Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
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>
6
7#define SG_MEMPOOL_NR ARRAY_SIZE(sg_pools)
8#define SG_MEMPOOL_SIZE 2
9
10struct 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
21static 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
40static 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
54static 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
62static 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 * @first_chunk: was first_chunk not NULL in sg_alloc_table_chained?
74 *
75 * Description:
76 * Free an sg table previously allocated and setup with
77 * sg_alloc_table_chained().
78 *
79 **/
80void sg_free_table_chained(struct sg_table *table, bool first_chunk)
81{
82 if (first_chunk && table->orig_nents <= SG_CHUNK_SIZE)
83 return;
84 __sg_free_table(table, SG_CHUNK_SIZE, first_chunk, sg_pool_free);
85}
86EXPORT_SYMBOL_GPL(sg_free_table_chained);
87
88/**
89 * sg_alloc_table_chained - Allocate and chain SGLs in an sg table
90 * @table: The sg table header to use
91 * @nents: Number of entries in sg list
92 * @first_chunk: first SGL
93 *
94 * Description:
95 * Allocate and chain SGLs in an sg table. If @nents@ is larger than
96 * SG_CHUNK_SIZE a chained sg table will be setup.
97 *
98 **/
99int sg_alloc_table_chained(struct sg_table *table, int nents,
100 struct scatterlist *first_chunk)
101{
102 int ret;
103
104 BUG_ON(!nents);
105
106 if (first_chunk) {
107 if (nents <= SG_CHUNK_SIZE) {
108 table->nents = table->orig_nents = nents;
109 sg_init_table(table->sgl, nents);
110 return 0;
111 }
112 }
113
114 ret = __sg_alloc_table(table, nents, SG_CHUNK_SIZE,
115 first_chunk, GFP_ATOMIC, sg_pool_alloc);
116 if (unlikely(ret))
117 sg_free_table_chained(table, (bool)first_chunk);
118 return ret;
119}
120EXPORT_SYMBOL_GPL(sg_alloc_table_chained);
121
122static __init int sg_pool_init(void)
123{
124 int i;
125
126 for (i = 0; i < SG_MEMPOOL_NR; i++) {
127 struct sg_pool *sgp = sg_pools + i;
128 int size = sgp->size * sizeof(struct scatterlist);
129
130 sgp->slab = kmem_cache_create(sgp->name, size, 0,
131 SLAB_HWCACHE_ALIGN, NULL);
132 if (!sgp->slab) {
133 printk(KERN_ERR "SG_POOL: can't init sg slab %s\n",
134 sgp->name);
135 goto cleanup_sdb;
136 }
137
138 sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
139 sgp->slab);
140 if (!sgp->pool) {
141 printk(KERN_ERR "SG_POOL: can't init sg mempool %s\n",
142 sgp->name);
143 goto cleanup_sdb;
144 }
145 }
146
147 return 0;
148
149cleanup_sdb:
150 for (i = 0; i < SG_MEMPOOL_NR; i++) {
151 struct sg_pool *sgp = sg_pools + i;
152
153 mempool_destroy(sgp->pool);
154 kmem_cache_destroy(sgp->slab);
155 }
156
157 return -ENOMEM;
158}
159
160static __exit void sg_pool_exit(void)
161{
162 int i;
163
164 for (i = 0; i < SG_MEMPOOL_NR; i++) {
165 struct sg_pool *sgp = sg_pools + i;
166 mempool_destroy(sgp->pool);
167 kmem_cache_destroy(sgp->slab);
168 }
169}
170
171module_init(sg_pool_init);
172module_exit(sg_pool_exit);