[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"

#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;
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 */
	unsigned int free_blocks;		/* free blocks */
	unsigned int nr_blocks;			/* total blocks */
	unsigned int next_non_full;
	unsigned int mmap_size;
};

struct block_hdr {
	unsigned int 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_mutex *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_mutex_down_read(lock);
}

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

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

static inline void global_write_unlock(void)
{
	fio_mutex_up_write(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 unsigned int size_to_blocks(unsigned int size)
{
	return (size + SMALLOC_BPB - 1) / SMALLOC_BPB;
}

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