diff options
Diffstat (limited to 'lib/sg_pool.c')
| -rw-r--r-- | lib/sg_pool.c | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/lib/sg_pool.c b/lib/sg_pool.c new file mode 100644 index 000000000000..6dd30615a201 --- /dev/null +++ b/lib/sg_pool.c @@ -0,0 +1,172 @@ +#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; + if (sgp->pool) + mempool_destroy(sgp->pool); + if (sgp->slab) + 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); |