sound/core/seq/seq_ports.c

   1 /*
   2  *   ALSA sequencer Ports
   3  *   Copyright (c) 1998 by Frank van de Pol <fvdpol@coil.demon.nl>
   4  *                         Jaroslav Kysela <perex@perex.cz>
   5  *
   6  *
   7  *   This program is free software; you can redistribute it and/or modify
   8  *   it under the terms of the GNU General Public License as published by
   9  *   the Free Software Foundation; either version 2 of the License, or
  10  *   (at your option) any later version.
  11  *
  12  *   This program is distributed in the hope that it will be useful,
  13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *   GNU General Public License for more details.
  16  *
  17  *   You should have received a copy of the GNU General Public License
  18  *   along with this program; if not, write to the Free Software
  19  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  20  *
  21  */
  22
  23 #include <sound/core.h>
  24 #include <linux/slab.h>
  25 #include <linux/module.h>
  26 #include "seq_system.h"
  27 #include "seq_ports.h"
  28 #include "seq_clientmgr.h"
  29
  30 /*
  31
  32    registration of client ports
  33
  34  */
  35
  36
  37 /*
  38
  39 NOTE: the current implementation of the port structure as a linked list is
  40 not optimal for clients that have many ports. For sending messages to all
  41 subscribers of a port we first need to find the address of the port
  42 structure, which means we have to traverse the list. A direct access table
  43 (array) would be better, but big preallocated arrays waste memory.
  44
  45 Possible actions:
  46
  47 1) leave it this way, a client does normaly does not have more than a few
  48 ports
  49
  50 2) replace the linked list of ports by a array of pointers which is
  51 dynamicly kmalloced. When a port is added or deleted we can simply allocate
  52 a new array, copy the corresponding pointers, and delete the old one. We
  53 then only need a pointer to this array, and an integer that tells us how
  54 much elements are in array.
  55
  56 */
  57
  58 /* return pointer to port structure - port is locked if found */
  59 struct snd_seq_client_port *snd_seq_port_use_ptr(struct snd_seq_client *client,
  60                                                  int num)
  61 {
  62         struct snd_seq_client_port *port;
  63
  64         if (client == NULL)
  65                 return NULL;
  66         read_lock(&client->ports_lock);
  67         list_for_each_entry(port, &client->ports_list_head, list) {
  68                 if (port->addr.port == num) {
  69                         if (port->closing)
  70                                 break; /* deleting now */
  71                         snd_use_lock_use(&port->use_lock);
  72                         read_unlock(&client->ports_lock);
  73                         return port;
  74                 }
  75         }
  76         read_unlock(&client->ports_lock);
  77         return NULL;            /* not found */
  78 }
  79
  80
  81 /* search for the next port - port is locked if found */
  82 struct snd_seq_client_port *snd_seq_port_query_nearest(struct snd_seq_client *client,
  83                                                        struct snd_seq_port_info *pinfo)
  84 {
  85         int num;
  86         struct snd_seq_client_port *port, *found;
  87
  88         num = pinfo->addr.port;
  89         found = NULL;
  90         read_lock(&client->ports_lock);
  91         list_for_each_entry(port, &client->ports_list_head, list) {
  92                 if (port->addr.port < num)
  93                         continue;
  94                 if (port->addr.port == num) {
  95                         found = port;
  96                         break;
  97                 }
  98                 if (found == NULL || port->addr.port < found->addr.port)
  99                         found = port;
 100         }
 101         if (found) {
 102                 if (found->closing)
 103                         found = NULL;
 104                 else
 105                         snd_use_lock_use(&found->use_lock);
 106         }
 107         read_unlock(&client->ports_lock);
 108         return found;
 109 }
 110
 111
 112 /* initialize snd_seq_port_subs_info */
 113 static void port_subs_info_init(struct snd_seq_port_subs_info *grp)
 114 {
 115         INIT_LIST_HEAD(&grp->list_head);
 116         grp->count = 0;
 117         grp->exclusive = 0;
 118         rwlock_init(&grp->list_lock);
 119         init_rwsem(&grp->list_mutex);
 120         grp->open = NULL;
 121         grp->close = NULL;
 122 }
 123
 124
 125 /* create a port, port number is returned (-1 on failure) */
 126 struct snd_seq_client_port *snd_seq_create_port(struct snd_seq_client *client,
 127                                                 int port)
 128 {
 129         unsigned long flags;
 130         struct snd_seq_client_port *new_port, *p;
 131         int num = -1;
 132
 133         /* sanity check */
 134         if (snd_BUG_ON(!client))
 135                 return NULL;
 136
 137         if (client->num_ports >= SNDRV_SEQ_MAX_PORTS) {
 138                 pr_warn("ALSA: seq: too many ports for client %d\n", client->number);
 139                 return NULL;
 140         }
 141
 142         /* create a new port */
 143         new_port = kzalloc(sizeof(*new_port), GFP_KERNEL);
 144         if (! new_port) {
 145                 pr_debug("ALSA: seq: malloc failed for registering client port\n");
 146                 return NULL;    /* failure, out of memory */
 147         }
 148         /* init port data */
 149         new_port->addr.client = client->number;
 150         new_port->addr.port = -1;
 151         new_port->owner = THIS_MODULE;
 152         sprintf(new_port->name, "port-%d", num);
 153         snd_use_lock_init(&new_port->use_lock);
 154         port_subs_info_init(&new_port->c_src);
 155         port_subs_info_init(&new_port->c_dest);
 156
 157         num = port >= 0 ? port : 0;
 158         mutex_lock(&client->ports_mutex);
 159         write_lock_irqsave(&client->ports_lock, flags);
 160         list_for_each_entry(p, &client->ports_list_head, list) {
 161                 if (p->addr.port > num)
 162                         break;
 163                 if (port < 0) /* auto-probe mode */
 164                         num = p->addr.port + 1;
 165         }
 166         /* insert the new port */
 167         list_add_tail(&new_port->list, &p->list);
 168         client->num_ports++;
 169         new_port->addr.port = num;      /* store the port number in the port */
 170         write_unlock_irqrestore(&client->ports_lock, flags);
 171         mutex_unlock(&client->ports_mutex);
 172         sprintf(new_port->name, "port-%d", num);
 173
 174         return new_port;
 175 }
 176
 177 /* */
 178 enum group_type {
 179         SRC_LIST, DEST_LIST
 180 };
 181
 182 static int subscribe_port(struct snd_seq_client *client,
 183                           struct snd_seq_client_port *port,
 184                           struct snd_seq_port_subs_info *grp,
 185                           struct snd_seq_port_subscribe *info, int send_ack);
 186 static int unsubscribe_port(struct snd_seq_client *client,
 187                             struct snd_seq_client_port *port,
 188                             struct snd_seq_port_subs_info *grp,
 189                             struct snd_seq_port_subscribe *info, int send_ack);
 190
 191
 192 static struct snd_seq_client_port *get_client_port(struct snd_seq_addr *addr,
 193                                                    struct snd_seq_client **cp)
 194 {
 195         struct snd_seq_client_port *p;
 196         *cp = snd_seq_client_use_ptr(addr->client);
 197         if (*cp) {
 198                 p = snd_seq_port_use_ptr(*cp, addr->port);
 199                 if (! p) {
 200                         snd_seq_client_unlock(*cp);
 201                         *cp = NULL;
 202                 }
 203                 return p;
 204         }
 205         return NULL;
 206 }
 207
 208 /*
 209  * remove all subscribers on the list
 210  * this is called from port_delete, for each src and dest list.
 211  */
 212 static void clear_subscriber_list(struct snd_seq_client *client,
 213                                   struct snd_seq_client_port *port,
 214                                   struct snd_seq_port_subs_info *grp,
 215                                   int grptype)
 216 {
 217         struct list_head *p, *n;
 218
 219         list_for_each_safe(p, n, &grp->list_head) {
 220                 struct snd_seq_subscribers *subs;
 221                 struct snd_seq_client *c;
 222                 struct snd_seq_client_port *aport;
 223
 224                 if (grptype == SRC_LIST) {
 225                         subs = list_entry(p, struct snd_seq_subscribers, src_list);
 226                         aport = get_client_port(&subs->info.dest, &c);
 227                 } else {
 228                         subs = list_entry(p, struct snd_seq_subscribers, dest_list);
 229                         aport = get_client_port(&subs->info.sender, &c);
 230                 }
 231                 list_del(p);
 232                 unsubscribe_port(client, port, grp, &subs->info, 0);
 233                 if (!aport) {
 234                         /* looks like the connected port is being deleted.
 235                          * we decrease the counter, and when both ports are deleted
 236                          * remove the subscriber info
 237                          */
 238                         if (atomic_dec_and_test(&subs->ref_count))
 239                                 kfree(subs);
 240                 } else {
 241                         /* ok we got the connected port */
 242                         struct snd_seq_port_subs_info *agrp;
 243                         agrp = (grptype == SRC_LIST) ? &aport->c_dest : &aport->c_src;
 244                         down_write(&agrp->list_mutex);
 245                         if (grptype == SRC_LIST)
 246                                 list_del(&subs->dest_list);
 247                         else
 248                                 list_del(&subs->src_list);
 249                         up_write(&agrp->list_mutex);
 250                         unsubscribe_port(c, aport, agrp, &subs->info, 1);
 251                         kfree(subs);
 252                         snd_seq_port_unlock(aport);
 253                         snd_seq_client_unlock(c);
 254                 }
 255         }
 256 }
 257
 258 /* delete port data */
 259 static int port_delete(struct snd_seq_client *client,
 260                        struct snd_seq_client_port *port)
 261 {
 262         /* set closing flag and wait for all port access are gone */
 263         port->closing = 1;
 264         snd_use_lock_sync(&port->use_lock);
 265
 266         /* clear subscribers info */
 267         clear_subscriber_list(client, port, &port->c_src, SRC_LIST);
 268         clear_subscriber_list(client, port, &port->c_dest, DEST_LIST);
 269
 270         if (port->private_free)
 271                 port->private_free(port->private_data);
 272
 273         snd_BUG_ON(port->c_src.count != 0);
 274         snd_BUG_ON(port->c_dest.count != 0);
 275
 276         kfree(port);
 277         return 0;
 278 }
 279
 280
 281 /* delete a port with the given port id */
 282 int snd_seq_delete_port(struct snd_seq_client *client, int port)
 283 {
 284         unsigned long flags;
 285         struct snd_seq_client_port *found = NULL, *p;
 286
 287         mutex_lock(&client->ports_mutex);
 288         write_lock_irqsave(&client->ports_lock, flags);
 289         list_for_each_entry(p, &client->ports_list_head, list) {
 290                 if (p->addr.port == port) {
 291                         /* ok found.  delete from the list at first */
 292                         list_del(&p->list);
 293                         client->num_ports--;
 294                         found = p;
 295                         break;
 296                 }
 297         }
 298         write_unlock_irqrestore(&client->ports_lock, flags);
 299         mutex_unlock(&client->ports_mutex);
 300         if (found)
 301                 return port_delete(client, found);
 302         else
 303                 return -ENOENT;
 304 }
 305
 306 /* delete the all ports belonging to the given client */
 307 int snd_seq_delete_all_ports(struct snd_seq_client *client)
 308 {
 309         unsigned long flags;
 310         struct list_head deleted_list;
 311         struct snd_seq_client_port *port, *tmp;
 312
 313         /* move the port list to deleted_list, and
 314          * clear the port list in the client data.
 315          */
 316         mutex_lock(&client->ports_mutex);
 317         write_lock_irqsave(&client->ports_lock, flags);
 318         if (! list_empty(&client->ports_list_head)) {
 319                 list_add(&deleted_list, &client->ports_list_head);
 320                 list_del_init(&client->ports_list_head);
 321         } else {
 322                 INIT_LIST_HEAD(&deleted_list);
 323         }
 324         client->num_ports = 0;
 325         write_unlock_irqrestore(&client->ports_lock, flags);
 326
 327         /* remove each port in deleted_list */
 328         list_for_each_entry_safe(port, tmp, &deleted_list, list) {
 329                 list_del(&port->list);
 330                 snd_seq_system_client_ev_port_exit(port->addr.client, port->addr.port);
 331                 port_delete(client, port);
 332         }
 333         mutex_unlock(&client->ports_mutex);
 334         return 0;
 335 }
 336
 337 /* set port info fields */
 338 int snd_seq_set_port_info(struct snd_seq_client_port * port,
 339                           struct snd_seq_port_info * info)
 340 {
 341         if (snd_BUG_ON(!port || !info))
 342                 return -EINVAL;
 343
 344         /* set port name */
 345         if (info->name[0])
 346                 strlcpy(port->name, info->name, sizeof(port->name));
 347
 348         /* set capabilities */
 349         port->capability = info->capability;
 350
 351         /* get port type */
 352         port->type = info->type;
 353
 354         /* information about supported channels/voices */
 355         port->midi_channels = info->midi_channels;
 356         port->midi_voices = info->midi_voices;
 357         port->synth_voices = info->synth_voices;
 358
 359         /* timestamping */
 360         port->timestamping = (info->flags & SNDRV_SEQ_PORT_FLG_TIMESTAMP) ? 1 : 0;
 361         port->time_real = (info->flags & SNDRV_SEQ_PORT_FLG_TIME_REAL) ? 1 : 0;
 362         port->time_queue = info->time_queue;
 363
 364         return 0;
 365 }
 366
 367 /* get port info fields */
 368 int snd_seq_get_port_info(struct snd_seq_client_port * port,
 369                           struct snd_seq_port_info * info)
 370 {
 371         if (snd_BUG_ON(!port || !info))
 372                 return -EINVAL;
 373
 374         /* get port name */
 375         strlcpy(info->name, port->name, sizeof(info->name));
 376
 377         /* get capabilities */
 378         info->capability = port->capability;
 379
 380         /* get port type */
 381         info->type = port->type;
 382
 383         /* information about supported channels/voices */
 384         info->midi_channels = port->midi_channels;
 385         info->midi_voices = port->midi_voices;
 386         info->synth_voices = port->synth_voices;
 387
 388         /* get subscriber counts */
 389         info->read_use = port->c_src.count;
 390         info->write_use = port->c_dest.count;
 391
 392         /* timestamping */
 393         info->flags = 0;
 394         if (port->timestamping) {
 395                 info->flags |= SNDRV_SEQ_PORT_FLG_TIMESTAMP;
 396                 if (port->time_real)
 397                         info->flags |= SNDRV_SEQ_PORT_FLG_TIME_REAL;
 398                 info->time_queue = port->time_queue;
 399         }
 400
 401         return 0;
 402 }
 403
 404
 405
 406 /*
 407  * call callback functions (if any):
 408  * the callbacks are invoked only when the first (for connection) or
 409  * the last subscription (for disconnection) is done.  Second or later
 410  * subscription results in increment of counter, but no callback is
 411  * invoked.
 412  * This feature is useful if these callbacks are associated with
 413  * initialization or termination of devices (see seq_midi.c).
 414  */
 415
 416 static int subscribe_port(struct snd_seq_client *client,
 417                           struct snd_seq_client_port *port,
 418                           struct snd_seq_port_subs_info *grp,
 419                           struct snd_seq_port_subscribe *info,
 420                           int send_ack)
 421 {
 422         int err = 0;
 423
 424         if (!try_module_get(port->owner))
 425                 return -EFAULT;
 426         grp->count++;
 427         if (grp->open && grp->count == 1) {
 428                 err = grp->open(port->private_data, info);
 429                 if (err < 0) {
 430                         module_put(port->owner);
 431                         grp->count--;
 432                 }
 433         }
 434         if (err >= 0 && send_ack && client->type == USER_CLIENT)
 435                 snd_seq_client_notify_subscription(port->addr.client, port->addr.port,
 436                                                    info, SNDRV_SEQ_EVENT_PORT_SUBSCRIBED);
 437
 438         return err;
 439 }
 440
 441 static int unsubscribe_port(struct snd_seq_client *client,
 442                             struct snd_seq_client_port *port,
 443                             struct snd_seq_port_subs_info *grp,
 444                             struct snd_seq_port_subscribe *info,
 445                             int send_ack)
 446 {
 447         int err = 0;
 448
 449         if (! grp->count)
 450                 return -EINVAL;
 451         grp->count--;
 452         if (grp->close && grp->count == 0)
 453                 err = grp->close(port->private_data, info);
 454         if (send_ack && client->type == USER_CLIENT)
 455                 snd_seq_client_notify_subscription(port->addr.client, port->addr.port,
 456                                                    info, SNDRV_SEQ_EVENT_PORT_UNSUBSCRIBED);
 457         module_put(port->owner);
 458         return err;
 459 }
 460
 461
 462
 463 /* check if both addresses are identical */
 464 static inline int addr_match(struct snd_seq_addr *r, struct snd_seq_addr *s)
 465 {
 466         return (r->client == s->client) && (r->port == s->port);
 467 }
 468
 469 /* check the two subscribe info match */
 470 /* if flags is zero, checks only sender and destination addresses */
 471 static int match_subs_info(struct snd_seq_port_subscribe *r,
 472                            struct snd_seq_port_subscribe *s)
 473 {
 474         if (addr_match(&r->sender, &s->sender) &&
 475             addr_match(&r->dest, &s->dest)) {
 476                 if (r->flags && r->flags == s->flags)
 477                         return r->queue == s->queue;
 478                 else if (! r->flags)
 479                         return 1;
 480         }
 481         return 0;
 482 }
 483
 484
 485 /* connect two ports */
 486 int snd_seq_port_connect(struct snd_seq_client *connector,
 487                          struct snd_seq_client *src_client,
 488                          struct snd_seq_client_port *src_port,
 489                          struct snd_seq_client *dest_client,
 490                          struct snd_seq_client_port *dest_port,
 491                          struct snd_seq_port_subscribe *info)
 492 {
 493         struct snd_seq_port_subs_info *src = &src_port->c_src;
 494         struct snd_seq_port_subs_info *dest = &dest_port->c_dest;
 495         struct snd_seq_subscribers *subs, *s;
 496         int err, src_called = 0;
 497         unsigned long flags;
 498         int exclusive;
 499
 500         subs = kzalloc(sizeof(*subs), GFP_KERNEL);
 501         if (! subs)
 502                 return -ENOMEM;
 503
 504         subs->info = *info;
 505         atomic_set(&subs->ref_count, 2);
 506
 507         down_write(&src->list_mutex);
 508         down_write_nested(&dest->list_mutex, SINGLE_DEPTH_NESTING);
 509
 510         exclusive = info->flags & SNDRV_SEQ_PORT_SUBS_EXCLUSIVE ? 1 : 0;
 511         err = -EBUSY;
 512         if (exclusive) {
 513                 if (! list_empty(&src->list_head) || ! list_empty(&dest->list_head))
 514                         goto __error;
 515         } else {
 516                 if (src->exclusive || dest->exclusive)
 517                         goto __error;
 518                 /* check whether already exists */
 519                 list_for_each_entry(s, &src->list_head, src_list) {
 520                         if (match_subs_info(info, &s->info))
 521                                 goto __error;
 522                 }
 523                 list_for_each_entry(s, &dest->list_head, dest_list) {
 524                         if (match_subs_info(info, &s->info))
 525                                 goto __error;
 526                 }
 527         }
 528
 529         if ((err = subscribe_port(src_client, src_port, src, info,
 530                                   connector->number != src_client->number)) < 0)
 531                 goto __error;
 532         src_called = 1;
 533
 534         if ((err = subscribe_port(dest_client, dest_port, dest, info,
 535                                   connector->number != dest_client->number)) < 0)
 536                 goto __error;
 537
 538         /* add to list */
 539         write_lock_irqsave(&src->list_lock, flags);
 540         // write_lock(&dest->list_lock); // no other lock yet
 541         list_add_tail(&subs->src_list, &src->list_head);
 542         list_add_tail(&subs->dest_list, &dest->list_head);
 543         // write_unlock(&dest->list_lock); // no other lock yet
 544         write_unlock_irqrestore(&src->list_lock, flags);
 545
 546         src->exclusive = dest->exclusive = exclusive;
 547
 548         up_write(&dest->list_mutex);
 549         up_write(&src->list_mutex);
 550         return 0;
 551
 552  __error:
 553         if (src_called)
 554                 unsubscribe_port(src_client, src_port, src, info,
 555                                  connector->number != src_client->number);
 556         kfree(subs);
 557         up_write(&dest->list_mutex);
 558         up_write(&src->list_mutex);
 559         return err;
 560 }
 561
 562
 563 /* remove the connection */
 564 int snd_seq_port_disconnect(struct snd_seq_client *connector,
 565                             struct snd_seq_client *src_client,
 566                             struct snd_seq_client_port *src_port,
 567                             struct snd_seq_client *dest_client,
 568                             struct snd_seq_client_port *dest_port,
 569                             struct snd_seq_port_subscribe *info)
 570 {
 571         struct snd_seq_port_subs_info *src = &src_port->c_src;
 572         struct snd_seq_port_subs_info *dest = &dest_port->c_dest;
 573         struct snd_seq_subscribers *subs;
 574         int err = -ENOENT;
 575         unsigned long flags;
 576
 577         down_write(&src->list_mutex);
 578         down_write_nested(&dest->list_mutex, SINGLE_DEPTH_NESTING);
 579
 580         /* look for the connection */
 581         list_for_each_entry(subs, &src->list_head, src_list) {
 582                 if (match_subs_info(info, &subs->info)) {
 583                         write_lock_irqsave(&src->list_lock, flags);
 584                         // write_lock(&dest->list_lock);  // no lock yet
 585                         list_del(&subs->src_list);
 586                         list_del(&subs->dest_list);
 587                         // write_unlock(&dest->list_lock);
 588                         write_unlock_irqrestore(&src->list_lock, flags);
 589                         src->exclusive = dest->exclusive = 0;
 590                         unsubscribe_port(src_client, src_port, src, info,
 591                                          connector->number != src_client->number);
 592                         unsubscribe_port(dest_client, dest_port, dest, info,
 593                                          connector->number != dest_client->number);
 594                         kfree(subs);
 595                         err = 0;
 596                         break;
 597                 }
 598         }
 599
 600         up_write(&dest->list_mutex);
 601         up_write(&src->list_mutex);
 602         return err;
 603 }
 604
 605
 606 /* get matched subscriber */
 607 struct snd_seq_subscribers *snd_seq_port_get_subscription(struct snd_seq_port_subs_info *src_grp,
 608                                                           struct snd_seq_addr *dest_addr)
 609 {
 610         struct snd_seq_subscribers *s, *found = NULL;
 611
 612         down_read(&src_grp->list_mutex);
 613         list_for_each_entry(s, &src_grp->list_head, src_list) {
 614                 if (addr_match(dest_addr, &s->info.dest)) {
 615                         found = s;
 616                         break;
 617                 }
 618         }
 619         up_read(&src_grp->list_mutex);
 620         return found;
 621 }
 622
 623 /*
 624  * Attach a device driver that wants to receive events from the
 625  * sequencer.  Returns the new port number on success.
 626  * A driver that wants to receive the events converted to midi, will
 627  * use snd_seq_midisynth_register_port().
 628  */
 629 /* exported */
 630 int snd_seq_event_port_attach(int client,
 631                               struct snd_seq_port_callback *pcbp,
 632                               int cap, int type, int midi_channels,
 633                               int midi_voices, char *portname)
 634 {
 635         struct snd_seq_port_info portinfo;
 636         int  ret;
 637
 638         /* Set up the port */
 639         memset(&portinfo, 0, sizeof(portinfo));
 640         portinfo.addr.client = client;
 641         strlcpy(portinfo.name, portname ? portname : "Unamed port",
 642                 sizeof(portinfo.name));
 643
 644         portinfo.capability = cap;
 645         portinfo.type = type;
 646         portinfo.kernel = pcbp;
 647         portinfo.midi_channels = midi_channels;
 648         portinfo.midi_voices = midi_voices;
 649
 650         /* Create it */
 651         ret = snd_seq_kernel_client_ctl(client,
 652                                         SNDRV_SEQ_IOCTL_CREATE_PORT,
 653                                         &portinfo);
 654
 655         if (ret >= 0)
 656                 ret = portinfo.addr.port;
 657
 658         return ret;
 659 }
 660
 661 EXPORT_SYMBOL(snd_seq_event_port_attach);
 662
 663 /*
 664  * Detach the driver from a port.
 665  */
 666 /* exported */
 667 int snd_seq_event_port_detach(int client, int port)
 668 {
 669         struct snd_seq_port_info portinfo;
 670         int  err;
 671
 672         memset(&portinfo, 0, sizeof(portinfo));
 673         portinfo.addr.client = client;
 674         portinfo.addr.port   = port;
 675         err = snd_seq_kernel_client_ctl(client,
 676                                         SNDRV_SEQ_IOCTL_DELETE_PORT,
 677                                         &portinfo);
 678
 679         return err;
 680 }
 681
 682 EXPORT_SYMBOL(snd_seq_event_port_detach);