[fio.git] / smalloc.c

/*
 * simple memory allocator, backed by mmap() so that it hands out memory
 * that can be shared across processes and threads
 */
#include <sys/mman.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>
#include <unistd.h>
#include <inttypes.h>
#include <sys/types.h>
#include <limits.h>
#include <fcntl.h>

#include "mutex.h"
#include "arch/arch.h"
#include "os/os.h"
#include "smalloc.h"

#define SMALLOC_REDZONE		/* define to detect memory corruption */

#define SMALLOC_BPB	32	/* block size, bytes-per-bit in bitmap */
#define SMALLOC_BPI	(sizeof(unsigned int) * 8)
#define SMALLOC_BPL	(SMALLOC_BPB * SMALLOC_BPI)

#define INITIAL_SIZE	8192*1024	/* new pool size */
#define MAX_POOLS	128		/* maximum number of pools to setup */

#define SMALLOC_PRE_RED		0xdeadbeefU
#define SMALLOC_POST_RED	0x5aa55aa5U

unsigned int smalloc_pool_size = INITIAL_SIZE;
static const int int_mask = sizeof(int) - 1;

struct pool {
	struct fio_mutex *lock;			/* protects this pool */
	void *map;				/* map of blocks */
	unsigned int *bitmap;			/* blocks free/busy map */
	size_t free_blocks;		/* free blocks */
	size_t nr_blocks;			/* total blocks */
	size_t next_non_full;
	size_t mmap_size;
};

struct block_hdr {
	size_t size;
#ifdef SMALLOC_REDZONE
	unsigned int prered;
#endif
};

static struct pool mp[MAX_POOLS];
static unsigned int nr_pools;
static unsigned int last_pool;
static struct fio_rwlock *lock;

static inline void pool_lock(struct pool *pool)
{
	fio_mutex_down(pool->lock);
}

static inline void pool_unlock(struct pool *pool)
{
	fio_mutex_up(pool->lock);
}

static inline void global_read_lock(void)
{
	fio_rwlock_read(lock);
}

static inline void global_read_unlock(void)
{
	fio_rwlock_unlock(lock);
}

static inline void global_write_lock(void)
{
	fio_rwlock_write(lock);
}

static inline void global_write_unlock(void)
{
	fio_rwlock_unlock(lock);
}

static inline int ptr_valid(struct pool *pool, void *ptr)
{
	unsigned int pool_size = pool->nr_blocks * SMALLOC_BPL;

	return (ptr >= pool->map) && (ptr < pool->map + pool_size);
}

static inline size_t size_to_blocks(size_t size)
{
	return (size + SMALLOC_BPB - 1) / SMALLOC_BPB;
}

static int blocks_iter(struct pool *pool, unsigned int pool_idx,
		       unsigned int idx, size_t nr_blocks,
		       int (*func)(unsigned int *map, unsigned int mask))
{

	while (nr_blocks) {
		unsigned int this_blocks, mask;
		unsigned int *map;

		if (pool_idx >= pool->nr_blocks)
			return 0;

		map = &pool->bitmap[pool_idx];

		this_blocks = nr_blocks;
		if (this_blocks + idx > SMALLOC_BPI) {
			this_blocks = SMALLOC_BPI - idx;
			idx = SMALLOC_BPI - this_blocks;
		}

		if (this_blocks == SMALLOC_BPI)
			mask = -1U;
		else
			mask = ((1U << this_blocks) - 1) << idx;

		if (!func(map, mask))
			return 0;

		nr_blocks -= this_blocks;
		idx = 0;
		pool_idx++;
	}

	return 1;
}

static int mask_cmp(unsigned int *map, unsigned int mask)
{
	return !(*map & mask);
}

static int mask_clear(unsigned int *map, unsigned int mask)
{
	assert((*map & mask) == mask);
	*map &= ~mask;
	return 1;
}

static int mask_set(unsigned int *map, unsigned int mask)
{
	assert(!(*map & mask));
	*map |= mask;
	return 1;
}

static int blocks_free(struct pool *pool, unsigned int pool_idx,
		       unsigned int idx, size_t nr_blocks)
{
	return blocks_iter(pool, pool_idx, idx, nr_blocks, mask_cmp);
}

static void set_blocks(struct pool *pool, unsigned int pool_idx,
		       unsigned int idx, size_t nr_blocks)
{
	blocks_iter(pool, pool_idx, idx, nr_blocks, mask_set);
}

static void clear_blocks(struct pool *pool, unsigned int pool_idx,
			 unsigned int idx, size_t nr_blocks)
{
	blocks_iter(pool, pool_idx, idx, nr_blocks, mask_clear);
}

static int find_next_zero(int word, int start)
{
	assert(word != -1U);
	word >>= start;
	return ffz(word) + start;
}

static int add_pool(struct pool *pool, unsigned int alloc_size)
{
	int bitmap_blocks;
	void *ptr;

#ifdef SMALLOC_REDZONE
	alloc_size += sizeof(unsigned int);
#endif
	alloc_size += sizeof(struct block_hdr);
	if (alloc_size < INITIAL_SIZE)
		alloc_size = INITIAL_SIZE;

	/* round up to nearest full number of blocks */
	alloc_size = (alloc_size + SMALLOC_BPL - 1) & ~(SMALLOC_BPL - 1);
	bitmap_blocks = alloc_size / SMALLOC_BPL;
	alloc_size += bitmap_blocks * sizeof(unsigned int);
	pool->mmap_size = alloc_size;

	pool->nr_blocks = bitmap_blocks;
	pool->free_blocks = bitmap_blocks * SMALLOC_BPB;

	ptr = mmap(NULL, alloc_size, PROT_READ|PROT_WRITE,
			MAP_SHARED | OS_MAP_ANON, -1, 0);
	if (ptr == MAP_FAILED)
		goto out_fail;

	memset(ptr, 0, alloc_size);
	pool->map = ptr;
	pool->bitmap = (void *) ptr + (pool->nr_blocks * SMALLOC_BPL);

	pool->lock = fio_mutex_init(FIO_MUTEX_UNLOCKED);
	if (!pool->lock)
		goto out_fail;

	nr_pools++;
	return 0;
out_fail:
	fprintf(stderr, "smalloc: failed adding pool\n");
	if (pool->map)
		munmap(pool->map, pool->mmap_size);
	return 1;
}

void sinit(void)
{
	int ret;

	lock = fio_rwlock_init();
	ret = add_pool(&mp[0], INITIAL_SIZE);
	assert(!ret);
}

static void cleanup_pool(struct pool *pool)
{
	/*
	 * This will also remove the temporary file we used as a backing
	 * store, it was already unlinked
	 */
	munmap(pool->map, pool->mmap_size);

	if (pool->lock)
		fio_mutex_remove(pool->lock);
}

void scleanup(void)
{
	unsigned int i;

	for (i = 0; i < nr_pools; i++)
		cleanup_pool(&mp[i]);

	if (lock)
		fio_rwlock_remove(lock);
}

#ifdef SMALLOC_REDZONE
static void *postred_ptr(struct block_hdr *hdr)
{
	uintptr_t ptr;

	ptr = (uintptr_t) hdr + hdr->size - sizeof(unsigned int);
	ptr = (ptr + int_mask) & ~int_mask;

	return (void *) ptr;
}

static void fill_redzone(struct block_hdr *hdr)
{
	unsigned int *postred = postred_ptr(hdr);

	hdr->prered = SMALLOC_PRE_RED;
	*postred = SMALLOC_POST_RED;
}

static void sfree_check_redzone(struct block_hdr *hdr)
{
	unsigned int *postred = postred_ptr(hdr);

	if (hdr->prered != SMALLOC_PRE_RED) {
		fprintf(stderr, "smalloc pre redzone destroyed!\n");
		fprintf(stderr, "  ptr=%p, prered=%x, expected %x\n",
				hdr, hdr->prered, SMALLOC_PRE_RED);
		assert(0);
	}
	if (*postred != SMALLOC_POST_RED) {
		fprintf(stderr, "smalloc post redzone destroyed!\n");
		fprintf(stderr, "  ptr=%p, postred=%x, expected %x\n",
				hdr, *postred, SMALLOC_POST_RED);
		assert(0);
	}
}
#else
static void fill_redzone(struct block_hdr *hdr)
{
}

static void sfree_check_redzone(struct block_hdr *hdr)
{
}
#endif

static void sfree_pool(struct pool *pool, void *ptr)
{
	struct block_hdr *hdr;
	unsigned int i, idx;
	unsigned long offset;

	if (!ptr)
		return;

	ptr -= sizeof(*hdr);
	hdr = ptr;

	assert(ptr_valid(pool, ptr));

	sfree_check_redzone(hdr);

	offset = ptr - pool->map;
	i = offset / SMALLOC_BPL;
	idx = (offset % SMALLOC_BPL) / SMALLOC_BPB;

	pool_lock(pool);
	clear_blocks(pool, i, idx, size_to_blocks(hdr->size));
	if (i < pool->next_non_full)
		pool->next_non_full = i;
	pool->free_blocks += size_to_blocks(hdr->size);
	pool_unlock(pool);
}

void sfree(void *ptr)
{
	struct pool *pool = NULL;
	unsigned int i;

	if (!ptr)
		return;

	global_read_lock();

	for (i = 0; i < nr_pools; i++) {
		if (ptr_valid(&mp[i], ptr)) {
			pool = &mp[i];
			break;
		}
	}

	global_read_unlock();

	assert(pool);
	sfree_pool(pool, ptr);
}

static void *__smalloc_pool(struct pool *pool, size_t size)
{
	size_t nr_blocks;
	unsigned int i;
	unsigned int offset;
	unsigned int last_idx;
	void *ret = NULL;

	pool_lock(pool);

	nr_blocks = size_to_blocks(size);
	if (nr_blocks > pool->free_blocks)
		goto fail;

	i = pool->next_non_full;
	last_idx = 0;
	offset = -1U;
	while (i < pool->nr_blocks) {
		unsigned int idx;

		if (pool->bitmap[i] == -1U) {
			i++;
			pool->next_non_full = i;
			last_idx = 0;
			continue;
		}

		idx = find_next_zero(pool->bitmap[i], last_idx);
		if (!blocks_free(pool, i, idx, nr_blocks)) {
			idx += nr_blocks;
			if (idx < SMALLOC_BPI)
				last_idx = idx;
			else {
				last_idx = 0;
				while (idx >= SMALLOC_BPI) {
					i++;
					idx -= SMALLOC_BPI;
				}
			}
			continue;
		}
		set_blocks(pool, i, idx, nr_blocks);
		offset = i * SMALLOC_BPL + idx * SMALLOC_BPB;
		break;
	}

	if (i < pool->nr_blocks) {
		pool->free_blocks -= nr_blocks;
		ret = pool->map + offset;
	}
fail:
	pool_unlock(pool);
	return ret;
}

static void *smalloc_pool(struct pool *pool, size_t size)
{
	size_t alloc_size = size + sizeof(struct block_hdr);
	void *ptr;

	/*
	 * Round to int alignment, so that the postred pointer will
	 * be naturally aligned as well.
	 */
#ifdef SMALLOC_REDZONE
	alloc_size += sizeof(unsigned int);
	alloc_size = (alloc_size + int_mask) & ~int_mask;
#endif

	ptr = __smalloc_pool(pool, alloc_size);
	if (ptr) {
		struct block_hdr *hdr = ptr;

		hdr->size = alloc_size;
		fill_redzone(hdr);

		ptr += sizeof(*hdr);
		memset(ptr, 0, size);
	}

	return ptr;
}

void *smalloc(size_t size)
{
	unsigned int i;

	if (size != (unsigned int) size)
		return NULL;

	global_write_lock();
	i = last_pool;

	do {
		for (; i < nr_pools; i++) {
			void *ptr = smalloc_pool(&mp[i], size);

			if (ptr) {
				last_pool = i;
				global_write_unlock();
				return ptr;
			}
		}
		if (last_pool) {
			last_pool = 0;
			continue;
		}

		if (nr_pools + 1 > MAX_POOLS)
			break;
		else {
			i = nr_pools;
			if (add_pool(&mp[nr_pools], size))
				goto out;
		}
	} while (1);

out:
	global_write_unlock();
	return NULL;
}

char *smalloc_strdup(const char *str)
{
	char *ptr;

	ptr = smalloc(strlen(str) + 1);
	strcpy(ptr, str);
	return ptr;
}
Commit	Line	Data
	1	/*
	2	* simple memory allocator, backed by mmap() so that it hands out memory
	3	* that can be shared across processes and threads
	4	*/
	5	#include <sys/mman.h>
	6	#include <stdio.h>
	7	#include <stdlib.h>
	8	#include <assert.h>
	9	#include <string.h>
	10	#include <unistd.h>
	11	#include <inttypes.h>
	12	#include <sys/types.h>
	13	#include <limits.h>
	14	#include <fcntl.h>
	15
	16	#include "mutex.h"
	17	#include "arch/arch.h"
	18	#include "os/os.h"
	19	#include "smalloc.h"
	20
	21	#define SMALLOC_REDZONE /* define to detect memory corruption */
	22
	23	#define SMALLOC_BPB 32 /* block size, bytes-per-bit in bitmap */
	24	#define SMALLOC_BPI (sizeof(unsigned int) * 8)
	25	#define SMALLOC_BPL (SMALLOC_BPB * SMALLOC_BPI)
	26
	27	#define INITIAL_SIZE 81921024 / new pool size */
	28	#define MAX_POOLS 128 /* maximum number of pools to setup */
	29
	30	#define SMALLOC_PRE_RED 0xdeadbeefU
	31	#define SMALLOC_POST_RED 0x5aa55aa5U
	32
	33	unsigned int smalloc_pool_size = INITIAL_SIZE;
	34	static const int int_mask = sizeof(int) - 1;
	35
	36	struct pool {
	37	struct fio_mutex lock; / protects this pool */
	38	void map; / map of blocks */
	39	unsigned int bitmap; / blocks free/busy map */
	40	size_t free_blocks; /* free blocks */
	41	size_t nr_blocks; /* total blocks */
	42	size_t next_non_full;
	43	size_t mmap_size;
	44	};
	45
	46	struct block_hdr {
	47	size_t size;
	48	#ifdef SMALLOC_REDZONE
	49	unsigned int prered;
	50	#endif
	51	};
	52
	53	static struct pool mp[MAX_POOLS];
	54	static unsigned int nr_pools;
	55	static unsigned int last_pool;
	56	static struct fio_rwlock *lock;
	57
	58	static inline void pool_lock(struct pool *pool)
	59	{
	60	fio_mutex_down(pool->lock);
	61	}
	62
	63	static inline void pool_unlock(struct pool *pool)
	64	{
	65	fio_mutex_up(pool->lock);
	66	}
	67
	68	static inline void global_read_lock(void)
	69	{
	70	fio_rwlock_read(lock);
	71	}
	72
	73	static inline void global_read_unlock(void)
	74	{
	75	fio_rwlock_unlock(lock);
	76	}
	77
	78	static inline void global_write_lock(void)
	79	{
	80	fio_rwlock_write(lock);
	81	}
	82
	83	static inline void global_write_unlock(void)
	84	{
	85	fio_rwlock_unlock(lock);
	86	}
	87
	88	static inline int ptr_valid(struct pool pool, void ptr)
	89	{
	90	unsigned int pool_size = pool->nr_blocks * SMALLOC_BPL;
	91
	92	return (ptr >= pool->map) && (ptr < pool->map + pool_size);
	93	}
	94
	95	static inline size_t size_to_blocks(size_t size)
	96	{
	97	return (size + SMALLOC_BPB - 1) / SMALLOC_BPB;
	98	}
	99
	100	static int blocks_iter(struct pool *pool, unsigned int pool_idx,
	101	unsigned int idx, size_t nr_blocks,
	102	int (func)(unsigned int map, unsigned int mask))
	103	{
	104
	105	while (nr_blocks) {
	106	unsigned int this_blocks, mask;
	107	unsigned int *map;
	108
	109	if (pool_idx >= pool->nr_blocks)
	110	return 0;
	111
	112	map = &pool->bitmap[pool_idx];
	113
	114	this_blocks = nr_blocks;
	115	if (this_blocks + idx > SMALLOC_BPI) {
	116	this_blocks = SMALLOC_BPI - idx;
	117	idx = SMALLOC_BPI - this_blocks;
	118	}
	119
	120	if (this_blocks == SMALLOC_BPI)
	121	mask = -1U;
	122	else
	123	mask = ((1U << this_blocks) - 1) << idx;
	124
	125	if (!func(map, mask))
	126	return 0;
	127
	128	nr_blocks -= this_blocks;
	129	idx = 0;
	130	pool_idx++;
	131	}
	132
	133	return 1;
	134	}
	135
	136	static int mask_cmp(unsigned int *map, unsigned int mask)
	137	{
	138	return !(*map & mask);
	139	}
	140
	141	static int mask_clear(unsigned int *map, unsigned int mask)
	142	{
	143	assert((*map & mask) == mask);
	144	*map &= ~mask;
	145	return 1;
	146	}
	147
	148	static int mask_set(unsigned int *map, unsigned int mask)
	149	{
	150	assert(!(*map & mask));
	151	*map \|= mask;
	152	return 1;
	153	}
	154
	155	static int blocks_free(struct pool *pool, unsigned int pool_idx,
	156	unsigned int idx, size_t nr_blocks)
	157	{
	158	return blocks_iter(pool, pool_idx, idx, nr_blocks, mask_cmp);
	159	}
	160
	161	static void set_blocks(struct pool *pool, unsigned int pool_idx,
	162	unsigned int idx, size_t nr_blocks)
	163	{
	164	blocks_iter(pool, pool_idx, idx, nr_blocks, mask_set);
	165	}
	166
	167	static void clear_blocks(struct pool *pool, unsigned int pool_idx,
	168	unsigned int idx, size_t nr_blocks)
	169	{
	170	blocks_iter(pool, pool_idx, idx, nr_blocks, mask_clear);
	171	}
	172
	173	static int find_next_zero(int word, int start)
	174	{
	175	assert(word != -1U);
	176	word >>= start;
	177	return ffz(word) + start;
	178	}
	179
	180	static int add_pool(struct pool *pool, unsigned int alloc_size)
	181	{
	182	int bitmap_blocks;
	183	void *ptr;
	184
	185	#ifdef SMALLOC_REDZONE
	186	alloc_size += sizeof(unsigned int);
	187	#endif
	188	alloc_size += sizeof(struct block_hdr);
	189	if (alloc_size < INITIAL_SIZE)
	190	alloc_size = INITIAL_SIZE;
	191
	192	/* round up to nearest full number of blocks */
	193	alloc_size = (alloc_size + SMALLOC_BPL - 1) & ~(SMALLOC_BPL - 1);
	194	bitmap_blocks = alloc_size / SMALLOC_BPL;
	195	alloc_size += bitmap_blocks * sizeof(unsigned int);
	196	pool->mmap_size = alloc_size;
	197
	198	pool->nr_blocks = bitmap_blocks;
	199	pool->free_blocks = bitmap_blocks * SMALLOC_BPB;
	200
	201	ptr = mmap(NULL, alloc_size, PROT_READ\|PROT_WRITE,
	202	MAP_SHARED \| OS_MAP_ANON, -1, 0);
	203	if (ptr == MAP_FAILED)
	204	goto out_fail;
	205
	206	memset(ptr, 0, alloc_size);
	207	pool->map = ptr;
	208	pool->bitmap = (void ) ptr + (pool->nr_blocks SMALLOC_BPL);
	209
	210	pool->lock = fio_mutex_init(FIO_MUTEX_UNLOCKED);
	211	if (!pool->lock)
	212	goto out_fail;
	213
	214	nr_pools++;
	215	return 0;
	216	out_fail:
	217	fprintf(stderr, "smalloc: failed adding pool\n");
	218	if (pool->map)
	219	munmap(pool->map, pool->mmap_size);
	220	return 1;
	221	}
	222
	223	void sinit(void)
	224	{
	225	int ret;
	226
	227	lock = fio_rwlock_init();
	228	ret = add_pool(&mp[0], INITIAL_SIZE);
	229	assert(!ret);
	230	}
	231
	232	static void cleanup_pool(struct pool *pool)
	233	{
	234	/*
	235	* This will also remove the temporary file we used as a backing
	236	* store, it was already unlinked
	237	*/
	238	munmap(pool->map, pool->mmap_size);
	239
	240	if (pool->lock)
	241	fio_mutex_remove(pool->lock);
	242	}
	243
	244	void scleanup(void)
	245	{
	246	unsigned int i;
	247
	248	for (i = 0; i < nr_pools; i++)
	249	cleanup_pool(&mp[i]);
	250
	251	if (lock)
	252	fio_rwlock_remove(lock);
	253	}
	254
	255	#ifdef SMALLOC_REDZONE
	256	static void postred_ptr(struct block_hdr hdr)
	257	{
	258	uintptr_t ptr;
	259
	260	ptr = (uintptr_t) hdr + hdr->size - sizeof(unsigned int);
	261	ptr = (ptr + int_mask) & ~int_mask;
	262
	263	return (void *) ptr;
	264	}
	265
	266	static void fill_redzone(struct block_hdr *hdr)
	267	{
	268	unsigned int *postred = postred_ptr(hdr);
	269
	270	hdr->prered = SMALLOC_PRE_RED;
	271	*postred = SMALLOC_POST_RED;
	272	}
	273
	274	static void sfree_check_redzone(struct block_hdr *hdr)
	275	{
	276	unsigned int *postred = postred_ptr(hdr);
	277
	278	if (hdr->prered != SMALLOC_PRE_RED) {
	279	fprintf(stderr, "smalloc pre redzone destroyed!\n");
	280	fprintf(stderr, " ptr=%p, prered=%x, expected %x\n",
	281	hdr, hdr->prered, SMALLOC_PRE_RED);
	282	assert(0);
	283	}
	284	if (*postred != SMALLOC_POST_RED) {
	285	fprintf(stderr, "smalloc post redzone destroyed!\n");
	286	fprintf(stderr, " ptr=%p, postred=%x, expected %x\n",
	287	hdr, *postred, SMALLOC_POST_RED);
	288	assert(0);
	289	}
	290	}
	291	#else
	292	static void fill_redzone(struct block_hdr *hdr)
	293	{
	294	}
	295
	296	static void sfree_check_redzone(struct block_hdr *hdr)
	297	{
	298	}
	299	#endif
	300
	301	static void sfree_pool(struct pool pool, void ptr)
	302	{
	303	struct block_hdr *hdr;
	304	unsigned int i, idx;
	305	unsigned long offset;
	306
	307	if (!ptr)
	308	return;
	309
	310	ptr -= sizeof(*hdr);
	311	hdr = ptr;
	312
	313	assert(ptr_valid(pool, ptr));
	314
	315	sfree_check_redzone(hdr);
	316
	317	offset = ptr - pool->map;
	318	i = offset / SMALLOC_BPL;
	319	idx = (offset % SMALLOC_BPL) / SMALLOC_BPB;
	320
	321	pool_lock(pool);
	322	clear_blocks(pool, i, idx, size_to_blocks(hdr->size));
	323	if (i < pool->next_non_full)
	324	pool->next_non_full = i;
	325	pool->free_blocks += size_to_blocks(hdr->size);
	326	pool_unlock(pool);
	327	}
	328
	329	void sfree(void *ptr)
	330	{
	331	struct pool *pool = NULL;
	332	unsigned int i;
	333
	334	if (!ptr)
	335	return;
	336
	337	global_read_lock();
	338
	339	for (i = 0; i < nr_pools; i++) {
	340	if (ptr_valid(&mp[i], ptr)) {
	341	pool = &mp[i];
	342	break;
	343	}
	344	}
	345
	346	global_read_unlock();
	347
	348	assert(pool);
	349	sfree_pool(pool, ptr);
	350	}
	351
	352	static void __smalloc_pool(struct pool pool, size_t size)
	353	{
	354	size_t nr_blocks;
	355	unsigned int i;
	356	unsigned int offset;
	357	unsigned int last_idx;
	358	void *ret = NULL;
	359
	360	pool_lock(pool);
	361
	362	nr_blocks = size_to_blocks(size);
	363	if (nr_blocks > pool->free_blocks)
	364	goto fail;
	365
	366	i = pool->next_non_full;
	367	last_idx = 0;
	368	offset = -1U;
	369	while (i < pool->nr_blocks) {
	370	unsigned int idx;
	371
	372	if (pool->bitmap[i] == -1U) {
	373	i++;
	374	pool->next_non_full = i;
	375	last_idx = 0;
	376	continue;
	377	}
	378
	379	idx = find_next_zero(pool->bitmap[i], last_idx);
	380	if (!blocks_free(pool, i, idx, nr_blocks)) {
	381	idx += nr_blocks;
	382	if (idx < SMALLOC_BPI)
	383	last_idx = idx;
	384	else {
	385	last_idx = 0;
	386	while (idx >= SMALLOC_BPI) {
	387	i++;
	388	idx -= SMALLOC_BPI;
	389	}
	390	}
	391	continue;
	392	}
	393	set_blocks(pool, i, idx, nr_blocks);
	394	offset = i * SMALLOC_BPL + idx * SMALLOC_BPB;
	395	break;
	396	}
	397
	398	if (i < pool->nr_blocks) {
	399	pool->free_blocks -= nr_blocks;
	400	ret = pool->map + offset;
	401	}
	402	fail:
	403	pool_unlock(pool);
	404	return ret;
	405	}
	406
	407	static void smalloc_pool(struct pool pool, size_t size)
	408	{
	409	size_t alloc_size = size + sizeof(struct block_hdr);
	410	void *ptr;
	411
	412	/*
	413	* Round to int alignment, so that the postred pointer will
	414	* be naturally aligned as well.
	415	*/
	416	#ifdef SMALLOC_REDZONE
	417	alloc_size += sizeof(unsigned int);
	418	alloc_size = (alloc_size + int_mask) & ~int_mask;
	419	#endif
	420
	421	ptr = __smalloc_pool(pool, alloc_size);
	422	if (ptr) {
	423	struct block_hdr *hdr = ptr;
	424
	425	hdr->size = alloc_size;
	426	fill_redzone(hdr);
	427
	428	ptr += sizeof(*hdr);
	429	memset(ptr, 0, size);
	430	}
	431
	432	return ptr;
	433	}
	434
	435	void *smalloc(size_t size)
	436	{
	437	unsigned int i;
	438
	439	if (size != (unsigned int) size)
	440	return NULL;
	441
	442	global_write_lock();
	443	i = last_pool;
	444
	445	do {
	446	for (; i < nr_pools; i++) {
	447	void *ptr = smalloc_pool(&mp[i], size);
	448
	449	if (ptr) {
	450	last_pool = i;
	451	global_write_unlock();
	452	return ptr;
	453	}
	454	}
	455	if (last_pool) {
	456	last_pool = 0;
	457	continue;
	458	}
	459
	460	if (nr_pools + 1 > MAX_POOLS)
	461	break;
	462	else {
	463	i = nr_pools;
	464	if (add_pool(&mp[nr_pools], size))
	465	goto out;
	466	}
	467	} while (1);
	468
	469	out:
	470	global_write_unlock();
	471	return NULL;
	472	}
	473
	474	char smalloc_strdup(const char str)
	475	{
	476	char *ptr;
	477
	478	ptr = smalloc(strlen(str) + 1);
	479	strcpy(ptr, str);
	480	return ptr;
	481	}