forked from rrcarlosr/Jetpack
173 lines
3.6 KiB
C
173 lines
3.6 KiB
C
#include <linux/module.h>
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#include <linux/scatterlist.h>
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#include <linux/mempool.h>
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#include <linux/slab.h>
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#define SG_MEMPOOL_NR ARRAY_SIZE(sg_pools)
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#define SG_MEMPOOL_SIZE 2
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struct sg_pool {
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size_t size;
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char *name;
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struct kmem_cache *slab;
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mempool_t *pool;
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};
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#define SP(x) { .size = x, "sgpool-" __stringify(x) }
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#if (SG_CHUNK_SIZE < 32)
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#error SG_CHUNK_SIZE is too small (must be 32 or greater)
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#endif
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static struct sg_pool sg_pools[] = {
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SP(8),
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SP(16),
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#if (SG_CHUNK_SIZE > 32)
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SP(32),
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#if (SG_CHUNK_SIZE > 64)
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SP(64),
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#if (SG_CHUNK_SIZE > 128)
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SP(128),
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#if (SG_CHUNK_SIZE > 256)
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#error SG_CHUNK_SIZE is too large (256 MAX)
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#endif
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#endif
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#endif
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#endif
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SP(SG_CHUNK_SIZE)
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};
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#undef SP
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static inline unsigned int sg_pool_index(unsigned short nents)
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{
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unsigned int index;
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BUG_ON(nents > SG_CHUNK_SIZE);
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if (nents <= 8)
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index = 0;
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else
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index = get_count_order(nents) - 3;
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return index;
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}
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static void sg_pool_free(struct scatterlist *sgl, unsigned int nents)
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{
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struct sg_pool *sgp;
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sgp = sg_pools + sg_pool_index(nents);
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mempool_free(sgl, sgp->pool);
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}
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static struct scatterlist *sg_pool_alloc(unsigned int nents, gfp_t gfp_mask)
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{
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struct sg_pool *sgp;
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sgp = sg_pools + sg_pool_index(nents);
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return mempool_alloc(sgp->pool, gfp_mask);
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}
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/**
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* sg_free_table_chained - Free a previously mapped sg table
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* @table: The sg table header to use
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* @first_chunk: was first_chunk not NULL in sg_alloc_table_chained?
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*
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* Description:
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* Free an sg table previously allocated and setup with
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* sg_alloc_table_chained().
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*
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**/
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void sg_free_table_chained(struct sg_table *table, bool first_chunk)
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{
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if (first_chunk && table->orig_nents <= SG_CHUNK_SIZE)
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return;
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__sg_free_table(table, SG_CHUNK_SIZE, first_chunk, sg_pool_free);
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}
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EXPORT_SYMBOL_GPL(sg_free_table_chained);
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/**
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* sg_alloc_table_chained - Allocate and chain SGLs in an sg table
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* @table: The sg table header to use
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* @nents: Number of entries in sg list
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* @first_chunk: first SGL
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*
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* Description:
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* Allocate and chain SGLs in an sg table. If @nents@ is larger than
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* SG_CHUNK_SIZE a chained sg table will be setup.
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*
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**/
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int sg_alloc_table_chained(struct sg_table *table, int nents,
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struct scatterlist *first_chunk)
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{
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int ret;
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BUG_ON(!nents);
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if (first_chunk) {
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if (nents <= SG_CHUNK_SIZE) {
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table->nents = table->orig_nents = nents;
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sg_init_table(table->sgl, nents);
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return 0;
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}
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}
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ret = __sg_alloc_table(table, nents, SG_CHUNK_SIZE,
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first_chunk, GFP_ATOMIC, sg_pool_alloc);
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if (unlikely(ret))
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sg_free_table_chained(table, (bool)first_chunk);
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return ret;
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}
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EXPORT_SYMBOL_GPL(sg_alloc_table_chained);
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static __init int sg_pool_init(void)
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{
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int i;
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for (i = 0; i < SG_MEMPOOL_NR; i++) {
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struct sg_pool *sgp = sg_pools + i;
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int size = sgp->size * sizeof(struct scatterlist);
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sgp->slab = kmem_cache_create(sgp->name, size, 0,
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SLAB_HWCACHE_ALIGN, NULL);
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if (!sgp->slab) {
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printk(KERN_ERR "SG_POOL: can't init sg slab %s\n",
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sgp->name);
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goto cleanup_sdb;
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}
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sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
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sgp->slab);
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if (!sgp->pool) {
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printk(KERN_ERR "SG_POOL: can't init sg mempool %s\n",
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sgp->name);
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goto cleanup_sdb;
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}
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}
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return 0;
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cleanup_sdb:
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for (i = 0; i < SG_MEMPOOL_NR; i++) {
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struct sg_pool *sgp = sg_pools + i;
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if (sgp->pool)
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mempool_destroy(sgp->pool);
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if (sgp->slab)
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kmem_cache_destroy(sgp->slab);
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}
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return -ENOMEM;
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}
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static __exit void sg_pool_exit(void)
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{
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int i;
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for (i = 0; i < SG_MEMPOOL_NR; i++) {
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struct sg_pool *sgp = sg_pools + i;
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mempool_destroy(sgp->pool);
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kmem_cache_destroy(sgp->slab);
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}
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}
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module_init(sg_pool_init);
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module_exit(sg_pool_exit);
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