// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  ALSA sequencer Client Manager
 *  Copyright (c) 1998-2001 by Frank van de Pol <fvdpol@coil.demon.nl>
 *                             Jaroslav Kysela <perex@perex.cz>
 *                             Takashi Iwai <tiwai@suse.de>
 */

#include <linux/init.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <sound/core.h>
#include <sound/minors.h>
#include <linux/kmod.h>

#include <sound/seq_kernel.h>
#include <sound/ump.h>
#include "seq_clientmgr.h"
#include "seq_memory.h"
#include "seq_queue.h"
#include "seq_timer.h"
#include "seq_info.h"
#include "seq_system.h"
#include "seq_ump_convert.h"
#include <sound/seq_device.h>
#ifdef CONFIG_COMPAT
#include <linux/compat.h>
#endif

/* Client Manager

 * this module handles the connections of userland and kernel clients
 * 
 */

/*
 * There are four ranges of client numbers (last two shared):
 * 0..15: global clients
 * 16..127: statically allocated client numbers for cards 0..27
 * 128..191: dynamically allocated client numbers for cards 28..31
 * 128..191: dynamically allocated client numbers for applications
 */

/* number of kernel non-card clients */
#define SNDRV_SEQ_GLOBAL_CLIENTS        16
/* clients per cards, for static clients */
#define SNDRV_SEQ_CLIENTS_PER_CARD      4
/* dynamically allocated client numbers (both kernel drivers and user space) */
#define SNDRV_SEQ_DYNAMIC_CLIENTS_BEGIN 128

#define SNDRV_SEQ_LFLG_INPUT    0x0001
#define SNDRV_SEQ_LFLG_OUTPUT   0x0002
#define SNDRV_SEQ_LFLG_OPEN     (SNDRV_SEQ_LFLG_INPUT|SNDRV_SEQ_LFLG_OUTPUT)

static DEFINE_SPINLOCK(clients_lock);
static DEFINE_MUTEX(register_mutex);

/*
 * client table
 */
static char clienttablock[SNDRV_SEQ_MAX_CLIENTS];
static struct snd_seq_client *clienttab[SNDRV_SEQ_MAX_CLIENTS];
static struct snd_seq_usage client_usage;

/*
 * prototypes
 */
static int bounce_error_event(struct snd_seq_client *client,
                              struct snd_seq_event *event,
                              int err, int atomic, int hop);
static int snd_seq_deliver_single_event(struct snd_seq_client *client,
                                        struct snd_seq_event *event,
                                        int atomic, int hop);

#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
static void free_ump_info(struct snd_seq_client *client);
#endif

/*
 */
static inline unsigned short snd_seq_file_flags(struct file *file)
{
        switch (file->f_mode & (FMODE_READ | FMODE_WRITE)) {
        case FMODE_WRITE:
                return SNDRV_SEQ_LFLG_OUTPUT;
        case FMODE_READ:
                return SNDRV_SEQ_LFLG_INPUT;
        default:
                return SNDRV_SEQ_LFLG_OPEN;
        }
}

static inline int snd_seq_write_pool_allocated(struct snd_seq_client *client)
{
        return snd_seq_total_cells(client->pool) > 0;
}

/* return pointer to client structure for specified id */
static struct snd_seq_client *clientptr(int clientid)
{
        if (clientid < 0 || clientid >= SNDRV_SEQ_MAX_CLIENTS) {
                pr_debug("ALSA: seq: oops. Trying to get pointer to client %d\n",
                           clientid);
                return NULL;
        }
        return clienttab[clientid];
}

static struct snd_seq_client *client_use_ptr(int clientid, bool load_module)
{
        struct snd_seq_client *client;

        if (clientid < 0 || clientid >= SNDRV_SEQ_MAX_CLIENTS) {
                pr_debug("ALSA: seq: oops. Trying to get pointer to client %d\n",
                           clientid);
                return NULL;
        }
        scoped_guard(spinlock_irqsave, &clients_lock) {
                client = clientptr(clientid);
                if (client)
                        return snd_seq_client_ref(client);
                if (clienttablock[clientid])
                        return NULL;
        }
#ifdef CONFIG_MODULES
        if (load_module) {
                static DECLARE_BITMAP(client_requested, SNDRV_SEQ_GLOBAL_CLIENTS);
                static DECLARE_BITMAP(card_requested, SNDRV_CARDS);

                if (clientid < SNDRV_SEQ_GLOBAL_CLIENTS) {
                        int idx;
                        
                        if (!test_and_set_bit(clientid, client_requested)) {
                                for (idx = 0; idx < 15; idx++) {
                                        if (seq_client_load[idx] < 0)
                                                break;
                                        if (seq_client_load[idx] == clientid) {
                                                request_module("snd-seq-client-%i",
                                                               clientid);
                                                break;
                                        }
                                }
                        }
                } else if (clientid < SNDRV_SEQ_DYNAMIC_CLIENTS_BEGIN) {
                        int card = (clientid - SNDRV_SEQ_GLOBAL_CLIENTS) /
                                SNDRV_SEQ_CLIENTS_PER_CARD;
                        if (card < snd_ecards_limit) {
                                if (!test_and_set_bit(card, card_requested))
                                        snd_request_card(card);
                                snd_seq_device_load_drivers();
                        }
                }
                scoped_guard(spinlock_irqsave, &clients_lock) {
                        client = clientptr(clientid);
                        if (client)
                                return snd_seq_client_ref(client);
                }
        }
#endif
        return NULL;
}

/* get snd_seq_client object for the given id quickly */
struct snd_seq_client *snd_seq_client_use_ptr(int clientid)
{
        return client_use_ptr(clientid, false);
}

/* get snd_seq_client object for the given id;
 * if not found, retry after loading the modules
 */
static struct snd_seq_client *client_load_and_use_ptr(int clientid)
{
        return client_use_ptr(clientid, IS_ENABLED(CONFIG_MODULES));
}

static void usage_alloc(struct snd_seq_usage *res, int num)
{
        res->cur += num;
        if (res->cur > res->peak)
                res->peak = res->cur;
}

static void usage_free(struct snd_seq_usage *res, int num)
{
        res->cur -= num;
}

/* initialise data structures */
int __init client_init_data(void)
{
        /* zap out the client table */
        memset(&clienttablock, 0, sizeof(clienttablock));
        memset(&clienttab, 0, sizeof(clienttab));
        return 0;
}


static struct snd_seq_client *seq_create_client1(int client_index, int poolsize)
{
        int c;
        struct snd_seq_client *client;

        /* init client data */
        client = kzalloc(sizeof(*client), GFP_KERNEL);
        if (client == NULL)
                return NULL;
        client->pool = snd_seq_pool_new(poolsize);
        if (client->pool == NULL) {
                kfree(client);
                return NULL;
        }
        client->type = NO_CLIENT;
        snd_use_lock_init(&client->use_lock);
        rwlock_init(&client->ports_lock);
        mutex_init(&client->ports_mutex);
        INIT_LIST_HEAD(&client->ports_list_head);
        mutex_init(&client->ioctl_mutex);
        client->ump_endpoint_port = -1;

        /* find free slot in the client table */
        scoped_guard(spinlock_irq, &clients_lock) {
                if (client_index < 0) {
                        for (c = SNDRV_SEQ_DYNAMIC_CLIENTS_BEGIN;
                             c < SNDRV_SEQ_MAX_CLIENTS;
                             c++) {
                                if (clienttab[c] || clienttablock[c])
                                        continue;
                                clienttab[client->number = c] = client;
                                return client;
                        }
                } else {
                        if (clienttab[client_index] == NULL && !clienttablock[client_index]) {
                                clienttab[client->number = client_index] = client;
                                return client;
                        }
                }
        }

        snd_seq_pool_delete(&client->pool);
        kfree(client);
        return NULL;    /* no free slot found or busy, return failure code */
}


static int seq_free_client1(struct snd_seq_client *client)
{
        if (!client)
                return 0;
        scoped_guard(spinlock_irq, &clients_lock) {
                clienttablock[client->number] = 1;
                clienttab[client->number] = NULL;
        }
        snd_seq_delete_all_ports(client);
        snd_seq_queue_client_leave(client->number);
        snd_use_lock_sync(&client->use_lock);
        if (client->pool)
                snd_seq_pool_delete(&client->pool);
        scoped_guard(spinlock_irq, &clients_lock) {
                clienttablock[client->number] = 0;
        }
        return 0;
}


static void seq_free_client(struct snd_seq_client * client)
{
        scoped_guard(mutex, &register_mutex) {
                switch (client->type) {
                case NO_CLIENT:
                        pr_warn("ALSA: seq: Trying to free unused client %d\n",
                                client->number);
                        break;
                case USER_CLIENT:
                case KERNEL_CLIENT:
                        seq_free_client1(client);
                        usage_free(&client_usage, 1);
                        break;

                default:
                        pr_err("ALSA: seq: Trying to free client %d with undefined type = %d\n",
                               client->number, client->type);
                }
        }

        snd_seq_system_client_ev_client_exit(client->number);
}



/* -------------------------------------------------------- */

/* create a user client */
static int snd_seq_open(struct inode *inode, struct file *file)
{
        int c, mode;                    /* client id */
        struct snd_seq_client *client;
        struct snd_seq_user_client *user;
        int err;

        err = stream_open(inode, file);
        if (err < 0)
                return err;

        scoped_guard(mutex, &register_mutex) {
                client = seq_create_client1(-1, SNDRV_SEQ_DEFAULT_EVENTS);
                if (!client)
                        return -ENOMEM; /* failure code */

                mode = snd_seq_file_flags(file);
                if (mode & SNDRV_SEQ_LFLG_INPUT)
                        client->accept_input = 1;
                if (mode & SNDRV_SEQ_LFLG_OUTPUT)
                        client->accept_output = 1;

                user = &client->data.user;
                user->fifo = NULL;
                user->fifo_pool_size = 0;

                if (mode & SNDRV_SEQ_LFLG_INPUT) {
                        user->fifo_pool_size = SNDRV_SEQ_DEFAULT_CLIENT_EVENTS;
                        user->fifo = snd_seq_fifo_new(user->fifo_pool_size);
                        if (user->fifo == NULL) {
                                seq_free_client1(client);
                                kfree(client);
                                return -ENOMEM;
                        }
                }

                usage_alloc(&client_usage, 1);
                client->type = USER_CLIENT;
        }

        c = client->number;
        file->private_data = client;

        /* fill client data */
        user->file = file;
        sprintf(client->name, "Client-%d", c);
        client->data.user.owner = get_pid(task_pid(current));

        /* make others aware this new client */
        snd_seq_system_client_ev_client_start(c);

        return 0;
}

/* delete a user client */
static int snd_seq_release(struct inode *inode, struct file *file)
{
        struct snd_seq_client *client = file->private_data;

        if (client) {
                seq_free_client(client);
                if (client->data.user.fifo)
                        snd_seq_fifo_delete(&client->data.user.fifo);
#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
                free_ump_info(client);
#endif
                put_pid(client->data.user.owner);
                kfree(client);
        }

        return 0;
}

static bool event_is_compatible(const struct snd_seq_client *client,
                                const struct snd_seq_event *ev)
{
        if (snd_seq_ev_is_ump(ev) && !client->midi_version)
                return false;
        if (snd_seq_ev_is_ump(ev) && snd_seq_ev_is_variable(ev))
                return false;
        return true;
}

/* handle client read() */
/* possible error values:
 *      -ENXIO  invalid client or file open mode
 *      -ENOSPC FIFO overflow (the flag is cleared after this error report)
 *      -EINVAL no enough user-space buffer to write the whole event
 *      -EFAULT seg. fault during copy to user space
 */
static ssize_t snd_seq_read(struct file *file, char __user *buf, size_t count,
                            loff_t *offset)
{
        struct snd_seq_client *client = file->private_data;
        struct snd_seq_fifo *fifo;
        size_t aligned_size;
        int err;
        long result = 0;
        struct snd_seq_event_cell *cell;

        if (!(snd_seq_file_flags(file) & SNDRV_SEQ_LFLG_INPUT))
                return -ENXIO;

        if (!access_ok(buf, count))
                return -EFAULT;

        /* check client structures are in place */
        if (snd_BUG_ON(!client))
                return -ENXIO;

        if (!client->accept_input)
                return -ENXIO;
        fifo = client->data.user.fifo;
        if (!fifo)
                return -ENXIO;

        if (atomic_read(&fifo->overflow) > 0) {
                /* buffer overflow is detected */
                snd_seq_fifo_clear(fifo);
                /* return error code */
                return -ENOSPC;
        }

        cell = NULL;
        err = 0;
        guard(snd_seq_fifo)(fifo);

        if (IS_ENABLED(CONFIG_SND_SEQ_UMP) && client->midi_version > 0)
                aligned_size = sizeof(struct snd_seq_ump_event);
        else
                aligned_size = sizeof(struct snd_seq_event);

        /* while data available in queue */
        while (count >= aligned_size) {
                int nonblock;

                nonblock = (file->f_flags & O_NONBLOCK) || result > 0;
                err = snd_seq_fifo_cell_out(fifo, &cell, nonblock);
                if (err < 0)
                        break;
                if (!event_is_compatible(client, &cell->event)) {
                        snd_seq_cell_free(cell);
                        cell = NULL;
                        continue;
                }
                if (snd_seq_ev_is_variable(&cell->event)) {
                        struct snd_seq_ump_event tmpev;

                        memcpy(&tmpev, &cell->event, aligned_size);
                        tmpev.data.ext.len &= ~SNDRV_SEQ_EXT_MASK;
                        if (copy_to_user(buf, &tmpev, aligned_size)) {
                                err = -EFAULT;
                                break;
                        }
                        count -= aligned_size;
                        buf += aligned_size;
                        err = snd_seq_expand_var_event(&cell->event, count,
                                                       (char __force *)buf, 0,
                                                       aligned_size);
                        if (err < 0)
                                break;
                        result += err;
                        count -= err;
                        buf += err;
                } else {
                        if (copy_to_user(buf, &cell->event, aligned_size)) {
                                err = -EFAULT;
                                break;
                        }
                        count -= aligned_size;
                        buf += aligned_size;
                }
                snd_seq_cell_free(cell);
                cell = NULL; /* to be sure */
                result += aligned_size;
        }

        if (err < 0) {
                if (cell)
                        snd_seq_fifo_cell_putback(fifo, cell);
                if (err == -EAGAIN && result > 0)
                        err = 0;
        }

        return (err < 0) ? err : result;
}


/*
 * check access permission to the port
 */
static int check_port_perm(struct snd_seq_client_port *port, unsigned int flags)
{
        if ((port->capability & flags) != flags)
                return 0;
        return flags;
}

/*
 * check if the destination client is available, and return the pointer
 */
static struct snd_seq_client *get_event_dest_client(struct snd_seq_event *event)
{
        struct snd_seq_client *dest __free(snd_seq_client) =
                snd_seq_client_use_ptr(event->dest.client);

        if (dest == NULL)
                return NULL;
        if (! dest->accept_input)
                return NULL;
        if (snd_seq_ev_is_ump(event))
                return no_free_ptr(dest); /* ok - no filter checks */

        if ((dest->filter & SNDRV_SEQ_FILTER_USE_EVENT) &&
            ! test_bit(event->type, dest->event_filter))
                return NULL;

        return no_free_ptr(dest); /* ok - accessible */
}


/*
 * Return the error event.
 *
 * If the receiver client is a user client, the original event is
 * encapsulated in SNDRV_SEQ_EVENT_BOUNCE as variable length event.  If
 * the original event is also variable length, the external data is
 * copied after the event record. 
 * If the receiver client is a kernel client, the original event is
 * quoted in SNDRV_SEQ_EVENT_KERNEL_ERROR, since this requires no extra
 * kmalloc.
 */
static int bounce_error_event(struct snd_seq_client *client,
                              struct snd_seq_event *event,
                              int err, int atomic, int hop)
{
        struct snd_seq_event bounce_ev;
        int result;

        if (client == NULL ||
            ! (client->filter & SNDRV_SEQ_FILTER_BOUNCE) ||
            ! client->accept_input)
                return 0; /* ignored */

        /* set up quoted error */
        memset(&bounce_ev, 0, sizeof(bounce_ev));
        bounce_ev.type = SNDRV_SEQ_EVENT_KERNEL_ERROR;
        bounce_ev.flags = SNDRV_SEQ_EVENT_LENGTH_FIXED;
        bounce_ev.queue = SNDRV_SEQ_QUEUE_DIRECT;
        bounce_ev.source.client = SNDRV_SEQ_CLIENT_SYSTEM;
        bounce_ev.source.port = SNDRV_SEQ_PORT_SYSTEM_ANNOUNCE;
        bounce_ev.dest.client = client->number;
        bounce_ev.dest.port = event->source.port;
        bounce_ev.data.quote.origin = event->dest;
        bounce_ev.data.quote.event = event;
        bounce_ev.data.quote.value = -err; /* use positive value */
        result = snd_seq_deliver_single_event(NULL, &bounce_ev, atomic, hop + 1);
        if (result < 0) {
                client->event_lost++;
                return result;
        }

        return result;
}


/*
 * rewrite the time-stamp of the event record with the curren time
 * of the given queue.
 * return non-zero if updated.
 */
static int update_timestamp_of_queue(struct snd_seq_event *event,
                                     int queue, int real_time)
{
        struct snd_seq_queue *q __free(snd_seq_queue) =
                queueptr(queue);

        if (! q)
                return 0;
        event->queue = queue;
        event->flags &= ~SNDRV_SEQ_TIME_STAMP_MASK;
        if (real_time) {
                event->time.time = snd_seq_timer_get_cur_time(q->timer, true);
                event->flags |= SNDRV_SEQ_TIME_STAMP_REAL;
        } else {
                event->time.tick = snd_seq_timer_get_cur_tick(q->timer);
                event->flags |= SNDRV_SEQ_TIME_STAMP_TICK;
        }
        return 1;
}

/* deliver a single event; called from below and UMP converter */
int __snd_seq_deliver_single_event(struct snd_seq_client *dest,
                                   struct snd_seq_client_port *dest_port,
                                   struct snd_seq_event *event,
                                   int atomic, int hop)
{
        switch (dest->type) {
        case USER_CLIENT:
                if (!dest->data.user.fifo)
                        return 0;
                return snd_seq_fifo_event_in(dest->data.user.fifo, event);
        case KERNEL_CLIENT:
                if (!dest_port->event_input)
                        return 0;
                return dest_port->event_input(event,
                                              snd_seq_ev_is_direct(event),
                                              dest_port->private_data,
                                              atomic, hop);
        }
        return 0;
}

/* deliver a single event; called from snd_seq_deliver_single_event() */
static int _snd_seq_deliver_single_event(struct snd_seq_client *client,
                                         struct snd_seq_event *event,
                                         int atomic, int hop)
{
        struct snd_seq_client *dest __free(snd_seq_client) =
                get_event_dest_client(event);
        if (dest == NULL)
                return -ENOENT;

        struct snd_seq_client_port *dest_port __free(snd_seq_port) =
                snd_seq_port_use_ptr(dest, event->dest.port);
        if (dest_port == NULL)
                return -ENOENT;

        /* check permission */
        if (!check_port_perm(dest_port, SNDRV_SEQ_PORT_CAP_WRITE))
                return -EPERM;

        if (dest_port->timestamping)
                update_timestamp_of_queue(event, dest_port->time_queue,
                                          dest_port->time_real);

#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
        if (snd_seq_ev_is_ump(event)) {
                if (!(dest->filter & SNDRV_SEQ_FILTER_NO_CONVERT))
                        return snd_seq_deliver_from_ump(client, dest, dest_port,
                                                        event, atomic, hop);
                else if (dest->type == USER_CLIENT &&
                         !snd_seq_client_is_ump(dest))
                        return 0; // drop the event
        } else if (snd_seq_client_is_ump(dest)) {
                if (!(dest->filter & SNDRV_SEQ_FILTER_NO_CONVERT))
                        return snd_seq_deliver_to_ump(client, dest, dest_port,
                                                      event, atomic, hop);
        }
#endif /* CONFIG_SND_SEQ_UMP */

        return __snd_seq_deliver_single_event(dest, dest_port, event,
                                              atomic, hop);
}

/*
 * deliver an event to the specified destination.
 * if filter is non-zero, client filter bitmap is tested.
 *
 *  RETURN VALUE: 0 : if succeeded
 *               <0 : error
 */
static int snd_seq_deliver_single_event(struct snd_seq_client *client,
                                        struct snd_seq_event *event,
                                        int atomic, int hop)
{
        int result = _snd_seq_deliver_single_event(client, event, atomic, hop);

        if (result < 0 && !snd_seq_ev_is_direct(event))
                return bounce_error_event(client, event, result, atomic, hop);
        return result;
}


/*
 * send the event to all subscribers:
 */
static int __deliver_to_subscribers(struct snd_seq_client *client,
                                    struct snd_seq_event *event,
                                    int port, int atomic, int hop)
{
        struct snd_seq_subscribers *subs;
        int err, result = 0, num_ev = 0;
        union __snd_seq_event event_saved;
        size_t saved_size;
        struct snd_seq_port_subs_info *grp;

        if (port < 0)
                return 0;

        struct snd_seq_client_port *src_port __free(snd_seq_port) =
                snd_seq_port_use_ptr(client, port);
        if (!src_port)
                return 0;

        /* save original event record */
        saved_size = snd_seq_event_packet_size(event);
        memcpy(&event_saved, event, saved_size);
        grp = &src_port->c_src;
        
        /* lock list */
        if (atomic)
                read_lock(&grp->list_lock);
        else
                down_read_nested(&grp->list_mutex, hop);
        list_for_each_entry(subs, &grp->list_head, src_list) {
                /* both ports ready? */
                if (atomic_read(&subs->ref_count) != 2)
                        continue;
                event->dest = subs->info.dest;
                if (subs->info.flags & SNDRV_SEQ_PORT_SUBS_TIMESTAMP)
                        /* convert time according to flag with subscription */
                        update_timestamp_of_queue(event, subs->info.queue,
                                                  subs->info.flags & SNDRV_SEQ_PORT_SUBS_TIME_REAL);
                err = snd_seq_deliver_single_event(client, event, atomic, hop);
                if (err < 0) {
                        /* save first error that occurs and continue */
                        if (!result)
                                result = err;
                        continue;
                }
                num_ev++;
                /* restore original event record */
                memcpy(event, &event_saved, saved_size);
        }
        if (atomic)
                read_unlock(&grp->list_lock);
        else
                up_read(&grp->list_mutex);
        memcpy(event, &event_saved, saved_size);
        return (result < 0) ? result : num_ev;
}

static int deliver_to_subscribers(struct snd_seq_client *client,
                                  struct snd_seq_event *event,
                                  int atomic, int hop)
{
        int ret;
#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
        int ret2;
#endif

        ret = __deliver_to_subscribers(client, event,
                                       event->source.port, atomic, hop);
#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
        if (!snd_seq_client_is_ump(client) || client->ump_endpoint_port < 0)
                return ret;
        /* If it's an event from EP port (and with a UMP group),
         * deliver to subscribers of the corresponding UMP group port, too.
         * Or, if it's from non-EP port, deliver to subscribers of EP port, too.
         */
        if (event->source.port == client->ump_endpoint_port)
                ret2 = __deliver_to_subscribers(client, event,
                                                snd_seq_ump_group_port(event),
                                                atomic, hop);
        else
                ret2 = __deliver_to_subscribers(client, event,
                                                client->ump_endpoint_port,
                                                atomic, hop);
        if (ret2 < 0)
                return ret2;
#endif
        return ret;
}

/* deliver an event to the destination port(s).
 * if the event is to subscribers or broadcast, the event is dispatched
 * to multiple targets.
 *
 * RETURN VALUE: n > 0  : the number of delivered events.
 *               n == 0 : the event was not passed to any client.
 *               n < 0  : error - event was not processed.
 */
static int snd_seq_deliver_event(struct snd_seq_client *client, struct snd_seq_event *event,
                                 int atomic, int hop)
{
        int result;

        hop++;
        if (hop >= SNDRV_SEQ_MAX_HOPS) {
                pr_debug("ALSA: seq: too long delivery path (%d:%d->%d:%d)\n",
                           event->source.client, event->source.port,
                           event->dest.client, event->dest.port);
                return -EMLINK;
        }

        if (snd_seq_ev_is_variable(event) &&
            snd_BUG_ON(atomic && (event->data.ext.len & SNDRV_SEQ_EXT_USRPTR)))
                return -EINVAL;

        if (event->queue == SNDRV_SEQ_ADDRESS_SUBSCRIBERS ||
            event->dest.client == SNDRV_SEQ_ADDRESS_SUBSCRIBERS)
                result = deliver_to_subscribers(client, event, atomic, hop);
        else
                result = snd_seq_deliver_single_event(client, event, atomic, hop);

        return result;
}

/*
 * dispatch an event cell:
 * This function is called only from queue check routines in timer
 * interrupts or after enqueued.
 * The event cell shall be released or re-queued in this function.
 *
 * RETURN VALUE: n > 0  : the number of delivered events.
 *               n == 0 : the event was not passed to any client.
 *               n < 0  : error - event was not processed.
 */
int snd_seq_dispatch_event(struct snd_seq_event_cell *cell, int atomic, int hop)
{
        int result;

        if (snd_BUG_ON(!cell))
                return -EINVAL;

        struct snd_seq_client *client __free(snd_seq_client) =
                snd_seq_client_use_ptr(cell->event.source.client);
        if (client == NULL) {
                snd_seq_cell_free(cell); /* release this cell */
                return -EINVAL;
        }

        if (!snd_seq_ev_is_ump(&cell->event) &&
            cell->event.type == SNDRV_SEQ_EVENT_NOTE) {
                /* NOTE event:
                 * the event cell is re-used as a NOTE-OFF event and
                 * enqueued again.
                 */
                struct snd_seq_event tmpev, *ev;

                /* reserve this event to enqueue note-off later */
                tmpev = cell->event;
                tmpev.type = SNDRV_SEQ_EVENT_NOTEON;
                result = snd_seq_deliver_event(client, &tmpev, atomic, hop);

                /*
                 * This was originally a note event.  We now re-use the
                 * cell for the note-off event.
                 */

                ev = &cell->event;
                ev->type = SNDRV_SEQ_EVENT_NOTEOFF;
                ev->flags |= SNDRV_SEQ_PRIORITY_HIGH;

                /* add the duration time */
                switch (ev->flags & SNDRV_SEQ_TIME_STAMP_MASK) {
                case SNDRV_SEQ_TIME_STAMP_TICK:
                        cell->event.time.tick += ev->data.note.duration;
                        break;
                case SNDRV_SEQ_TIME_STAMP_REAL:
                        /* unit for duration is ms */
                        ev->time.time.tv_nsec += 1000000 * (ev->data.note.duration % 1000);
                        ev->time.time.tv_sec += ev->data.note.duration / 1000 +
                                                ev->time.time.tv_nsec / 1000000000;
                        ev->time.time.tv_nsec %= 1000000000;
                        break;
                }
                ev->data.note.velocity = ev->data.note.off_velocity;

                /* Now queue this cell as the note off event */
                if (snd_seq_enqueue_event(cell, atomic, hop) < 0)
                        snd_seq_cell_free(cell); /* release this cell */

        } else {
                /* Normal events:
                 * event cell is freed after processing the event
                 */

                result = snd_seq_deliver_event(client, &cell->event, atomic, hop);
                snd_seq_cell_free(cell);
        }

        return result;
}


/* Allocate a cell from client pool and enqueue it to queue:
 * if pool is empty and blocking is TRUE, sleep until a new cell is
 * available.
 */
static int snd_seq_client_enqueue_event(struct snd_seq_client *client,
                                        struct snd_seq_event *event,
                                        struct file *file, int blocking,
                                        int atomic, int hop,
                                        struct mutex *mutexp)
{
        struct snd_seq_event_cell *cell;
        int err;

        /* special queue values - force direct passing */
        if (event->queue == SNDRV_SEQ_ADDRESS_SUBSCRIBERS) {
                event->dest.client = SNDRV_SEQ_ADDRESS_SUBSCRIBERS;
                event->queue = SNDRV_SEQ_QUEUE_DIRECT;
        } else if (event->dest.client == SNDRV_SEQ_ADDRESS_SUBSCRIBERS) {
                /* check presence of source port */
                struct snd_seq_client_port *src_port __free(snd_seq_port) =
                        snd_seq_port_use_ptr(client, event->source.port);
                if (!src_port)
                        return -EINVAL;
        }

        /* direct event processing without enqueued */
        if (snd_seq_ev_is_direct(event)) {
                if (!snd_seq_ev_is_ump(event) &&
                    event->type == SNDRV_SEQ_EVENT_NOTE)
                        return -EINVAL; /* this event must be enqueued! */
                return snd_seq_deliver_event(client, event, atomic, hop);
        }

        /* Not direct, normal queuing */
        if (snd_seq_queue_is_used(event->queue, client->number) <= 0)
                return -EINVAL;  /* invalid queue */
        if (! snd_seq_write_pool_allocated(client))
                return -ENXIO; /* queue is not allocated */

        /* allocate an event cell */
        err = snd_seq_event_dup(client->pool, event, &cell, !blocking || atomic,
                                file, mutexp);
        if (err < 0)
                return err;

        /* we got a cell. enqueue it. */
        err = snd_seq_enqueue_event(cell, atomic, hop);
        if (err < 0) {
                snd_seq_cell_free(cell);
                return err;
        }

        return 0;
}


/*
 * check validity of event type and data length.
 * return non-zero if invalid.
 */
static int check_event_type_and_length(struct snd_seq_event *ev)
{
        switch (snd_seq_ev_length_type(ev)) {
        case SNDRV_SEQ_EVENT_LENGTH_FIXED:
                if (snd_seq_ev_is_variable_type(ev))
                        return -EINVAL;
                break;
        case SNDRV_SEQ_EVENT_LENGTH_VARIABLE:
                if (! snd_seq_ev_is_variable_type(ev) ||
                    (ev->data.ext.len & ~SNDRV_SEQ_EXT_MASK) >= SNDRV_SEQ_MAX_EVENT_LEN)
                        return -EINVAL;
                break;
        case SNDRV_SEQ_EVENT_LENGTH_VARUSR:
                if (! snd_seq_ev_is_direct(ev))
                        return -EINVAL;
                break;
        }
        return 0;
}


/* handle write() */
/* possible error values:
 *      -ENXIO  invalid client or file open mode
 *      -ENOMEM malloc failed
 *      -EFAULT seg. fault during copy from user space
 *      -EINVAL invalid event
 *      -EAGAIN no space in output pool
 *      -EINTR  interrupts while sleep
 *      -EMLINK too many hops
 *      others  depends on return value from driver callback
 */
static ssize_t snd_seq_write(struct file *file, const char __user *buf,
                             size_t count, loff_t *offset)
{
        struct snd_seq_client *client = file->private_data;
        int written = 0, len;
        int err, handled;
        union __snd_seq_event __event;
        struct snd_seq_event *ev = &__event.legacy;

        if (!(snd_seq_file_flags(file) & SNDRV_SEQ_LFLG_OUTPUT))
                return -ENXIO;

        /* check client structures are in place */
        if (snd_BUG_ON(!client))
                return -ENXIO;
                
        if (!client->accept_output || client->pool == NULL)
                return -ENXIO;

 repeat:
        handled = 0;
        /* allocate the pool now if the pool is not allocated yet */ 
        mutex_lock(&client->ioctl_mutex);
        if (client->pool->size > 0 && !snd_seq_write_pool_allocated(client)) {
                err = snd_seq_pool_init(client->pool);
                if (err < 0)
                        goto out;
        }

        /* only process whole events */
        err = -EINVAL;
        while (count >= sizeof(struct snd_seq_event)) {
                /* Read in the event header from the user */
                len = sizeof(struct snd_seq_event);
                if (copy_from_user(ev, buf, len)) {
                        err = -EFAULT;
                        break;
                }
                /* read in the rest bytes for UMP events */
                if (snd_seq_ev_is_ump(ev)) {
                        if (count < sizeof(struct snd_seq_ump_event))
                                break;
                        if (copy_from_user((char *)ev + len, buf + len,
                                           sizeof(struct snd_seq_ump_event) - len)) {
                                err = -EFAULT;
                                break;
                        }
                        len = sizeof(struct snd_seq_ump_event);
                }

                ev->source.client = client->number;     /* fill in client number */
                /* Check for extension data length */
                if (check_event_type_and_length(ev)) {
                        err = -EINVAL;
                        break;
                }

                if (!event_is_compatible(client, ev)) {
                        err = -EINVAL;
                        break;
                }

                /* check for special events */
                if (!snd_seq_ev_is_ump(ev)) {
                        if (ev->type == SNDRV_SEQ_EVENT_NONE)
                                goto __skip_event;
                        else if (snd_seq_ev_is_reserved(ev)) {
                                err = -EINVAL;
                                break;
                        }
                }

                if (snd_seq_ev_is_variable(ev)) {
                        int extlen = ev->data.ext.len & ~SNDRV_SEQ_EXT_MASK;
                        if ((size_t)(extlen + len) > count) {
                                /* back out, will get an error this time or next */
                                err = -EINVAL;
                                break;
                        }
                        /* set user space pointer */
                        ev->data.ext.len = extlen | SNDRV_SEQ_EXT_USRPTR;
                        ev->data.ext.ptr = (char __force *)buf + len;
                        len += extlen; /* increment data length */
                } else {
#ifdef CONFIG_COMPAT
                        if (client->convert32 && snd_seq_ev_is_varusr(ev))
                                ev->data.ext.ptr =
                                        (void __force *)compat_ptr(ev->data.raw32.d[1]);
#endif
                }

                /* ok, enqueue it */
                err = snd_seq_client_enqueue_event(client, ev, file,
                                                   !(file->f_flags & O_NONBLOCK),
                                                   0, 0, &client->ioctl_mutex);
                if (err < 0)
                        break;
                handled++;

        __skip_event:
                /* Update pointers and counts */
                count -= len;
                buf += len;
                written += len;

                /* let's have a coffee break if too many events are queued */
                if (++handled >= 200) {
                        mutex_unlock(&client->ioctl_mutex);
                        goto repeat;
                }
        }

 out:
        mutex_unlock(&client->ioctl_mutex);
        return written ? written : err;
}


/*
 * handle polling
 */
static __poll_t snd_seq_poll(struct file *file, poll_table * wait)
{
        struct snd_seq_client *client = file->private_data;
        __poll_t mask = 0;

        /* check client structures are in place */
        if (snd_BUG_ON(!client))
                return EPOLLERR;

        if ((snd_seq_file_flags(file) & SNDRV_SEQ_LFLG_INPUT) &&
            client->data.user.fifo) {

                /* check if data is available in the outqueue */
                if (snd_seq_fifo_poll_wait(client->data.user.fifo, file, wait))
                        mask |= EPOLLIN | EPOLLRDNORM;
        }

        if (snd_seq_file_flags(file) & SNDRV_SEQ_LFLG_OUTPUT) {

                /* check if data is available in the pool */
                if (snd_seq_pool_poll_wait(client->pool, file, wait))
                        mask |= EPOLLOUT | EPOLLWRNORM;
        }

        return mask;
}


/*-----------------------------------------------------*/

static int snd_seq_ioctl_pversion(struct snd_seq_client *client, void *arg)
{
        int *pversion = arg;

        *pversion = SNDRV_SEQ_VERSION;
        return 0;
}

static int snd_seq_ioctl_user_pversion(struct snd_seq_client *client, void *arg)
{
        client->user_pversion = *(unsigned int *)arg;
        return 0;
}

static int snd_seq_ioctl_client_id(struct snd_seq_client *client, void *arg)
{
        int *client_id = arg;

        *client_id = client->number;
        return 0;
}

/* SYSTEM_INFO ioctl() */
static int snd_seq_ioctl_system_info(struct snd_seq_client *client, void *arg)
{
        struct snd_seq_system_info *info = arg;

        memset(info, 0, sizeof(*info));
        /* fill the info fields */
        info->queues = SNDRV_SEQ_MAX_QUEUES;
        info->clients = SNDRV_SEQ_MAX_CLIENTS;
        info->ports = SNDRV_SEQ_MAX_PORTS;
        info->channels = 256;   /* fixed limit */
        info->cur_clients = client_usage.cur;
        info->cur_queues = snd_seq_queue_get_cur_queues();

        return 0;
}


/* RUNNING_MODE ioctl() */
static int snd_seq_ioctl_running_mode(struct snd_seq_client *client, void  *arg)
{
        struct snd_seq_running_info *info = arg;
        /* requested client number */
        struct snd_seq_client *cptr __free(snd_seq_client) =
                client_load_and_use_ptr(info->client);

        if (cptr == NULL)
                return -ENOENT;         /* don't change !!! */

#ifdef SNDRV_BIG_ENDIAN
        if (!info->big_endian)
                return -EINVAL;
#else
        if (info->big_endian)
                return -EINVAL;
#endif
        if (info->cpu_mode > sizeof(long))
                return -EINVAL;
        cptr->convert32 = (info->cpu_mode < sizeof(long));
        return 0;
}

/* CLIENT_INFO ioctl() */
static void get_client_info(struct snd_seq_client *cptr,
                            struct snd_seq_client_info *info)
{
        info->client = cptr->number;

        /* fill the info fields */
        info->type = cptr->type;
        strscpy(info->name, cptr->name);
        info->filter = cptr->filter;
        info->event_lost = cptr->event_lost;
        memcpy(info->event_filter, cptr->event_filter, 32);
        info->group_filter = cptr->group_filter;
        info->num_ports = cptr->num_ports;

        if (cptr->type == USER_CLIENT)
                info->pid = pid_vnr(cptr->data.user.owner);
        else
                info->pid = -1;

        if (cptr->type == KERNEL_CLIENT)
                info->card = cptr->data.kernel.card ? cptr->data.kernel.card->number : -1;
        else
                info->card = -1;

        info->midi_version = cptr->midi_version;
        memset(info->reserved, 0, sizeof(info->reserved));
}

static int snd_seq_ioctl_get_client_info(struct snd_seq_client *client,
                                         void *arg)
{
        struct snd_seq_client_info *client_info = arg;
        /* requested client number */
        struct snd_seq_client *cptr __free(snd_seq_client) =
                client_load_and_use_ptr(client_info->client);

        if (cptr == NULL)
                return -ENOENT;         /* don't change !!! */

        get_client_info(cptr, client_info);
        return 0;
}


/* CLIENT_INFO ioctl() */
static int snd_seq_ioctl_set_client_info(struct snd_seq_client *client,
                                         void *arg)
{
        struct snd_seq_client_info *client_info = arg;

        /* it is not allowed to set the info fields for an another client */
        if (client->number != client_info->client)
                return -EPERM;
        /* also client type must be set now */
        if (client->type != client_info->type)
                return -EINVAL;

        if (client->user_pversion >= SNDRV_PROTOCOL_VERSION(1, 0, 3)) {
                /* check validity of midi_version field */
                if (client_info->midi_version > SNDRV_SEQ_CLIENT_UMP_MIDI_2_0)
                        return -EINVAL;

                /* check if UMP is supported in kernel */
                if (!IS_ENABLED(CONFIG_SND_SEQ_UMP) &&
                    client_info->midi_version > 0)
                        return -EINVAL;
        }

        /* fill the info fields */
        if (client_info->name[0])
                strscpy(client->name, client_info->name, sizeof(client->name));

        client->filter = client_info->filter;
        client->event_lost = client_info->event_lost;
        if (client->user_pversion >= SNDRV_PROTOCOL_VERSION(1, 0, 3))
                client->midi_version = client_info->midi_version;
        memcpy(client->event_filter, client_info->event_filter, 32);
        client->group_filter = client_info->group_filter;

        /* notify the change */
        snd_seq_system_client_ev_client_change(client->number);

        return 0;
}


/* 
 * CREATE PORT ioctl() 
 */
static int snd_seq_ioctl_create_port(struct snd_seq_client *client, void *arg)
{
        struct snd_seq_port_info *info = arg;
        struct snd_seq_client_port *port;
        struct snd_seq_port_callback *callback;
        int port_idx, err;

        /* it is not allowed to create the port for an another client */
        if (info->addr.client != client->number)
                return -EPERM;
        if (client->type == USER_CLIENT && info->kernel)
                return -EINVAL;
        if ((info->capability & SNDRV_SEQ_PORT_CAP_UMP_ENDPOINT) &&
            client->ump_endpoint_port >= 0)
                return -EBUSY;

        if (info->flags & SNDRV_SEQ_PORT_FLG_GIVEN_PORT)
                port_idx = info->addr.port;
        else
                port_idx = -1;
        if (port_idx >= SNDRV_SEQ_ADDRESS_UNKNOWN)
                return -EINVAL;
        err = snd_seq_create_port(client, port_idx, &port);
        if (err < 0)
                return err;

        if (client->type == KERNEL_CLIENT) {
                callback = info->kernel;
                if (callback) {
                        if (callback->owner)
                                port->owner = callback->owner;
                        port->private_data = callback->private_data;
                        port->private_free = callback->private_free;
                        port->event_input = callback->event_input;
                        port->c_src.open = callback->subscribe;
                        port->c_src.close = callback->unsubscribe;
                        port->c_dest.open = callback->use;
                        port->c_dest.close = callback->unuse;
                }
        }

        info->addr = port->addr;

        snd_seq_set_port_info(port, info);
        if (info->capability & SNDRV_SEQ_PORT_CAP_UMP_ENDPOINT)
                client->ump_endpoint_port = port->addr.port;
        snd_seq_system_client_ev_port_start(port->addr.client, port->addr.port);
        snd_seq_port_unlock(port);

        return 0;
}

/* 
 * DELETE PORT ioctl() 
 */
static int snd_seq_ioctl_delete_port(struct snd_seq_client *client, void *arg)
{
        struct snd_seq_port_info *info = arg;
        int err;

        /* it is not allowed to remove the port for an another client */
        if (info->addr.client != client->number)
                return -EPERM;

        err = snd_seq_delete_port(client, info->addr.port);
        if (err >= 0) {
                if (client->ump_endpoint_port == info->addr.port)
                        client->ump_endpoint_port = -1;
                snd_seq_system_client_ev_port_exit(client->number, info->addr.port);
        }
        return err;
}


/* 
 * GET_PORT_INFO ioctl() (on any client) 
 */
static int snd_seq_ioctl_get_port_info(struct snd_seq_client *client, void *arg)
{
        struct snd_seq_port_info *info = arg;

        struct snd_seq_client *cptr __free(snd_seq_client) =
                client_load_and_use_ptr(info->addr.client);
        if (cptr == NULL)
                return -ENXIO;

        struct snd_seq_client_port *port __free(snd_seq_port) =
                snd_seq_port_use_ptr(cptr, info->addr.port);
        if (port == NULL)
                return -ENOENT;                 /* don't change */

        /* get port info */
        snd_seq_get_port_info(port, info);
        return 0;
}


/* 
 * SET_PORT_INFO ioctl() (only ports on this/own client) 
 */
static int snd_seq_ioctl_set_port_info(struct snd_seq_client *client, void *arg)
{
        struct snd_seq_port_info *info = arg;

        if (info->addr.client != client->number) /* only set our own ports ! */
                return -EPERM;

        struct snd_seq_client_port *port __free(snd_seq_port) =
                snd_seq_port_use_ptr(client, info->addr.port);
        if (port) {
                snd_seq_set_port_info(port, info);
                /* notify the change */
                snd_seq_system_client_ev_port_change(info->addr.client,
                                                     info->addr.port);
        }
        return 0;
}


/*
 * port subscription (connection)
 */
#define PERM_RD         (SNDRV_SEQ_PORT_CAP_READ|SNDRV_SEQ_PORT_CAP_SUBS_READ)
#define PERM_WR         (SNDRV_SEQ_PORT_CAP_WRITE|SNDRV_SEQ_PORT_CAP_SUBS_WRITE)

static int check_subscription_permission(struct snd_seq_client *client,
                                         struct snd_seq_client_port *sport,
                                         struct snd_seq_client_port *dport,
                                         struct snd_seq_port_subscribe *subs)
{
        if (client->number != subs->sender.client &&
            client->number != subs->dest.client) {
                /* connection by third client - check export permission */
                if (check_port_perm(sport, SNDRV_SEQ_PORT_CAP_NO_EXPORT))
                        return -EPERM;
                if (check_port_perm(dport, SNDRV_SEQ_PORT_CAP_NO_EXPORT))
                        return -EPERM;
        }

        /* check read permission */
        /* if sender or receiver is the subscribing client itself,
         * no permission check is necessary
         */
        if (client->number != subs->sender.client) {
                if (! check_port_perm(sport, PERM_RD))
                        return -EPERM;
        }
        /* check write permission */
        if (client->number != subs->dest.client) {
                if (! check_port_perm(dport, PERM_WR))
                        return -EPERM;
        }
        return 0;
}

/*
 * send an subscription notify event to user client:
 * client must be user client.
 */
int snd_seq_client_notify_subscription(int client, int port,
                                       struct snd_seq_port_subscribe *info,
                                       int evtype)
{
        struct snd_seq_event event;

        memset(&event, 0, sizeof(event));
        event.type = evtype;
        event.data.connect.dest = info->dest;
        event.data.connect.sender = info->sender;

        return snd_seq_system_notify(client, port, &event, false);  /* non-atomic */
}


/* 
 * add to port's subscription list IOCTL interface 
 */
static int snd_seq_ioctl_subscribe_port(struct snd_seq_client *client,
                                        void *arg)
{
        struct snd_seq_port_subscribe *subs = arg;
        int result;

        struct snd_seq_client *receiver __free(snd_seq_client) =
                client_load_and_use_ptr(subs->dest.client);
        if (!receiver)
                return -EINVAL;
        struct snd_seq_client *sender __free(snd_seq_client) =
                client_load_and_use_ptr(subs->sender.client);
        if (!sender)
                return -EINVAL;
        struct snd_seq_client_port *sport __free(snd_seq_port) =
                snd_seq_port_use_ptr(sender, subs->sender.port);
        if (!sport)
                return -EINVAL;
        struct snd_seq_client_port *dport __free(snd_seq_port) =
                snd_seq_port_use_ptr(receiver, subs->dest.port);
        if (!dport)
                return -EINVAL;

        result = check_subscription_permission(client, sport, dport, subs);
        if (result < 0)
                return result;

        /* connect them */
        result = snd_seq_port_connect(client, sender, sport, receiver, dport, subs);
        if (! result) /* broadcast announce */
                snd_seq_client_notify_subscription(SNDRV_SEQ_ADDRESS_SUBSCRIBERS, 0,
                                                   subs, SNDRV_SEQ_EVENT_PORT_SUBSCRIBED);
        return result;
}


/* 
 * remove from port's subscription list 
 */
static int snd_seq_ioctl_unsubscribe_port(struct snd_seq_client *client,
                                          void *arg)
{
        struct snd_seq_port_subscribe *subs = arg;
        int result;

        struct snd_seq_client *receiver __free(snd_seq_client) =
                snd_seq_client_use_ptr(subs->dest.client);
        if (!receiver)
                return -ENXIO;
        struct snd_seq_client *sender __free(snd_seq_client) =
                snd_seq_client_use_ptr(subs->sender.client);
        if (!sender)
                return -ENXIO;
        struct snd_seq_client_port *sport __free(snd_seq_port) =
                snd_seq_port_use_ptr(sender, subs->sender.port);
        if (!sport)
                return -ENXIO;
        struct snd_seq_client_port *dport __free(snd_seq_port) =
                snd_seq_port_use_ptr(receiver, subs->dest.port);
        if (!dport)
                return -ENXIO;

        result = check_subscription_permission(client, sport, dport, subs);
        if (result < 0)
                return result;

        result = snd_seq_port_disconnect(client, sender, sport, receiver, dport, subs);
        if (! result) /* broadcast announce */
                snd_seq_client_notify_subscription(SNDRV_SEQ_ADDRESS_SUBSCRIBERS, 0,
                                                   subs, SNDRV_SEQ_EVENT_PORT_UNSUBSCRIBED);
        return result;
}


/* CREATE_QUEUE ioctl() */
static int snd_seq_ioctl_create_queue(struct snd_seq_client *client, void *arg)
{
        struct snd_seq_queue_info *info = arg;
        struct snd_seq_queue *q __free(snd_seq_queue) =
                snd_seq_queue_alloc(client->number, info->locked, info->flags);

        if (IS_ERR(q))
                return PTR_ERR(q);

        info->queue = q->queue;
        info->locked = q->locked;
        info->owner = q->owner;

        /* set queue name */
        if (!info->name[0])
                snprintf(info->name, sizeof(info->name), "Queue-%d", q->queue);
        strscpy(q->name, info->name, sizeof(q->name));

        return 0;
}

/* DELETE_QUEUE ioctl() */
static int snd_seq_ioctl_delete_queue(struct snd_seq_client *client, void *arg)
{
        struct snd_seq_queue_info *info = arg;

        return snd_seq_queue_delete(client->number, info->queue);
}

/* GET_QUEUE_INFO ioctl() */
static int snd_seq_ioctl_get_queue_info(struct snd_seq_client *client,
                                        void *arg)
{
        struct snd_seq_queue_info *info = arg;
        struct snd_seq_queue *q __free(snd_seq_queue) =
                queueptr(info->queue);

        if (q == NULL)
                return -EINVAL;

        memset(info, 0, sizeof(*info));
        info->queue = q->queue;
        info->owner = q->owner;
        info->locked = q->locked;
        strscpy(info->name, q->name, sizeof(info->name));

        return 0;
}

/* SET_QUEUE_INFO ioctl() */
static int snd_seq_ioctl_set_queue_info(struct snd_seq_client *client,
                                        void *arg)
{
        struct snd_seq_queue_info *info = arg;

        if (info->owner != client->number)
                return -EINVAL;

        /* change owner/locked permission */
        if (snd_seq_queue_check_access(info->queue, client->number)) {
                if (snd_seq_queue_set_owner(info->queue, client->number, info->locked) < 0)
                        return -EPERM;
                if (info->locked)
                        snd_seq_queue_use(info->queue, client->number, 1);
        } else {
                return -EPERM;
        }       

        struct snd_seq_queue *q __free(snd_seq_queue) =
                queueptr(info->queue);
        if (! q)
                return -EINVAL;
        if (q->owner != client->number)
                return -EPERM;
        strscpy(q->name, info->name, sizeof(q->name));

        return 0;
}

/* GET_NAMED_QUEUE ioctl() */
static int snd_seq_ioctl_get_named_queue(struct snd_seq_client *client,
                                         void *arg)
{
        struct snd_seq_queue_info *info = arg;
        struct snd_seq_queue *q __free(snd_seq_queue) =
                snd_seq_queue_find_name(info->name);

        if (q == NULL)
                return -EINVAL;
        info->queue = q->queue;
        info->owner = q->owner;
        info->locked = q->locked;

        return 0;
}

/* GET_QUEUE_STATUS ioctl() */
static int snd_seq_ioctl_get_queue_status(struct snd_seq_client *client,
                                          void *arg)
{
        struct snd_seq_queue_status *status = arg;
        struct snd_seq_timer *tmr;
        struct snd_seq_queue *queue __free(snd_seq_queue) =
                queueptr(status->queue);

        if (queue == NULL)
                return -EINVAL;
        memset(status, 0, sizeof(*status));
        status->queue = queue->queue;
        
        tmr = queue->timer;
        status->events = queue->tickq->cells + queue->timeq->cells;

        status->time = snd_seq_timer_get_cur_time(tmr, true);
        status->tick = snd_seq_timer_get_cur_tick(tmr);

        status->running = tmr->running;

        status->flags = queue->flags;

        return 0;
}


/* GET_QUEUE_TEMPO ioctl() */
static int snd_seq_ioctl_get_queue_tempo(struct snd_seq_client *client,
                                         void *arg)
{
        struct snd_seq_queue_tempo *tempo = arg;
        struct snd_seq_timer *tmr;
        struct snd_seq_queue *queue __free(snd_seq_queue) =
                queueptr(tempo->queue);

        if (queue == NULL)
                return -EINVAL;
        memset(tempo, 0, sizeof(*tempo));
        tempo->queue = queue->queue;
        
        tmr = queue->timer;

        tempo->tempo = tmr->tempo;
        tempo->ppq = tmr->ppq;
        tempo->skew_value = tmr->skew;
        tempo->skew_base = tmr->skew_base;
        if (client->user_pversion >= SNDRV_PROTOCOL_VERSION(1, 0, 4))
                tempo->tempo_base = tmr->tempo_base;

        return 0;
}


/* SET_QUEUE_TEMPO ioctl() */
int snd_seq_set_queue_tempo(int client, struct snd_seq_queue_tempo *tempo)
{
        if (!snd_seq_queue_check_access(tempo->queue, client))
                return -EPERM;
        return snd_seq_queue_timer_set_tempo(tempo->queue, client, tempo);
}
EXPORT_SYMBOL(snd_seq_set_queue_tempo);

static int snd_seq_ioctl_set_queue_tempo(struct snd_seq_client *client,
                                         void *arg)
{
        struct snd_seq_queue_tempo *tempo = arg;
        int result;

        if (client->user_pversion < SNDRV_PROTOCOL_VERSION(1, 0, 4))
                tempo->tempo_base = 0;
        result = snd_seq_set_queue_tempo(client->number, tempo);
        return result < 0 ? result : 0;
}


/* GET_QUEUE_TIMER ioctl() */
static int snd_seq_ioctl_get_queue_timer(struct snd_seq_client *client,
                                         void *arg)
{
        struct snd_seq_queue_timer *timer = arg;
        struct snd_seq_timer *tmr;
        struct snd_seq_queue *queue __free(snd_seq_queue) =
                queueptr(timer->queue);

        if (queue == NULL)
                return -EINVAL;

        guard(mutex)(&queue->timer_mutex);
        tmr = queue->timer;
        memset(timer, 0, sizeof(*timer));
        timer->queue = queue->queue;

        timer->type = tmr->type;
        if (tmr->type == SNDRV_SEQ_TIMER_ALSA) {
                timer->u.alsa.id = tmr->alsa_id;
                timer->u.alsa.resolution = tmr->preferred_resolution;
        }
        
        return 0;
}


/* SET_QUEUE_TIMER ioctl() */
static int snd_seq_ioctl_set_queue_timer(struct snd_seq_client *client,
                                         void *arg)
{
        struct snd_seq_queue_timer *timer = arg;
        int result = 0;

        if (timer->type != SNDRV_SEQ_TIMER_ALSA)
                return -EINVAL;

        if (snd_seq_queue_check_access(timer->queue, client->number)) {
                struct snd_seq_timer *tmr;
                struct snd_seq_queue *q __free(snd_seq_queue) =
                        queueptr(timer->queue);

                if (q == NULL)
                        return -ENXIO;
                guard(mutex)(&q->timer_mutex);
                tmr = q->timer;
                snd_seq_queue_timer_close(timer->queue);
                tmr->type = timer->type;
                if (tmr->type == SNDRV_SEQ_TIMER_ALSA) {
                        tmr->alsa_id = timer->u.alsa.id;
                        tmr->preferred_resolution = timer->u.alsa.resolution;
                }
                result = snd_seq_queue_timer_open(timer->queue);
        } else {
                return -EPERM;
        }       

        return result;
}


/* GET_QUEUE_CLIENT ioctl() */
static int snd_seq_ioctl_get_queue_client(struct snd_seq_client *client,
                                          void *arg)
{
        struct snd_seq_queue_client *info = arg;
        int used;

        used = snd_seq_queue_is_used(info->queue, client->number);
        if (used < 0)
                return -EINVAL;
        info->used = used;
        info->client = client->number;

        return 0;
}


/* SET_QUEUE_CLIENT ioctl() */
static int snd_seq_ioctl_set_queue_client(struct snd_seq_client *client,
                                          void *arg)
{
        struct snd_seq_queue_client *info = arg;
        int err;

        if (info->used >= 0) {
                err = snd_seq_queue_use(info->queue, client->number, info->used);
                if (err < 0)
                        return err;
        }

        return snd_seq_ioctl_get_queue_client(client, arg);
}


/* GET_CLIENT_POOL ioctl() */
static int snd_seq_ioctl_get_client_pool(struct snd_seq_client *client,
                                         void *arg)
{
        struct snd_seq_client_pool *info = arg;
        struct snd_seq_client *cptr __free(snd_seq_client) =
                client_load_and_use_ptr(info->client);

        if (cptr == NULL)
                return -ENOENT;
        memset(info, 0, sizeof(*info));
        info->client = cptr->number;
        info->output_pool = cptr->pool->size;
        info->output_room = cptr->pool->room;
        info->output_free = info->output_pool;
        info->output_free = snd_seq_unused_cells(cptr->pool);
        if (cptr->type == USER_CLIENT) {
                info->input_pool = cptr->data.user.fifo_pool_size;
                info->input_free = info->input_pool;
                info->input_free = snd_seq_fifo_unused_cells(cptr->data.user.fifo);
        } else {
                info->input_pool = 0;
                info->input_free = 0;
        }
        
        return 0;
}

/* SET_CLIENT_POOL ioctl() */
static int snd_seq_ioctl_set_client_pool(struct snd_seq_client *client,
                                         void *arg)
{
        struct snd_seq_client_pool *info = arg;
        int rc;

        if (client->number != info->client)
                return -EINVAL; /* can't change other clients */

        if (info->output_pool >= 1 && info->output_pool <= SNDRV_SEQ_MAX_EVENTS &&
            (! snd_seq_write_pool_allocated(client) ||
             info->output_pool != client->pool->size)) {
                if (snd_seq_write_pool_allocated(client)) {
                        /* is the pool in use? */
                        if (atomic_read(&client->pool->counter))
                                return -EBUSY;
                        /* remove all existing cells */
                        snd_seq_pool_mark_closing(client->pool);
                        snd_seq_pool_done(client->pool);
                }
                client->pool->size = info->output_pool;
                rc = snd_seq_pool_init(client->pool);
                if (rc < 0)
                        return rc;
        }
        if (client->type == USER_CLIENT && client->data.user.fifo != NULL &&
            info->input_pool >= 1 &&
            info->input_pool <= SNDRV_SEQ_MAX_CLIENT_EVENTS &&
            info->input_pool != client->data.user.fifo_pool_size) {
                /* change pool size */
                rc = snd_seq_fifo_resize(client->data.user.fifo, info->input_pool);
                if (rc < 0)
                        return rc;
                client->data.user.fifo_pool_size = info->input_pool;
        }
        if (info->output_room >= 1 &&
            info->output_room <= client->pool->size) {
                client->pool->room  = info->output_room;
        }

        return snd_seq_ioctl_get_client_pool(client, arg);
}


/* REMOVE_EVENTS ioctl() */
static int snd_seq_ioctl_remove_events(struct snd_seq_client *client,
                                       void *arg)
{
        struct snd_seq_remove_events *info = arg;

        /*
         * Input mostly not implemented XXX.
         */
        if (info->remove_mode & SNDRV_SEQ_REMOVE_INPUT) {
                /*
                 * No restrictions so for a user client we can clear
                 * the whole fifo
                 */
                if (client->type == USER_CLIENT && client->data.user.fifo)
                        snd_seq_fifo_clear(client->data.user.fifo);
        }

        if (info->remove_mode & SNDRV_SEQ_REMOVE_OUTPUT)
                snd_seq_queue_remove_cells(client->number, info);

        return 0;
}


/*
 * get subscription info
 */
static int snd_seq_ioctl_get_subscription(struct snd_seq_client *client,
                                          void *arg)
{
        struct snd_seq_port_subscribe *subs = arg;

        struct snd_seq_client *sender __free(snd_seq_client) =
                client_load_and_use_ptr(subs->sender.client);
        if (!sender)
                return -EINVAL;
        struct snd_seq_client_port *sport __free(snd_seq_port) =
                snd_seq_port_use_ptr(sender, subs->sender.port);
        if (!sport)
                return -EINVAL;
        return snd_seq_port_get_subscription(&sport->c_src, &subs->dest, subs);
}


/*
 * get subscription info - check only its presence
 */
static int snd_seq_ioctl_query_subs(struct snd_seq_client *client, void *arg)
{
        struct snd_seq_query_subs *subs = arg;
        struct snd_seq_port_subs_info *group;
        struct list_head *p;
        int i;

        struct snd_seq_client *cptr __free(snd_seq_client) =
                client_load_and_use_ptr(subs->root.client);
        if (!cptr)
                return -ENXIO;
        struct snd_seq_client_port *port __free(snd_seq_port) =
                snd_seq_port_use_ptr(cptr, subs->root.port);
        if (!port)
                return -ENXIO;

        switch (subs->type) {
        case SNDRV_SEQ_QUERY_SUBS_READ:
                group = &port->c_src;
                break;
        case SNDRV_SEQ_QUERY_SUBS_WRITE:
                group = &port->c_dest;
                break;
        default:
                return -ENXIO;
        }

        guard(rwsem_read)(&group->list_mutex);
        /* search for the subscriber */
        subs->num_subs = group->count;
        i = 0;
        list_for_each(p, &group->list_head) {
                if (i++ == subs->index) {
                        /* found! */
                        struct snd_seq_subscribers *s;
                        if (subs->type == SNDRV_SEQ_QUERY_SUBS_READ) {
                                s = list_entry(p, struct snd_seq_subscribers, src_list);
                                subs->addr = s->info.dest;
                        } else {
                                s = list_entry(p, struct snd_seq_subscribers, dest_list);
                                subs->addr = s->info.sender;
                        }
                        subs->flags = s->info.flags;
                        subs->queue = s->info.queue;
                        return 0;
                }
        }

        return -ENOENT;
}


/*
 * query next client
 */
static int snd_seq_ioctl_query_next_client(struct snd_seq_client *client,
                                           void *arg)
{
        struct snd_seq_client_info *info = arg;

        /* search for next client */
        if (info->client < INT_MAX)
                info->client++;
        if (info->client < 0)
                info->client = 0;
        for (; info->client < SNDRV_SEQ_MAX_CLIENTS; info->client++) {
                struct snd_seq_client *cptr __free(snd_seq_client) =
                        client_load_and_use_ptr(info->client);
                if (cptr) {
                        get_client_info(cptr, info);
                        return 0; /* found */
                }
        }
        return -ENOENT;
}

/* 
 * query next port
 */
static int snd_seq_ioctl_query_next_port(struct snd_seq_client *client,
                                         void *arg)
{
        struct snd_seq_port_info *info = arg;

        struct snd_seq_client *cptr __free(snd_seq_client) =
                client_load_and_use_ptr(info->addr.client);
        if (cptr == NULL)
                return -ENXIO;

        /* search for next port */
        info->addr.port++;
        struct snd_seq_client_port *port __free(snd_seq_port) =
                snd_seq_port_query_nearest(cptr, info);
        if (port == NULL)
                return -ENOENT;

        /* get port info */
        info->addr = port->addr;
        snd_seq_get_port_info(port, info);

        return 0;
}

#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
#define NUM_UMP_INFOS (SNDRV_UMP_MAX_BLOCKS + 1)

static void free_ump_info(struct snd_seq_client *client)
{
        int i;

        if (!client->ump_info)
                return;
        for (i = 0; i < NUM_UMP_INFOS; i++)
                kfree(client->ump_info[i]);
        kfree(client->ump_info);
        client->ump_info = NULL;
}

static void terminate_ump_info_strings(void *p, int type)
{
        if (type == SNDRV_SEQ_CLIENT_UMP_INFO_ENDPOINT) {
                struct snd_ump_endpoint_info *ep = p;
                ep->name[sizeof(ep->name) - 1] = 0;
        } else {
                struct snd_ump_block_info *bp = p;
                bp->name[sizeof(bp->name) - 1] = 0;
        }
}

#ifdef CONFIG_SND_PROC_FS
static void dump_ump_info(struct snd_info_buffer *buffer,
                          struct snd_seq_client *client)
{
        struct snd_ump_endpoint_info *ep;
        struct snd_ump_block_info *bp;
        int i;

        if (!client->ump_info)
                return;
        ep = client->ump_info[SNDRV_SEQ_CLIENT_UMP_INFO_ENDPOINT];
        if (ep && *ep->name)
                snd_iprintf(buffer, "  UMP Endpoint: \"%s\"\n", ep->name);
        for (i = 0; i < SNDRV_UMP_MAX_BLOCKS; i++) {
                bp = client->ump_info[i + 1];
                if (bp && *bp->name) {
                        snd_iprintf(buffer, "  UMP Block %d: \"%s\" [%s]\n",
                                    i, bp->name,
                                    bp->active ? "Active" : "Inactive");
                        snd_iprintf(buffer, "    Groups: %d-%d\n",
                                    bp->first_group + 1,
                                    bp->first_group + bp->num_groups);
                }
        }
}
#endif

/* UMP-specific ioctls -- called directly without data copy */
static int snd_seq_ioctl_client_ump_info(struct snd_seq_client *caller,
                                         unsigned int cmd,
                                         unsigned long arg)
{
        struct snd_seq_client_ump_info __user *argp =
                (struct snd_seq_client_ump_info __user *)arg;
        int client, type, err = 0;
        size_t size;
        void *p;

        if (get_user(client, &argp->client) || get_user(type, &argp->type))
                return -EFAULT;
        if (cmd == SNDRV_SEQ_IOCTL_SET_CLIENT_UMP_INFO &&
            caller->number != client)
                return -EPERM;
        if (type < 0 || type >= NUM_UMP_INFOS)
                return -EINVAL;
        if (type == SNDRV_SEQ_CLIENT_UMP_INFO_ENDPOINT)
                size = sizeof(struct snd_ump_endpoint_info);
        else
                size = sizeof(struct snd_ump_block_info);

        struct snd_seq_client *cptr __free(snd_seq_client) =
                client_load_and_use_ptr(client);
        if (!cptr)
                return -ENOENT;

        scoped_guard(mutex, &cptr->ioctl_mutex) {
                if (!cptr->midi_version) {
                        err = -EBADFD;
                        break;
                }

                if (cmd == SNDRV_SEQ_IOCTL_GET_CLIENT_UMP_INFO) {
                        if (!cptr->ump_info)
                                p = NULL;
                        else
                                p = cptr->ump_info[type];
                        if (!p) {
                                err = -ENODEV;
                                break;
                        }
                        if (copy_to_user(argp->info, p, size)) {
                                err = -EFAULT;
                                break;
                        }
                } else {
                        if (cptr->type != USER_CLIENT) {
                                err = -EBADFD;
                                break;
                        }
                        if (!cptr->ump_info) {
                                cptr->ump_info = kcalloc(NUM_UMP_INFOS,
                                                         sizeof(void *), GFP_KERNEL);
                                if (!cptr->ump_info) {
                                        err = -ENOMEM;
                                        break;
                                }
                        }
                        p = memdup_user(argp->info, size);
                        if (IS_ERR(p)) {
                                err = PTR_ERR(p);
                                break;
                        }
                        kfree(cptr->ump_info[type]);
                        terminate_ump_info_strings(p, type);
                        cptr->ump_info[type] = p;
                }

        }
        if (!err && cmd == SNDRV_SEQ_IOCTL_SET_CLIENT_UMP_INFO) {
                if (type == SNDRV_SEQ_CLIENT_UMP_INFO_ENDPOINT)
                        snd_seq_system_ump_notify(client, 0,
                                                  SNDRV_SEQ_EVENT_UMP_EP_CHANGE,
                                                  false);
                else
                        snd_seq_system_ump_notify(client, type - 1,
                                                  SNDRV_SEQ_EVENT_UMP_BLOCK_CHANGE,
                                                  false);
        }
        return err;
}
#endif

/* -------------------------------------------------------- */

static const struct ioctl_handler {
        unsigned int cmd;
        int (*func)(struct snd_seq_client *client, void *arg);
} ioctl_handlers[] = {
        { SNDRV_SEQ_IOCTL_PVERSION, snd_seq_ioctl_pversion },
        { SNDRV_SEQ_IOCTL_USER_PVERSION, snd_seq_ioctl_user_pversion },
        { SNDRV_SEQ_IOCTL_CLIENT_ID, snd_seq_ioctl_client_id },
        { SNDRV_SEQ_IOCTL_SYSTEM_INFO, snd_seq_ioctl_system_info },
        { SNDRV_SEQ_IOCTL_RUNNING_MODE, snd_seq_ioctl_running_mode },
        { SNDRV_SEQ_IOCTL_GET_CLIENT_INFO, snd_seq_ioctl_get_client_info },
        { SNDRV_SEQ_IOCTL_SET_CLIENT_INFO, snd_seq_ioctl_set_client_info },
        { SNDRV_SEQ_IOCTL_CREATE_PORT, snd_seq_ioctl_create_port },
        { SNDRV_SEQ_IOCTL_DELETE_PORT, snd_seq_ioctl_delete_port },
        { SNDRV_SEQ_IOCTL_GET_PORT_INFO, snd_seq_ioctl_get_port_info },
        { SNDRV_SEQ_IOCTL_SET_PORT_INFO, snd_seq_ioctl_set_port_info },
        { SNDRV_SEQ_IOCTL_SUBSCRIBE_PORT, snd_seq_ioctl_subscribe_port },
        { SNDRV_SEQ_IOCTL_UNSUBSCRIBE_PORT, snd_seq_ioctl_unsubscribe_port },
        { SNDRV_SEQ_IOCTL_CREATE_QUEUE, snd_seq_ioctl_create_queue },
        { SNDRV_SEQ_IOCTL_DELETE_QUEUE, snd_seq_ioctl_delete_queue },
        { SNDRV_SEQ_IOCTL_GET_QUEUE_INFO, snd_seq_ioctl_get_queue_info },
        { SNDRV_SEQ_IOCTL_SET_QUEUE_INFO, snd_seq_ioctl_set_queue_info },
        { SNDRV_SEQ_IOCTL_GET_NAMED_QUEUE, snd_seq_ioctl_get_named_queue },
        { SNDRV_SEQ_IOCTL_GET_QUEUE_STATUS, snd_seq_ioctl_get_queue_status },
        { SNDRV_SEQ_IOCTL_GET_QUEUE_TEMPO, snd_seq_ioctl_get_queue_tempo },
        { SNDRV_SEQ_IOCTL_SET_QUEUE_TEMPO, snd_seq_ioctl_set_queue_tempo },
        { SNDRV_SEQ_IOCTL_GET_QUEUE_TIMER, snd_seq_ioctl_get_queue_timer },
        { SNDRV_SEQ_IOCTL_SET_QUEUE_TIMER, snd_seq_ioctl_set_queue_timer },
        { SNDRV_SEQ_IOCTL_GET_QUEUE_CLIENT, snd_seq_ioctl_get_queue_client },
        { SNDRV_SEQ_IOCTL_SET_QUEUE_CLIENT, snd_seq_ioctl_set_queue_client },
        { SNDRV_SEQ_IOCTL_GET_CLIENT_POOL, snd_seq_ioctl_get_client_pool },
        { SNDRV_SEQ_IOCTL_SET_CLIENT_POOL, snd_seq_ioctl_set_client_pool },
        { SNDRV_SEQ_IOCTL_GET_SUBSCRIPTION, snd_seq_ioctl_get_subscription },
        { SNDRV_SEQ_IOCTL_QUERY_NEXT_CLIENT, snd_seq_ioctl_query_next_client },
        { SNDRV_SEQ_IOCTL_QUERY_NEXT_PORT, snd_seq_ioctl_query_next_port },
        { SNDRV_SEQ_IOCTL_REMOVE_EVENTS, snd_seq_ioctl_remove_events },
        { SNDRV_SEQ_IOCTL_QUERY_SUBS, snd_seq_ioctl_query_subs },
        { 0, NULL },
};

static long snd_seq_ioctl(struct file *file, unsigned int cmd,
                          unsigned long arg)
{
        struct snd_seq_client *client = file->private_data;
        /* To use kernel stack for ioctl data. */
        union {
                int pversion;
                int client_id;
                struct snd_seq_system_info      system_info;
                struct snd_seq_running_info     running_info;
                struct snd_seq_client_info      client_info;
                struct snd_seq_port_info        port_info;
                struct snd_seq_port_subscribe   port_subscribe;
                struct snd_seq_queue_info       queue_info;
                struct snd_seq_queue_status     queue_status;
                struct snd_seq_queue_tempo      tempo;
                struct snd_seq_queue_timer      queue_timer;
                struct snd_seq_queue_client     queue_client;
                struct snd_seq_client_pool      client_pool;
                struct snd_seq_remove_events    remove_events;
                struct snd_seq_query_subs       query_subs;
        } buf;
        const struct ioctl_handler *handler;
        unsigned long size;
        int err;

        if (snd_BUG_ON(!client))
                return -ENXIO;

#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
        /* exception - handling large data */
        switch (cmd) {
        case SNDRV_SEQ_IOCTL_GET_CLIENT_UMP_INFO:
        case SNDRV_SEQ_IOCTL_SET_CLIENT_UMP_INFO:
                return snd_seq_ioctl_client_ump_info(client, cmd, arg);
        }
#endif

        for (handler = ioctl_handlers; handler->cmd > 0; ++handler) {
                if (handler->cmd == cmd)
                        break;
        }
        if (handler->cmd == 0)
                return -ENOTTY;

        memset(&buf, 0, sizeof(buf));

        /*
         * All of ioctl commands for ALSA sequencer get an argument of size
         * within 13 bits. We can safely pick up the size from the command.
         */
        size = _IOC_SIZE(handler->cmd);
        if (handler->cmd & IOC_IN) {
                if (copy_from_user(&buf, (const void __user *)arg, size))
                        return -EFAULT;
        }

        scoped_guard(mutex, &client->ioctl_mutex) {
                err = handler->func(client, &buf);
        }
        if (err >= 0) {
                /* Some commands includes a bug in 'dir' field. */
                if (handler->cmd == SNDRV_SEQ_IOCTL_SET_QUEUE_CLIENT ||
                    handler->cmd == SNDRV_SEQ_IOCTL_SET_CLIENT_POOL ||
                    (handler->cmd & IOC_OUT))
                        if (copy_to_user((void __user *)arg, &buf, size))
                                return -EFAULT;
        }

        return err;
}

#ifdef CONFIG_COMPAT
#include "seq_compat.c"
#else
#define snd_seq_ioctl_compat    NULL
#endif

/* -------------------------------------------------------- */


/* exported to kernel modules */
int snd_seq_create_kernel_client(struct snd_card *card, int client_index,
                                 const char *name_fmt, ...)
{
        struct snd_seq_client *client;
        va_list args;

        if (snd_BUG_ON(in_interrupt()))
                return -EBUSY;

        if (card && client_index >= SNDRV_SEQ_CLIENTS_PER_CARD)
                return -EINVAL;
        if (card == NULL && client_index >= SNDRV_SEQ_GLOBAL_CLIENTS)
                return -EINVAL;

        scoped_guard(mutex, &register_mutex) {

                if (card) {
                        client_index += SNDRV_SEQ_GLOBAL_CLIENTS
                                + card->number * SNDRV_SEQ_CLIENTS_PER_CARD;
                        if (client_index >= SNDRV_SEQ_DYNAMIC_CLIENTS_BEGIN)
                                client_index = -1;
                }

                /* empty write queue as default */
                client = seq_create_client1(client_index, 0);
                if (client == NULL)
                        return -EBUSY;  /* failure code */
                usage_alloc(&client_usage, 1);

                client->accept_input = 1;
                client->accept_output = 1;
                client->data.kernel.card = card;
                client->user_pversion = SNDRV_SEQ_VERSION;
                
                va_start(args, name_fmt);
                vsnprintf(client->name, sizeof(client->name), name_fmt, args);
                va_end(args);

                client->type = KERNEL_CLIENT;
        }

        /* make others aware this new client */
        snd_seq_system_client_ev_client_start(client->number);
        
        /* return client number to caller */
        return client->number;
}
EXPORT_SYMBOL(snd_seq_create_kernel_client);

/* exported to kernel modules */
int snd_seq_delete_kernel_client(int client)
{
        struct snd_seq_client *ptr;

        if (snd_BUG_ON(in_interrupt()))
                return -EBUSY;

        ptr = clientptr(client);
        if (ptr == NULL)
                return -EINVAL;

        seq_free_client(ptr);
        kfree(ptr);
        return 0;
}
EXPORT_SYMBOL(snd_seq_delete_kernel_client);

/*
 * exported, called by kernel clients to enqueue events (w/o blocking)
 *
 * RETURN VALUE: zero if succeed, negative if error
 */
int snd_seq_kernel_client_enqueue(int client, struct snd_seq_event *ev,
                                  struct file *file, bool blocking)
{
        if (snd_BUG_ON(!ev))
                return -EINVAL;

        if (!snd_seq_ev_is_ump(ev)) {
                if (ev->type == SNDRV_SEQ_EVENT_NONE)
                        return 0; /* ignore this */
                if (ev->type == SNDRV_SEQ_EVENT_KERNEL_ERROR)
                        return -EINVAL; /* quoted events can't be enqueued */
        }

        /* fill in client number */
        ev->source.client = client;

        if (check_event_type_and_length(ev))
                return -EINVAL;

        struct snd_seq_client *cptr __free(snd_seq_client) =
                client_load_and_use_ptr(client);
        if (cptr == NULL)
                return -EINVAL;
        
        if (!cptr->accept_output) {
                return -EPERM;
        } else { /* send it */
                guard(mutex)(&cptr->ioctl_mutex);
                return snd_seq_client_enqueue_event(cptr, ev, file, blocking,
                                                    false, 0,
                                                    &cptr->ioctl_mutex);
        }
}
EXPORT_SYMBOL(snd_seq_kernel_client_enqueue);

/* 
 * exported, called by kernel clients to dispatch events directly to other
 * clients, bypassing the queues.  Event time-stamp will be updated.
 *
 * RETURN VALUE: negative = delivery failed,
 *               zero, or positive: the number of delivered events
 */
int snd_seq_kernel_client_dispatch(int client, struct snd_seq_event * ev,
                                   int atomic, int hop)
{
        if (snd_BUG_ON(!ev))
                return -EINVAL;

        /* fill in client number */
        ev->queue = SNDRV_SEQ_QUEUE_DIRECT;
        ev->source.client = client;

        if (check_event_type_and_length(ev))
                return -EINVAL;

        struct snd_seq_client *cptr __free(snd_seq_client) =
                snd_seq_client_use_ptr(client);
        if (cptr == NULL)
                return -EINVAL;

        if (!cptr->accept_output)
                return -EPERM;
        else
                return snd_seq_deliver_event(cptr, ev, atomic, hop);
}
EXPORT_SYMBOL(snd_seq_kernel_client_dispatch);

static int call_seq_client_ctl(struct snd_seq_client *client,
                               unsigned int cmd, void *arg)
{
        const struct ioctl_handler *handler;

        for (handler = ioctl_handlers; handler->cmd > 0; ++handler) {
                if (handler->cmd == cmd)
                        return handler->func(client, arg);
        }

        pr_debug("ALSA: seq unknown ioctl() 0x%x (type='%c', number=0x%02x)\n",
                 cmd, _IOC_TYPE(cmd), _IOC_NR(cmd));
        return -ENOTTY;
}

/**
 * snd_seq_kernel_client_ctl - operate a command for a client with data in
 *                             kernel space.
 * @clientid:   A numerical ID for a client.
 * @cmd:        An ioctl(2) command for ALSA sequencer operation.
 * @arg:        A pointer to data in kernel space.
 *
 * Against its name, both kernel/application client can be handled by this
 * kernel API. A pointer of 'arg' argument should be in kernel space.
 *
 * Return: 0 at success. Negative error code at failure.
 */
int snd_seq_kernel_client_ctl(int clientid, unsigned int cmd, void *arg)
{
        struct snd_seq_client *client;

        client = clientptr(clientid);
        if (client == NULL)
                return -ENXIO;

        return call_seq_client_ctl(client, cmd, arg);
}
EXPORT_SYMBOL(snd_seq_kernel_client_ctl);

/* a similar like above but taking locks; used only from OSS sequencer layer */
int snd_seq_kernel_client_ioctl(int clientid, unsigned int cmd, void *arg)
{
        struct snd_seq_client *client __free(snd_seq_client) =
                client_load_and_use_ptr(clientid);

        if (!client)
                return -ENXIO;
        guard(mutex)(&client->ioctl_mutex);
        return call_seq_client_ctl(client, cmd, arg);
}
EXPORT_SYMBOL_GPL(snd_seq_kernel_client_ioctl);

/* exported (for OSS emulator) */
int snd_seq_kernel_client_write_poll(int clientid, struct file *file, poll_table *wait)
{
        struct snd_seq_client *client;

        client = clientptr(clientid);
        if (client == NULL)
                return -ENXIO;

        if (snd_seq_pool_poll_wait(client->pool, file, wait))
                return 1;
        return 0;
}
EXPORT_SYMBOL(snd_seq_kernel_client_write_poll);

/* get a sequencer client object; for internal use from a kernel client */
struct snd_seq_client *snd_seq_kernel_client_get(int id)
{
        return snd_seq_client_use_ptr(id);
}
EXPORT_SYMBOL_GPL(snd_seq_kernel_client_get);

/* put a sequencer client object; for internal use from a kernel client */
void snd_seq_kernel_client_put(struct snd_seq_client *cptr)
{
        if (cptr)
                snd_seq_client_unref(cptr);
}
EXPORT_SYMBOL_GPL(snd_seq_kernel_client_put);

/*---------------------------------------------------------------------------*/

#ifdef CONFIG_SND_PROC_FS
/*
 *  /proc interface
 */
static void snd_seq_info_dump_subscribers(struct snd_info_buffer *buffer,
                                          struct snd_seq_port_subs_info *group,
                                          int is_src, char *msg)
{
        struct list_head *p;
        struct snd_seq_subscribers *s;
        int count = 0;

        guard(rwsem_read)(&group->list_mutex);
        if (list_empty(&group->list_head))
                return;
        snd_iprintf(buffer, msg);
        list_for_each(p, &group->list_head) {
                if (is_src)
                        s = list_entry(p, struct snd_seq_subscribers, src_list);
                else
                        s = list_entry(p, struct snd_seq_subscribers, dest_list);
                if (count++)
                        snd_iprintf(buffer, ", ");
                snd_iprintf(buffer, "%d:%d",
                            is_src ? s->info.dest.client : s->info.sender.client,
                            is_src ? s->info.dest.port : s->info.sender.port);
                if (s->info.flags & SNDRV_SEQ_PORT_SUBS_TIMESTAMP)
                        snd_iprintf(buffer, "[%c:%d]", ((s->info.flags & SNDRV_SEQ_PORT_SUBS_TIME_REAL) ? 'r' : 't'), s->info.queue);
                if (group->exclusive)
                        snd_iprintf(buffer, "[ex]");
        }
        snd_iprintf(buffer, "\n");
}

#define FLAG_PERM_RD(perm) ((perm) & SNDRV_SEQ_PORT_CAP_READ ? ((perm) & SNDRV_SEQ_PORT_CAP_SUBS_READ ? 'R' : 'r') : '-')
#define FLAG_PERM_WR(perm) ((perm) & SNDRV_SEQ_PORT_CAP_WRITE ? ((perm) & SNDRV_SEQ_PORT_CAP_SUBS_WRITE ? 'W' : 'w') : '-')
#define FLAG_PERM_EX(perm) ((perm) & SNDRV_SEQ_PORT_CAP_NO_EXPORT ? '-' : 'e')

#define FLAG_PERM_DUPLEX(perm) ((perm) & SNDRV_SEQ_PORT_CAP_DUPLEX ? 'X' : '-')

static const char *port_direction_name(unsigned char dir)
{
        static const char *names[4] = {
                "-", "In", "Out", "In/Out"
        };

        if (dir > SNDRV_SEQ_PORT_DIR_BIDIRECTION)
                return "Invalid";
        return names[dir];
}

static void snd_seq_info_dump_ports(struct snd_info_buffer *buffer,
                                    struct snd_seq_client *client)
{
        struct snd_seq_client_port *p;

        guard(mutex)(&client->ports_mutex);
        list_for_each_entry(p, &client->ports_list_head, list) {
                if (p->capability & SNDRV_SEQ_PORT_CAP_INACTIVE)
                        continue;
                snd_iprintf(buffer, "  Port %3d : \"%s\" (%c%c%c%c) [%s]",
                            p->addr.port, p->name,
                            FLAG_PERM_RD(p->capability),
                            FLAG_PERM_WR(p->capability),
                            FLAG_PERM_EX(p->capability),
                            FLAG_PERM_DUPLEX(p->capability),
                            port_direction_name(p->direction));
#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
                if (snd_seq_client_is_midi2(client) && p->is_midi1)
                        snd_iprintf(buffer, " [MIDI1]");
#endif
                snd_iprintf(buffer, "\n");
                snd_seq_info_dump_subscribers(buffer, &p->c_src, 1, "    Connecting To: ");
                snd_seq_info_dump_subscribers(buffer, &p->c_dest, 0, "    Connected From: ");
        }
}

static const char *midi_version_string(unsigned int version)
{
        switch (version) {
        case SNDRV_SEQ_CLIENT_LEGACY_MIDI:
                return "Legacy";
        case SNDRV_SEQ_CLIENT_UMP_MIDI_1_0:
                return "UMP MIDI1";
        case SNDRV_SEQ_CLIENT_UMP_MIDI_2_0:
                return "UMP MIDI2";
        default:
                return "Unknown";
        }
}

/* exported to seq_info.c */
void snd_seq_info_clients_read(struct snd_info_entry *entry, 
                               struct snd_info_buffer *buffer)
{
        int c;

        snd_iprintf(buffer, "Client info\n");
        snd_iprintf(buffer, "  cur  clients : %d\n", client_usage.cur);
        snd_iprintf(buffer, "  peak clients : %d\n", client_usage.peak);
        snd_iprintf(buffer, "  max  clients : %d\n", SNDRV_SEQ_MAX_CLIENTS);
        snd_iprintf(buffer, "\n");

        /* list the client table */
        for (c = 0; c < SNDRV_SEQ_MAX_CLIENTS; c++) {
                struct snd_seq_client *client __free(snd_seq_client) =
                        client_load_and_use_ptr(c);

                if (client == NULL)
                        continue;
                if (client->type == NO_CLIENT)
                        continue;

                guard(mutex)(&client->ioctl_mutex);
                snd_iprintf(buffer, "Client %3d : \"%s\" [%s %s]\n",
                            c, client->name,
                            client->type == USER_CLIENT ? "User" : "Kernel",
                            midi_version_string(client->midi_version));
#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
                dump_ump_info(buffer, client);
#endif
                snd_seq_info_dump_ports(buffer, client);
                if (snd_seq_write_pool_allocated(client)) {
                        snd_iprintf(buffer, "  Output pool :\n");
                        snd_seq_info_pool(buffer, client->pool, "    ");
                }
                if (client->type == USER_CLIENT && client->data.user.fifo &&
                    client->data.user.fifo->pool) {
                        snd_iprintf(buffer, "  Input pool :\n");
                        snd_seq_info_pool(buffer, client->data.user.fifo->pool, "    ");
                }
        }
}
#endif /* CONFIG_SND_PROC_FS */

/*---------------------------------------------------------------------------*/


/*
 *  REGISTRATION PART
 */

static const struct file_operations snd_seq_f_ops =
{
        .owner =        THIS_MODULE,
        .read =         snd_seq_read,
        .write =        snd_seq_write,
        .open =         snd_seq_open,
        .release =      snd_seq_release,
        .poll =         snd_seq_poll,
        .unlocked_ioctl =       snd_seq_ioctl,
        .compat_ioctl = snd_seq_ioctl_compat,
};

static struct device *seq_dev;

/* 
 * register sequencer device 
 */
int __init snd_sequencer_device_init(void)
{
        int err;

        err = snd_device_alloc(&seq_dev, NULL);
        if (err < 0)
                return err;
        dev_set_name(seq_dev, "seq");

        scoped_guard(mutex, &register_mutex) {
                err = snd_register_device(SNDRV_DEVICE_TYPE_SEQUENCER, NULL, 0,
                                          &snd_seq_f_ops, NULL, seq_dev);
        }
        if (err < 0) {
                put_device(seq_dev);
                return err;
        }
        
        return 0;
}



/* 
 * unregister sequencer device 
 */
void snd_sequencer_device_done(void)
{
        snd_unregister_device(seq_dev);
        put_device(seq_dev);
}