/* * linux/mm/mempool.c * * memory buffer pool support. Such pools are mostly used * for guaranteed, deadlock-free memory allocations during * extreme VM load. * * started by Ingo Molnar, Copyright (C) 2001 */ #include <linux/mm.h>#include <linux/slab.h>#include <linux/export.h>#include <linux/mempool.h>#include <linux/blkdev.h>#include <linux/writeback.h> static void add_element(mempool_t *pool, void *element){ BUG_ON(pool->curr_nr >= pool->min_nr); pool->elements[pool->curr_nr++] = element;} static void *remove_element(mempool_t *pool){ BUG_ON(pool->curr_nr <= 0); return pool->elements[--pool->curr_nr];} /** * mempool_destroy - deallocate a memory pool * @pool: pointer to the memory pool which was allocated via * mempool_create(). * * Free all reserved elements in @pool and @pool itself. This function * only sleeps if the free_fn() function sleeps. */void mempool_destroy(mempool_t *pool){ while (pool->curr_nr) { void *element = remove_element(pool); pool->free(element, pool->pool_data); } kfree(pool->elements); kfree(pool);}EXPORT_SYMBOL(mempool_destroy); /** * mempool_create - create a memory pool * @min_nr: the minimum number of elements guaranteed to be * allocated for this pool. * @alloc_fn: user-defined element-allocation function. * @free_fn: user-defined element-freeing function. * @pool_data: optional private data available to the user-defined functions. * * this function creates and allocates a guaranteed size, preallocated * memory pool. The pool can be used from the mempool_alloc() and mempool_free() * functions. This function might sleep. Both the alloc_fn() and the free_fn() * functions might sleep - as long as the mempool_alloc() function is not called * from IRQ contexts. */mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn, mempool_free_t *free_fn, void *pool_data){ return mempool_create_node(min_nr,alloc_fn,free_fn, pool_data,-1);}EXPORT_SYMBOL(mempool_create); mempool_t *mempool_create_node(int min_nr, mempool_alloc_t *alloc_fn, mempool_free_t *free_fn, void *pool_data, int node_id){ mempool_t *pool; pool = kmalloc_node(sizeof(*pool), GFP_KERNEL | __GFP_ZERO, node_id); if (!pool) return NULL; pool->elements = kmalloc_node(min_nr * sizeof(void *), GFP_KERNEL, node_id); if (!pool->elements) { kfree(pool); return NULL; } spin_lock_init(&pool->lock); pool->min_nr = min_nr; pool->pool_data = pool_data; init_waitqueue_head(&pool->wait); pool->alloc = alloc_fn; pool->free = free_fn; /* * First pre-allocate the guaranteed number of buffers. */ while (pool->curr_nr < pool->min_nr) { void *element; element = pool->alloc(GFP_KERNEL, pool->pool_data); if (unlikely(!element)) { mempool_destroy(pool); return NULL; } add_element(pool, element); } return pool;}EXPORT_SYMBOL(mempool_create_node); /** * mempool_resize - resize an existing memory pool * @pool: pointer to the memory pool which was allocated via * mempool_create(). * @new_min_nr: the new minimum number of elements guaranteed to be * allocated for this pool. * @gfp_mask: the usual allocation bitmask. * * This function shrinks/grows the pool. In the case of growing, * it cannot be guaranteed that the pool will be grown to the new * size immediately, but new mempool_free() calls will refill it. * * Note, the caller must guarantee that no mempool_destroy is called * while this function is running. mempool_alloc() & mempool_free() * might be called (eg. from IRQ contexts) while this function executes. */int mempool_resize(mempool_t *pool, int new_min_nr, gfp_t gfp_mask){ void *element; void **new_elements; unsigned long flags; BUG_ON(new_min_nr <= 0); spin_lock_irqsave(&pool->lock, flags); if (new_min_nr <= pool->min_nr) { while (new_min_nr < pool->curr_nr) { element = remove_element(pool); spin_unlock_irqrestore(&pool->lock, flags); pool->free(element, pool->pool_data); spin_lock_irqsave(&pool->lock, flags); } pool->min_nr = new_min_nr; goto out_unlock; } spin_unlock_irqrestore(&pool->lock, flags); /* Grow the pool */ new_elements = kmalloc(new_min_nr * sizeof(*new_elements), gfp_mask); if (!new_elements) return -ENOMEM; spin_lock_irqsave(&pool->lock, flags); if (unlikely(new_min_nr <= pool->min_nr)) { /* Raced, other resize will do our work */ spin_unlock_irqrestore(&pool->lock, flags); kfree(new_elements); goto out; } memcpy(new_elements, pool->elements, pool->curr_nr * sizeof(*new_elements)); kfree(pool->elements); pool->elements = new_elements; pool->min_nr = new_min_nr; while (pool->curr_nr < pool->min_nr) { spin_unlock_irqrestore(&pool->lock, flags); element = pool->alloc(gfp_mask, pool->pool_data); if (!element) goto out; spin_lock_irqsave(&pool->lock, flags); if (pool->curr_nr < pool->min_nr) { add_element(pool, element); } else { spin_unlock_irqrestore(&pool->lock, flags); pool->free(element, pool->pool_data); /* Raced */ goto out; } }out_unlock: spin_unlock_irqrestore(&pool->lock, flags);out: return 0;}EXPORT_SYMBOL(mempool_resize); /** * mempool_alloc - allocate an element from a specific memory pool * @pool: pointer to the memory pool which was allocated via * mempool_create(). * @gfp_mask: the usual allocation bitmask. * * this function only sleeps if the alloc_fn() function sleeps or * returns NULL. Note that due to preallocation, this function * *never* fails when called from process contexts. (it might * fail if called from an IRQ context.) */void * mempool_alloc(mempool_t *pool, gfp_t gfp_mask){ void *element; unsigned long flags; wait_queue_t wait; gfp_t gfp_temp; might_sleep_if(gfp_mask & __GFP_WAIT); gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */ gfp_mask |= __GFP_NORETRY; /* don't loop in __alloc_pages */ gfp_mask |= __GFP_NOWARN; /* failures are OK */ gfp_temp = gfp_mask & ~(__GFP_WAIT|__GFP_IO); repeat_alloc: element = pool->alloc(gfp_temp, pool->pool_data); if (likely(element != NULL)) return element; spin_lock_irqsave(&pool->lock, flags); if (likely(pool->curr_nr)) { element = remove_element(pool); spin_unlock_irqrestore(&pool->lock, flags); /* paired with rmb in mempool_free(), read comment there */ smp_wmb(); return element; } /* * We use gfp mask w/o __GFP_WAIT or IO for the first round. If * alloc failed with that and @pool was empty, retry immediately. */ if (gfp_temp != gfp_mask) { spin_unlock_irqrestore(&pool->lock, flags); gfp_temp = gfp_mask; goto repeat_alloc; } /* We must not sleep if !__GFP_WAIT */ if (!(gfp_mask & __GFP_WAIT)) { spin_unlock_irqrestore(&pool->lock, flags); return NULL; } /* Let's wait for someone else to return an element to @pool */ init_wait(&wait); prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE); spin_unlock_irqrestore(&pool->lock, flags); /* * FIXME: this should be io_schedule(). The timeout is there as a * workaround for some DM problems in 2.6.18. */ io_schedule_timeout(5*HZ); finish_wait(&pool->wait, &wait); goto repeat_alloc;}EXPORT_SYMBOL(mempool_alloc); /** * mempool_free - return an element to the pool. * @element: pool element pointer. * @pool: pointer to the memory pool which was allocated via * mempool_create(). * * this function only sleeps if the free_fn() function sleeps. */void mempool_free(void *element, mempool_t *pool){ unsigned long flags; if (unlikely(element == NULL)) return; /* * Paired with the wmb in mempool_alloc(). The preceding read is * for @element and the following @pool->curr_nr. This ensures * that the visible value of @pool->curr_nr is from after the * allocation of @element. This is necessary for fringe cases * where @element was passed to this task without going through * barriers. * * For example, assume @p is %NULL at the beginning and one task * performs "p = mempool_alloc(...);" while another task is doing * "while (!p) cpu_relax(); mempool_free(p, ...);". This function * may end up using curr_nr value which is from before allocation * of @p without the following rmb. */ smp_rmb(); /* * For correctness, we need a test which is guaranteed to trigger * if curr_nr + #allocated == min_nr. Testing curr_nr < min_nr * without locking achieves that and refilling as soon as possible * is desirable. * * Because curr_nr visible here is always a value after the * allocation of @element, any task which decremented curr_nr below * min_nr is guaranteed to see curr_nr < min_nr unless curr_nr gets * incremented to min_nr afterwards. If curr_nr gets incremented * to min_nr after the allocation of @element, the elements * allocated after that are subject to the same guarantee. * * Waiters happen iff curr_nr is 0 and the above guarantee also * ensures that there will be frees which return elements to the * pool waking up the waiters. */ if (pool->curr_nr < pool->min_nr) { spin_lock_irqsave(&pool->lock, flags); if (pool->curr_nr < pool->min_nr) { add_element(pool, element); spin_unlock_irqrestore(&pool->lock, flags); wake_up(&pool->wait); return; } spin_unlock_irqrestore(&pool->lock, flags); } pool->free(element, pool->pool_data);}EXPORT_SYMBOL(mempool_free); /* * A commonly used alloc and free fn. */void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data){ struct kmem_cache *mem = pool_data; return kmem_cache_alloc(mem, gfp_mask);}EXPORT_SYMBOL(mempool_alloc_slab); void mempool_free_slab(void *element, void *pool_data){ struct kmem_cache *mem = pool_data; kmem_cache_free(mem, element);}EXPORT_SYMBOL(mempool_free_slab); /* * A commonly used alloc and free fn that kmalloc/kfrees the amount of memory * specified by pool_data */void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data){ size_t size = (size_t)pool_data; return kmalloc(size, gfp_mask);}EXPORT_SYMBOL(mempool_kmalloc); void mempool_kfree(void *element, void *pool_data){ kfree(element);}EXPORT_SYMBOL(mempool_kfree); /* * A simple mempool-backed page allocator that allocates pages * of the order specified by pool_data. */void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data){ int order = (int)(long)pool_data; return alloc_pages(gfp_mask, order);}EXPORT_SYMBOL(mempool_alloc_pages); void mempool_free_pages(void *element, void *pool_data){ int order = (int)(long)pool_data; __free_pages(element, order);}EXPORT_SYMBOL(mempool_free_pages);
/*
* linux/mm/mempool.c
*
* memory buffer pool support. Such pools are mostly used
* for guaranteed, deadlock-free memory allocations during
* extreme VM load.
*
* started by Ingo Molnar, Copyright (C) 2001
*/
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <linux/mempool.h>
#include <linux/blkdev.h>
#include <linux/writeback.h>
static void add_element(mempool_t *pool, void *element)
{
BUG_ON(pool->curr_nr >= pool->min_nr);
pool->elements[pool->curr_nr++] = element;
}
static void *remove_element(mempool_t *pool)
{
BUG_ON(pool->curr_nr <= 0);
return pool->elements[--pool->curr_nr];
}
/**
* mempool_destroy - deallocate a memory pool
* @pool: pointer to the memory pool which was allocated via
* mempool_create().
*
* Free all reserved elements in @pool and @pool itself. This function
* only sleeps if the free_fn() function sleeps.
*/
void mempool_destroy(mempool_t *pool)
{
while (pool->curr_nr) {
void *element = remove_element(pool);
pool->free(element, pool->pool_data);
}
kfree(pool->elements);
kfree(pool);
}
EXPORT_SYMBOL(mempool_destroy);
/**
* mempool_create - create a memory pool
* @min_nr: the minimum number of elements guaranteed to be
* allocated for this pool.
* @alloc_fn: user-defined element-allocation function.
* @free_fn: user-defined element-freeing function.
* @pool_data: optional private data available to the user-defined functions.
*
* this function creates and allocates a guaranteed size, preallocated
* memory pool. The pool can be used from the mempool_alloc() and mempool_free()
* functions. This function might sleep. Both the alloc_fn() and the free_fn()
* functions might sleep - as long as the mempool_alloc() function is not called
* from IRQ contexts.
*/
mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
mempool_free_t *free_fn, void *pool_data)
{
return mempool_create_node(min_nr,alloc_fn,free_fn, pool_data,-1);
}
EXPORT_SYMBOL(mempool_create);
mempool_t *mempool_create_node(int min_nr, mempool_alloc_t *alloc_fn,
mempool_free_t *free_fn, void *pool_data, int node_id)
{
mempool_t *pool;
pool = kmalloc_node(sizeof(*pool), GFP_KERNEL | __GFP_ZERO, node_id);
if (!pool)
return NULL;
pool->elements = kmalloc_node(min_nr * sizeof(void *),
GFP_KERNEL, node_id);
if (!pool->elements) {
kfree(pool);
return NULL;
}
spin_lock_init(&pool->lock);
pool->min_nr = min_nr;
pool->pool_data = pool_data;
init_waitqueue_head(&pool->wait);
pool->alloc = alloc_fn;
pool->free = free_fn;
/*
* First pre-allocate the guaranteed number of buffers.
*/
while (pool->curr_nr < pool->min_nr) {
void *element;
element = pool->alloc(GFP_KERNEL, pool->pool_data);
if (unlikely(!element)) {
mempool_destroy(pool);
return NULL;
}
add_element(pool, element);
}
return pool;
}
EXPORT_SYMBOL(mempool_create_node);
/**
* mempool_resize - resize an existing memory pool
* @pool: pointer to the memory pool which was allocated via
* mempool_create().
* @new_min_nr: the new minimum number of elements guaranteed to be
* allocated for this pool.
* @gfp_mask: the usual allocation bitmask.
*
* This function shrinks/grows the pool. In the case of growing,
* it cannot be guaranteed that the pool will be grown to the new
* size immediately, but new mempool_free() calls will refill it.
*
* Note, the caller must guarantee that no mempool_destroy is called
* while this function is running. mempool_alloc() & mempool_free()
* might be called (eg. from IRQ contexts) while this function executes.
*/
int mempool_resize(mempool_t *pool, int new_min_nr, gfp_t gfp_mask)
{
void *element;
void **new_elements;
unsigned long flags;
BUG_ON(new_min_nr <= 0);
spin_lock_irqsave(&pool->lock, flags);
if (new_min_nr <= pool->min_nr) {
while (new_min_nr < pool->curr_nr) {
element = remove_element(pool);
spin_unlock_irqrestore(&pool->lock, flags);
pool->free(element, pool->pool_data);
spin_lock_irqsave(&pool->lock, flags);
}
pool->min_nr = new_min_nr;
goto out_unlock;
}
spin_unlock_irqrestore(&pool->lock, flags);
/* Grow the pool */
new_elements = kmalloc(new_min_nr * sizeof(*new_elements), gfp_mask);
if (!new_elements)
return -ENOMEM;
spin_lock_irqsave(&pool->lock, flags);
if (unlikely(new_min_nr <= pool->min_nr)) {
/* Raced, other resize will do our work */
spin_unlock_irqrestore(&pool->lock, flags);
kfree(new_elements);
goto out;
}
memcpy(new_elements, pool->elements,
pool->curr_nr * sizeof(*new_elements));
kfree(pool->elements);
pool->elements = new_elements;
pool->min_nr = new_min_nr;
while (pool->curr_nr < pool->min_nr) {
spin_unlock_irqrestore(&pool->lock, flags);
element = pool->alloc(gfp_mask, pool->pool_data);
if (!element)
goto out;
spin_lock_irqsave(&pool->lock, flags);
if (pool->curr_nr < pool->min_nr) {
add_element(pool, element);
} else {
spin_unlock_irqrestore(&pool->lock, flags);
pool->free(element, pool->pool_data); /* Raced */
goto out;
}
}
out_unlock:
spin_unlock_irqrestore(&pool->lock, flags);
out:
return 0;
}
EXPORT_SYMBOL(mempool_resize);
/**
* mempool_alloc - allocate an element from a specific memory pool
* @pool: pointer to the memory pool which was allocated via
* mempool_create().
* @gfp_mask: the usual allocation bitmask.
*
* this function only sleeps if the alloc_fn() function sleeps or
* returns NULL. Note that due to preallocation, this function
* *never* fails when called from process contexts. (it might
* fail if called from an IRQ context.)
*/
void * mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
{
void *element;
unsigned long flags;
wait_queue_t wait;
gfp_t gfp_temp;
might_sleep_if(gfp_mask & __GFP_WAIT);
gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */
gfp_mask |= __GFP_NORETRY; /* don't loop in __alloc_pages */
gfp_mask |= __GFP_NOWARN; /* failures are OK */
gfp_temp = gfp_mask & ~(__GFP_WAIT|__GFP_IO);
repeat_alloc:
element = pool->alloc(gfp_temp, pool->pool_data);
if (likely(element != NULL))
return element;
spin_lock_irqsave(&pool->lock, flags);
if (likely(pool->curr_nr)) {
element = remove_element(pool);
spin_unlock_irqrestore(&pool->lock, flags);
/* paired with rmb in mempool_free(), read comment there */
smp_wmb();
return element;
}
/*
* We use gfp mask w/o __GFP_WAIT or IO for the first round. If
* alloc failed with that and @pool was empty, retry immediately.
*/
if (gfp_temp != gfp_mask) {
spin_unlock_irqrestore(&pool->lock, flags);
gfp_temp = gfp_mask;
goto repeat_alloc;
}
/* We must not sleep if !__GFP_WAIT */
if (!(gfp_mask & __GFP_WAIT)) {
spin_unlock_irqrestore(&pool->lock, flags);
return NULL;
}
/* Let's wait for someone else to return an element to @pool */
init_wait(&wait);
prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
spin_unlock_irqrestore(&pool->lock, flags);
/*
* FIXME: this should be io_schedule(). The timeout is there as a
* workaround for some DM problems in 2.6.18.
*/
io_schedule_timeout(5*HZ);
finish_wait(&pool->wait, &wait);
goto repeat_alloc;
}
EXPORT_SYMBOL(mempool_alloc);
/**
* mempool_free - return an element to the pool.
* @element: pool element pointer.
* @pool: pointer to the memory pool which was allocated via
* mempool_create().
*
* this function only sleeps if the free_fn() function sleeps.
*/
void mempool_free(void *element, mempool_t *pool)
{
unsigned long flags;
if (unlikely(element == NULL))
return;
/*
* Paired with the wmb in mempool_alloc(). The preceding read is
* for @element and the following @pool->curr_nr. This ensures
* that the visible value of @pool->curr_nr is from after the
* allocation of @element. This is necessary for fringe cases
* where @element was passed to this task without going through
* barriers.
*
* For example, assume @p is %NULL at the beginning and one task
* performs "p = mempool_alloc(...);" while another task is doing
* "while (!p) cpu_relax(); mempool_free(p, ...);". This function
* may end up using curr_nr value which is from before allocation
* of @p without the following rmb.
*/
smp_rmb();
/*
* For correctness, we need a test which is guaranteed to trigger
* if curr_nr + #allocated == min_nr. Testing curr_nr < min_nr
* without locking achieves that and refilling as soon as possible
* is desirable.
*
* Because curr_nr visible here is always a value after the
* allocation of @element, any task which decremented curr_nr below
* min_nr is guaranteed to see curr_nr < min_nr unless curr_nr gets
* incremented to min_nr afterwards. If curr_nr gets incremented
* to min_nr after the allocation of @element, the elements
* allocated after that are subject to the same guarantee.
*
* Waiters happen iff curr_nr is 0 and the above guarantee also
* ensures that there will be frees which return elements to the
* pool waking up the waiters.
*/
if (pool->curr_nr < pool->min_nr) {
spin_lock_irqsave(&pool->lock, flags);
if (pool->curr_nr < pool->min_nr) {
add_element(pool, element);
spin_unlock_irqrestore(&pool->lock, flags);
wake_up(&pool->wait);
return;
}
spin_unlock_irqrestore(&pool->lock, flags);
}
pool->free(element, pool->pool_data);
}
EXPORT_SYMBOL(mempool_free);
/*
* A commonly used alloc and free fn.
*/
void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data)
{
struct kmem_cache *mem = pool_data;
return kmem_cache_alloc(mem, gfp_mask);
}
EXPORT_SYMBOL(mempool_alloc_slab);
void mempool_free_slab(void *element, void *pool_data)
{
struct kmem_cache *mem = pool_data;
kmem_cache_free(mem, element);
}
EXPORT_SYMBOL(mempool_free_slab);
/*
* A commonly used alloc and free fn that kmalloc/kfrees the amount of memory
* specified by pool_data
*/
void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data)
{
size_t size = (size_t)pool_data;
return kmalloc(size, gfp_mask);
}
EXPORT_SYMBOL(mempool_kmalloc);
void mempool_kfree(void *element, void *pool_data)
{
kfree(element);
}
EXPORT_SYMBOL(mempool_kfree);
/*
* A simple mempool-backed page allocator that allocates pages
* of the order specified by pool_data.
*/
void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data)
{
int order = (int)(long)pool_data;
return alloc_pages(gfp_mask, order);
}
EXPORT_SYMBOL(mempool_alloc_pages);
void mempool_free_pages(void *element, void *pool_data)
{
int order = (int)(long)pool_data;
__free_pages(element, order);
}
EXPORT_SYMBOL(mempool_free_pages);