1 // SPDX-License-Identifier: GPL-2.0-only 2 #include <linux/init.h> 3 #include <linux/scatterlist.h> 4 #include <linux/mempool.h> 5 #include <linux/slab.h> 6 7 #define SG_MEMPOOL_NR ARRAY_SIZE(sg_pools) 8 #define SG_MEMPOOL_SIZE 2 9 10 struct sg_pool { 11 size_t size; 12 char *name; 13 struct kmem_cache *slab; 14 mempool_t *pool; 15 }; 16 17 #define SP(x) { .size = x, "sgpool-" __stringify(x) } 18 #if (SG_CHUNK_SIZE < 32) 19 #error SG_CHUNK_SIZE is too small (must be 32 or greater) 20 #endif 21 static struct sg_pool sg_pools[] = { 22 SP(8), 23 SP(16), 24 #if (SG_CHUNK_SIZE > 32) 25 SP(32), 26 #if (SG_CHUNK_SIZE > 64) 27 SP(64), 28 #if (SG_CHUNK_SIZE > 128) 29 SP(128), 30 #if (SG_CHUNK_SIZE > 256) 31 #error SG_CHUNK_SIZE is too large (256 MAX) 32 #endif 33 #endif 34 #endif 35 #endif 36 SP(SG_CHUNK_SIZE) 37 }; 38 #undef SP 39 40 static inline unsigned int sg_pool_index(unsigned short nents) 41 { 42 unsigned int index; 43 44 BUG_ON(nents > SG_CHUNK_SIZE); 45 46 if (nents <= 8) 47 index = 0; 48 else 49 index = get_count_order(nents) - 3; 50 51 return index; 52 } 53 54 static void sg_pool_free(struct scatterlist *sgl, unsigned int nents) 55 { 56 struct sg_pool *sgp; 57 58 sgp = sg_pools + sg_pool_index(nents); 59 mempool_free(sgl, sgp->pool); 60 } 61 62 static struct scatterlist *sg_pool_alloc(unsigned int nents, gfp_t gfp_mask) 63 { 64 struct sg_pool *sgp; 65 66 sgp = sg_pools + sg_pool_index(nents); 67 return mempool_alloc(sgp->pool, gfp_mask); 68 } 69 70 /** 71 * sg_free_table_chained - Free a previously mapped sg table 72 * @table: The sg table header to use 73 * @nents_first_chunk: size of the first_chunk SGL passed to 74 * sg_alloc_table_chained 75 * 76 * Description: 77 * Free an sg table previously allocated and setup with 78 * sg_alloc_table_chained(). 79 * 80 * @nents_first_chunk has to be same with that same parameter passed 81 * to sg_alloc_table_chained(). 82 * 83 **/ 84 void sg_free_table_chained(struct sg_table *table, 85 unsigned nents_first_chunk) 86 { 87 if (table->orig_nents <= nents_first_chunk) 88 return; 89 90 if (nents_first_chunk == 1) 91 nents_first_chunk = 0; 92 93 __sg_free_table(table, SG_CHUNK_SIZE, nents_first_chunk, sg_pool_free, 94 table->orig_nents); 95 } 96 EXPORT_SYMBOL_GPL(sg_free_table_chained); 97 98 /** 99 * sg_alloc_table_chained - Allocate and chain SGLs in an sg table 100 * @table: The sg table header to use 101 * @nents: Number of entries in sg list 102 * @first_chunk: first SGL 103 * @nents_first_chunk: number of the SGL of @first_chunk 104 * 105 * Description: 106 * Allocate and chain SGLs in an sg table. If @nents@ is larger than 107 * @nents_first_chunk a chained sg table will be setup. @first_chunk is 108 * ignored if nents_first_chunk <= 1 because user expects the SGL points 109 * non-chain SGL. 110 * 111 **/ 112 int sg_alloc_table_chained(struct sg_table *table, int nents, 113 struct scatterlist *first_chunk, unsigned nents_first_chunk) 114 { 115 int ret; 116 117 BUG_ON(!nents); 118 119 if (first_chunk && nents_first_chunk) { 120 if (nents <= nents_first_chunk) { 121 table->nents = table->orig_nents = nents; 122 sg_init_table(table->sgl, nents); 123 return 0; 124 } 125 } 126 127 /* User supposes that the 1st SGL includes real entry */ 128 if (nents_first_chunk <= 1) { 129 first_chunk = NULL; 130 nents_first_chunk = 0; 131 } 132 133 ret = __sg_alloc_table(table, nents, SG_CHUNK_SIZE, 134 first_chunk, nents_first_chunk, 135 GFP_ATOMIC, sg_pool_alloc); 136 if (unlikely(ret)) 137 sg_free_table_chained(table, nents_first_chunk); 138 return ret; 139 } 140 EXPORT_SYMBOL_GPL(sg_alloc_table_chained); 141 142 static __init int sg_pool_init(void) 143 { 144 int i; 145 146 for (i = 0; i < SG_MEMPOOL_NR; i++) { 147 struct sg_pool *sgp = sg_pools + i; 148 int size = sgp->size * sizeof(struct scatterlist); 149 150 sgp->slab = kmem_cache_create(sgp->name, size, 0, 151 SLAB_HWCACHE_ALIGN, NULL); 152 if (!sgp->slab) { 153 printk(KERN_ERR "SG_POOL: can't init sg slab %s\n", 154 sgp->name); 155 goto cleanup_sdb; 156 } 157 158 sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE, 159 sgp->slab); 160 if (!sgp->pool) { 161 printk(KERN_ERR "SG_POOL: can't init sg mempool %s\n", 162 sgp->name); 163 goto cleanup_sdb; 164 } 165 } 166 167 return 0; 168 169 cleanup_sdb: 170 for (i = 0; i < SG_MEMPOOL_NR; i++) { 171 struct sg_pool *sgp = sg_pools + i; 172 173 mempool_destroy(sgp->pool); 174 kmem_cache_destroy(sgp->slab); 175 } 176 177 return -ENOMEM; 178 } 179 180 subsys_initcall(sg_pool_init); 181