: fix builds without CONFIG_RTC_LIB
  sfc: clean up some inconsistent indentings
  net/mlx4_en: Introduce flexible array to silence overflow warning
  net: lan966x: Fix possible deadlock inside PTP
  net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
  ...

1 files changed, 731 insertions, 0 deletions

diff --git a/net/tipc/topsrv.c b/net/tipc/topsrv.c
new file mode 100644
index 000000000..8ee0c07d0
--- /dev/null
+++ b/net/tipc/topsrv.c
@@ -0,0 +1,731 @@
+/*
+ * net/tipc/server.c: TIPC server infrastructure
+ *
+ * Copyright (c) 2012-2013, Wind River Systems
+ * Copyright (c) 2017-2018, Ericsson AB
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the names of the copyright holders nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * Alternatively, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2 as published by the Free
+ * Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "subscr.h"
+#include "topsrv.h"
+#include "core.h"
+#include "socket.h"
+#include "addr.h"
+#include "msg.h"
+#include "bearer.h"
+#include <net/sock.h>
+#include <linux/module.h>
+#include <trace/events/sock.h>
+
+/* Number of messages to send before rescheduling */
+#define MAX_SEND_MSG_COUNT	25
+#define MAX_RECV_MSG_COUNT	25
+#define CF_CONNECTED		1
+
+#define TIPC_SERVER_NAME_LEN	32
+
+/**
+ * struct tipc_topsrv - TIPC server structure
+ * @conn_idr: identifier set of connection
+ * @idr_lock: protect the connection identifier set
+ * @idr_in_use: amount of allocated identifier entry
+ * @net: network namspace instance
+ * @awork: accept work item
+ * @rcv_wq: receive workqueue
+ * @send_wq: send workqueue
+ * @listener: topsrv listener socket
+ * @name: server name
+ */
+struct tipc_topsrv {
+	struct idr conn_idr;
+	spinlock_t idr_lock; /* for idr list */
+	int idr_in_use;
+	struct net *net;
+	struct work_struct awork;
+	struct workqueue_struct *rcv_wq;
+	struct workqueue_struct *send_wq;
+	struct socket *listener;
+	char name[TIPC_SERVER_NAME_LEN];
+};
+
+/**
+ * struct tipc_conn - TIPC connection structure
+ * @kref: reference counter to connection object
+ * @conid: connection identifier
+ * @sock: socket handler associated with connection
+ * @flags: indicates connection state
+ * @server: pointer to connected server
+ * @sub_list: lsit to all pertaing subscriptions
+ * @sub_lock: lock protecting the subscription list
+ * @rwork: receive work item
+ * @outqueue: pointer to first outbound message in queue
+ * @outqueue_lock: control access to the outqueue
+ * @swork: send work item
+ */
+struct tipc_conn {
+	struct kref kref;
+	int conid;
+	struct socket *sock;
+	unsigned long flags;
+	struct tipc_topsrv *server;
+	struct list_head sub_list;
+	spinlock_t sub_lock; /* for subscription list */
+	struct work_struct rwork;
+	struct list_head outqueue;
+	spinlock_t outqueue_lock; /* for outqueue */
+	struct work_struct swork;
+};
+
+/* An entry waiting to be sent */
+struct outqueue_entry {
+	bool inactive;
+	struct tipc_event evt;
+	struct list_head list;
+};
+
+static void tipc_conn_recv_work(struct work_struct *work);
+static void tipc_conn_send_work(struct work_struct *work);
+static void tipc_topsrv_kern_evt(struct net *net, struct tipc_event *evt);
+static void tipc_conn_delete_sub(struct tipc_conn *con, struct tipc_subscr *s);
+
+static bool connected(struct tipc_conn *con)
+{
+	return con && test_bit(CF_CONNECTED, &con->flags);
+}
+
+static void tipc_conn_kref_release(struct kref *kref)
+{
+	struct tipc_conn *con = container_of(kref, struct tipc_conn, kref);
+	struct tipc_topsrv *s = con->server;
+	struct outqueue_entry *e, *safe;
+
+	spin_lock_bh(&s->idr_lock);
+	idr_remove(&s->conn_idr, con->conid);
+	s->idr_in_use--;
+	spin_unlock_bh(&s->idr_lock);
+	if (con->sock)
+		sock_release(con->sock);
+
+	spin_lock_bh(&con->outqueue_lock);
+	list_for_each_entry_safe(e, safe, &con->outqueue, list) {
+		list_del(&e->list);
+		kfree(e);
+	}
+	spin_unlock_bh(&con->outqueue_lock);
+	kfree(con);
+}
+
+static void conn_put(struct tipc_conn *con)
+{
+	kref_put(&con->kref, tipc_conn_kref_release);
+}
+
+static void conn_get(struct tipc_conn *con)
+{
+	kref_get(&con->kref);
+}
+
+static void tipc_conn_close(struct tipc_conn *con)
+{
+	struct sock *sk = con->sock->sk;
+	bool disconnect = false;
+
+	write_lock_bh(&sk->sk_callback_lock);
+	disconnect = test_and_clear_bit(CF_CONNECTED, &con->flags);
+
+	if (disconnect) {
+		sk->sk_user_data = NULL;
+		tipc_conn_delete_sub(con, NULL);
+	}
+	write_unlock_bh(&sk->sk_callback_lock);
+
+	/* Handle concurrent calls from sending and receiving threads */
+	if (!disconnect)
+		return;
+
+	/* Don't flush pending works, -just let them expire */
+	kernel_sock_shutdown(con->sock, SHUT_RDWR);
+
+	conn_put(con);
+}
+
+static struct tipc_conn *tipc_conn_alloc(struct tipc_topsrv *s, struct socket *sock)
+{
+	struct tipc_conn *con;
+	int ret;
+
+	con = kzalloc(sizeof(*con), GFP_ATOMIC);
+	if (!con)
+		return ERR_PTR(-ENOMEM);
+
+	kref_init(&con->kref);
+	INIT_LIST_HEAD(&con->outqueue);
+	INIT_LIST_HEAD(&con->sub_list);
+	spin_lock_init(&con->outqueue_lock);
+	spin_lock_init(&con->sub_lock);
+	INIT_WORK(&con->swork, tipc_conn_send_work);
+	INIT_WORK(&con->rwork, tipc_conn_recv_work);
+
+	spin_lock_bh(&s->idr_lock);
+	ret = idr_alloc(&s->conn_idr, con, 0, 0, GFP_ATOMIC);
+	if (ret < 0) {
+		kfree(con);
+		spin_unlock_bh(&s->idr_lock);
+		return ERR_PTR(-ENOMEM);
+	}
+	con->conid = ret;
+	s->idr_in_use++;
+
+	set_bit(CF_CONNECTED, &con->flags);
+	con->server = s;
+	con->sock = sock;
+	conn_get(con);
+	spin_unlock_bh(&s->idr_lock);
+
+	return con;
+}
+
+static struct tipc_conn *tipc_conn_lookup(struct tipc_topsrv *s, int conid)
+{
+	struct tipc_conn *con;
+
+	spin_lock_bh(&s->idr_lock);
+	con = idr_find(&s->conn_idr, conid);
+	if (!connected(con) || !kref_get_unless_zero(&con->kref))
+		con = NULL;
+	spin_unlock_bh(&s->idr_lock);
+	return con;
+}
+
+/* tipc_conn_delete_sub - delete a specific or all subscriptions
+ * for a given subscriber
+ */
+static void tipc_conn_delete_sub(struct tipc_conn *con, struct tipc_subscr *s)
+{
+	struct tipc_net *tn = tipc_net(con->server->net);
+	struct list_head *sub_list = &con->sub_list;
+	struct tipc_subscription *sub, *tmp;
+
+	spin_lock_bh(&con->sub_lock);
+	list_for_each_entry_safe(sub, tmp, sub_list, sub_list) {
+		if (!s || !memcmp(s, &sub->evt.s, sizeof(*s))) {
+			tipc_sub_unsubscribe(sub);
+			atomic_dec(&tn->subscription_count);
+			if (s)
+				break;
+		}
+	}
+	spin_unlock_bh(&con->sub_lock);
+}
+
+static void tipc_conn_send_to_sock(struct tipc_conn *con)
+{
+	struct list_head *queue = &con->outqueue;
+	struct tipc_topsrv *srv = con->server;
+	struct outqueue_entry *e;
+	struct tipc_event *evt;
+	struct msghdr msg;
+	struct kvec iov;
+	int count = 0;
+	int ret;
+
+	spin_lock_bh(&con->outqueue_lock);
+
+	while (!list_empty(queue)) {
+		e = list_first_entry(queue, struct outqueue_entry, list);
+		evt = &e->evt;
+		spin_unlock_bh(&con->outqueue_lock);
+
+		if (e->inactive)
+			tipc_conn_delete_sub(con, &evt->s);
+
+		memset(&msg, 0, sizeof(msg));
+		msg.msg_flags = MSG_DONTWAIT;
+		iov.iov_base = evt;
+		iov.iov_len = sizeof(*evt);
+		msg.msg_name = NULL;
+
+		if (con->sock) {
+			ret = kernel_sendmsg(con->sock, &msg, &iov,
+					     1, sizeof(*evt));
+			if (ret == -EWOULDBLOCK || ret == 0) {
+				cond_resched();
+				return;
+			} else if (ret < 0) {
+				return tipc_conn_close(con);
+			}
+		} else {
+			tipc_topsrv_kern_evt(srv->net, evt);
+		}
+
+		/* Don't starve users filling buffers */
+		if (++count >= MAX_SEND_MSG_COUNT) {
+			cond_resched();
+			count = 0;
+		}
+		spin_lock_bh(&con->outqueue_lock);
+		list_del(&e->list);
+		kfree(e);
+	}
+	spin_unlock_bh(&con->outqueue_lock);
+}
+
+static void tipc_conn_send_work(struct work_struct *work)
+{
+	struct tipc_conn *con = container_of(work, struct tipc_conn, swork);
+
+	if (connected(con))
+		tipc_conn_send_to_sock(con);
+
+	conn_put(con);
+}
+
+/* tipc_topsrv_queue_evt() - interrupt level call from a subscription instance
+ * The queued work is launched into tipc_conn_send_work()->tipc_conn_send_to_sock()
+ */
+void tipc_topsrv_queue_evt(struct net *net, int conid,
+			   u32 event, struct tipc_event *evt)
+{
+	struct tipc_topsrv *srv = tipc_topsrv(net);
+	struct outqueue_entry *e;
+	struct tipc_conn *con;
+
+	con = tipc_conn_lookup(srv, conid);
+	if (!con)
+		return;
+
+	if (!connected(con))
+		goto err;
+
+	e = kmalloc(sizeof(*e), GFP_ATOMIC);
+	if (!e)
+		goto err;
+	e->inactive = (event == TIPC_SUBSCR_TIMEOUT);
+	memcpy(&e->evt, evt, sizeof(*evt));
+	spin_lock_bh(&con->outqueue_lock);
+	list_add_tail(&e->list, &con->outqueue);
+	spin_unlock_bh(&con->outqueue_lock);
+
+	if (queue_work(srv->send_wq, &con->swork))
+		return;
+err:
+	conn_put(con);
+}
+
+/* tipc_conn_write_space - interrupt callback after a sendmsg EAGAIN
+ * Indicates that there now is more space in the send buffer
+ * The queued work is launched into tipc_send_work()->tipc_conn_send_to_sock()
+ */
+static void tipc_conn_write_space(struct sock *sk)
+{
+	struct tipc_conn *con;
+
+	read_lock_bh(&sk->sk_callback_lock);
+	con = sk->sk_user_data;
+	if (connected(con)) {
+		conn_get(con);
+		if (!queue_work(con->server->send_wq, &con->swork))
+			conn_put(con);
+	}
+	read_unlock_bh(&sk->sk_callback_lock);
+}
+
+static int tipc_conn_rcv_sub(struct tipc_topsrv *srv,
+			     struct tipc_conn *con,
+			     struct tipc_subscr *s)
+{
+	struct tipc_net *tn = tipc_net(srv->net);
+	struct tipc_subscription *sub;
+	u32 s_filter = tipc_sub_read(s, filter);
+
+	if (s_filter & TIPC_SUB_CANCEL) {
+		tipc_sub_write(s, filter, s_filter & ~TIPC_SUB_CANCEL);
+		tipc_conn_delete_sub(con, s);
+		return 0;
+	}
+	if (atomic_read(&tn->subscription_count) >= TIPC_MAX_SUBSCR) {
+		pr_warn("Subscription rejected, max (%u)\n", TIPC_MAX_SUBSCR);
+		return -1;
+	}
+	sub = tipc_sub_subscribe(srv->net, s, con->conid);
+	if (!sub)
+		return -1;
+	atomic_inc(&tn->subscription_count);
+	spin_lock_bh(&con->sub_lock);
+	list_add(&sub->sub_list, &con->sub_list);
+	spin_unlock_bh(&con->sub_lock);
+	return 0;
+}
+
+static int tipc_conn_rcv_from_sock(struct tipc_conn *con)
+{
+	struct tipc_topsrv *srv = con->server;
+	struct sock *sk = con->sock->sk;
+	struct msghdr msg = {};
+	struct tipc_subscr s;
+	struct kvec iov;
+	int ret;
+
+	iov.iov_base = &s;
+	iov.iov_len = sizeof(s);
+	msg.msg_name = NULL;
+	iov_iter_kvec(&msg.msg_iter, ITER_DEST, &iov, 1, iov.iov_len);
+	ret = sock_recvmsg(con->sock, &msg, MSG_DONTWAIT);
+	if (ret == -EWOULDBLOCK)
+		return -EWOULDBLOCK;
+	if (ret == sizeof(s)) {
+		read_lock_bh(&sk->sk_callback_lock);
+		/* RACE: the connection can be closed in the meantime */
+		if (likely(connected(con)))
+			ret = tipc_conn_rcv_sub(srv, con, &s);
+		read_unlock_bh(&sk->sk_callback_lock);
+		if (!ret)
+			return 0;
+	}
+
+	tipc_conn_close(con);
+	return ret;
+}
+
+static void tipc_conn_recv_work(struct work_struct *work)
+{
+	struct tipc_conn *con = container_of(work, struct tipc_conn, rwork);
+	int count = 0;
+
+	while (connected(con)) {
+		if (tipc_conn_rcv_from_sock(con))
+			break;
+
+		/* Don't flood Rx machine */
+		if (++count >= MAX_RECV_MSG_COUNT) {
+			cond_resched();
+			count = 0;
+		}
+	}
+	conn_put(con);
+}
+
+/* tipc_conn_data_ready - interrupt callback indicating the socket has data
+ * The queued work is launched into tipc_recv_work()->tipc_conn_rcv_from_sock()
+ */
+static void tipc_conn_data_ready(struct sock *sk)
+{
+	struct tipc_conn *con;
+
+	trace_sk_data_ready(sk);
+
+	read_lock_bh(&sk->sk_callback_lock);
+	con = sk->sk_user_data;
+	if (connected(con)) {
+		conn_get(con);
+		if (!queue_work(con->server->rcv_wq, &con->rwork))
+			conn_put(con);
+	}
+	read_unlock_bh(&sk->sk_callback_lock);
+}
+
+static void tipc_topsrv_accept(struct work_struct *work)
+{
+	struct tipc_topsrv *srv = container_of(work, struct tipc_topsrv, awork);
+	struct socket *newsock, *lsock;
+	struct tipc_conn *con;
+	struct sock *newsk;
+	int ret;
+
+	spin_lock_bh(&srv->idr_lock);
+	if (!srv->listener) {
+		spin_unlock_bh(&srv->idr_lock);
+		return;
+	}
+	lsock = srv->listener;
+	spin_unlock_bh(&srv->idr_lock);
+
+	while (1) {
+		ret = kernel_accept(lsock, &newsock, O_NONBLOCK);
+		if (ret < 0)
+			return;
+		con = tipc_conn_alloc(srv, newsock);
+		if (IS_ERR(con)) {
+			ret = PTR_ERR(con);
+			sock_release(newsock);
+			return;
+		}
+		/* Register callbacks */
+		newsk = newsock->sk;
+		write_lock_bh(&newsk->sk_callback_lock);
+		newsk->sk_data_ready = tipc_conn_data_ready;
+		newsk->sk_write_space = tipc_conn_write_space;
+		newsk->sk_user_data = con;
+		write_unlock_bh(&newsk->sk_callback_lock);
+
+		/* Wake up receive process in case of 'SYN+' message */
+		newsk->sk_data_ready(newsk);
+		conn_put(con);
+	}
+}
+
+/* tipc_topsrv_listener_data_ready - interrupt callback with connection request
+ * The queued job is launched into tipc_topsrv_accept()
+ */
+static void tipc_topsrv_listener_data_ready(struct sock *sk)
+{
+	struct tipc_topsrv *srv;
+
+	trace_sk_data_ready(sk);
+
+	read_lock_bh(&sk->sk_callback_lock);
+	srv = sk->sk_user_data;
+	if (srv)
+		queue_work(srv->rcv_wq, &srv->awork);
+	read_unlock_bh(&sk->sk_callback_lock);
+}
+
+static int tipc_topsrv_create_listener(struct tipc_topsrv *srv)
+{
+	struct socket *lsock = NULL;
+	struct sockaddr_tipc saddr;
+	struct sock *sk;
+	int rc;
+
+	rc = sock_create_kern(srv->net, AF_TIPC, SOCK_SEQPACKET, 0, &lsock);
+	if (rc < 0)
+		return rc;
+
+	srv->listener = lsock;
+	sk = lsock->sk;
+	write_lock_bh(&sk->sk_callback_lock);
+	sk->sk_data_ready = tipc_topsrv_listener_data_ready;
+	sk->sk_user_data = srv;
+	write_unlock_bh(&sk->sk_callback_lock);
+
+	lock_sock(sk);
+	rc = tsk_set_importance(sk, TIPC_CRITICAL_IMPORTANCE);
+	release_sock(sk);
+	if (rc < 0)
+		goto err;
+
+	saddr.family	                = AF_TIPC;
+	saddr.addrtype		        = TIPC_SERVICE_RANGE;
+	saddr.addr.nameseq.type	= TIPC_TOP_SRV;
+	saddr.addr.nameseq.lower	= TIPC_TOP_SRV;
+	saddr.addr.nameseq.upper	= TIPC_TOP_SRV;
+	saddr.scope			= TIPC_NODE_SCOPE;
+
+	rc = tipc_sk_bind(lsock, (struct sockaddr *)&saddr, sizeof(saddr));
+	if (rc < 0)
+		goto err;
+	rc = kernel_listen(lsock, 0);
+	if (rc < 0)
+		goto err;
+
+	/* As server's listening socket owner and creator is the same module,
+	 * we have to decrease TIPC module reference count to guarantee that
+	 * it remains zero after the server socket is created, otherwise,
+	 * executing "rmmod" command is unable to make TIPC module deleted
+	 * after TIPC module is inserted successfully.
+	 *
+	 * However, the reference count is ever increased twice in
+	 * sock_create_kern(): one is to increase the reference count of owner
+	 * of TIPC socket's proto_ops struct; another is to increment the
+	 * reference count of owner of TIPC proto struct. Therefore, we must
+	 * decrement the module reference count twice to ensure that it keeps
+	 * zero after server's listening socket is created. Of course, we
+	 * must bump the module reference count twice as well before the socket
+	 * is closed.
+	 */
+	module_put(lsock->ops->owner);
+	module_put(sk->sk_prot_creator->owner);
+
+	return 0;
+err:
+	sock_release(lsock);
+	return -EINVAL;
+}
+
+bool tipc_topsrv_kern_subscr(struct net *net, u32 port, u32 type, u32 lower,
+			     u32 upper, u32 filter, int *conid)
+{
+	struct tipc_subscr sub;
+	struct tipc_conn *con;
+	int rc;
+
+	sub.seq.type = type;
+	sub.seq.lower = lower;
+	sub.seq.upper = upper;
+	sub.timeout = TIPC_WAIT_FOREVER;
+	sub.filter = filter;
+	*(u64 *)&sub.usr_handle = (u64)port;
+
+	con = tipc_conn_alloc(tipc_topsrv(net), NULL);
+	if (IS_ERR(con))
+		return false;
+
+	*conid = con->conid;
+	rc = tipc_conn_rcv_sub(tipc_topsrv(net), con, &sub);
+	if (rc)
+		conn_put(con);
+
+	conn_put(con);
+	return !rc;
+}
+
+void tipc_topsrv_kern_unsubscr(struct net *net, int conid)
+{
+	struct tipc_conn *con;
+
+	con = tipc_conn_lookup(tipc_topsrv(net), conid);
+	if (!con)
+		return;
+
+	test_and_clear_bit(CF_CONNECTED, &con->flags);
+	tipc_conn_delete_sub(con, NULL);
+	conn_put(con);
+	conn_put(con);
+}
+
+static void tipc_topsrv_kern_evt(struct net *net, struct tipc_event *evt)
+{
+	u32 port = *(u32 *)&evt->s.usr_handle;
+	u32 self = tipc_own_addr(net);
+	struct sk_buff_head evtq;
+	struct sk_buff *skb;
+
+	skb = tipc_msg_create(TOP_SRV, 0, INT_H_SIZE, sizeof(*evt),
+			      self, self, port, port, 0);
+	if (!skb)
+		return;
+	msg_set_dest_droppable(buf_msg(skb), true);
+	memcpy(msg_data(buf_msg(skb)), evt, sizeof(*evt));
+	skb_queue_head_init(&evtq);
+	__skb_queue_tail(&evtq, skb);
+	tipc_loopback_trace(net, &evtq);
+	tipc_sk_rcv(net, &evtq);
+}
+
+static int tipc_topsrv_work_start(struct tipc_topsrv *s)
+{
+	s->rcv_wq = alloc_ordered_workqueue("tipc_rcv", 0);
+	if (!s->rcv_wq) {
+		pr_err("can't start tipc receive workqueue\n");
+		return -ENOMEM;
+	}
+
+	s->send_wq = alloc_ordered_workqueue("tipc_send", 0);
+	if (!s->send_wq) {
+		pr_err("can't start tipc send workqueue\n");
+		destroy_workqueue(s->rcv_wq);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static void tipc_topsrv_work_stop(struct tipc_topsrv *s)
+{
+	destroy_workqueue(s->rcv_wq);
+	destroy_workqueue(s->send_wq);
+}
+
+static int tipc_topsrv_start(struct net *net)
+{
+	struct tipc_net *tn = tipc_net(net);
+	const char name[] = "topology_server";
+	struct tipc_topsrv *srv;
+	int ret;
+
+	srv = kzalloc(sizeof(*srv), GFP_ATOMIC);
+	if (!srv)
+		return -ENOMEM;
+
+	srv->net = net;
+	INIT_WORK(&srv->awork, tipc_topsrv_accept);
+
+	strscpy(srv->name, name, sizeof(srv->name));
+	tn->topsrv = srv;
+	atomic_set(&tn->subscription_count, 0);
+
+	spin_lock_init(&srv->idr_lock);
+	idr_init(&srv->conn_idr);
+	srv->idr_in_use = 0;
+
+	ret = tipc_topsrv_work_start(srv);
+	if (ret < 0)
+		goto err_start;
+
+	ret = tipc_topsrv_create_listener(srv);
+	if (ret < 0)
+		goto err_create;
+
+	return 0;
+
+err_create:
+	tipc_topsrv_work_stop(srv);
+err_start:
+	kfree(srv);
+	return ret;
+}
+
+static void tipc_topsrv_stop(struct net *net)
+{
+	struct tipc_topsrv *srv = tipc_topsrv(net);
+	struct socket *lsock = srv->listener;
+	struct tipc_conn *con;
+	int id;
+
+	spin_lock_bh(&srv->idr_lock);
+	for (id = 0; srv->idr_in_use; id++) {
+		con = idr_find(&srv->conn_idr, id);
+		if (con) {
+			spin_unlock_bh(&srv->idr_lock);
+			tipc_conn_close(con);
+			spin_lock_bh(&srv->idr_lock);
+		}
+	}
+	__module_get(lsock->ops->owner);
+	__module_get(lsock->sk->sk_prot_creator->owner);
+	srv->listener = NULL;
+	spin_unlock_bh(&srv->idr_lock);
+
+	tipc_topsrv_work_stop(srv);
+	sock_release(lsock);
+	idr_destroy(&srv->conn_idr);
+	kfree(srv);
+}
+
+int __net_init tipc_topsrv_init_net(struct net *net)
+{
+	return tipc_topsrv_start(net);
+}
+
+void __net_exit tipc_topsrv_exit_net(struct net *net)
+{
+	tipc_topsrv_stop(net);
+}