seq_ports.c

linux-2.6.15.6

/*
 *   ALSA sequencer Ports
 *   Copyright (c) 1998 by Frank van de Pol <[e-mail]>
 *                         Jaroslav Kysela <[e-mail]>
 *
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */

#include <sound/driver.h>
#include <sound/core.h>
#include <linux/slab.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 */
client_port_t *snd_seq_port_use_ptr(client_t *client, int num)
{
	struct list_head *p;
	client_port_t *port;

	if (client == NULL)
		return NULL;
	read_lock(&client->ports_lock);
	list_for_each(p, &client->ports_list_head) {
		port = list_entry(p, client_port_t, 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 */
client_port_t *snd_seq_port_query_nearest(client_t *client, snd_seq_port_info_t *pinfo)
{
	int num;
	struct list_head *p;
	client_port_t *port, *found;

	num = pinfo->addr.port;
	found = NULL;
	read_lock(&client->ports_lock);
	list_for_each(p, &client->ports_list_head) {
		port = list_entry(p, client_port_t, 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 port_subs_info_t */
static void port_subs_info_init(port_subs_info_t *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) */
client_port_t *snd_seq_create_port(client_t *client, int port)
{
	unsigned long flags;
	client_port_t *new_port;
	struct list_head *l;
	int num = -1;
	
	/* sanity check */
	snd_assert(client, return NULL);

	if (client->num_ports >= SNDRV_SEQ_MAX_PORTS - 1) {
		snd_printk(KERN_WARNING "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) {
		snd_printd("malloc failed for registering client port\n");
		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);

	num = port >= 0 ? port : 0;
	down(&client->ports_mutex);
	write_lock_irqsave(&client->ports_lock, flags);
	list_for_each(l, &client->ports_list_head) {
		client_port_t *p = list_entry(l, client_port_t, 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, l);
	client->num_ports++;
	new_port->addr.port = num;	/* store the port number in the port */
	write_unlock_irqrestore(&client->ports_lock, flags);
	up(&client->ports_mutex);
	sprintf(new_port->name, "port-%d", num);

	return new_port;
}

/* */
enum group_type_t {
	SRC_LIST, DEST_LIST
};

static int subscribe_port(client_t *client, client_port_t *port, port_subs_info_t *grp, snd_seq_port_subscribe_t *info, int send_ack);
static int unsubscribe_port(client_t *client, client_port_t *port, port_subs_info_t *grp, snd_seq_port_subscribe_t *info, int send_ack);


static client_port_t *get_client_port(snd_seq_addr_t *addr, client_t **cp)
{
	client_port_t *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;
}

/*
 * remove all subscribers on the list
 * this is called from port_delete, for each src and dest list.
 */
static void clear_subscriber_list(client_t *client, client_port_t *port,
				  port_subs_info_t *grp, int grptype)
{
	struct list_head *p, *n;

	down_write(&grp->list_mutex);
	list_for_each_safe(p, n, &grp->list_head) {
		subscribers_t *subs;
		client_t *c;
		client_port_t *aport;

		if (grptype == SRC_LIST) {
			subs = list_entry(p, subscribers_t, src_list);
			aport = get_client_port(&subs->info.dest, &c);
		} else {
			subs = list_entry(p, subscribers_t, dest_list);
			aport = get_client_port(&subs->info.sender, &c);
		}
		list_del(p);
		unsubscribe_port(client, port, grp, &subs->info, 0);
		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);
		} else {
			/* ok we got the connected port */
			port_subs_info_t *agrp;
			agrp = (grptype == SRC_LIST) ? &aport->c_dest : &aport->c_src;
			down_write(&agrp->list_mutex);
			if (grptype == SRC_LIST)
				list_del(&subs->dest_list);
			else
				list_del(&subs->src_list);
			unsubscribe_port(c, aport, agrp, &subs->info, 1);
			kfree(subs);
			up_write(&agrp->list_mutex);
			snd_seq_port_unlock(aport);
			snd_seq_client_unlock(c);
		}
	}
	up_write(&grp->list_mutex);
}

/* delete port data */
static int port_delete(client_t *client, client_port_t *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, SRC_LIST);
	clear_subscriber_list(client, port, &port->c_dest, DEST_LIST);

	if (port->private_free)
		port->private_free(port->private_data);

	snd_assert(port->c_src.count == 0,);
	snd_assert(port->c_dest.count == 0,);

	kfree(port);
	return 0;
}


/* delete a port with the given port id */
int snd_seq_delete_port(client_t *client, int port)
{
	unsigned long flags;
	struct list_head *l;
	client_port_t *found = NULL;

	down(&client->ports_mutex);
	write_lock_irqsave(&client->ports_lock, flags);
	list_for_each(l, &client->ports_list_head) {
		client_port_t *p = list_entry(l, client_port_t, list);
		if (p->addr.port == port) {
			/* ok found.  delete from the list at first */
			list_del(l);
			client->num_ports--;
			found = p;
			break;
		}
	}
	write_unlock_irqrestore(&client->ports_lock, flags);
	up(&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(client_t *client)
{
	unsigned long flags;
	struct list_head deleted_list, *p, *n;
	
	/* move the port list to deleted_list, and
	 * clear the port list in the client data.
	 */
	down(&client->ports_mutex);
	write_lock_irqsave(&client->ports_lock, flags);
	if (! list_empty(&client->ports_list_head)) {
		__list_add(&deleted_list,
			   client->ports_list_head.prev,
			   client->ports_list_head.next);
		INIT_LIST_HEAD(&client->ports_list_head);
	} else {
		INIT_LIST_HEAD(&deleted_list);
	}
	client->num_ports = 0;
	write_unlock_irqrestore(&client->ports_lock, flags);

	/* remove each port in deleted_list */
	list_for_each_safe(p, n, &deleted_list) {
		client_port_t *port = list_entry(p, client_port_t, list);
		list_del(p);
		snd_seq_system_client_ev_port_exit(port->addr.client, port->addr.port);
		port_delete(client, port);
	}
	up(&client->ports_mutex);
	return 0;
}

/* set port info fields */
int snd_seq_set_port_info(client_port_t * port, snd_seq_port_info_t * info)
{
	snd_assert(port && info, return -EINVAL);