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1/*
2 * Copyright (c) 2006 Oracle. All rights reserved.
3 *
4 * This software is available to you under a choice of one of two
5 * licenses. You may choose to be licensed under the terms of the GNU
6 * General Public License (GPL) Version 2, available from the file
7 * COPYING in the main directory of this source tree, or the
8 * OpenIB.org BSD license below:
9 *
10 * Redistribution and use in source and binary forms, with or
11 * without modification, are permitted provided that the following
12 * conditions are met:
13 *
14 * - Redistributions of source code must retain the above
15 * copyright notice, this list of conditions and the following
16 * disclaimer.
17 *
18 * - Redistributions in binary form must reproduce the above
19 * copyright notice, this list of conditions and the following
20 * disclaimer in the documentation and/or other materials
21 * provided with the distribution.
22 *
23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30 * SOFTWARE.
31 *
32 */
33#include <linux/highmem.h>
34#include <linux/gfp.h>
35#include <linux/cpu.h>
36#include <linux/export.h>
37
38#include "rds.h"
39
40struct rds_page_remainder {
41 struct page *r_page;
42 unsigned long r_offset;
43};
44
45static DEFINE_PER_CPU_SHARED_ALIGNED(struct rds_page_remainder,
46 rds_page_remainders);
47
48/*
49 * returns 0 on success or -errno on failure.
50 *
51 * We don't have to worry about flush_dcache_page() as this only works
52 * with private pages. If, say, we were to do directed receive to pinned
53 * user pages we'd have to worry more about cache coherence. (Though
54 * the flush_dcache_page() in get_user_pages() would probably be enough).
55 */
56int rds_page_copy_user(struct page *page, unsigned long offset,
57 void __user *ptr, unsigned long bytes,
58 int to_user)
59{
60 unsigned long ret;
61 void *addr;
62
63 addr = kmap(page);
64 if (to_user) {
65 rds_stats_add(s_copy_to_user, bytes);
66 ret = copy_to_user(ptr, addr + offset, bytes);
67 } else {
68 rds_stats_add(s_copy_from_user, bytes);
69 ret = copy_from_user(addr + offset, ptr, bytes);
70 }
71 kunmap(page);
72
73 return ret ? -EFAULT : 0;
74}
75EXPORT_SYMBOL_GPL(rds_page_copy_user);
76
77/*
78 * Message allocation uses this to build up regions of a message.
79 *
80 * @bytes - the number of bytes needed.
81 * @gfp - the waiting behaviour of the allocation
82 *
83 * @gfp is always ored with __GFP_HIGHMEM. Callers must be prepared to
84 * kmap the pages, etc.
85 *
86 * If @bytes is at least a full page then this just returns a page from
87 * alloc_page().
88 *
89 * If @bytes is a partial page then this stores the unused region of the
90 * page in a per-cpu structure. Future partial-page allocations may be
91 * satisfied from that cached region. This lets us waste less memory on
92 * small allocations with minimal complexity. It works because the transmit
93 * path passes read-only page regions down to devices. They hold a page
94 * reference until they are done with the region.
95 */
96int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes,
97 gfp_t gfp)
98{
99 struct rds_page_remainder *rem;
100 unsigned long flags;
101 struct page *page;
102 int ret;
103
104 gfp |= __GFP_HIGHMEM;
105
106 /* jump straight to allocation if we're trying for a huge page */
107 if (bytes >= PAGE_SIZE) {
108 page = alloc_page(gfp);
109 if (!page) {
110 ret = -ENOMEM;
111 } else {
112 sg_set_page(scat, page, PAGE_SIZE, 0);
113 ret = 0;
114 }
115 goto out;
116 }
117
118 rem = &per_cpu(rds_page_remainders, get_cpu());
119 local_irq_save(flags);
120
121 while (1) {
122 /* avoid a tiny region getting stuck by tossing it */
123 if (rem->r_page && bytes > (PAGE_SIZE - rem->r_offset)) {
124 rds_stats_inc(s_page_remainder_miss);
125 __free_page(rem->r_page);
126 rem->r_page = NULL;
127 }
128
129 /* hand out a fragment from the cached page */
130 if (rem->r_page && bytes <= (PAGE_SIZE - rem->r_offset)) {
131 sg_set_page(scat, rem->r_page, bytes, rem->r_offset);
132 get_page(sg_page(scat));
133
134 if (rem->r_offset != 0)
135 rds_stats_inc(s_page_remainder_hit);
136
137 rem->r_offset += bytes;
138 if (rem->r_offset == PAGE_SIZE) {
139 __free_page(rem->r_page);
140 rem->r_page = NULL;
141 }
142 ret = 0;
143 break;
144 }
145
146 /* alloc if there is nothing for us to use */
147 local_irq_restore(flags);
148 put_cpu();
149
150 page = alloc_page(gfp);
151
152 rem = &per_cpu(rds_page_remainders, get_cpu());
153 local_irq_save(flags);
154
155 if (!page) {
156 ret = -ENOMEM;
157 break;
158 }
159
160 /* did someone race to fill the remainder before us? */
161 if (rem->r_page) {
162 __free_page(page);
163 continue;
164 }
165
166 /* otherwise install our page and loop around to alloc */
167 rem->r_page = page;
168 rem->r_offset = 0;
169 }
170
171 local_irq_restore(flags);
172 put_cpu();
173out:
174 rdsdebug("bytes %lu ret %d %p %u %u\n", bytes, ret,
175 ret ? NULL : sg_page(scat), ret ? 0 : scat->offset,
176 ret ? 0 : scat->length);
177 return ret;
178}
179EXPORT_SYMBOL_GPL(rds_page_remainder_alloc);
180
181static int rds_page_remainder_cpu_notify(struct notifier_block *self,
182 unsigned long action, void *hcpu)
183{
184 struct rds_page_remainder *rem;
185 long cpu = (long)hcpu;
186
187 rem = &per_cpu(rds_page_remainders, cpu);
188
189 rdsdebug("cpu %ld action 0x%lx\n", cpu, action);
190
191 switch (action) {
192 case CPU_DEAD:
193 if (rem->r_page)
194 __free_page(rem->r_page);
195 rem->r_page = NULL;
196 break;
197 }
198
199 return 0;
200}
201
202static struct notifier_block rds_page_remainder_nb = {
203 .notifier_call = rds_page_remainder_cpu_notify,
204};
205
206void rds_page_exit(void)
207{
208 int i;
209
210 for_each_possible_cpu(i)
211 rds_page_remainder_cpu_notify(&rds_page_remainder_nb,
212 (unsigned long)CPU_DEAD,
213 (void *)(long)i);
214}
1/*
2 * Copyright (c) 2006 Oracle. All rights reserved.
3 *
4 * This software is available to you under a choice of one of two
5 * licenses. You may choose to be licensed under the terms of the GNU
6 * General Public License (GPL) Version 2, available from the file
7 * COPYING in the main directory of this source tree, or the
8 * OpenIB.org BSD license below:
9 *
10 * Redistribution and use in source and binary forms, with or
11 * without modification, are permitted provided that the following
12 * conditions are met:
13 *
14 * - Redistributions of source code must retain the above
15 * copyright notice, this list of conditions and the following
16 * disclaimer.
17 *
18 * - Redistributions in binary form must reproduce the above
19 * copyright notice, this list of conditions and the following
20 * disclaimer in the documentation and/or other materials
21 * provided with the distribution.
22 *
23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30 * SOFTWARE.
31 *
32 */
33#include <linux/highmem.h>
34#include <linux/gfp.h>
35#include <linux/cpu.h>
36
37#include "rds.h"
38
39struct rds_page_remainder {
40 struct page *r_page;
41 unsigned long r_offset;
42};
43
44static DEFINE_PER_CPU_SHARED_ALIGNED(struct rds_page_remainder,
45 rds_page_remainders);
46
47/*
48 * returns 0 on success or -errno on failure.
49 *
50 * We don't have to worry about flush_dcache_page() as this only works
51 * with private pages. If, say, we were to do directed receive to pinned
52 * user pages we'd have to worry more about cache coherence. (Though
53 * the flush_dcache_page() in get_user_pages() would probably be enough).
54 */
55int rds_page_copy_user(struct page *page, unsigned long offset,
56 void __user *ptr, unsigned long bytes,
57 int to_user)
58{
59 unsigned long ret;
60 void *addr;
61
62 addr = kmap(page);
63 if (to_user) {
64 rds_stats_add(s_copy_to_user, bytes);
65 ret = copy_to_user(ptr, addr + offset, bytes);
66 } else {
67 rds_stats_add(s_copy_from_user, bytes);
68 ret = copy_from_user(addr + offset, ptr, bytes);
69 }
70 kunmap(page);
71
72 return ret ? -EFAULT : 0;
73}
74EXPORT_SYMBOL_GPL(rds_page_copy_user);
75
76/*
77 * Message allocation uses this to build up regions of a message.
78 *
79 * @bytes - the number of bytes needed.
80 * @gfp - the waiting behaviour of the allocation
81 *
82 * @gfp is always ored with __GFP_HIGHMEM. Callers must be prepared to
83 * kmap the pages, etc.
84 *
85 * If @bytes is at least a full page then this just returns a page from
86 * alloc_page().
87 *
88 * If @bytes is a partial page then this stores the unused region of the
89 * page in a per-cpu structure. Future partial-page allocations may be
90 * satisfied from that cached region. This lets us waste less memory on
91 * small allocations with minimal complexity. It works because the transmit
92 * path passes read-only page regions down to devices. They hold a page
93 * reference until they are done with the region.
94 */
95int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes,
96 gfp_t gfp)
97{
98 struct rds_page_remainder *rem;
99 unsigned long flags;
100 struct page *page;
101 int ret;
102
103 gfp |= __GFP_HIGHMEM;
104
105 /* jump straight to allocation if we're trying for a huge page */
106 if (bytes >= PAGE_SIZE) {
107 page = alloc_page(gfp);
108 if (!page) {
109 ret = -ENOMEM;
110 } else {
111 sg_set_page(scat, page, PAGE_SIZE, 0);
112 ret = 0;
113 }
114 goto out;
115 }
116
117 rem = &per_cpu(rds_page_remainders, get_cpu());
118 local_irq_save(flags);
119
120 while (1) {
121 /* avoid a tiny region getting stuck by tossing it */
122 if (rem->r_page && bytes > (PAGE_SIZE - rem->r_offset)) {
123 rds_stats_inc(s_page_remainder_miss);
124 __free_page(rem->r_page);
125 rem->r_page = NULL;
126 }
127
128 /* hand out a fragment from the cached page */
129 if (rem->r_page && bytes <= (PAGE_SIZE - rem->r_offset)) {
130 sg_set_page(scat, rem->r_page, bytes, rem->r_offset);
131 get_page(sg_page(scat));
132
133 if (rem->r_offset != 0)
134 rds_stats_inc(s_page_remainder_hit);
135
136 rem->r_offset += bytes;
137 if (rem->r_offset == PAGE_SIZE) {
138 __free_page(rem->r_page);
139 rem->r_page = NULL;
140 }
141 ret = 0;
142 break;
143 }
144
145 /* alloc if there is nothing for us to use */
146 local_irq_restore(flags);
147 put_cpu();
148
149 page = alloc_page(gfp);
150
151 rem = &per_cpu(rds_page_remainders, get_cpu());
152 local_irq_save(flags);
153
154 if (!page) {
155 ret = -ENOMEM;
156 break;
157 }
158
159 /* did someone race to fill the remainder before us? */
160 if (rem->r_page) {
161 __free_page(page);
162 continue;
163 }
164
165 /* otherwise install our page and loop around to alloc */
166 rem->r_page = page;
167 rem->r_offset = 0;
168 }
169
170 local_irq_restore(flags);
171 put_cpu();
172out:
173 rdsdebug("bytes %lu ret %d %p %u %u\n", bytes, ret,
174 ret ? NULL : sg_page(scat), ret ? 0 : scat->offset,
175 ret ? 0 : scat->length);
176 return ret;
177}
178EXPORT_SYMBOL_GPL(rds_page_remainder_alloc);
179
180static int rds_page_remainder_cpu_notify(struct notifier_block *self,
181 unsigned long action, void *hcpu)
182{
183 struct rds_page_remainder *rem;
184 long cpu = (long)hcpu;
185
186 rem = &per_cpu(rds_page_remainders, cpu);
187
188 rdsdebug("cpu %ld action 0x%lx\n", cpu, action);
189
190 switch (action) {
191 case CPU_DEAD:
192 if (rem->r_page)
193 __free_page(rem->r_page);
194 rem->r_page = NULL;
195 break;
196 }
197
198 return 0;
199}
200
201static struct notifier_block rds_page_remainder_nb = {
202 .notifier_call = rds_page_remainder_cpu_notify,
203};
204
205void rds_page_exit(void)
206{
207 int i;
208
209 for_each_possible_cpu(i)
210 rds_page_remainder_cpu_notify(&rds_page_remainder_nb,
211 (unsigned long)CPU_DEAD,
212 (void *)(long)i);
213}