lib, Make gen_pool memory allocator lockless

extern int bitmap_allocate_region(unsigned long *bitmap, int pos, int order);

extern void bitmap_copy_le(void *dst, const unsigned long *src, int nbits);

#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) % BITS_PER_LONG))

#define BITMAP_LAST_WORD_MASK(nbits)					\

(									\

	((nbits) % BITS_PER_LONG) ?					\

/*

 * Basic general purpose allocator for managing special purpose memory

 * not managed by the regular kmalloc/kfree interface.

 * Uses for this includes on-device special memory, uncached memory

 * etc.

 * Basic general purpose allocator for managing special purpose

 * memory, for example, memory that is not managed by the regular

 * kmalloc/kfree interface.  Uses for this includes on-device special

 * memory, uncached memory etc.

 *

 * It is safe to use the allocator in NMI handlers and other special

 * unblockable contexts that could otherwise deadlock on locks.  This

 * is implemented by using atomic operations and retries on any

 * conflicts.  The disadvantage is that there may be livelocks in

 * extreme cases.  For better scalability, one allocator can be used

 * for each CPU.

 *

 * The lockless operation only works if there is enough memory

 * available.  If new memory is added to the pool a lock has to be

 * still taken.  So any user relying on locklessness has to ensure

 * that sufficient memory is preallocated.

 *

 * The basic atomic operation of this allocator is cmpxchg on long.

 * On architectures that don't have NMI-safe cmpxchg implementation,

 * the allocator can NOT be used in NMI handler.  So code uses the

 * allocator in NMI handler should depend on

 * CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG.

 *

 * This source code is licensed under the GNU General Public License,

 * Version 2.  See the file COPYING for more details.

 *  General purpose special memory pool descriptor.

 */

struct gen_pool {

	rwlock_t lock;

	spinlock_t lock;

	struct list_head chunks;	/* list of chunks in this pool */

	int min_alloc_order;		/* minimum allocation order */

};

 *  General purpose special memory pool chunk descriptor.

 */

struct gen_pool_chunk {

	spinlock_t lock;

	struct list_head next_chunk;	/* next chunk in pool */

	atomic_t avail;

	phys_addr_t phys_addr;		/* physical starting address of memory chunk */

	unsigned long start_addr;	/* starting address of memory chunk */

	unsigned long end_addr;		/* ending address of memory chunk */

extern void gen_pool_destroy(struct gen_pool *);

extern unsigned long gen_pool_alloc(struct gen_pool *, size_t);

extern void gen_pool_free(struct gen_pool *, unsigned long, size_t);

extern void gen_pool_for_each_chunk(struct gen_pool *,

	void (*)(struct gen_pool *, struct gen_pool_chunk *, void *), void *);

extern size_t gen_pool_avail(struct gen_pool *);

extern size_t gen_pool_size(struct gen_pool *);

#endif /* __GENALLOC_H__ */

}

EXPORT_SYMBOL(__bitmap_weight);

#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) % BITS_PER_LONG))

void bitmap_set(unsigned long *map, int start, int nr)

{

	unsigned long *p = map + BIT_WORD(start);

/*

 * Basic general purpose allocator for managing special purpose memory

 * not managed by the regular kmalloc/kfree interface.

 * Uses for this includes on-device special memory, uncached memory

 * etc.

 * Basic general purpose allocator for managing special purpose

 * memory, for example, memory that is not managed by the regular

 * kmalloc/kfree interface.  Uses for this includes on-device special

 * memory, uncached memory etc.

 *

 * It is safe to use the allocator in NMI handlers and other special

 * unblockable contexts that could otherwise deadlock on locks.  This

 * is implemented by using atomic operations and retries on any

 * conflicts.  The disadvantage is that there may be livelocks in

 * extreme cases.  For better scalability, one allocator can be used

 * for each CPU.

 *

 * The lockless operation only works if there is enough memory

 * available.  If new memory is added to the pool a lock has to be

 * still taken.  So any user relying on locklessness has to ensure

 * that sufficient memory is preallocated.

 *

 * The basic atomic operation of this allocator is cmpxchg on long.

 * On architectures that don't have NMI-safe cmpxchg implementation,

 * the allocator can NOT be used in NMI handler.  So code uses the

 * allocator in NMI handler should depend on

 * CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG.

 *

 * Copyright 2005 (C) Jes Sorensen <jes@trained-monkey.org>

 *

#include <linux/slab.h>

#include <linux/module.h>

#include <linux/bitmap.h>

#include <linux/rculist.h>

#include <linux/interrupt.h>

#include <linux/genalloc.h>

static int set_bits_ll(unsigned long *addr, unsigned long mask_to_set)

{

	unsigned long val, nval;

	nval = *addr;

	do {

		val = nval;

		if (val & mask_to_set)

			return -EBUSY;

		cpu_relax();

	} while ((nval = cmpxchg(addr, val, val | mask_to_set)) != val);

	return 0;

}

static int clear_bits_ll(unsigned long *addr, unsigned long mask_to_clear)

{

	unsigned long val, nval;

	nval = *addr;

	do {

		val = nval;

		if ((val & mask_to_clear) != mask_to_clear)

			return -EBUSY;

		cpu_relax();

	} while ((nval = cmpxchg(addr, val, val & ~mask_to_clear)) != val);

	return 0;

}

/*

 * bitmap_set_ll - set the specified number of bits at the specified position

 * @map: pointer to a bitmap

 * @start: a bit position in @map

 * @nr: number of bits to set

 *

 * Set @nr bits start from @start in @map lock-lessly. Several users

 * can set/clear the same bitmap simultaneously without lock. If two

 * users set the same bit, one user will return remain bits, otherwise

 * return 0.

 */

static int bitmap_set_ll(unsigned long *map, int start, int nr)

{

	unsigned long *p = map + BIT_WORD(start);

	const int size = start + nr;

	int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);

	unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);

	while (nr - bits_to_set >= 0) {

		if (set_bits_ll(p, mask_to_set))

			return nr;

		nr -= bits_to_set;

		bits_to_set = BITS_PER_LONG;

		mask_to_set = ~0UL;

		p++;

	}

	if (nr) {

		mask_to_set &= BITMAP_LAST_WORD_MASK(size);

		if (set_bits_ll(p, mask_to_set))

			return nr;

	}

	return 0;

}

/*

 * bitmap_clear_ll - clear the specified number of bits at the specified position

 * @map: pointer to a bitmap

 * @start: a bit position in @map

 * @nr: number of bits to set

 *

 * Clear @nr bits start from @start in @map lock-lessly. Several users

 * can set/clear the same bitmap simultaneously without lock. If two

 * users clear the same bit, one user will return remain bits,

 * otherwise return 0.

 */

static int bitmap_clear_ll(unsigned long *map, int start, int nr)

{

	unsigned long *p = map + BIT_WORD(start);

	const int size = start + nr;

	int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);

	unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);

	while (nr - bits_to_clear >= 0) {

		if (clear_bits_ll(p, mask_to_clear))

			return nr;

		nr -= bits_to_clear;

		bits_to_clear = BITS_PER_LONG;

		mask_to_clear = ~0UL;

		p++;

	}

	if (nr) {

		mask_to_clear &= BITMAP_LAST_WORD_MASK(size);

		if (clear_bits_ll(p, mask_to_clear))

			return nr;

	}

	return 0;

}

/**

 * gen_pool_create - create a new special memory pool

	pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid);

	if (pool != NULL) {

		rwlock_init(&pool->lock);

		spin_lock_init(&pool->lock);

		INIT_LIST_HEAD(&pool->chunks);

		pool->min_alloc_order = min_alloc_order;

	}

	if (unlikely(chunk == NULL))

		return -ENOMEM;

	spin_lock_init(&chunk->lock);

	chunk->phys_addr = phys;

	chunk->start_addr = virt;

	chunk->end_addr = virt + size;

	atomic_set(&chunk->avail, size);

	write_lock(&pool->lock);

	list_add(&chunk->next_chunk, &pool->chunks);

	write_unlock(&pool->lock);

	spin_lock(&pool->lock);

	list_add_rcu(&chunk->next_chunk, &pool->chunks);

	spin_unlock(&pool->lock);

	return 0;

}

 */

phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long addr)

{

	struct list_head *_chunk;

	struct gen_pool_chunk *chunk;

	phys_addr_t paddr = -1;

	read_lock(&pool->lock);

	list_for_each(_chunk, &pool->chunks) {

		chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);

		if (addr >= chunk->start_addr && addr < chunk->end_addr)

			return chunk->phys_addr + addr - chunk->start_addr;

	rcu_read_lock();

	list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {

		if (addr >= chunk->start_addr && addr < chunk->end_addr) {

			paddr = chunk->phys_addr + (addr - chunk->start_addr);

			break;

		}

	}

	read_unlock(&pool->lock);

	rcu_read_unlock();

	return -1;

	return paddr;

}

EXPORT_SYMBOL(gen_pool_virt_to_phys);

	int order = pool->min_alloc_order;

	int bit, end_bit;

	list_for_each_safe(_chunk, _next_chunk, &pool->chunks) {

		chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);

		list_del(&chunk->next_chunk);

 * @size: number of bytes to allocate from the pool

 *

 * Allocate the requested number of bytes from the specified pool.

 * Uses a first-fit algorithm.

 * Uses a first-fit algorithm. Can not be used in NMI handler on

 * architectures without NMI-safe cmpxchg implementation.

 */

unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)

{

	struct list_head *_chunk;

	struct gen_pool_chunk *chunk;

	unsigned long addr, flags;

	unsigned long addr = 0;

	int order = pool->min_alloc_order;

	int nbits, start_bit, end_bit;

	int nbits, start_bit = 0, end_bit, remain;

#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG

	BUG_ON(in_nmi());

#endif

	if (size == 0)

		return 0;

	nbits = (size + (1UL << order) - 1) >> order;

	read_lock(&pool->lock);

	list_for_each(_chunk, &pool->chunks) {

		chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);

	rcu_read_lock();

	list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {

		if (size > atomic_read(&chunk->avail))

			continue;

		end_bit = (chunk->end_addr - chunk->start_addr) >> order;

		spin_lock_irqsave(&chunk->lock, flags);

		start_bit = bitmap_find_next_zero_area(chunk->bits, end_bit, 0,

						nbits, 0);

		if (start_bit >= end_bit) {

			spin_unlock_irqrestore(&chunk->lock, flags);

retry:

		start_bit = bitmap_find_next_zero_area(chunk->bits, end_bit,

						       start_bit, nbits, 0);

		if (start_bit >= end_bit)

			continue;

		remain = bitmap_set_ll(chunk->bits, start_bit, nbits);

		if (remain) {

			remain = bitmap_clear_ll(chunk->bits, start_bit,

						 nbits - remain);

			BUG_ON(remain);

			goto retry;

		}

		addr = chunk->start_addr + ((unsigned long)start_bit << order);

		bitmap_set(chunk->bits, start_bit, nbits);

		spin_unlock_irqrestore(&chunk->lock, flags);

		read_unlock(&pool->lock);

		return addr;

		size = nbits << order;

		atomic_sub(size, &chunk->avail);

		break;

	}

	read_unlock(&pool->lock);

	return 0;

	rcu_read_unlock();

	return addr;

}

EXPORT_SYMBOL(gen_pool_alloc);

 * @addr: starting address of memory to free back to pool

 * @size: size in bytes of memory to free

 *

 * Free previously allocated special memory back to the specified pool.

 * Free previously allocated special memory back to the specified

 * pool.  Can not be used in NMI handler on architectures without

 * NMI-safe cmpxchg implementation.

 */

void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size)

{

	struct list_head *_chunk;

	struct gen_pool_chunk *chunk;

	unsigned long flags;

	int order = pool->min_alloc_order;

	int bit, nbits;

	int start_bit, nbits, remain;

	nbits = (size + (1UL << order) - 1) >> order;

	read_lock(&pool->lock);

	list_for_each(_chunk, &pool->chunks) {

		chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);

#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG

	BUG_ON(in_nmi());

#endif

	nbits = (size + (1UL << order) - 1) >> order;

	rcu_read_lock();

	list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {

		if (addr >= chunk->start_addr && addr < chunk->end_addr) {

			BUG_ON(addr + size > chunk->end_addr);

			spin_lock_irqsave(&chunk->lock, flags);

			bit = (addr - chunk->start_addr) >> order;

			while (nbits--)

				__clear_bit(bit++, chunk->bits);

			spin_unlock_irqrestore(&chunk->lock, flags);

			break;

			start_bit = (addr - chunk->start_addr) >> order;

			remain = bitmap_clear_ll(chunk->bits, start_bit, nbits);

			BUG_ON(remain);

			size = nbits << order;

			atomic_add(size, &chunk->avail);

			rcu_read_unlock();

			return;

		}

	}

	BUG_ON(nbits > 0);

	read_unlock(&pool->lock);

	rcu_read_unlock();

	BUG();

}

EXPORT_SYMBOL(gen_pool_free);

/**

 * gen_pool_for_each_chunk - call func for every chunk of generic memory pool

 * @pool:	the generic memory pool

 * @func:	func to call

 * @data:	additional data used by @func

 *

 * Call @func for every chunk of generic memory pool.  The @func is

 * called with rcu_read_lock held.

 */

void gen_pool_for_each_chunk(struct gen_pool *pool,

	void (*func)(struct gen_pool *pool, struct gen_pool_chunk *chunk, void *data),

	void *data)

{

	struct gen_pool_chunk *chunk;

	rcu_read_lock();

	list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk)

		func(pool, chunk, data);

	rcu_read_unlock();

}

EXPORT_SYMBOL(gen_pool_for_each_chunk);

/**

 * gen_pool_avail - get available free space of the pool

 * @pool: pool to get available free space

 *

 * Return available free space of the specified pool.

 */

size_t gen_pool_avail(struct gen_pool *pool)

{

	struct gen_pool_chunk *chunk;

	size_t avail = 0;

	rcu_read_lock();

	list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)

		avail += atomic_read(&chunk->avail);

	rcu_read_unlock();

	return avail;

}

EXPORT_SYMBOL_GPL(gen_pool_avail);

/**

 * gen_pool_size - get size in bytes of memory managed by the pool

 * @pool: pool to get size

 *

 * Return size in bytes of memory managed by the pool.

 */

size_t gen_pool_size(struct gen_pool *pool)

{

	struct gen_pool_chunk *chunk;

	size_t size = 0;

	rcu_read_lock();

	list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)

		size += chunk->end_addr - chunk->start_addr;

	rcu_read_unlock();

	return size;

}

EXPORT_SYMBOL_GPL(gen_pool_size);