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