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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 | |
36 | #include "rds.h" |
37 | |
38 | struct rds_page_remainder { |
39 | struct page *r_page; |
40 | unsigned long r_offset; |
41 | }; |
42 | |
43 | DEFINE_PER_CPU_SHARED_ALIGNED(struct rds_page_remainder, rds_page_remainders); |
44 | |
45 | /* |
46 | * returns 0 on success or -errno on failure. |
47 | * |
48 | * We don't have to worry about flush_dcache_page() as this only works |
49 | * with private pages. If, say, we were to do directed receive to pinned |
50 | * user pages we'd have to worry more about cache coherence. (Though |
51 | * the flush_dcache_page() in get_user_pages() would probably be enough). |
52 | */ |
53 | int rds_page_copy_user(struct page *page, unsigned long offset, |
54 | void __user *ptr, unsigned long bytes, |
55 | int to_user) |
56 | { |
57 | unsigned long ret; |
58 | void *addr; |
59 | |
60 | addr = kmap(page); |
61 | if (to_user) { |
62 | rds_stats_add(s_copy_to_user, bytes); |
63 | ret = copy_to_user(ptr, addr + offset, bytes); |
64 | } else { |
65 | rds_stats_add(s_copy_from_user, bytes); |
66 | ret = copy_from_user(addr + offset, ptr, bytes); |
67 | } |
68 | kunmap(page); |
69 | |
70 | return ret ? -EFAULT : 0; |
71 | } |
72 | EXPORT_SYMBOL_GPL(rds_page_copy_user); |
73 | |
74 | /* |
75 | * Message allocation uses this to build up regions of a message. |
76 | * |
77 | * @bytes - the number of bytes needed. |
78 | * @gfp - the waiting behaviour of the allocation |
79 | * |
80 | * @gfp is always ored with __GFP_HIGHMEM. Callers must be prepared to |
81 | * kmap the pages, etc. |
82 | * |
83 | * If @bytes is at least a full page then this just returns a page from |
84 | * alloc_page(). |
85 | * |
86 | * If @bytes is a partial page then this stores the unused region of the |
87 | * page in a per-cpu structure. Future partial-page allocations may be |
88 | * satisfied from that cached region. This lets us waste less memory on |
89 | * small allocations with minimal complexity. It works because the transmit |
90 | * path passes read-only page regions down to devices. They hold a page |
91 | * reference until they are done with the region. |
92 | */ |
93 | int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes, |
94 | gfp_t gfp) |
95 | { |
96 | struct rds_page_remainder *rem; |
97 | unsigned long flags; |
98 | struct page *page; |
99 | int ret; |
100 | |
101 | gfp |= __GFP_HIGHMEM; |
102 | |
103 | /* jump straight to allocation if we're trying for a huge page */ |
104 | if (bytes >= PAGE_SIZE) { |
105 | page = alloc_page(gfp); |
106 | if (page == NULL) { |
107 | ret = -ENOMEM; |
108 | } else { |
109 | sg_set_page(scat, page, PAGE_SIZE, 0); |
110 | ret = 0; |
111 | } |
112 | goto out; |
113 | } |
114 | |
115 | rem = &per_cpu(rds_page_remainders, get_cpu()); |
116 | local_irq_save(flags); |
117 | |
118 | while (1) { |
119 | /* avoid a tiny region getting stuck by tossing it */ |
120 | if (rem->r_page && bytes > (PAGE_SIZE - rem->r_offset)) { |
121 | rds_stats_inc(s_page_remainder_miss); |
122 | __free_page(rem->r_page); |
123 | rem->r_page = NULL; |
124 | } |
125 | |
126 | /* hand out a fragment from the cached page */ |
127 | if (rem->r_page && bytes <= (PAGE_SIZE - rem->r_offset)) { |
128 | sg_set_page(scat, rem->r_page, bytes, rem->r_offset); |
129 | get_page(sg_page(scat)); |
130 | |
131 | if (rem->r_offset != 0) |
132 | rds_stats_inc(s_page_remainder_hit); |
133 | |
134 | rem->r_offset += bytes; |
135 | if (rem->r_offset == PAGE_SIZE) { |
136 | __free_page(rem->r_page); |
137 | rem->r_page = NULL; |
138 | } |
139 | ret = 0; |
140 | break; |
141 | } |
142 | |
143 | /* alloc if there is nothing for us to use */ |
144 | local_irq_restore(flags); |
145 | put_cpu(); |
146 | |
147 | page = alloc_page(gfp); |
148 | |
149 | rem = &per_cpu(rds_page_remainders, get_cpu()); |
150 | local_irq_save(flags); |
151 | |
152 | if (page == NULL) { |
153 | ret = -ENOMEM; |
154 | break; |
155 | } |
156 | |
157 | /* did someone race to fill the remainder before us? */ |
158 | if (rem->r_page) { |
159 | __free_page(page); |
160 | continue; |
161 | } |
162 | |
163 | /* otherwise install our page and loop around to alloc */ |
164 | rem->r_page = page; |
165 | rem->r_offset = 0; |
166 | } |
167 | |
168 | local_irq_restore(flags); |
169 | put_cpu(); |
170 | out: |
171 | rdsdebug("bytes %lu ret %d %p %u %u\n", bytes, ret, |
172 | ret ? NULL : sg_page(scat), ret ? 0 : scat->offset, |
173 | ret ? 0 : scat->length); |
174 | return ret; |
175 | } |
176 | |
177 | static int rds_page_remainder_cpu_notify(struct notifier_block *self, |
178 | unsigned long action, void *hcpu) |
179 | { |
180 | struct rds_page_remainder *rem; |
181 | long cpu = (long)hcpu; |
182 | |
183 | rem = &per_cpu(rds_page_remainders, cpu); |
184 | |
185 | rdsdebug("cpu %ld action 0x%lx\n", cpu, action); |
186 | |
187 | switch (action) { |
188 | case CPU_DEAD: |
189 | if (rem->r_page) |
190 | __free_page(rem->r_page); |
191 | rem->r_page = NULL; |
192 | break; |
193 | } |
194 | |
195 | return 0; |
196 | } |
197 | |
198 | static struct notifier_block rds_page_remainder_nb = { |
199 | .notifier_call = rds_page_remainder_cpu_notify, |
200 | }; |
201 | |
202 | void rds_page_exit(void) |
203 | { |
204 | int i; |
205 | |
206 | for_each_possible_cpu(i) |
207 | rds_page_remainder_cpu_notify(&rds_page_remainder_nb, |
208 | (unsigned long)CPU_DEAD, |
209 | (void *)(long)i); |
210 | } |
211 |
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