[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 <sys/types.h>
#include <limits.h>

#include "mutex.h"

#undef ENABLE_RESIZE		/* define to enable pool resizing */
#define MP_SAFE			/* define to made allocator thread safe */

#define INITIAL_SIZE	1048576	/* new pool size */
#define MAX_POOLS	32	/* maximum number of pools to setup */

#ifdef ENABLE_RESIZE
#define MAX_SIZE	8 * INITIAL_SIZE
static unsigned int resize_error;
#endif

struct pool {
	struct fio_mutex *lock;			/* protects this pool */
	void *map;				/* map of blocks */
	void *last;				/* next free block hint */
	unsigned int size;			/* size of pool */
	unsigned int room;			/* size left in pool */
	unsigned int largest_block;		/* largest block free */
	unsigned int free_since_compact;	/* sfree() since compact() */
	int fd;					/* memory backing fd */
	char file[PATH_MAX];			/* filename for fd */
};

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

struct mem_hdr {
	unsigned int size;
};

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

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

static inline void global_read_lock(void)
{
	if (lock)
		fio_mutex_down_read(lock);
}

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

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

static inline void global_write_unlock(void)
{
	if (lock)
		fio_mutex_up_write(lock);
}

#define hdr_free(hdr)		((hdr)->size & 0x80000000)
#define hdr_size(hdr)		((hdr)->size & ~0x80000000)
#define hdr_mark_free(hdr)	((hdr)->size |= 0x80000000)

static inline int ptr_valid(struct pool *pool, void *ptr)
{
	return (ptr >= pool->map) && (ptr < pool->map + pool->size);
}

static inline int __hdr_valid(struct pool *pool, struct mem_hdr *hdr,
			      unsigned int size)
{
	return ptr_valid(pool, hdr) && ptr_valid(pool, (void *) hdr + size - 1);
}

static inline int hdr_valid(struct pool *pool, struct mem_hdr *hdr)
{
	return __hdr_valid(pool, hdr, hdr_size(hdr));
}

static inline int region_free(struct mem_hdr *hdr)
{
	return hdr_free(hdr) || (!hdr_free(hdr) && !hdr_size(hdr));
}

static inline struct mem_hdr *__hdr_nxt(struct pool *pool, struct mem_hdr *hdr,
					unsigned int size)
{
	struct mem_hdr *nxt = (void *) hdr + size + sizeof(*hdr);

	if (__hdr_valid(pool, nxt, size))
		return nxt;

	return NULL;
}

static inline struct mem_hdr *hdr_nxt(struct pool *pool, struct mem_hdr *hdr)
{
	return __hdr_nxt(pool, hdr, hdr_size(hdr));
}

static void merge(struct pool *pool, struct mem_hdr *hdr, struct mem_hdr *nxt)
{
	unsigned int hfree = hdr_free(hdr);
	unsigned int nfree = hdr_free(nxt);

	hdr->size = hdr_size(hdr) + hdr_size(nxt) + sizeof(*nxt);
	nxt->size = 0;

	if (hfree)
		hdr_mark_free(hdr);
	if (nfree)
		hdr_mark_free(nxt);

	if (pool->last == nxt)
		pool->last = hdr;
}

static int combine(struct pool *pool, struct mem_hdr *prv, struct mem_hdr *hdr)
{
	if (prv && hdr_free(prv) && hdr_free(hdr)) {
		merge(pool, prv, hdr);
		return 1;
	}

	return 0;
}

static int compact_pool(struct pool *pool)
{
	struct mem_hdr *hdr = pool->map, *nxt;
	unsigned int compacted = 0;

	if (pool->free_since_compact < 50)
		return 1;

	while (hdr) {
		nxt = hdr_nxt(pool, hdr);
		if (!nxt)
			break;
		if (hdr_free(nxt) && hdr_free(hdr)) {
			merge(pool, hdr, nxt);
			compacted++;
			continue;
		}
		hdr = hdr_nxt(pool, hdr);
	}

	pool->free_since_compact = 0;
	return !!compacted;
}

static int resize_pool(struct pool *pool)
{
#ifdef ENABLE_RESIZE
	unsigned int new_size = pool->size << 1;
	struct mem_hdr *hdr, *last_hdr;
	void *ptr;

	if (new_size >= MAX_SIZE || resize_error)
		return 1;

	if (ftruncate(pool->fd, new_size) < 0)
		goto fail;

	ptr = mremap(pool->map, pool->size, new_size, 0);
	if (ptr == MAP_FAILED)
		goto fail;

	pool->map = ptr;
	hdr = pool;
	do {
		last_hdr = hdr;
	} while ((hdr = hdr_nxt(hdr)) != NULL);

	if (hdr_free(last_hdr)) {
		last_hdr->size = hdr_size(last_hdr) + new_size - pool_size;
		hdr_mark_free(last_hdr);
	} else {
		struct mem_hdr *nxt;

		nxt = (void *) last_hdr + hdr_size(last_hdr) + sizeof(*hdr);
		nxt->size = new_size - pool_size - sizeof(*hdr);
		hdr_mark_free(nxt);
	}

	pool_room += new_size - pool_size;
	pool_size = new_size;
	return 0;
fail:
	perror("resize");
	resize_error = 1;
#else
	return 1;
#endif
}

static int add_pool(struct pool *pool)
{
	struct mem_hdr *hdr;
	void *ptr;
	int fd;

	strcpy(pool->file, "/tmp/.fio_smalloc.XXXXXX");
	fd = mkstemp(pool->file);
	if (fd < 0)
		goto out_close;

	pool->size = INITIAL_SIZE;
	if (ftruncate(fd, pool->size) < 0)
		goto out_unlink;

	ptr = mmap(NULL, pool->size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
	if (ptr == MAP_FAILED)
		goto out_unlink;

	memset(ptr, 0, pool->size);
	pool->map = pool->last = ptr;

#ifdef MP_SAFE
	pool->lock = fio_mutex_init(1);
	if (!pool->lock)
		goto out_unlink;
#endif

	pool->fd = fd;

	hdr = pool->map;
	pool->room = hdr->size = pool->size - sizeof(*hdr);
	pool->largest_block = pool->room;
	hdr_mark_free(hdr);
	global_write_lock();
	nr_pools++;
	global_write_unlock();
	return 0;
out_unlink:
	if (pool->map)
		munmap(pool->map, pool->size);
	unlink(pool->file);
out_close:
	if (fd >= 0)
		close(fd);
	return 1;
}

void sinit(void)
{
	int ret;

#ifdef MP_SAFE
	lock = fio_mutex_rw_init();
#endif
	ret = add_pool(&mp[0]);
	assert(!ret);
}

static void cleanup_pool(struct pool *pool)
{
	unlink(pool->file);
	close(pool->fd);
	munmap(pool->map, pool->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);
}

static void sfree_pool(struct pool *pool, void *ptr)
{
	struct mem_hdr *hdr, *nxt;

	if (!ptr)
		return;

	assert(ptr_valid(pool, ptr));

	pool_lock(pool);
	hdr = ptr - sizeof(*hdr);
	assert(!hdr_free(hdr));
	hdr_mark_free(hdr);
	pool->room -= hdr_size(hdr);

	nxt = hdr_nxt(pool, hdr);
	if (nxt && hdr_free(nxt))
		merge(pool, hdr, nxt);

	if (hdr_size(hdr) > pool->largest_block)
		pool->largest_block = hdr_size(hdr);

	pool->free_since_compact++;
	pool_unlock(pool);
}

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

	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)
{
	struct mem_hdr *hdr, *prv;
	int did_restart = 0;
	void *ret;

	/*
	 * slight chance of race with sfree() here, but acceptable
	 */
	if (!size || size > pool->room + sizeof(*hdr) ||
	    ((size > pool->largest_block) && pool->largest_block))
		return NULL;

	pool_lock(pool);
restart:
	hdr = pool->last;
	prv = NULL;
	do {
		if (combine(pool, prv, hdr))
			hdr = prv;

		if (hdr_free(hdr) && hdr_size(hdr) >= size)
			break;

		prv = hdr;
	} while ((hdr = hdr_nxt(pool, hdr)) != NULL);

	if (!hdr)
		goto fail;

	/*
	 * more room, adjust next header if any
	 */
	if (hdr_size(hdr) - size >= 2 * sizeof(*hdr)) {
		struct mem_hdr *nxt = __hdr_nxt(pool, hdr, size);

		if (nxt) {
			nxt->size = hdr_size(hdr) - size - sizeof(*hdr);
			if (hdr_size(hdr) == pool->largest_block)
				pool->largest_block = hdr_size(nxt);
			hdr_mark_free(nxt);
		} else
			size = hdr_size(hdr);
	} else
		size = hdr_size(hdr);

	if (size == hdr_size(hdr) && size == pool->largest_block)
		pool->largest_block = 0;

	/*
	 * also clears free bit
	 */
	hdr->size = size;
	pool->last = hdr_nxt(pool, hdr);
	if (!pool->last)
		pool->last = pool->map;
	pool->room -= size;
	pool_unlock(pool);

	ret = (void *) hdr + sizeof(*hdr);
	memset(ret, 0, size);
	return ret;
fail:
	/*
	 * if we fail to allocate, first compact the entries that we missed.
	 * if that also fails, increase the size of the pool
	 */
	++did_restart;
	if (did_restart <= 1) {
		if (!compact_pool(pool)) {
			pool->last = pool->map;
			goto restart;
		}
	}
	++did_restart;
	if (did_restart <= 2) {
		if (!resize_pool(pool)) {
			pool->last = pool->map;
			goto restart;
		}
	}
	pool_unlock(pool);
	return NULL;
}

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

	global_read_lock();
	i = last_pool;

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

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

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

	global_read_unlock();
out:
	return NULL;
}

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

	ptr = smalloc(strlen(str) + 1);
	strcpy(ptr, str);
	return ptr;
}
Commit	Line	Data
d24c33a4 JA	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 <sys/types.h>
	12	#include <limits.h>
	13
	14	#include "mutex.h"
	15
	16	#undef ENABLE_RESIZE /* define to enable pool resizing */
	17	#define MP_SAFE /* define to made allocator thread safe */
	18
85f46703	19	#define INITIAL_SIZE 1048576 /* new pool size */
d24c33a4 JA	20	#define MAX_POOLS 32 /* maximum number of pools to setup */
	21
	22	#ifdef ENABLE_RESIZE
	23	#define MAX_SIZE 8 * INITIAL_SIZE
	24	static unsigned int resize_error;
	25	#endif
	26
	27	struct pool {
	28	struct fio_mutex lock; / protects this pool */
	29	void map; / map of blocks */
	30	void last; / next free block hint */
	31	unsigned int size; /* size of pool */
	32	unsigned int room; /* size left in pool */
	33	unsigned int largest_block; /* largest block free */
	34	unsigned int free_since_compact; /* sfree() since compact() */
	35	int fd; /* memory backing fd */
	36	char file[PATH_MAX]; /* filename for fd */
	37	};
	38
	39	static struct pool mp[MAX_POOLS];
	40	static unsigned int nr_pools;
	41	static unsigned int last_pool;
	42	static struct fio_mutex *lock;
	43
	44	struct mem_hdr {
	45	unsigned int size;
	46	};
	47
	48	static inline void pool_lock(struct pool *pool)
	49	{
	50	if (pool->lock)
	51	fio_mutex_down(pool->lock);
	52	}
	53
	54	static inline void pool_unlock(struct pool *pool)
	55	{
	56	if (pool->lock)
	57	fio_mutex_up(pool->lock);
	58	}
	59
65864cf7	60	static inline void global_read_lock(void)
d24c33a4 JA	61	{
d24c33a4 JA	62	if (lock)
65864cf7	63	fio_mutex_down_read(lock);
d24c33a4 JA	64	}
d24c33a4 JA	65
65864cf7	66	static inline void global_read_unlock(void)
d24c33a4 JA	67	{
d24c33a4 JA	68	if (lock)
65864cf7 JA	69	fio_mutex_up_read(lock);
	70	}
	71
	72	static inline void global_write_lock(void)
	73	{
	74	if (lock)
	75	fio_mutex_down_write(lock);
	76	}
	77
	78	static inline void global_write_unlock(void)
	79	{
	80	if (lock)
	81	fio_mutex_up_write(lock);
d24c33a4 JA	82	}
	83
	84	#define hdr_free(hdr) ((hdr)->size & 0x80000000)
	85	#define hdr_size(hdr) ((hdr)->size & ~0x80000000)
	86	#define hdr_mark_free(hdr) ((hdr)->size \|= 0x80000000)
	87
	88	static inline int ptr_valid(struct pool pool, void ptr)
	89	{
	90	return (ptr >= pool->map) && (ptr < pool->map + pool->size);
	91	}
	92
	93	static inline int __hdr_valid(struct pool pool, struct mem_hdr hdr,
	94	unsigned int size)
	95	{
	96	return ptr_valid(pool, hdr) && ptr_valid(pool, (void *) hdr + size - 1);
	97	}
	98
	99	static inline int hdr_valid(struct pool pool, struct mem_hdr hdr)
	100	{
	101	return __hdr_valid(pool, hdr, hdr_size(hdr));
	102	}
	103
	104	static inline int region_free(struct mem_hdr *hdr)
	105	{
	106	return hdr_free(hdr) \|\| (!hdr_free(hdr) && !hdr_size(hdr));
	107	}
	108
	109	static inline struct mem_hdr __hdr_nxt(struct pool pool, struct mem_hdr *hdr,
	110	unsigned int size)
	111	{
	112	struct mem_hdr nxt = (void ) hdr + size + sizeof(*hdr);
	113
	114	if (__hdr_valid(pool, nxt, size))
	115	return nxt;
	116
	117	return NULL;
	118	}
	119
	120	static inline struct mem_hdr hdr_nxt(struct pool pool, struct mem_hdr *hdr)
	121	{
	122	return __hdr_nxt(pool, hdr, hdr_size(hdr));
	123	}
	124
	125	static void merge(struct pool pool, struct mem_hdr hdr, struct mem_hdr *nxt)
	126	{
	127	unsigned int hfree = hdr_free(hdr);
	128	unsigned int nfree = hdr_free(nxt);
	129
	130	hdr->size = hdr_size(hdr) + hdr_size(nxt) + sizeof(*nxt);
	131	nxt->size = 0;
	132
	133	if (hfree)
	134	hdr_mark_free(hdr);
	135	if (nfree)
	136	hdr_mark_free(nxt);
	137
	138	if (pool->last == nxt)
	139	pool->last = hdr;
	140	}
	141
	142	static int combine(struct pool pool, struct mem_hdr prv, struct mem_hdr *hdr)
	143	{
	144	if (prv && hdr_free(prv) && hdr_free(hdr)) {
	145	merge(pool, prv, hdr);
146	return 1;
147	}
148
149	return 0;
150	}
151
152	static int compact_pool(struct pool *pool)
153	{
154	struct mem_hdr hdr = pool->map, nxt;
155	unsigned int compacted = 0;
156
157	if (pool->free_since_compact < 50)
158	return 1;
159
160	while (hdr) {
161	nxt = hdr_nxt(pool, hdr);
162	if (!nxt)
163	break;
164	if (hdr_free(nxt) && hdr_free(hdr)) {
165	merge(pool, hdr, nxt);
166	compacted++;
167	continue;
168	}
169	hdr = hdr_nxt(pool, hdr);
170	}
171
172	pool->free_since_compact = 0;
173	return !!compacted;
174	}
175
176	static int resize_pool(struct pool *pool)
177	{
178	#ifdef ENABLE_RESIZE
179	unsigned int new_size = pool->size << 1;
180	struct mem_hdr hdr, last_hdr;
181	void *ptr;
182
183	if (new_size >= MAX_SIZE \|\| resize_error)
184	return 1;
185
186	if (ftruncate(pool->fd, new_size) < 0)
187	goto fail;
188
189	ptr = mremap(pool->map, pool->size, new_size, 0);
190	if (ptr == MAP_FAILED)
191	goto fail;
192
193	pool->map = ptr;
194	hdr = pool;
195	do {
196	last_hdr = hdr;
197	} while ((hdr = hdr_nxt(hdr)) != NULL);
198
199	if (hdr_free(last_hdr)) {
200	last_hdr->size = hdr_size(last_hdr) + new_size - pool_size;
201	hdr_mark_free(last_hdr);
202	} else {
203	struct mem_hdr *nxt;
204
205	nxt = (void ) last_hdr + hdr_size(last_hdr) + sizeof(hdr);
206	nxt->size = new_size - pool_size - sizeof(*hdr);
207	hdr_mark_free(nxt);
208	}
209
210	pool_room += new_size - pool_size;
211	pool_size = new_size;
212	return 0;
213	fail:
214	perror("resize");
215	resize_error = 1;
216	#else
217	return 1;
218	#endif
219	}
220
221	static int add_pool(struct pool *pool)
222	{
223	struct mem_hdr *hdr;
224	void *ptr;
225	int fd;
226
227	strcpy(pool->file, "/tmp/.fio_smalloc.XXXXXX");
228	fd = mkstemp(pool->file);
229	if (fd < 0)
230	goto out_close;
231
232	pool->size = INITIAL_SIZE;
233	if (ftruncate(fd, pool->size) < 0)
234	goto out_unlink;
235
236	ptr = mmap(NULL, pool->size, PROT_READ\|PROT_WRITE, MAP_SHARED, fd, 0);
237	if (ptr == MAP_FAILED)
238	goto out_unlink;
239
240	memset(ptr, 0, pool->size);
241	pool->map = pool->last = ptr;
242
243	#ifdef MP_SAFE
244	pool->lock = fio_mutex_init(1);
245	if (!pool->lock)
246	goto out_unlink;
247	#endif
248
249	pool->fd = fd;
250
251	hdr = pool->map;
252	pool->room = hdr->size = pool->size - sizeof(*hdr);
253	pool->largest_block = pool->room;
254	hdr_mark_free(hdr);
65864cf7	255	global_write_lock();
d24c33a4	256	nr_pools++;
65864cf7	257	global_write_unlock();
d24c33a4 JA	258	return 0;
	259	out_unlink:
	260	if (pool->map)
	261	munmap(pool->map, pool->size);
	262	unlink(pool->file);
	263	out_close:
	264	if (fd >= 0)
	265	close(fd);
	266	return 1;
	267	}
	268
	269	void sinit(void)
	270	{
4d4e80f2	271	int ret;
d24c33a4 JA	272
d24c33a4 JA	273	#ifdef MP_SAFE
9c5b5290	274	lock = fio_mutex_rw_init();
d24c33a4	275	#endif
4d4e80f2	276	ret = add_pool(&mp[0]);
d24c33a4 JA	277	assert(!ret);
	278	}
	279
	280	static void cleanup_pool(struct pool *pool)
	281	{
	282	unlink(pool->file);
	283	close(pool->fd);
	284	munmap(pool->map, pool->size);
	285
	286	if (pool->lock)
	287	fio_mutex_remove(pool->lock);
	288	}
	289
	290	void scleanup(void)
	291	{
	292	unsigned int i;
	293
	294	for (i = 0; i < nr_pools; i++)
	295	cleanup_pool(&mp[i]);
	296
	297	if (lock)
	298	fio_mutex_remove(lock);
	299	}
	300
	301	static void sfree_pool(struct pool pool, void ptr)
	302	{
	303	struct mem_hdr hdr, nxt;
	304
	305	if (!ptr)
	306	return;
	307
	308	assert(ptr_valid(pool, ptr));
	309
	310	pool_lock(pool);
	311	hdr = ptr - sizeof(*hdr);
	312	assert(!hdr_free(hdr));
	313	hdr_mark_free(hdr);
	314	pool->room -= hdr_size(hdr);
	315
	316	nxt = hdr_nxt(pool, hdr);
	317	if (nxt && hdr_free(nxt))
	318	merge(pool, hdr, nxt);
	319
	320	if (hdr_size(hdr) > pool->largest_block)
	321	pool->largest_block = hdr_size(hdr);
	322
	323	pool->free_since_compact++;
	324	pool_unlock(pool);
	325	}
	326
	327	void sfree(void *ptr)
	328	{
	329	struct pool *pool = NULL;
	330	unsigned int i;
	331
65864cf7	332	global_read_lock();
d24c33a4 JA	333
	334	for (i = 0; i < nr_pools; i++) {
	335	if (ptr_valid(&mp[i], ptr)) {
	336	pool = &mp[i];
	337	break;
	338	}
	339	}
	340
65864cf7	341	global_read_unlock();
d24c33a4 JA	342
	343	assert(pool);
	344	sfree_pool(pool, ptr);
	345	}
	346
	347	static void smalloc_pool(struct pool pool, unsigned int size)
	348	{
	349	struct mem_hdr hdr, prv;
	350	int did_restart = 0;
	351	void *ret;
	352
	353	/*
	354	* slight chance of race with sfree() here, but acceptable
	355	*/
	356	if (!size \|\| size > pool->room + sizeof(*hdr) \|\|
	357	((size > pool->largest_block) && pool->largest_block))
	358	return NULL;
	359
	360	pool_lock(pool);
	361	restart:
	362	hdr = pool->last;
	363	prv = NULL;
	364	do {
	365	if (combine(pool, prv, hdr))
	366	hdr = prv;
5ec10eaa	367
d24c33a4 JA	368	if (hdr_free(hdr) && hdr_size(hdr) >= size)
	369	break;
	370
	371	prv = hdr;
	372	} while ((hdr = hdr_nxt(pool, hdr)) != NULL);
	373
	374	if (!hdr)
	375	goto fail;
	376
	377	/*
	378	* more room, adjust next header if any
	379	*/
	380	if (hdr_size(hdr) - size >= 2 * sizeof(*hdr)) {
	381	struct mem_hdr *nxt = __hdr_nxt(pool, hdr, size);
	382
	383	if (nxt) {
	384	nxt->size = hdr_size(hdr) - size - sizeof(*hdr);
	385	if (hdr_size(hdr) == pool->largest_block)
	386	pool->largest_block = hdr_size(nxt);
	387	hdr_mark_free(nxt);
	388	} else
	389	size = hdr_size(hdr);
	390	} else
	391	size = hdr_size(hdr);
	392
	393	if (size == hdr_size(hdr) && size == pool->largest_block)
	394	pool->largest_block = 0;
	395
	396	/*
	397	* also clears free bit
	398	*/
	399	hdr->size = size;
	400	pool->last = hdr_nxt(pool, hdr);
	401	if (!pool->last)
	402	pool->last = pool->map;
	403	pool->room -= size;
	404	pool_unlock(pool);
	405
	406	ret = (void ) hdr + sizeof(hdr);
	407	memset(ret, 0, size);
	408	return ret;
	409	fail:
	410	/*
	411	* if we fail to allocate, first compact the entries that we missed.
	412	* if that also fails, increase the size of the pool
	413	*/
	414	++did_restart;
	415	if (did_restart <= 1) {
	416	if (!compact_pool(pool)) {
	417	pool->last = pool->map;
	418	goto restart;
	419	}
	420	}
	421	++did_restart;
	422	if (did_restart <= 2) {
	423	if (!resize_pool(pool)) {
	424	pool->last = pool->map;
	425	goto restart;
	426	}
	427	}
	428	pool_unlock(pool);
	429	return NULL;
	430	}
	431
432	void *smalloc(unsigned int size)
433	{
434	unsigned int i;
435
65864cf7	436	global_read_lock();
d24c33a4 JA	437	i = last_pool;
	438
	439	do {
	440	for (; i < nr_pools; i++) {
	441	void *ptr = smalloc_pool(&mp[i], size);
	442
	443	if (ptr) {
	444	last_pool = i;
65864cf7	445	global_read_unlock();
d24c33a4 JA	446	return ptr;
	447	}
	448	}
	449	if (last_pool) {
	450	last_pool = 0;
	451	continue;
	452	}
	453
	454	if (nr_pools + 1 >= MAX_POOLS)
	455	break;
	456	else {
	457	i = nr_pools;
65864cf7	458	global_read_unlock();
d24c33a4	459	if (add_pool(&mp[nr_pools]))
65864cf7 JA	460	goto out;
65864cf7 JA	461	global_read_lock();
d24c33a4 JA	462	}
	463	} while (1);
	464
65864cf7 JA	465	global_read_unlock();
65864cf7 JA	466	out:
d24c33a4 JA	467	return NULL;
	468	}
	469
	470	char smalloc_strdup(const char str)
	471	{
	472	char *ptr;
	473
	474	ptr = smalloc(strlen(str) + 1);
	475	strcpy(ptr, str);
	476	return ptr;
	477	}