// SPDX-License-Identifier: GPL-2.0
#include <stdlib.h>
#include <string.h>
#include <malloc.h>
#include <pthread.h>
#include <unistd.h>
#include <assert.h>

#include <linux/gfp.h>
#include <linux/poison.h>
#include <linux/slab.h>
#include <linux/radix-tree.h>
#include <urcu/uatomic.h>

int nr_allocated;
int preempt_count;
int test_verbose;

void kmem_cache_set_callback(struct kmem_cache *cachep, void (*callback)(void *))
{
        cachep->callback = callback;
}

void kmem_cache_set_private(struct kmem_cache *cachep, void *private)
{
        cachep->private = private;
}

void kmem_cache_set_non_kernel(struct kmem_cache *cachep, unsigned int val)
{
        cachep->non_kernel = val;
}

unsigned long kmem_cache_get_alloc(struct kmem_cache *cachep)
{
        return cachep->size * cachep->nr_allocated;
}

unsigned long kmem_cache_nr_allocated(struct kmem_cache *cachep)
{
        return cachep->nr_allocated;
}

unsigned long kmem_cache_nr_tallocated(struct kmem_cache *cachep)
{
        return cachep->nr_tallocated;
}

void kmem_cache_zero_nr_tallocated(struct kmem_cache *cachep)
{
        cachep->nr_tallocated = 0;
}

void *kmem_cache_alloc_lru(struct kmem_cache *cachep, struct list_lru *lru,
                int gfp)
{
        void *p;

        if (cachep->exec_callback) {
                if (cachep->callback)
                        cachep->callback(cachep->private);
                cachep->exec_callback = false;
        }

        if (!(gfp & __GFP_DIRECT_RECLAIM)) {
                if (!cachep->non_kernel) {
                        if (cachep->callback)
                                cachep->exec_callback = true;
                        return NULL;
                }

                cachep->non_kernel--;
        }

        pthread_mutex_lock(&cachep->lock);
        if (cachep->nr_objs) {
                struct radix_tree_node *node = cachep->objs;
                cachep->nr_objs--;
                cachep->objs = node->parent;
                pthread_mutex_unlock(&cachep->lock);
                node->parent = NULL;
                p = node;
        } else {
                pthread_mutex_unlock(&cachep->lock);
                if (cachep->align) {
                        if (posix_memalign(&p, cachep->align, cachep->size) < 0)
                                return NULL;
                } else {
                        p = malloc(cachep->size);
                }

                if (cachep->ctor)
                        cachep->ctor(p);
                else if (gfp & __GFP_ZERO)
                        memset(p, 0, cachep->size);
        }

        uatomic_inc(&cachep->nr_allocated);
        uatomic_inc(&nr_allocated);
        uatomic_inc(&cachep->nr_tallocated);
        if (kmalloc_verbose)
                printf("Allocating %p from slab\n", p);
        return p;
}

void __kmem_cache_free_locked(struct kmem_cache *cachep, void *objp)
{
        assert(objp);
        if (cachep->nr_objs > 10 || cachep->align) {
                memset(objp, POISON_FREE, cachep->size);
                free(objp);
        } else {
                struct radix_tree_node *node = objp;
                cachep->nr_objs++;
                node->parent = cachep->objs;
                cachep->objs = node;
        }
}

void kmem_cache_free_locked(struct kmem_cache *cachep, void *objp)
{
        uatomic_dec(&nr_allocated);
        uatomic_dec(&cachep->nr_allocated);
        if (kmalloc_verbose)
                printf("Freeing %p to slab\n", objp);
        __kmem_cache_free_locked(cachep, objp);
}

void kmem_cache_free(struct kmem_cache *cachep, void *objp)
{
        pthread_mutex_lock(&cachep->lock);
        kmem_cache_free_locked(cachep, objp);
        pthread_mutex_unlock(&cachep->lock);
}

void kmem_cache_free_bulk(struct kmem_cache *cachep, size_t size, void **list)
{
        if (kmalloc_verbose)
                pr_debug("Bulk free %p[0-%zu]\n", list, size - 1);

        if (cachep->exec_callback) {
                if (cachep->callback)
                        cachep->callback(cachep->private);
                cachep->exec_callback = false;
        }

        pthread_mutex_lock(&cachep->lock);
        for (int i = 0; i < size; i++)
                kmem_cache_free_locked(cachep, list[i]);
        pthread_mutex_unlock(&cachep->lock);
}

void kmem_cache_shrink(struct kmem_cache *cachep)
{
}

int kmem_cache_alloc_bulk(struct kmem_cache *cachep, gfp_t gfp, size_t size,
                          void **p)
{
        size_t i;

        if (kmalloc_verbose)
                pr_debug("Bulk alloc %zu\n", size);

        pthread_mutex_lock(&cachep->lock);
        if (cachep->nr_objs >= size) {
                struct radix_tree_node *node;

                for (i = 0; i < size; i++) {
                        if (!(gfp & __GFP_DIRECT_RECLAIM)) {
                                if (!cachep->non_kernel)
                                        break;
                                cachep->non_kernel--;
                        }

                        node = cachep->objs;
                        cachep->nr_objs--;
                        cachep->objs = node->parent;
                        p[i] = node;
                        node->parent = NULL;
                }
                pthread_mutex_unlock(&cachep->lock);
        } else {
                pthread_mutex_unlock(&cachep->lock);
                for (i = 0; i < size; i++) {
                        if (!(gfp & __GFP_DIRECT_RECLAIM)) {
                                if (!cachep->non_kernel)
                                        break;
                                cachep->non_kernel--;
                        }

                        if (cachep->align) {
                                if (posix_memalign(&p[i], cachep->align,
                                               cachep->size) < 0)
                                        break;
                        } else {
                                p[i] = malloc(cachep->size);
                                if (!p[i])
                                        break;
                        }
                        if (cachep->ctor)
                                cachep->ctor(p[i]);
                        else if (gfp & __GFP_ZERO)
                                memset(p[i], 0, cachep->size);
                }
        }

        if (i < size) {
                size = i;
                pthread_mutex_lock(&cachep->lock);
                for (i = 0; i < size; i++)
                        __kmem_cache_free_locked(cachep, p[i]);
                pthread_mutex_unlock(&cachep->lock);
                if (cachep->callback)
                        cachep->exec_callback = true;
                return 0;
        }

        for (i = 0; i < size; i++) {
                uatomic_inc(&nr_allocated);
                uatomic_inc(&cachep->nr_allocated);
                uatomic_inc(&cachep->nr_tallocated);
                if (kmalloc_verbose)
                        printf("Allocating %p from slab\n", p[i]);
        }

        return size;
}

struct kmem_cache *
__kmem_cache_create_args(const char *name, unsigned int size,
                          struct kmem_cache_args *args,
                          unsigned int flags)
{
        struct kmem_cache *ret = malloc(sizeof(*ret));

        pthread_mutex_init(&ret->lock, NULL);
        ret->size = size;
        ret->align = args->align;
        ret->sheaf_capacity = args->sheaf_capacity;
        ret->nr_objs = 0;
        ret->nr_allocated = 0;
        ret->nr_tallocated = 0;
        ret->objs = NULL;
        ret->ctor = args->ctor;
        ret->non_kernel = 0;
        ret->exec_callback = false;
        ret->callback = NULL;
        ret->private = NULL;

        return ret;
}

struct slab_sheaf *
kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned int size)
{
        struct slab_sheaf *sheaf;
        unsigned int capacity;

        if (s->exec_callback) {
                if (s->callback)
                        s->callback(s->private);
                s->exec_callback = false;
        }

        capacity = max(size, s->sheaf_capacity);

        sheaf = calloc(1, sizeof(*sheaf) + sizeof(void *) * capacity);
        if (!sheaf)
                return NULL;

        sheaf->cache = s;
        sheaf->capacity = capacity;
        sheaf->size = kmem_cache_alloc_bulk(s, gfp, size, sheaf->objects);
        if (!sheaf->size) {
                free(sheaf);
                return NULL;
        }

        return sheaf;
}

int kmem_cache_refill_sheaf(struct kmem_cache *s, gfp_t gfp,
                 struct slab_sheaf **sheafp, unsigned int size)
{
        struct slab_sheaf *sheaf = *sheafp;
        int refill;

        if (sheaf->size >= size)
                return 0;

        if (size > sheaf->capacity) {
                sheaf = kmem_cache_prefill_sheaf(s, gfp, size);
                if (!sheaf)
                        return -ENOMEM;

                kmem_cache_return_sheaf(s, gfp, *sheafp);
                *sheafp = sheaf;
                return 0;
        }

        refill = kmem_cache_alloc_bulk(s, gfp, size - sheaf->size,
                                       &sheaf->objects[sheaf->size]);
        if (!refill)
                return -ENOMEM;

        sheaf->size += refill;
        return 0;
}

void kmem_cache_return_sheaf(struct kmem_cache *s, gfp_t gfp,
                 struct slab_sheaf *sheaf)
{
        if (sheaf->size)
                kmem_cache_free_bulk(s, sheaf->size, &sheaf->objects[0]);

        free(sheaf);
}

void *
kmem_cache_alloc_from_sheaf(struct kmem_cache *s, gfp_t gfp,
                struct slab_sheaf *sheaf)
{
        void *obj;

        if (sheaf->size == 0) {
                printf("Nothing left in sheaf!\n");
                return NULL;
        }

        obj = sheaf->objects[--sheaf->size];
        sheaf->objects[sheaf->size] = NULL;

        return obj;
}

/*
 * Test the test infrastructure for kem_cache_alloc/free and bulk counterparts.
 */
void test_kmem_cache_bulk(void)
{
        int i;
        void *list[12];
        static struct kmem_cache *test_cache, *test_cache2;

        /*
         * Testing the bulk allocators without aligned kmem_cache to force the
         * bulk alloc/free to reuse
         */
        test_cache = kmem_cache_create("test_cache", 256, 0, SLAB_PANIC, NULL);

        for (i = 0; i < 5; i++)
                list[i] = kmem_cache_alloc(test_cache, __GFP_DIRECT_RECLAIM);

        for (i = 0; i < 5; i++)
                kmem_cache_free(test_cache, list[i]);
        assert(test_cache->nr_objs == 5);

        kmem_cache_alloc_bulk(test_cache, __GFP_DIRECT_RECLAIM, 5, list);
        kmem_cache_free_bulk(test_cache, 5, list);

        for (i = 0; i < 12 ; i++)
                list[i] = kmem_cache_alloc(test_cache, __GFP_DIRECT_RECLAIM);

        for (i = 0; i < 12; i++)
                kmem_cache_free(test_cache, list[i]);

        /* The last free will not be kept around */
        assert(test_cache->nr_objs == 11);

        /* Aligned caches will immediately free */
        test_cache2 = kmem_cache_create("test_cache2", 128, 128, SLAB_PANIC, NULL);

        kmem_cache_alloc_bulk(test_cache2, __GFP_DIRECT_RECLAIM, 10, list);
        kmem_cache_free_bulk(test_cache2, 10, list);
        assert(!test_cache2->nr_objs);


}