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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>
5a0e3ad6 34#include <linux/gfp.h>
80f1ff97 35#include <linux/cpu.h>
bc3b2d7f 36#include <linux/export.h>
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37
38#include "rds.h"
39
40struct rds_page_remainder {
41 struct page *r_page;
42 unsigned long r_offset;
43};
44
25528213
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45static
46DEFINE_PER_CPU_SHARED_ALIGNED(struct rds_page_remainder, rds_page_remainders);
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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
799c1055
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63 addr = kmap(page);
64 if (to_user) {
7875e18e 65 rds_stats_add(s_copy_to_user, bytes);
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66 ret = copy_to_user(ptr, addr + offset, bytes);
67 } else {
7875e18e 68 rds_stats_add(s_copy_from_user, bytes);
799c1055 69 ret = copy_from_user(addr + offset, ptr, bytes);
7875e18e 70 }
799c1055 71 kunmap(page);
7875e18e 72
799c1055 73 return ret ? -EFAULT : 0;
7875e18e 74}
616b757a 75EXPORT_SYMBOL_GPL(rds_page_copy_user);
7875e18e 76
2c53040f
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77/**
78 * rds_page_remainder_alloc - build up regions of a message.
7875e18e 79 *
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80 * @scat: Scatter list for message
81 * @bytes: the number of bytes needed.
82 * @gfp: the waiting behaviour of the allocation
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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);
8690bfa1 110 if (!page) {
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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
e98499ac 138 rem->r_offset += ALIGN(bytes, 8);
139 if (rem->r_offset >= PAGE_SIZE) {
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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
8690bfa1 156 if (!page) {
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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}
0b088e00 180EXPORT_SYMBOL_GPL(rds_page_remainder_alloc);
7875e18e 181
f2830d09 182void rds_page_exit(void)
7875e18e 183{
f2830d09 184 unsigned int cpu;
7875e18e 185
f2830d09
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186 for_each_possible_cpu(cpu) {
187 struct rds_page_remainder *rem;
7875e18e 188
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189 rem = &per_cpu(rds_page_remainders, cpu);
190 rdsdebug("cpu %u\n", cpu);
7875e18e 191
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192 if (rem->r_page)
193 __free_page(rem->r_page);
194 rem->r_page = NULL;
7875e18e 195 }
7875e18e 196}