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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#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
46DEFINE_PER_CPU_SHARED_ALIGNED(struct rds_page_remainder, 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 * rds_page_remainder_alloc - build up regions of a message.
79 *
80 * @scat: Scatter list for message
81 * @bytes: the number of bytes needed.
82 * @gfp: the waiting behaviour of the allocation
83 *
84 * @gfp is always ored with __GFP_HIGHMEM. Callers must be prepared to
85 * kmap the pages, etc.
86 *
87 * If @bytes is at least a full page then this just returns a page from
88 * alloc_page().
89 *
90 * If @bytes is a partial page then this stores the unused region of the
91 * page in a per-cpu structure. Future partial-page allocations may be
92 * satisfied from that cached region. This lets us waste less memory on
93 * small allocations with minimal complexity. It works because the transmit
94 * path passes read-only page regions down to devices. They hold a page
95 * reference until they are done with the region.
96 */
97int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes,
98 gfp_t gfp)
99{
100 struct rds_page_remainder *rem;
101 unsigned long flags;
102 struct page *page;
103 int ret;
104
105 gfp |= __GFP_HIGHMEM;
106
107 /* jump straight to allocation if we're trying for a huge page */
108 if (bytes >= PAGE_SIZE) {
109 page = alloc_page(gfp);
110 if (!page) {
111 ret = -ENOMEM;
112 } else {
113 sg_set_page(scat, page, PAGE_SIZE, 0);
114 ret = 0;
115 }
116 goto out;
117 }
118
119 rem = &per_cpu(rds_page_remainders, get_cpu());
120 local_irq_save(flags);
121
122 while (1) {
123 /* avoid a tiny region getting stuck by tossing it */
124 if (rem->r_page && bytes > (PAGE_SIZE - rem->r_offset)) {
125 rds_stats_inc(s_page_remainder_miss);
126 __free_page(rem->r_page);
127 rem->r_page = NULL;
128 }
129
130 /* hand out a fragment from the cached page */
131 if (rem->r_page && bytes <= (PAGE_SIZE - rem->r_offset)) {
132 sg_set_page(scat, rem->r_page, bytes, rem->r_offset);
133 get_page(sg_page(scat));
134
135 if (rem->r_offset != 0)
136 rds_stats_inc(s_page_remainder_hit);
137
138 rem->r_offset += ALIGN(bytes, 8);
139 if (rem->r_offset >= PAGE_SIZE) {
140 __free_page(rem->r_page);
141 rem->r_page = NULL;
142 }
143 ret = 0;
144 break;
145 }
146
147 /* alloc if there is nothing for us to use */
148 local_irq_restore(flags);
149 put_cpu();
150
151 page = alloc_page(gfp);
152
153 rem = &per_cpu(rds_page_remainders, get_cpu());
154 local_irq_save(flags);
155
156 if (!page) {
157 ret = -ENOMEM;
158 break;
159 }
160
161 /* did someone race to fill the remainder before us? */
162 if (rem->r_page) {
163 __free_page(page);
164 continue;
165 }
166
167 /* otherwise install our page and loop around to alloc */
168 rem->r_page = page;
169 rem->r_offset = 0;
170 }
171
172 local_irq_restore(flags);
173 put_cpu();
174out:
175 rdsdebug("bytes %lu ret %d %p %u %u\n", bytes, ret,
176 ret ? NULL : sg_page(scat), ret ? 0 : scat->offset,
177 ret ? 0 : scat->length);
178 return ret;
179}
180EXPORT_SYMBOL_GPL(rds_page_remainder_alloc);
181
182void rds_page_exit(void)
183{
184 unsigned int cpu;
185
186 for_each_possible_cpu(cpu) {
187 struct rds_page_remainder *rem;
188
189 rem = &per_cpu(rds_page_remainders, cpu);
190 rdsdebug("cpu %u\n", cpu);
191
192 if (rem->r_page)
193 __free_page(rem->r_page);
194 rem->r_page = NULL;
195 }
196}