1 // SPDX-License-Identifier: GPL-2.0-only 1 // SPDX-License-Identifier: GPL-2.0-only
2 /* 2 /*
3 * Copyright (C) 2015 Robert Jarzmik <robert.j 3 * Copyright (C) 2015 Robert Jarzmik <robert.jarzmik@free.fr>
4 * 4 *
5 * Scatterlist splitting helpers. 5 * Scatterlist splitting helpers.
6 */ 6 */
7 7
8 #include <linux/scatterlist.h> 8 #include <linux/scatterlist.h>
9 #include <linux/slab.h> 9 #include <linux/slab.h>
10 10
11 struct sg_splitter { 11 struct sg_splitter {
12 struct scatterlist *in_sg0; 12 struct scatterlist *in_sg0;
13 int nents; 13 int nents;
14 off_t skip_sg0; 14 off_t skip_sg0;
15 unsigned int length_last_sg; 15 unsigned int length_last_sg;
16 16
17 struct scatterlist *out_sg; 17 struct scatterlist *out_sg;
18 }; 18 };
19 19
20 static int sg_calculate_split(struct scatterli 20 static int sg_calculate_split(struct scatterlist *in, int nents, int nb_splits,
21 off_t skip, cons 21 off_t skip, const size_t *sizes,
22 struct sg_splitt 22 struct sg_splitter *splitters, bool mapped)
23 { 23 {
24 int i; 24 int i;
25 unsigned int sglen; 25 unsigned int sglen;
26 size_t size = sizes[0], len; 26 size_t size = sizes[0], len;
27 struct sg_splitter *curr = splitters; 27 struct sg_splitter *curr = splitters;
28 struct scatterlist *sg; 28 struct scatterlist *sg;
29 29
30 for (i = 0; i < nb_splits; i++) { 30 for (i = 0; i < nb_splits; i++) {
31 splitters[i].in_sg0 = NULL; 31 splitters[i].in_sg0 = NULL;
32 splitters[i].nents = 0; 32 splitters[i].nents = 0;
33 } 33 }
34 34
35 for_each_sg(in, sg, nents, i) { 35 for_each_sg(in, sg, nents, i) {
36 sglen = mapped ? sg_dma_len(sg 36 sglen = mapped ? sg_dma_len(sg) : sg->length;
37 if (skip > sglen) { 37 if (skip > sglen) {
38 skip -= sglen; 38 skip -= sglen;
39 continue; 39 continue;
40 } 40 }
41 41
42 len = min_t(size_t, size, sgle 42 len = min_t(size_t, size, sglen - skip);
43 if (!curr->in_sg0) { 43 if (!curr->in_sg0) {
44 curr->in_sg0 = sg; 44 curr->in_sg0 = sg;
45 curr->skip_sg0 = skip; 45 curr->skip_sg0 = skip;
46 } 46 }
47 size -= len; 47 size -= len;
48 curr->nents++; 48 curr->nents++;
49 curr->length_last_sg = len; 49 curr->length_last_sg = len;
50 50
51 while (!size && (skip + len < 51 while (!size && (skip + len < sglen) && (--nb_splits > 0)) {
52 curr++; 52 curr++;
53 size = *(++sizes); 53 size = *(++sizes);
54 skip += len; 54 skip += len;
55 len = min_t(size_t, si 55 len = min_t(size_t, size, sglen - skip);
56 56
57 curr->in_sg0 = sg; 57 curr->in_sg0 = sg;
58 curr->skip_sg0 = skip; 58 curr->skip_sg0 = skip;
59 curr->nents = 1; 59 curr->nents = 1;
60 curr->length_last_sg = 60 curr->length_last_sg = len;
61 size -= len; 61 size -= len;
62 } 62 }
63 skip = 0; 63 skip = 0;
64 64
65 if (!size && --nb_splits > 0) 65 if (!size && --nb_splits > 0) {
66 curr++; 66 curr++;
67 size = *(++sizes); 67 size = *(++sizes);
68 } 68 }
69 69
70 if (!nb_splits) 70 if (!nb_splits)
71 break; 71 break;
72 } 72 }
73 73
74 return (size || !splitters[0].in_sg0) 74 return (size || !splitters[0].in_sg0) ? -EINVAL : 0;
75 } 75 }
76 76
77 static void sg_split_phys(struct sg_splitter * 77 static void sg_split_phys(struct sg_splitter *splitters, const int nb_splits)
78 { 78 {
79 int i, j; 79 int i, j;
80 struct scatterlist *in_sg, *out_sg; 80 struct scatterlist *in_sg, *out_sg;
81 struct sg_splitter *split; 81 struct sg_splitter *split;
82 82
83 for (i = 0, split = splitters; i < nb_ 83 for (i = 0, split = splitters; i < nb_splits; i++, split++) {
84 in_sg = split->in_sg0; 84 in_sg = split->in_sg0;
85 out_sg = split->out_sg; 85 out_sg = split->out_sg;
86 for (j = 0; j < split->nents; 86 for (j = 0; j < split->nents; j++, out_sg++) {
87 *out_sg = *in_sg; 87 *out_sg = *in_sg;
88 if (!j) { 88 if (!j) {
89 out_sg->offset 89 out_sg->offset += split->skip_sg0;
90 out_sg->length 90 out_sg->length -= split->skip_sg0;
91 } else { 91 } else {
92 out_sg->offset 92 out_sg->offset = 0;
93 } 93 }
94 sg_dma_address(out_sg) 94 sg_dma_address(out_sg) = 0;
95 sg_dma_len(out_sg) = 0 95 sg_dma_len(out_sg) = 0;
96 in_sg = sg_next(in_sg) 96 in_sg = sg_next(in_sg);
97 } 97 }
98 out_sg[-1].length = split->len 98 out_sg[-1].length = split->length_last_sg;
99 sg_mark_end(out_sg - 1); 99 sg_mark_end(out_sg - 1);
100 } 100 }
101 } 101 }
102 102
103 static void sg_split_mapped(struct sg_splitter 103 static void sg_split_mapped(struct sg_splitter *splitters, const int nb_splits)
104 { 104 {
105 int i, j; 105 int i, j;
106 struct scatterlist *in_sg, *out_sg; 106 struct scatterlist *in_sg, *out_sg;
107 struct sg_splitter *split; 107 struct sg_splitter *split;
108 108
109 for (i = 0, split = splitters; i < nb_ 109 for (i = 0, split = splitters; i < nb_splits; i++, split++) {
110 in_sg = split->in_sg0; 110 in_sg = split->in_sg0;
111 out_sg = split->out_sg; 111 out_sg = split->out_sg;
112 for (j = 0; j < split->nents; 112 for (j = 0; j < split->nents; j++, out_sg++) {
113 sg_dma_address(out_sg) 113 sg_dma_address(out_sg) = sg_dma_address(in_sg);
114 sg_dma_len(out_sg) = s 114 sg_dma_len(out_sg) = sg_dma_len(in_sg);
115 if (!j) { 115 if (!j) {
116 sg_dma_address 116 sg_dma_address(out_sg) += split->skip_sg0;
117 sg_dma_len(out 117 sg_dma_len(out_sg) -= split->skip_sg0;
118 } 118 }
119 in_sg = sg_next(in_sg) 119 in_sg = sg_next(in_sg);
120 } 120 }
121 sg_dma_len(--out_sg) = split-> 121 sg_dma_len(--out_sg) = split->length_last_sg;
122 } 122 }
123 } 123 }
124 124
125 /** 125 /**
126 * sg_split - split a scatterlist into several 126 * sg_split - split a scatterlist into several scatterlists
127 * @in: the input sg list 127 * @in: the input sg list
128 * @in_mapped_nents: the result of a dma_map_s 128 * @in_mapped_nents: the result of a dma_map_sg(in, ...), or 0 if not mapped.
129 * @skip: the number of bytes to skip in the i 129 * @skip: the number of bytes to skip in the input sg list
130 * @nb_splits: the number of desired sg output 130 * @nb_splits: the number of desired sg outputs
131 * @split_sizes: the respective size of each o 131 * @split_sizes: the respective size of each output sg list in bytes
132 * @out: an array where to store the allocated 132 * @out: an array where to store the allocated output sg lists
133 * @out_mapped_nents: the resulting sg lists m 133 * @out_mapped_nents: the resulting sg lists mapped number of sg entries. Might
134 * be NULL if sglist not al 134 * be NULL if sglist not already mapped (in_mapped_nents = 0)
135 * @gfp_mask: the allocation flag 135 * @gfp_mask: the allocation flag
136 * 136 *
137 * This function splits the input sg list into 137 * This function splits the input sg list into nb_splits sg lists, which are
138 * allocated and stored into out. 138 * allocated and stored into out.
139 * The @in is split into : 139 * The @in is split into :
140 * - @out[0], which covers bytes [@skip .. @s 140 * - @out[0], which covers bytes [@skip .. @skip + @split_sizes[0] - 1] of @in
141 * - @out[1], which covers bytes [@skip + spl 141 * - @out[1], which covers bytes [@skip + split_sizes[0] ..
142 * @skip + @sp 142 * @skip + @split_sizes[0] + @split_sizes[1] -1]
143 * etc ... 143 * etc ...
144 * It will be the caller's duty to kfree() out 144 * It will be the caller's duty to kfree() out array members.
145 * 145 *
146 * Returns 0 upon success, or error code 146 * Returns 0 upon success, or error code
147 */ 147 */
148 int sg_split(struct scatterlist *in, const int 148 int sg_split(struct scatterlist *in, const int in_mapped_nents,
149 const off_t skip, const int nb_sp 149 const off_t skip, const int nb_splits,
150 const size_t *split_sizes, 150 const size_t *split_sizes,
151 struct scatterlist **out, int *ou 151 struct scatterlist **out, int *out_mapped_nents,
152 gfp_t gfp_mask) 152 gfp_t gfp_mask)
153 { 153 {
154 int i, ret; 154 int i, ret;
155 struct sg_splitter *splitters; 155 struct sg_splitter *splitters;
156 156
157 splitters = kcalloc(nb_splits, sizeof( 157 splitters = kcalloc(nb_splits, sizeof(*splitters), gfp_mask);
158 if (!splitters) 158 if (!splitters)
159 return -ENOMEM; 159 return -ENOMEM;
160 160
161 ret = sg_calculate_split(in, sg_nents( 161 ret = sg_calculate_split(in, sg_nents(in), nb_splits, skip, split_sizes,
162 splitters, false); 162 splitters, false);
163 if (ret < 0) 163 if (ret < 0)
164 goto err; 164 goto err;
165 165
166 ret = -ENOMEM; 166 ret = -ENOMEM;
167 for (i = 0; i < nb_splits; i++) { 167 for (i = 0; i < nb_splits; i++) {
168 splitters[i].out_sg = kmalloc_ 168 splitters[i].out_sg = kmalloc_array(splitters[i].nents,
169 169 sizeof(struct scatterlist),
170 170 gfp_mask);
171 if (!splitters[i].out_sg) 171 if (!splitters[i].out_sg)
172 goto err; 172 goto err;
173 } 173 }
174 174
175 /* 175 /*
176 * The order of these 3 calls is impor 176 * The order of these 3 calls is important and should be kept.
177 */ 177 */
178 sg_split_phys(splitters, nb_splits); 178 sg_split_phys(splitters, nb_splits);
179 if (in_mapped_nents) { 179 if (in_mapped_nents) {
180 ret = sg_calculate_split(in, i 180 ret = sg_calculate_split(in, in_mapped_nents, nb_splits, skip,
181 split 181 split_sizes, splitters, true);
182 if (ret < 0) 182 if (ret < 0)
183 goto err; 183 goto err;
184 sg_split_mapped(splitters, nb_ 184 sg_split_mapped(splitters, nb_splits);
185 } 185 }
186 186
187 for (i = 0; i < nb_splits; i++) { 187 for (i = 0; i < nb_splits; i++) {
188 out[i] = splitters[i].out_sg; 188 out[i] = splitters[i].out_sg;
189 if (out_mapped_nents) 189 if (out_mapped_nents)
190 out_mapped_nents[i] = 190 out_mapped_nents[i] = splitters[i].nents;
191 } 191 }
192 192
193 kfree(splitters); 193 kfree(splitters);
194 return 0; 194 return 0;
195 195
196 err: 196 err:
197 for (i = 0; i < nb_splits; i++) 197 for (i = 0; i < nb_splits; i++)
198 kfree(splitters[i].out_sg); 198 kfree(splitters[i].out_sg);
199 kfree(splitters); 199 kfree(splitters);
200 return ret; 200 return ret;
201 } 201 }
202 EXPORT_SYMBOL(sg_split); 202 EXPORT_SYMBOL(sg_split);
203 203
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