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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 | #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); |