// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  ALSA sequencer Memory Manager
 *  Copyright (c) 1998 by Frank van de Pol <fvdpol@coil.demon.nl>
 *                        Jaroslav Kysela <perex@perex.cz>
 *                2000 by Takashi Iwai <tiwai@suse.de>
 */

#include <linux/init.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/sched/signal.h>
#include <linux/mm.h>
#include <sound/core.h>

#include <sound/seq_kernel.h>
#include "seq_memory.h"
#include "seq_queue.h"
#include "seq_info.h"
#include "seq_lock.h"

static inline int snd_seq_pool_available(struct snd_seq_pool *pool)
{
        return pool->total_elements - atomic_read(&pool->counter);
}

static inline int snd_seq_output_ok(struct snd_seq_pool *pool)
{
        return snd_seq_pool_available(pool) >= pool->room;
}

/*
 * Variable length event:
 * The event like sysex uses variable length type.
 * The external data may be stored in three different formats.
 * 1) kernel space
 *    This is the normal case.
 *      ext.data.len = length
 *      ext.data.ptr = buffer pointer
 * 2) user space
 *    When an event is generated via read(), the external data is
 *    kept in user space until expanded.
 *      ext.data.len = length | SNDRV_SEQ_EXT_USRPTR
 *      ext.data.ptr = userspace pointer
 * 3) chained cells
 *    When the variable length event is enqueued (in prioq or fifo),
 *    the external data is decomposed to several cells.
 *      ext.data.len = length | SNDRV_SEQ_EXT_CHAINED
 *      ext.data.ptr = the additiona cell head
 *         -> cell.next -> cell.next -> ..
 */

/*
 * exported:
 * call dump function to expand external data.
 */

static int get_var_len(const struct snd_seq_event *event)
{
        if ((event->flags & SNDRV_SEQ_EVENT_LENGTH_MASK) != SNDRV_SEQ_EVENT_LENGTH_VARIABLE)
                return -EINVAL;

        return event->data.ext.len & ~SNDRV_SEQ_EXT_MASK;
}

static int dump_var_event(const struct snd_seq_event *event,
                          snd_seq_dump_func_t func, void *private_data,
                          int offset, int maxlen)
{
        int len, err;
        struct snd_seq_event_cell *cell;

        len = get_var_len(event);
        if (len <= 0)
                return len;
        if (len <= offset)
                return 0;
        if (maxlen && len > offset + maxlen)
                len = offset + maxlen;

        if (event->data.ext.len & SNDRV_SEQ_EXT_USRPTR) {
                char buf[32];
                char __user *curptr = (char __force __user *)event->data.ext.ptr;
                curptr += offset;
                len -= offset;
                while (len > 0) {
                        int size = sizeof(buf);
                        if (len < size)
                                size = len;
                        if (copy_from_user(buf, curptr, size))
                                return -EFAULT;
                        err = func(private_data, buf, size);
                        if (err < 0)
                                return err;
                        curptr += size;
                        len -= size;
                }
                return 0;
        }
        if (!(event->data.ext.len & SNDRV_SEQ_EXT_CHAINED))
                return func(private_data, event->data.ext.ptr + offset,
                            len - offset);

        cell = (struct snd_seq_event_cell *)event->data.ext.ptr;
        for (; len > 0 && cell; cell = cell->next) {
                int size = sizeof(struct snd_seq_event);
                char *curptr = (char *)&cell->event;

                if (offset >= size) {
                        offset -= size;
                        len -= size;
                        continue;
                }
                if (len < size)
                        size = len;
                err = func(private_data, curptr + offset, size - offset);
                if (err < 0)
                        return err;
                offset = 0;
                len -= size;
        }
        return 0;
}

int snd_seq_dump_var_event(const struct snd_seq_event *event,
                           snd_seq_dump_func_t func, void *private_data)
{
        return dump_var_event(event, func, private_data, 0, 0);
}
EXPORT_SYMBOL(snd_seq_dump_var_event);


/*
 * exported:
 * expand the variable length event to linear buffer space.
 */

static int seq_copy_in_kernel(void *ptr, void *src, int size)
{
        char **bufptr = ptr;

        memcpy(*bufptr, src, size);
        *bufptr += size;
        return 0;
}

static int seq_copy_in_user(void *ptr, void *src, int size)
{
        char __user **bufptr = ptr;

        if (copy_to_user(*bufptr, src, size))
                return -EFAULT;
        *bufptr += size;
        return 0;
}

static int expand_var_event(const struct snd_seq_event *event,
                            int offset, int size, char *buf, bool in_kernel)
{
        if (event->data.ext.len & SNDRV_SEQ_EXT_USRPTR) {
                if (! in_kernel)
                        return -EINVAL;
                if (copy_from_user(buf,
                                   (char __force __user *)event->data.ext.ptr + offset,
                                   size))
                        return -EFAULT;
                return 0;
        }
        return dump_var_event(event,
                             in_kernel ? seq_copy_in_kernel : seq_copy_in_user,
                             &buf, offset, size);
}

int snd_seq_expand_var_event(const struct snd_seq_event *event, int count, char *buf,
                             int in_kernel, int size_aligned)
{
        int len, newlen, err;

        len = get_var_len(event);
        if (len < 0)
                return len;
        newlen = len;
        if (size_aligned > 0)
                newlen = roundup(len, size_aligned);
        if (count < newlen)
                return -EAGAIN;
        err = expand_var_event(event, 0, len, buf, in_kernel);
        if (err < 0)
                return err;
        if (len != newlen) {
                if (in_kernel)
                        memset(buf + len, 0, newlen - len);
                else if (clear_user((__force void __user *)buf + len,
                                    newlen - len))
                        return -EFAULT;
        }
        return newlen;
}
EXPORT_SYMBOL(snd_seq_expand_var_event);

int snd_seq_expand_var_event_at(const struct snd_seq_event *event, int count,
                                char *buf, int offset)
{
        int len, err;

        len = get_var_len(event);
        if (len < 0)
                return len;
        if (len <= offset)
                return 0;
        len -= offset;
        if (len > count)
                len = count;
        err = expand_var_event(event, offset, count, buf, true);
        if (err < 0)
                return err;
        return len;
}
EXPORT_SYMBOL_GPL(snd_seq_expand_var_event_at);

/*
 * release this cell, free extended data if available
 */

static inline void free_cell(struct snd_seq_pool *pool,
                             struct snd_seq_event_cell *cell)
{
        cell->next = pool->free;
        pool->free = cell;
        atomic_dec(&pool->counter);
}

void snd_seq_cell_free(struct snd_seq_event_cell * cell)
{
        struct snd_seq_pool *pool;

        if (snd_BUG_ON(!cell))
                return;
        pool = cell->pool;
        if (snd_BUG_ON(!pool))
                return;

        guard(spinlock_irqsave)(&pool->lock);
        free_cell(pool, cell);
        if (snd_seq_ev_is_variable(&cell->event)) {
                if (cell->event.data.ext.len & SNDRV_SEQ_EXT_CHAINED) {
                        struct snd_seq_event_cell *curp, *nextptr;
                        curp = cell->event.data.ext.ptr;
                        for (; curp; curp = nextptr) {
                                nextptr = curp->next;
                                curp->next = pool->free;
                                free_cell(pool, curp);
                        }
                }
        }
        if (waitqueue_active(&pool->output_sleep)) {
                /* has enough space now? */
                if (snd_seq_output_ok(pool))
                        wake_up(&pool->output_sleep);
        }
}


/*
 * allocate an event cell.
 */
static int snd_seq_cell_alloc(struct snd_seq_pool *pool,
                              struct snd_seq_event_cell **cellp,
                              int nonblock, struct file *file,
                              struct mutex *mutexp)
{
        struct snd_seq_event_cell *cell;
        unsigned long flags;
        int err = -EAGAIN;
        wait_queue_entry_t wait;

        if (pool == NULL)
                return -EINVAL;

        *cellp = NULL;

        init_waitqueue_entry(&wait, current);
        spin_lock_irqsave(&pool->lock, flags);
        if (pool->ptr == NULL) {        /* not initialized */
                pr_debug("ALSA: seq: pool is not initialized\n");
                err = -EINVAL;
                goto __error;
        }
        while (pool->free == NULL && ! nonblock && ! pool->closing) {

                set_current_state(TASK_INTERRUPTIBLE);
                add_wait_queue(&pool->output_sleep, &wait);
                spin_unlock_irqrestore(&pool->lock, flags);
                if (mutexp)
                        mutex_unlock(mutexp);
                schedule();
                if (mutexp)
                        mutex_lock(mutexp);
                spin_lock_irqsave(&pool->lock, flags);
                remove_wait_queue(&pool->output_sleep, &wait);
                /* interrupted? */
                if (signal_pending(current)) {
                        err = -ERESTARTSYS;
                        goto __error;
                }
        }
        if (pool->closing) { /* closing.. */
                err = -ENOMEM;
                goto __error;
        }

        cell = pool->free;
        if (cell) {
                int used;
                pool->free = cell->next;
                atomic_inc(&pool->counter);
                used = atomic_read(&pool->counter);
                if (pool->max_used < used)
                        pool->max_used = used;
                pool->event_alloc_success++;
                /* clear cell pointers */
                cell->next = NULL;
                err = 0;
        } else
                pool->event_alloc_failures++;
        *cellp = cell;

__error:
        spin_unlock_irqrestore(&pool->lock, flags);
        return err;
}


/*
 * duplicate the event to a cell.
 * if the event has external data, the data is decomposed to additional
 * cells.
 */
int snd_seq_event_dup(struct snd_seq_pool *pool, struct snd_seq_event *event,
                      struct snd_seq_event_cell **cellp, int nonblock,
                      struct file *file, struct mutex *mutexp)
{
        int ncells, err;
        unsigned int extlen;
        struct snd_seq_event_cell *cell;
        int size;

        *cellp = NULL;

        ncells = 0;
        extlen = 0;
        if (snd_seq_ev_is_variable(event)) {
                extlen = event->data.ext.len & ~SNDRV_SEQ_EXT_MASK;
                ncells = DIV_ROUND_UP(extlen, sizeof(struct snd_seq_event));
        }
        if (ncells >= pool->total_elements)
                return -ENOMEM;

        err = snd_seq_cell_alloc(pool, &cell, nonblock, file, mutexp);
        if (err < 0)
                return err;

        /* copy the event */
        size = snd_seq_event_packet_size(event);
        memcpy(&cell->ump, event, size);
#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
        if (size < sizeof(cell->event))
                cell->ump.raw.extra = 0;
#endif

        /* decompose */
        if (snd_seq_ev_is_variable(event)) {
                int len = extlen;
                int is_chained = event->data.ext.len & SNDRV_SEQ_EXT_CHAINED;
                int is_usrptr = event->data.ext.len & SNDRV_SEQ_EXT_USRPTR;
                struct snd_seq_event_cell *src, *tmp, *tail;
                char *buf;

                cell->event.data.ext.len = extlen | SNDRV_SEQ_EXT_CHAINED;
                cell->event.data.ext.ptr = NULL;

                src = (struct snd_seq_event_cell *)event->data.ext.ptr;
                buf = (char *)event->data.ext.ptr;
                tail = NULL;

                while (ncells-- > 0) {
                        size = sizeof(struct snd_seq_event);
                        if (len < size)
                                size = len;
                        err = snd_seq_cell_alloc(pool, &tmp, nonblock, file,
                                                 mutexp);
                        if (err < 0)
                                goto __error;
                        if (cell->event.data.ext.ptr == NULL)
                                cell->event.data.ext.ptr = tmp;
                        if (tail)
                                tail->next = tmp;
                        tail = tmp;
                        /* copy chunk */
                        if (is_chained && src) {
                                tmp->event = src->event;
                                src = src->next;
                        } else if (is_usrptr) {
                                if (copy_from_user(&tmp->event, (char __force __user *)buf, size)) {
                                        err = -EFAULT;
                                        goto __error;
                                }
                        } else {
                                memcpy(&tmp->event, buf, size);
                        }
                        buf += size;
                        len -= size;
                }
        }

        *cellp = cell;
        return 0;

__error:
        snd_seq_cell_free(cell);
        return err;
}
  

/* poll wait */
int snd_seq_pool_poll_wait(struct snd_seq_pool *pool, struct file *file,
                           poll_table *wait)
{
        poll_wait(file, &pool->output_sleep, wait);
        guard(spinlock_irq)(&pool->lock);
        return snd_seq_output_ok(pool);
}


/* allocate room specified number of events */
int snd_seq_pool_init(struct snd_seq_pool *pool)
{
        int cell;
        struct snd_seq_event_cell *cellptr;

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

        cellptr = kvmalloc_objs(struct snd_seq_event_cell, pool->size);
        if (!cellptr)
                return -ENOMEM;

        /* add new cells to the free cell list */
        guard(spinlock_irq)(&pool->lock);
        if (pool->ptr) {
                kvfree(cellptr);
                return 0;
        }

        pool->ptr = cellptr;
        pool->free = NULL;

        for (cell = 0; cell < pool->size; cell++) {
                cellptr = pool->ptr + cell;
                cellptr->pool = pool;
                cellptr->next = pool->free;
                pool->free = cellptr;
        }
        pool->room = (pool->size + 1) / 2;

        /* init statistics */
        pool->max_used = 0;
        pool->total_elements = pool->size;
        return 0;
}

/* refuse the further insertion to the pool */
void snd_seq_pool_mark_closing(struct snd_seq_pool *pool)
{
        if (snd_BUG_ON(!pool))
                return;
        guard(spinlock_irqsave)(&pool->lock);
        pool->closing = 1;
}

/* remove events */
int snd_seq_pool_done(struct snd_seq_pool *pool)
{
        struct snd_seq_event_cell *ptr;

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

        /* wait for closing all threads */
        if (waitqueue_active(&pool->output_sleep))
                wake_up(&pool->output_sleep);

        while (atomic_read(&pool->counter) > 0)
                schedule_timeout_uninterruptible(1);
        
        /* release all resources */
        scoped_guard(spinlock_irq, &pool->lock) {
                ptr = pool->ptr;
                pool->ptr = NULL;
                pool->free = NULL;
                pool->total_elements = 0;
        }

        kvfree(ptr);

        guard(spinlock_irq)(&pool->lock);
        pool->closing = 0;

        return 0;
}


/* init new memory pool */
struct snd_seq_pool *snd_seq_pool_new(int poolsize)
{
        struct snd_seq_pool *pool;

        /* create pool block */
        pool = kzalloc_obj(*pool);
        if (!pool)
                return NULL;
        spin_lock_init(&pool->lock);
        pool->ptr = NULL;
        pool->free = NULL;
        pool->total_elements = 0;
        atomic_set(&pool->counter, 0);
        pool->closing = 0;
        init_waitqueue_head(&pool->output_sleep);
        
        pool->size = poolsize;

        /* init statistics */
        pool->max_used = 0;
        return pool;
}

/* remove memory pool */
int snd_seq_pool_delete(struct snd_seq_pool **ppool)
{
        struct snd_seq_pool *pool = *ppool;

        *ppool = NULL;
        if (pool == NULL)
                return 0;
        snd_seq_pool_mark_closing(pool);
        snd_seq_pool_done(pool);
        kfree(pool);
        return 0;
}

/* exported to seq_clientmgr.c */
void snd_seq_info_pool(struct snd_info_buffer *buffer,
                       struct snd_seq_pool *pool, char *space)
{
        if (pool == NULL)
                return;
        snd_iprintf(buffer, "%sPool size          : %d\n", space, pool->total_elements);
        snd_iprintf(buffer, "%sCells in use       : %d\n", space, atomic_read(&pool->counter));
        snd_iprintf(buffer, "%sPeak cells in use  : %d\n", space, pool->max_used);
        snd_iprintf(buffer, "%sAlloc success      : %d\n", space, pool->event_alloc_success);
        snd_iprintf(buffer, "%sAlloc failures     : %d\n", space, pool->event_alloc_failures);
}