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, 711 insertions, 0 deletions

diff --git a/sound/core/seq/seq_ports.c b/sound/core/seq/seq_ports.c
new file mode 100644
index 000000000..25fcf5a2c
--- /dev/null
+++ b/sound/core/seq/seq_ports.c
@@ -0,0 +1,711 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *   ALSA sequencer Ports
+ *   Copyright (c) 1998 by Frank van de Pol <fvdpol@coil.demon.nl>
+ *                         Jaroslav Kysela <perex@perex.cz>
+ */
+
+#include <sound/core.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include "seq_system.h"
+#include "seq_ports.h"
+#include "seq_clientmgr.h"
+
+/*
+
+   registration of client ports
+
+ */
+
+
+/* 
+
+NOTE: the current implementation of the port structure as a linked list is
+not optimal for clients that have many ports. For sending messages to all
+subscribers of a port we first need to find the address of the port
+structure, which means we have to traverse the list. A direct access table
+(array) would be better, but big preallocated arrays waste memory.
+
+Possible actions:
+
+1) leave it this way, a client does normaly does not have more than a few
+ports
+
+2) replace the linked list of ports by a array of pointers which is
+dynamicly kmalloced. When a port is added or deleted we can simply allocate
+a new array, copy the corresponding pointers, and delete the old one. We
+then only need a pointer to this array, and an integer that tells us how
+much elements are in array.
+
+*/
+
+/* return pointer to port structure - port is locked if found */
+struct snd_seq_client_port *snd_seq_port_use_ptr(struct snd_seq_client *client,
+						 int num)
+{
+	struct snd_seq_client_port *port;
+
+	if (client == NULL)
+		return NULL;
+	read_lock(&client->ports_lock);
+	list_for_each_entry(port, &client->ports_list_head, list) {
+		if (port->addr.port == num) {
+			if (port->closing)
+				break; /* deleting now */
+			snd_use_lock_use(&port->use_lock);
+			read_unlock(&client->ports_lock);
+			return port;
+		}
+	}
+	read_unlock(&client->ports_lock);
+	return NULL;		/* not found */
+}
+
+
+/* search for the next port - port is locked if found */
+struct snd_seq_client_port *snd_seq_port_query_nearest(struct snd_seq_client *client,
+						       struct snd_seq_port_info *pinfo)
+{
+	int num;
+	struct snd_seq_client_port *port, *found;
+
+	num = pinfo->addr.port;
+	found = NULL;
+	read_lock(&client->ports_lock);
+	list_for_each_entry(port, &client->ports_list_head, list) {
+		if (port->addr.port < num)
+			continue;
+		if (port->addr.port == num) {
+			found = port;
+			break;
+		}
+		if (found == NULL || port->addr.port < found->addr.port)
+			found = port;
+	}
+	if (found) {
+		if (found->closing)
+			found = NULL;
+		else
+			snd_use_lock_use(&found->use_lock);
+	}
+	read_unlock(&client->ports_lock);
+	return found;
+}
+
+
+/* initialize snd_seq_port_subs_info */
+static void port_subs_info_init(struct snd_seq_port_subs_info *grp)
+{
+	INIT_LIST_HEAD(&grp->list_head);
+	grp->count = 0;
+	grp->exclusive = 0;
+	rwlock_init(&grp->list_lock);
+	init_rwsem(&grp->list_mutex);
+	grp->open = NULL;
+	grp->close = NULL;
+}
+
+
+/* create a port, port number is returned (-1 on failure);
+ * the caller needs to unref the port via snd_seq_port_unlock() appropriately
+ */
+struct snd_seq_client_port *snd_seq_create_port(struct snd_seq_client *client,
+						int port)
+{
+	struct snd_seq_client_port *new_port, *p;
+	int num = -1;
+	
+	/* sanity check */
+	if (snd_BUG_ON(!client))
+		return NULL;
+
+	if (client->num_ports >= SNDRV_SEQ_MAX_PORTS) {
+		pr_warn("ALSA: seq: too many ports for client %d\n", client->number);
+		return NULL;
+	}
+
+	/* create a new port */
+	new_port = kzalloc(sizeof(*new_port), GFP_KERNEL);
+	if (!new_port)
+		return NULL;	/* failure, out of memory */
+	/* init port data */
+	new_port->addr.client = client->number;
+	new_port->addr.port = -1;
+	new_port->owner = THIS_MODULE;
+	sprintf(new_port->name, "port-%d", num);
+	snd_use_lock_init(&new_port->use_lock);
+	port_subs_info_init(&new_port->c_src);
+	port_subs_info_init(&new_port->c_dest);
+	snd_use_lock_use(&new_port->use_lock);
+
+	num = max(port, 0);
+	mutex_lock(&client->ports_mutex);
+	write_lock_irq(&client->ports_lock);
+	list_for_each_entry(p, &client->ports_list_head, list) {
+		if (p->addr.port > num)
+			break;
+		if (port < 0) /* auto-probe mode */
+			num = p->addr.port + 1;
+	}
+	/* insert the new port */
+	list_add_tail(&new_port->list, &p->list);
+	client->num_ports++;
+	new_port->addr.port = num;	/* store the port number in the port */
+	sprintf(new_port->name, "port-%d", num);
+	write_unlock_irq(&client->ports_lock);
+	mutex_unlock(&client->ports_mutex);
+
+	return new_port;
+}
+
+/* */
+static int subscribe_port(struct snd_seq_client *client,
+			  struct snd_seq_client_port *port,
+			  struct snd_seq_port_subs_info *grp,
+			  struct snd_seq_port_subscribe *info, int send_ack);
+static int unsubscribe_port(struct snd_seq_client *client,
+			    struct snd_seq_client_port *port,
+			    struct snd_seq_port_subs_info *grp,
+			    struct snd_seq_port_subscribe *info, int send_ack);
+
+
+static struct snd_seq_client_port *get_client_port(struct snd_seq_addr *addr,
+						   struct snd_seq_client **cp)
+{
+	struct snd_seq_client_port *p;
+	*cp = snd_seq_client_use_ptr(addr->client);
+	if (*cp) {
+		p = snd_seq_port_use_ptr(*cp, addr->port);
+		if (! p) {
+			snd_seq_client_unlock(*cp);
+			*cp = NULL;
+		}
+		return p;
+	}
+	return NULL;
+}
+
+static void delete_and_unsubscribe_port(struct snd_seq_client *client,
+					struct snd_seq_client_port *port,
+					struct snd_seq_subscribers *subs,
+					bool is_src, bool ack);
+
+static inline struct snd_seq_subscribers *
+get_subscriber(struct list_head *p, bool is_src)
+{
+	if (is_src)
+		return list_entry(p, struct snd_seq_subscribers, src_list);
+	else
+		return list_entry(p, struct snd_seq_subscribers, dest_list);
+}
+
+/*
+ * remove all subscribers on the list
+ * this is called from port_delete, for each src and dest list.
+ */
+static void clear_subscriber_list(struct snd_seq_client *client,
+				  struct snd_seq_client_port *port,
+				  struct snd_seq_port_subs_info *grp,
+				  int is_src)
+{
+	struct list_head *p, *n;
+
+	list_for_each_safe(p, n, &grp->list_head) {
+		struct snd_seq_subscribers *subs;
+		struct snd_seq_client *c;
+		struct snd_seq_client_port *aport;
+
+		subs = get_subscriber(p, is_src);
+		if (is_src)
+			aport = get_client_port(&subs->info.dest, &c);
+		else
+			aport = get_client_port(&subs->info.sender, &c);
+		delete_and_unsubscribe_port(client, port, subs, is_src, false);
+
+		if (!aport) {
+			/* looks like the connected port is being deleted.
+			 * we decrease the counter, and when both ports are deleted
+			 * remove the subscriber info
+			 */
+			if (atomic_dec_and_test(&subs->ref_count))
+				kfree(subs);
+			continue;
+		}
+
+		/* ok we got the connected port */
+		delete_and_unsubscribe_port(c, aport, subs, !is_src, true);
+		kfree(subs);
+		snd_seq_port_unlock(aport);
+		snd_seq_client_unlock(c);
+	}
+}
+
+/* delete port data */
+static int port_delete(struct snd_seq_client *client,
+		       struct snd_seq_client_port *port)
+{
+	/* set closing flag and wait for all port access are gone */
+	port->closing = 1;
+	snd_use_lock_sync(&port->use_lock); 
+
+	/* clear subscribers info */
+	clear_subscriber_list(client, port, &port->c_src, true);
+	clear_subscriber_list(client, port, &port->c_dest, false);
+
+	if (port->private_free)
+		port->private_free(port->private_data);
+
+	snd_BUG_ON(port->c_src.count != 0);
+	snd_BUG_ON(port->c_dest.count != 0);
+
+	kfree(port);
+	return 0;
+}
+
+
+/* delete a port with the given port id */
+int snd_seq_delete_port(struct snd_seq_client *client, int port)
+{
+	struct snd_seq_client_port *found = NULL, *p;
+
+	mutex_lock(&client->ports_mutex);
+	write_lock_irq(&client->ports_lock);
+	list_for_each_entry(p, &client->ports_list_head, list) {
+		if (p->addr.port == port) {
+			/* ok found.  delete from the list at first */
+			list_del(&p->list);
+			client->num_ports--;
+			found = p;
+			break;
+		}
+	}
+	write_unlock_irq(&client->ports_lock);
+	mutex_unlock(&client->ports_mutex);
+	if (found)
+		return port_delete(client, found);
+	else
+		return -ENOENT;
+}
+
+/* delete the all ports belonging to the given client */
+int snd_seq_delete_all_ports(struct snd_seq_client *client)
+{
+	struct list_head deleted_list;
+	struct snd_seq_client_port *port, *tmp;
+	
+	/* move the port list to deleted_list, and
+	 * clear the port list in the client data.
+	 */
+	mutex_lock(&client->ports_mutex);
+	write_lock_irq(&client->ports_lock);
+	if (! list_empty(&client->ports_list_head)) {
+		list_add(&deleted_list, &client->ports_list_head);
+		list_del_init(&client->ports_list_head);
+	} else {
+		INIT_LIST_HEAD(&deleted_list);
+	}
+	client->num_ports = 0;
+	write_unlock_irq(&client->ports_lock);
+
+	/* remove each port in deleted_list */
+	list_for_each_entry_safe(port, tmp, &deleted_list, list) {
+		list_del(&port->list);
+		snd_seq_system_client_ev_port_exit(port->addr.client, port->addr.port);
+		port_delete(client, port);
+	}
+	mutex_unlock(&client->ports_mutex);
+	return 0;
+}
+
+/* set port info fields */
+int snd_seq_set_port_info(struct snd_seq_client_port * port,
+			  struct snd_seq_port_info * info)
+{
+	if (snd_BUG_ON(!port || !info))
+		return -EINVAL;
+
+	/* set port name */
+	if (info->name[0])
+		strscpy(port->name, info->name, sizeof(port->name));
+	
+	/* set capabilities */
+	port->capability = info->capability;
+	
+	/* get port type */
+	port->type = info->type;
+
+	/* information about supported channels/voices */
+	port->midi_channels = info->midi_channels;
+	port->midi_voices = info->midi_voices;
+	port->synth_voices = info->synth_voices;
+
+	/* timestamping */
+	port->timestamping = (info->flags & SNDRV_SEQ_PORT_FLG_TIMESTAMP) ? 1 : 0;
+	port->time_real = (info->flags & SNDRV_SEQ_PORT_FLG_TIME_REAL) ? 1 : 0;
+	port->time_queue = info->time_queue;
+
+	return 0;
+}
+
+/* get port info fields */
+int snd_seq_get_port_info(struct snd_seq_client_port * port,
+			  struct snd_seq_port_info * info)
+{
+	if (snd_BUG_ON(!port || !info))
+		return -EINVAL;
+
+	/* get port name */
+	strscpy(info->name, port->name, sizeof(info->name));
+	
+	/* get capabilities */
+	info->capability = port->capability;
+
+	/* get port type */
+	info->type = port->type;
+
+	/* information about supported channels/voices */
+	info->midi_channels = port->midi_channels;
+	info->midi_voices = port->midi_voices;
+	info->synth_voices = port->synth_voices;
+
+	/* get subscriber counts */
+	info->read_use = port->c_src.count;
+	info->write_use = port->c_dest.count;
+	
+	/* timestamping */
+	info->flags = 0;
+	if (port->timestamping) {
+		info->flags |= SNDRV_SEQ_PORT_FLG_TIMESTAMP;
+		if (port->time_real)
+			info->flags |= SNDRV_SEQ_PORT_FLG_TIME_REAL;
+		info->time_queue = port->time_queue;
+	}
+
+	return 0;
+}
+
+
+
+/*
+ * call callback functions (if any):
+ * the callbacks are invoked only when the first (for connection) or
+ * the last subscription (for disconnection) is done.  Second or later
+ * subscription results in increment of counter, but no callback is
+ * invoked.
+ * This feature is useful if these callbacks are associated with
+ * initialization or termination of devices (see seq_midi.c).
+ */
+
+static int subscribe_port(struct snd_seq_client *client,
+			  struct snd_seq_client_port *port,
+			  struct snd_seq_port_subs_info *grp,
+			  struct snd_seq_port_subscribe *info,
+			  int send_ack)
+{
+	int err = 0;
+
+	if (!try_module_get(port->owner))
+		return -EFAULT;
+	grp->count++;
+	if (grp->open && grp->count == 1) {
+		err = grp->open(port->private_data, info);
+		if (err < 0) {
+			module_put(port->owner);
+			grp->count--;
+		}
+	}
+	if (err >= 0 && send_ack && client->type == USER_CLIENT)
+		snd_seq_client_notify_subscription(port->addr.client, port->addr.port,
+						   info, SNDRV_SEQ_EVENT_PORT_SUBSCRIBED);
+
+	return err;
+}
+
+static int unsubscribe_port(struct snd_seq_client *client,
+			    struct snd_seq_client_port *port,
+			    struct snd_seq_port_subs_info *grp,
+			    struct snd_seq_port_subscribe *info,
+			    int send_ack)
+{
+	int err = 0;
+
+	if (! grp->count)
+		return -EINVAL;
+	grp->count--;
+	if (grp->close && grp->count == 0)
+		err = grp->close(port->private_data, info);
+	if (send_ack && client->type == USER_CLIENT)
+		snd_seq_client_notify_subscription(port->addr.client, port->addr.port,
+						   info, SNDRV_SEQ_EVENT_PORT_UNSUBSCRIBED);
+	module_put(port->owner);
+	return err;
+}
+
+
+
+/* check if both addresses are identical */
+static inline int addr_match(struct snd_seq_addr *r, struct snd_seq_addr *s)
+{
+	return (r->client == s->client) && (r->port == s->port);
+}
+
+/* check the two subscribe info match */
+/* if flags is zero, checks only sender and destination addresses */
+static int match_subs_info(struct snd_seq_port_subscribe *r,
+			   struct snd_seq_port_subscribe *s)
+{
+	if (addr_match(&r->sender, &s->sender) &&
+	    addr_match(&r->dest, &s->dest)) {
+		if (r->flags && r->flags == s->flags)
+			return r->queue == s->queue;
+		else if (! r->flags)
+			return 1;
+	}
+	return 0;
+}
+
+static int check_and_subscribe_port(struct snd_seq_client *client,
+				    struct snd_seq_client_port *port,
+				    struct snd_seq_subscribers *subs,
+				    bool is_src, bool exclusive, bool ack)
+{
+	struct snd_seq_port_subs_info *grp;
+	struct list_head *p;
+	struct snd_seq_subscribers *s;
+	int err;
+
+	grp = is_src ? &port->c_src : &port->c_dest;
+	err = -EBUSY;
+	down_write(&grp->list_mutex);
+	if (exclusive) {
+		if (!list_empty(&grp->list_head))
+			goto __error;
+	} else {
+		if (grp->exclusive)
+			goto __error;
+		/* check whether already exists */
+		list_for_each(p, &grp->list_head) {
+			s = get_subscriber(p, is_src);
+			if (match_subs_info(&subs->info, &s->info))
+				goto __error;
+		}
+	}
+
+	err = subscribe_port(client, port, grp, &subs->info, ack);
+	if (err < 0) {
+		grp->exclusive = 0;
+		goto __error;
+	}
+
+	/* add to list */
+	write_lock_irq(&grp->list_lock);
+	if (is_src)
+		list_add_tail(&subs->src_list, &grp->list_head);
+	else
+		list_add_tail(&subs->dest_list, &grp->list_head);
+	grp->exclusive = exclusive;
+	atomic_inc(&subs->ref_count);
+	write_unlock_irq(&grp->list_lock);
+	err = 0;
+
+ __error:
+	up_write(&grp->list_mutex);
+	return err;
+}
+
+/* called with grp->list_mutex held */
+static void __delete_and_unsubscribe_port(struct snd_seq_client *client,
+					  struct snd_seq_client_port *port,
+					  struct snd_seq_subscribers *subs,
+					  bool is_src, bool ack)
+{
+	struct snd_seq_port_subs_info *grp;
+	struct list_head *list;
+	bool empty;
+
+	grp = is_src ? &port->c_src : &port->c_dest;
+	list = is_src ? &subs->src_list : &subs->dest_list;
+	write_lock_irq(&grp->list_lock);
+	empty = list_empty(list);
+	if (!empty)
+		list_del_init(list);
+	grp->exclusive = 0;
+	write_unlock_irq(&grp->list_lock);
+
+	if (!empty)
+		unsubscribe_port(client, port, grp, &subs->info, ack);
+}
+
+static void delete_and_unsubscribe_port(struct snd_seq_client *client,
+					struct snd_seq_client_port *port,
+					struct snd_seq_subscribers *subs,
+					bool is_src, bool ack)
+{
+	struct snd_seq_port_subs_info *grp;
+
+	grp = is_src ? &port->c_src : &port->c_dest;
+	down_write(&grp->list_mutex);
+	__delete_and_unsubscribe_port(client, port, subs, is_src, ack);
+	up_write(&grp->list_mutex);
+}
+
+/* connect two ports */
+int snd_seq_port_connect(struct snd_seq_client *connector,
+			 struct snd_seq_client *src_client,
+			 struct snd_seq_client_port *src_port,
+			 struct snd_seq_client *dest_client,
+			 struct snd_seq_client_port *dest_port,
+			 struct snd_seq_port_subscribe *info)
+{
+	struct snd_seq_subscribers *subs;
+	bool exclusive;
+	int err;
+
+	subs = kzalloc(sizeof(*subs), GFP_KERNEL);
+	if (!subs)
+		return -ENOMEM;
+
+	subs->info = *info;
+	atomic_set(&subs->ref_count, 0);
+	INIT_LIST_HEAD(&subs->src_list);
+	INIT_LIST_HEAD(&subs->dest_list);
+
+	exclusive = !!(info->flags & SNDRV_SEQ_PORT_SUBS_EXCLUSIVE);
+
+	err = check_and_subscribe_port(src_client, src_port, subs, true,
+				       exclusive,
+				       connector->number != src_client->number);
+	if (err < 0)
+		goto error;
+	err = check_and_subscribe_port(dest_client, dest_port, subs, false,
+				       exclusive,
+				       connector->number != dest_client->number);
+	if (err < 0)
+		goto error_dest;
+
+	return 0;
+
+ error_dest:
+	delete_and_unsubscribe_port(src_client, src_port, subs, true,
+				    connector->number != src_client->number);
+ error:
+	kfree(subs);
+	return err;
+}
+
+/* remove the connection */
+int snd_seq_port_disconnect(struct snd_seq_client *connector,
+			    struct snd_seq_client *src_client,
+			    struct snd_seq_client_port *src_port,
+			    struct snd_seq_client *dest_client,
+			    struct snd_seq_client_port *dest_port,
+			    struct snd_seq_port_subscribe *info)
+{
+	struct snd_seq_port_subs_info *dest = &dest_port->c_dest;
+	struct snd_seq_subscribers *subs;
+	int err = -ENOENT;
+
+	/* always start from deleting the dest port for avoiding concurrent
+	 * deletions
+	 */
+	down_write(&dest->list_mutex);
+	/* look for the connection */
+	list_for_each_entry(subs, &dest->list_head, dest_list) {
+		if (match_subs_info(info, &subs->info)) {
+			__delete_and_unsubscribe_port(dest_client, dest_port,
+						      subs, false,
+						      connector->number != dest_client->number);
+			err = 0;
+			break;
+		}
+	}
+	up_write(&dest->list_mutex);
+	if (err < 0)
+		return err;
+
+	delete_and_unsubscribe_port(src_client, src_port, subs, true,
+				    connector->number != src_client->number);
+	kfree(subs);
+	return 0;
+}
+
+
+/* get matched subscriber */
+int snd_seq_port_get_subscription(struct snd_seq_port_subs_info *src_grp,
+				  struct snd_seq_addr *dest_addr,
+				  struct snd_seq_port_subscribe *subs)
+{
+	struct snd_seq_subscribers *s;
+	int err = -ENOENT;
+
+	down_read(&src_grp->list_mutex);
+	list_for_each_entry(s, &src_grp->list_head, src_list) {
+		if (addr_match(dest_addr, &s->info.dest)) {
+			*subs = s->info;
+			err = 0;
+			break;
+		}
+	}
+	up_read(&src_grp->list_mutex);
+	return err;
+}
+
+/*
+ * Attach a device driver that wants to receive events from the
+ * sequencer.  Returns the new port number on success.
+ * A driver that wants to receive the events converted to midi, will
+ * use snd_seq_midisynth_register_port().
+ */
+/* exported */
+int snd_seq_event_port_attach(int client,
+			      struct snd_seq_port_callback *pcbp,
+			      int cap, int type, int midi_channels,
+			      int midi_voices, char *portname)
+{
+	struct snd_seq_port_info portinfo;
+	int  ret;
+
+	/* Set up the port */
+	memset(&portinfo, 0, sizeof(portinfo));
+	portinfo.addr.client = client;
+	strscpy(portinfo.name, portname ? portname : "Unnamed port",
+		sizeof(portinfo.name));
+
+	portinfo.capability = cap;
+	portinfo.type = type;
+	portinfo.kernel = pcbp;
+	portinfo.midi_channels = midi_channels;
+	portinfo.midi_voices = midi_voices;
+
+	/* Create it */
+	ret = snd_seq_kernel_client_ctl(client,
+					SNDRV_SEQ_IOCTL_CREATE_PORT,
+					&portinfo);
+
+	if (ret >= 0)
+		ret = portinfo.addr.port;
+
+	return ret;
+}
+EXPORT_SYMBOL(snd_seq_event_port_attach);
+
+/*
+ * Detach the driver from a port.
+ */
+/* exported */
+int snd_seq_event_port_detach(int client, int port)
+{
+	struct snd_seq_port_info portinfo;
+	int  err;
+
+	memset(&portinfo, 0, sizeof(portinfo));
+	portinfo.addr.client = client;
+	portinfo.addr.port   = port;
+	err = snd_seq_kernel_client_ctl(client,
+					SNDRV_SEQ_IOCTL_DELETE_PORT,
+					&portinfo);
+
+	return err;
+}
+EXPORT_SYMBOL(snd_seq_event_port_detach);