1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/module.h>
3 #include <linux/scatterlist.h>
4 #include <linux/mempool.h>
5 #include <linux/slab.h>
7 #define SG_MEMPOOL_NR ARRAY_SIZE(sg_pools)
8 #define SG_MEMPOOL_SIZE 2
13 struct kmem_cache *slab;
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)
21 static struct sg_pool sg_pools[] = {
24 #if (SG_CHUNK_SIZE > 32)
26 #if (SG_CHUNK_SIZE > 64)
28 #if (SG_CHUNK_SIZE > 128)
30 #if (SG_CHUNK_SIZE > 256)
31 #error SG_CHUNK_SIZE is too large (256 MAX)
40 static inline unsigned int sg_pool_index(unsigned short nents)
44 BUG_ON(nents > SG_CHUNK_SIZE);
49 index = get_count_order(nents) - 3;
54 static void sg_pool_free(struct scatterlist *sgl, unsigned int nents)
58 sgp = sg_pools + sg_pool_index(nents);
59 mempool_free(sgl, sgp->pool);
62 static struct scatterlist *sg_pool_alloc(unsigned int nents, gfp_t gfp_mask)
66 sgp = sg_pools + sg_pool_index(nents);
67 return mempool_alloc(sgp->pool, gfp_mask);
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
77 * Free an sg table previously allocated and setup with
78 * sg_alloc_table_chained().
80 * @nents_first_chunk has to be same with that same parameter passed
81 * to sg_alloc_table_chained().
84 void sg_free_table_chained(struct sg_table *table,
85 unsigned nents_first_chunk)
87 if (table->orig_nents <= nents_first_chunk)
90 if (nents_first_chunk == 1)
91 nents_first_chunk = 0;
93 __sg_free_table(table, SG_CHUNK_SIZE, nents_first_chunk, sg_pool_free);
95 EXPORT_SYMBOL_GPL(sg_free_table_chained);
98 * sg_alloc_table_chained - Allocate and chain SGLs in an sg table
99 * @table: The sg table header to use
100 * @nents: Number of entries in sg list
101 * @first_chunk: first SGL
102 * @nents_first_chunk: number of the SGL of @first_chunk
105 * Allocate and chain SGLs in an sg table. If @nents@ is larger than
106 * @nents_first_chunk a chained sg table will be setup. @first_chunk is
107 * ignored if nents_first_chunk <= 1 because user expects the SGL points
111 int sg_alloc_table_chained(struct sg_table *table, int nents,
112 struct scatterlist *first_chunk, unsigned nents_first_chunk)
118 if (first_chunk && nents_first_chunk) {
119 if (nents <= nents_first_chunk) {
120 table->nents = table->orig_nents = nents;
121 sg_init_table(table->sgl, nents);
126 /* User supposes that the 1st SGL includes real entry */
127 if (nents_first_chunk <= 1) {
129 nents_first_chunk = 0;
132 ret = __sg_alloc_table(table, nents, SG_CHUNK_SIZE,
133 first_chunk, nents_first_chunk,
134 GFP_ATOMIC, sg_pool_alloc);
136 sg_free_table_chained(table, nents_first_chunk);
139 EXPORT_SYMBOL_GPL(sg_alloc_table_chained);
141 static __init int sg_pool_init(void)
145 for (i = 0; i < SG_MEMPOOL_NR; i++) {
146 struct sg_pool *sgp = sg_pools + i;
147 int size = sgp->size * sizeof(struct scatterlist);
149 sgp->slab = kmem_cache_create(sgp->name, size, 0,
150 SLAB_HWCACHE_ALIGN, NULL);
152 printk(KERN_ERR "SG_POOL: can't init sg slab %s\n",
157 sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
160 printk(KERN_ERR "SG_POOL: can't init sg mempool %s\n",
169 for (i = 0; i < SG_MEMPOOL_NR; i++) {
170 struct sg_pool *sgp = sg_pools + i;
172 mempool_destroy(sgp->pool);
173 kmem_cache_destroy(sgp->slab);
179 static __exit void sg_pool_exit(void)
183 for (i = 0; i < SG_MEMPOOL_NR; i++) {
184 struct sg_pool *sgp = sg_pools + i;
185 mempool_destroy(sgp->pool);
186 kmem_cache_destroy(sgp->slab);
190 module_init(sg_pool_init);
191 module_exit(sg_pool_exit);