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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
46DEFINE_PER_CPU_SHARED_ALIGNED(struct rds_page_remainder, rds_page_remainders);
47
48/**
49 * rds_page_remainder_alloc - build up regions of a message.
50 *
51 * @scat: Scatter list for message
52 * @bytes: the number of bytes needed.
53 * @gfp: the waiting behaviour of the allocation
54 *
55 * @gfp is always ored with __GFP_HIGHMEM. Callers must be prepared to
56 * kmap the pages, etc.
57 *
58 * If @bytes is at least a full page then this just returns a page from
59 * alloc_page().
60 *
61 * If @bytes is a partial page then this stores the unused region of the
62 * page in a per-cpu structure. Future partial-page allocations may be
63 * satisfied from that cached region. This lets us waste less memory on
64 * small allocations with minimal complexity. It works because the transmit
65 * path passes read-only page regions down to devices. They hold a page
66 * reference until they are done with the region.
67 */
68int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes,
69 gfp_t gfp)
70{
71 struct rds_page_remainder *rem;
72 unsigned long flags;
73 struct page *page;
74 int ret;
75
76 gfp |= __GFP_HIGHMEM;
77
78 /* jump straight to allocation if we're trying for a huge page */
79 if (bytes >= PAGE_SIZE) {
80 page = alloc_page(gfp);
81 if (!page) {
82 ret = -ENOMEM;
83 } else {
84 sg_set_page(scat, page, PAGE_SIZE, 0);
85 ret = 0;
86 }
87 goto out;
88 }
89
90 rem = &per_cpu(rds_page_remainders, get_cpu());
91 local_irq_save(flags);
92
93 while (1) {
94 /* avoid a tiny region getting stuck by tossing it */
95 if (rem->r_page && bytes > (PAGE_SIZE - rem->r_offset)) {
96 rds_stats_inc(s_page_remainder_miss);
97 __free_page(rem->r_page);
98 rem->r_page = NULL;
99 }
100
101 /* hand out a fragment from the cached page */
102 if (rem->r_page && bytes <= (PAGE_SIZE - rem->r_offset)) {
103 sg_set_page(scat, rem->r_page, bytes, rem->r_offset);
104 get_page(sg_page(scat));
105
106 if (rem->r_offset != 0)
107 rds_stats_inc(s_page_remainder_hit);
108
109 rem->r_offset += ALIGN(bytes, 8);
110 if (rem->r_offset >= PAGE_SIZE) {
111 __free_page(rem->r_page);
112 rem->r_page = NULL;
113 }
114 ret = 0;
115 break;
116 }
117
118 /* alloc if there is nothing for us to use */
119 local_irq_restore(flags);
120 put_cpu();
121
122 page = alloc_page(gfp);
123
124 rem = &per_cpu(rds_page_remainders, get_cpu());
125 local_irq_save(flags);
126
127 if (!page) {
128 ret = -ENOMEM;
129 break;
130 }
131
132 /* did someone race to fill the remainder before us? */
133 if (rem->r_page) {
134 __free_page(page);
135 continue;
136 }
137
138 /* otherwise install our page and loop around to alloc */
139 rem->r_page = page;
140 rem->r_offset = 0;
141 }
142
143 local_irq_restore(flags);
144 put_cpu();
145out:
146 rdsdebug("bytes %lu ret %d %p %u %u\n", bytes, ret,
147 ret ? NULL : sg_page(scat), ret ? 0 : scat->offset,
148 ret ? 0 : scat->length);
149 return ret;
150}
151EXPORT_SYMBOL_GPL(rds_page_remainder_alloc);
152
153void rds_page_exit(void)
154{
155 unsigned int cpu;
156
157 for_each_possible_cpu(cpu) {
158 struct rds_page_remainder *rem;
159
160 rem = &per_cpu(rds_page_remainders, cpu);
161 rdsdebug("cpu %u\n", cpu);
162
163 if (rem->r_page)
164 __free_page(rem->r_page);
165 rem->r_page = NULL;
166 }
167}
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}