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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 | |
40 | struct rds_page_remainder { |
41 | struct page *r_page; |
42 | unsigned long r_offset; |
43 | }; |
44 | |
45 | static 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 | */ |
56 | int 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 | } |
75 | EXPORT_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 | */ |
97 | int 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 += bytes; |
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(); |
174 | out: |
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 | } |
180 | EXPORT_SYMBOL_GPL(rds_page_remainder_alloc); |
181 | |
182 | static int rds_page_remainder_cpu_notify(struct notifier_block *self, |
183 | unsigned long action, void *hcpu) |
184 | { |
185 | struct rds_page_remainder *rem; |
186 | long cpu = (long)hcpu; |
187 | |
188 | rem = &per_cpu(rds_page_remainders, cpu); |
189 | |
190 | rdsdebug("cpu %ld action 0x%lx\n", cpu, action); |
191 | |
192 | switch (action) { |
193 | case CPU_DEAD: |
194 | if (rem->r_page) |
195 | __free_page(rem->r_page); |
196 | rem->r_page = NULL; |
197 | break; |
198 | } |
199 | |
200 | return 0; |
201 | } |
202 | |
203 | static struct notifier_block rds_page_remainder_nb = { |
204 | .notifier_call = rds_page_remainder_cpu_notify, |
205 | }; |
206 | |
207 | void rds_page_exit(void) |
208 | { |
209 | int i; |
210 | |
211 | for_each_possible_cpu(i) |
212 | rds_page_remainder_cpu_notify(&rds_page_remainder_nb, |
213 | (unsigned long)CPU_DEAD, |
214 | (void *)(long)i); |
215 | } |
216 |
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