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