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Subject[PATCHv7 03/10] lib: genalloc: Generic allocator improvements
This commit adds a gen_pool_alloc_aligned() function to the
generic allocator API. It allows specifying alignment for the
allocated block. This feature uses
the bitmap_find_next_zero_area_off() function.

It also fixes possible issue with bitmap's last element being
not fully allocated (ie. space allocated for chunk->bits is
not a multiple of sizeof(long)).

It also makes some other smaller changes:
- moves structure definitions out of the header file,
- adds __must_check to functions returning value,
- makes gen_pool_add() return -ENOMEM rater than -1 on error,
- changes list_for_each to list_for_each_entry, and
- makes use of bitmap_clear().

Signed-off-by: Michal Nazarewicz <m.nazarewicz@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
---
include/linux/genalloc.h | 46 ++++++------
lib/genalloc.c | 182 ++++++++++++++++++++++++++-------------------
2 files changed, 129 insertions(+), 99 deletions(-)
diff --git a/include/linux/genalloc.h b/include/linux/genalloc.h
index 9869ef3..8ac7337 100644
--- a/include/linux/genalloc.h
+++ b/include/linux/genalloc.h
@@ -8,29 +8,31 @@
* Version 2. See the file COPYING for more details.
*/

+struct gen_pool;

-/*
- * General purpose special memory pool descriptor.
- */
-struct gen_pool {
- rwlock_t lock;
- struct list_head chunks; /* list of chunks in this pool */
- int min_alloc_order; /* minimum allocation order */
-};
+struct gen_pool *__must_check gen_pool_create(unsigned order, int nid);

-/*
- * General purpose special memory pool chunk descriptor.
+int __must_check gen_pool_add(struct gen_pool *pool, unsigned long addr,
+ size_t size, int nid);
+
+void gen_pool_destroy(struct gen_pool *pool);
+
+unsigned long __must_check
+gen_pool_alloc_aligned(struct gen_pool *pool, size_t size,
+ unsigned alignment_order);
+
+/**
+ * gen_pool_alloc() - allocate special memory from the pool
+ * @pool: Pool to allocate from.
+ * @size: Number of bytes to allocate from the pool.
+ *
+ * Allocate the requested number of bytes from the specified pool.
+ * Uses a first-fit algorithm.
*/
-struct gen_pool_chunk {
- spinlock_t lock;
- struct list_head next_chunk; /* next chunk in pool */
- unsigned long start_addr; /* starting address of memory chunk */
- unsigned long end_addr; /* ending address of memory chunk */
- unsigned long bits[0]; /* bitmap for allocating memory chunk */
-};
+static inline unsigned long __must_check
+gen_pool_alloc(struct gen_pool *pool, size_t size)
+{
+ return gen_pool_alloc_aligned(pool, size, 0);
+}

-extern struct gen_pool *gen_pool_create(int, int);
-extern int gen_pool_add(struct gen_pool *, unsigned long, size_t, int);
-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);
+void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size);
diff --git a/lib/genalloc.c b/lib/genalloc.c
index 1923f14..0761079 100644
--- a/lib/genalloc.c
+++ b/lib/genalloc.c
@@ -16,53 +16,80 @@
#include <linux/genalloc.h>


+/* General purpose special memory pool descriptor. */
+struct gen_pool {
+ rwlock_t lock; /* protects chunks list */
+ struct list_head chunks; /* list of chunks in this pool */
+ unsigned order; /* minimum allocation order */
+};
+
+/* General purpose special memory pool chunk descriptor. */
+struct gen_pool_chunk {
+ spinlock_t lock; /* protects bits */
+ struct list_head next_chunk; /* next chunk in pool */
+ unsigned long start; /* start of memory chunk */
+ unsigned long size; /* number of bits */
+ unsigned long bits[0]; /* bitmap for allocating memory chunk */
+};
+
+
/**
- * gen_pool_create - create a new special memory pool
- * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
- * @nid: node id of the node the pool structure should be allocated on, or -1
+ * gen_pool_create() - create a new special memory pool
+ * @order: Log base 2 of number of bytes each bitmap bit
+ * represents.
+ * @nid: Node id of the node the pool structure should be allocated
+ * on, or -1. This will be also used for other allocations.
*
* Create a new special memory pool that can be used to manage special purpose
* memory not managed by the regular kmalloc/kfree interface.
*/
-struct gen_pool *gen_pool_create(int min_alloc_order, int nid)
+struct gen_pool *__must_check gen_pool_create(unsigned order, int nid)
{
struct gen_pool *pool;

- pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid);
- if (pool != NULL) {
+ if (WARN_ON(order >= BITS_PER_LONG))
+ return NULL;
+
+ pool = kmalloc_node(sizeof *pool, GFP_KERNEL, nid);
+ if (pool) {
rwlock_init(&pool->lock);
INIT_LIST_HEAD(&pool->chunks);
- pool->min_alloc_order = min_alloc_order;
+ pool->order = order;
}
return pool;
}
EXPORT_SYMBOL(gen_pool_create);

/**
- * gen_pool_add - add a new chunk of special memory to the pool
- * @pool: pool to add new memory chunk to
- * @addr: starting address of memory chunk to add to pool
- * @size: size in bytes of the memory chunk to add to pool
- * @nid: node id of the node the chunk structure and bitmap should be
- * allocated on, or -1
+ * gen_pool_add() - add a new chunk of special memory to the pool
+ * @pool: Pool to add new memory chunk to.
+ * @addr: Starting address of memory chunk to add to pool.
+ * @size: Size in bytes of the memory chunk to add to pool.
*
* Add a new chunk of special memory to the specified pool.
*/
-int gen_pool_add(struct gen_pool *pool, unsigned long addr, size_t size,
- int nid)
+int __must_check
+gen_pool_add(struct gen_pool *pool, unsigned long addr, size_t size, int nid)
{
struct gen_pool_chunk *chunk;
- int nbits = size >> pool->min_alloc_order;
- int nbytes = sizeof(struct gen_pool_chunk) +
- (nbits + BITS_PER_BYTE - 1) / BITS_PER_BYTE;
+ size_t nbytes;
+
+ if (WARN_ON(!addr || addr + size < addr ||
+ (addr & ((1 << pool->order) - 1))))
+ return -EINVAL;

- chunk = kmalloc_node(nbytes, GFP_KERNEL | __GFP_ZERO, nid);
- if (unlikely(chunk == NULL))
- return -1;
+ size = size >> pool->order;
+ if (WARN_ON(!size))
+ return -EINVAL;
+
+ nbytes = sizeof *chunk + BITS_TO_LONGS(size) * sizeof *chunk->bits;
+ chunk = kzalloc_node(nbytes, GFP_KERNEL, nid);
+ if (!chunk)
+ return -ENOMEM;

spin_lock_init(&chunk->lock);
- chunk->start_addr = addr;
- chunk->end_addr = addr + size;
+ chunk->start = addr >> pool->order;
+ chunk->size = size;

write_lock(&pool->lock);
list_add(&chunk->next_chunk, &pool->chunks);
@@ -73,115 +100,116 @@ int gen_pool_add(struct gen_pool *pool, unsigned long addr, size_t size,
EXPORT_SYMBOL(gen_pool_add);

/**
- * gen_pool_destroy - destroy a special memory pool
- * @pool: pool to destroy
+ * gen_pool_destroy() - destroy a special memory pool
+ * @pool: Pool to destroy.
*
* Destroy the specified special memory pool. Verifies that there are no
* outstanding allocations.
*/
void gen_pool_destroy(struct gen_pool *pool)
{
- struct list_head *_chunk, *_next_chunk;
struct gen_pool_chunk *chunk;
- int order = pool->min_alloc_order;
- int bit, end_bit;
-
+ int bit;

- list_for_each_safe(_chunk, _next_chunk, &pool->chunks) {
- chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
+ while (!list_empty(&pool->chunks)) {
+ chunk = list_entry(pool->chunks.next, struct gen_pool_chunk,
+ next_chunk);
list_del(&chunk->next_chunk);

- end_bit = (chunk->end_addr - chunk->start_addr) >> order;
- bit = find_next_bit(chunk->bits, end_bit, 0);
- BUG_ON(bit < end_bit);
+ bit = find_next_bit(chunk->bits, chunk->size, 0);
+ BUG_ON(bit < chunk->size);

kfree(chunk);
}
kfree(pool);
- return;
}
EXPORT_SYMBOL(gen_pool_destroy);

/**
- * gen_pool_alloc - allocate special memory from the pool
- * @pool: pool to allocate from
- * @size: number of bytes to allocate from the pool
+ * gen_pool_alloc_aligned() - allocate special memory from the pool
+ * @pool: Pool to allocate from.
+ * @size: Number of bytes to allocate from the pool.
+ * @alignment_order: Order the allocated space should be
+ * aligned to (eg. 20 means allocated space
+ * must be aligned to 1MiB).
*
* Allocate the requested number of bytes from the specified pool.
* Uses a first-fit algorithm.
*/
-unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
+unsigned long __must_check
+gen_pool_alloc_aligned(struct gen_pool *pool, size_t size,
+ unsigned alignment_order)
{
- struct list_head *_chunk;
+ unsigned long addr, align_mask = 0, flags, start;
struct gen_pool_chunk *chunk;
- unsigned long addr, flags;
- int order = pool->min_alloc_order;
- int nbits, start_bit, end_bit;

if (size == 0)
return 0;

- nbits = (size + (1UL << order) - 1) >> order;
+ if (alignment_order > pool->order)
+ align_mask = (1 << (alignment_order - pool->order)) - 1;

- read_lock(&pool->lock);
- list_for_each(_chunk, &pool->chunks) {
- chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
+ size = (size + (1UL << pool->order) - 1) >> pool->order;

- end_bit = (chunk->end_addr - chunk->start_addr) >> order;
+ read_lock(&pool->lock);
+ list_for_each_entry(chunk, &pool->chunks, next_chunk) {
+ if (chunk->size < size)
+ continue;

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) {
+ start = bitmap_find_next_zero_area_off(chunk->bits, chunk->size,
+ 0, size, align_mask,
+ chunk->start);
+ if (start >= chunk->size) {
spin_unlock_irqrestore(&chunk->lock, flags);
continue;
}

- addr = chunk->start_addr + ((unsigned long)start_bit << order);
-
- bitmap_set(chunk->bits, start_bit, nbits);
+ bitmap_set(chunk->bits, start, size);
spin_unlock_irqrestore(&chunk->lock, flags);
- read_unlock(&pool->lock);
- return addr;
+ addr = (chunk->start + start) << pool->order;
+ goto done;
}
+
+ addr = 0;
+done:
read_unlock(&pool->lock);
- return 0;
+ return addr;
}
-EXPORT_SYMBOL(gen_pool_alloc);
+EXPORT_SYMBOL(gen_pool_alloc_aligned);

/**
- * gen_pool_free - free allocated special memory back to the pool
- * @pool: pool to free to
- * @addr: starting address of memory to free back to pool
- * @size: size in bytes of memory to free
+ * gen_pool_free() - free allocated special memory back to the pool
+ * @pool: Pool to free to.
+ * @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.
*/
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;

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

- read_lock(&pool->lock);
- list_for_each(_chunk, &pool->chunks) {
- chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
+ addr = addr >> pool->order;
+ size = (size + (1UL << pool->order) - 1) >> pool->order;
+
+ BUG_ON(addr + size < addr);

- if (addr >= chunk->start_addr && addr < chunk->end_addr) {
- BUG_ON(addr + size > chunk->end_addr);
+ read_lock(&pool->lock);
+ list_for_each_entry(chunk, &pool->chunks, next_chunk)
+ if (addr >= chunk->start &&
+ addr + size <= chunk->start + chunk->size) {
spin_lock_irqsave(&chunk->lock, flags);
- bit = (addr - chunk->start_addr) >> order;
- while (nbits--)
- __clear_bit(bit++, chunk->bits);
+ bitmap_clear(chunk->bits, addr - chunk->start, size);
spin_unlock_irqrestore(&chunk->lock, flags);
- break;
+ goto done;
}
- }
- BUG_ON(nbits > 0);
+ BUG_ON(1);
+done:
read_unlock(&pool->lock);
}
EXPORT_SYMBOL(gen_pool_free);
--
1.7.2.3


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