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7875e18e AG |
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 | ||
35 | #include "rds.h" | |
36 | ||
37 | struct rds_page_remainder { | |
38 | struct page *r_page; | |
39 | unsigned long r_offset; | |
40 | }; | |
41 | ||
42 | DEFINE_PER_CPU(struct rds_page_remainder, rds_page_remainders) ____cacheline_aligned; | |
43 | ||
44 | /* | |
45 | * returns 0 on success or -errno on failure. | |
46 | * | |
47 | * We don't have to worry about flush_dcache_page() as this only works | |
48 | * with private pages. If, say, we were to do directed receive to pinned | |
49 | * user pages we'd have to worry more about cache coherence. (Though | |
50 | * the flush_dcache_page() in get_user_pages() would probably be enough). | |
51 | */ | |
52 | int rds_page_copy_user(struct page *page, unsigned long offset, | |
53 | void __user *ptr, unsigned long bytes, | |
54 | int to_user) | |
55 | { | |
56 | unsigned long ret; | |
57 | void *addr; | |
58 | ||
59 | if (to_user) | |
60 | rds_stats_add(s_copy_to_user, bytes); | |
61 | else | |
62 | rds_stats_add(s_copy_from_user, bytes); | |
63 | ||
64 | addr = kmap_atomic(page, KM_USER0); | |
65 | if (to_user) | |
66 | ret = __copy_to_user_inatomic(ptr, addr + offset, bytes); | |
67 | else | |
68 | ret = __copy_from_user_inatomic(addr + offset, ptr, bytes); | |
69 | kunmap_atomic(addr, KM_USER0); | |
70 | ||
71 | if (ret) { | |
72 | addr = kmap(page); | |
73 | if (to_user) | |
74 | ret = copy_to_user(ptr, addr + offset, bytes); | |
75 | else | |
76 | ret = copy_from_user(addr + offset, ptr, bytes); | |
77 | kunmap(page); | |
78 | if (ret) | |
79 | return -EFAULT; | |
80 | } | |
81 | ||
82 | return 0; | |
83 | } | |
84 | ||
85 | /* | |
86 | * Message allocation uses this to build up regions of a message. | |
87 | * | |
88 | * @bytes - the number of bytes needed. | |
89 | * @gfp - the waiting behaviour of the allocation | |
90 | * | |
91 | * @gfp is always ored with __GFP_HIGHMEM. Callers must be prepared to | |
92 | * kmap the pages, etc. | |
93 | * | |
94 | * If @bytes is at least a full page then this just returns a page from | |
95 | * alloc_page(). | |
96 | * | |
97 | * If @bytes is a partial page then this stores the unused region of the | |
98 | * page in a per-cpu structure. Future partial-page allocations may be | |
99 | * satisfied from that cached region. This lets us waste less memory on | |
100 | * small allocations with minimal complexity. It works because the transmit | |
101 | * path passes read-only page regions down to devices. They hold a page | |
102 | * reference until they are done with the region. | |
103 | */ | |
104 | int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes, | |
105 | gfp_t gfp) | |
106 | { | |
107 | struct rds_page_remainder *rem; | |
108 | unsigned long flags; | |
109 | struct page *page; | |
110 | int ret; | |
111 | ||
112 | gfp |= __GFP_HIGHMEM; | |
113 | ||
114 | /* jump straight to allocation if we're trying for a huge page */ | |
115 | if (bytes >= PAGE_SIZE) { | |
116 | page = alloc_page(gfp); | |
117 | if (page == NULL) { | |
118 | ret = -ENOMEM; | |
119 | } else { | |
120 | sg_set_page(scat, page, PAGE_SIZE, 0); | |
121 | ret = 0; | |
122 | } | |
123 | goto out; | |
124 | } | |
125 | ||
126 | rem = &per_cpu(rds_page_remainders, get_cpu()); | |
127 | local_irq_save(flags); | |
128 | ||
129 | while (1) { | |
130 | /* avoid a tiny region getting stuck by tossing it */ | |
131 | if (rem->r_page && bytes > (PAGE_SIZE - rem->r_offset)) { | |
132 | rds_stats_inc(s_page_remainder_miss); | |
133 | __free_page(rem->r_page); | |
134 | rem->r_page = NULL; | |
135 | } | |
136 | ||
137 | /* hand out a fragment from the cached page */ | |
138 | if (rem->r_page && bytes <= (PAGE_SIZE - rem->r_offset)) { | |
139 | sg_set_page(scat, rem->r_page, bytes, rem->r_offset); | |
140 | get_page(sg_page(scat)); | |
141 | ||
142 | if (rem->r_offset != 0) | |
143 | rds_stats_inc(s_page_remainder_hit); | |
144 | ||
145 | rem->r_offset += bytes; | |
146 | if (rem->r_offset == PAGE_SIZE) { | |
147 | __free_page(rem->r_page); | |
148 | rem->r_page = NULL; | |
149 | } | |
150 | ret = 0; | |
151 | break; | |
152 | } | |
153 | ||
154 | /* alloc if there is nothing for us to use */ | |
155 | local_irq_restore(flags); | |
156 | put_cpu(); | |
157 | ||
158 | page = alloc_page(gfp); | |
159 | ||
160 | rem = &per_cpu(rds_page_remainders, get_cpu()); | |
161 | local_irq_save(flags); | |
162 | ||
163 | if (page == NULL) { | |
164 | ret = -ENOMEM; | |
165 | break; | |
166 | } | |
167 | ||
168 | /* did someone race to fill the remainder before us? */ | |
169 | if (rem->r_page) { | |
170 | __free_page(page); | |
171 | continue; | |
172 | } | |
173 | ||
174 | /* otherwise install our page and loop around to alloc */ | |
175 | rem->r_page = page; | |
176 | rem->r_offset = 0; | |
177 | } | |
178 | ||
179 | local_irq_restore(flags); | |
180 | put_cpu(); | |
181 | out: | |
182 | rdsdebug("bytes %lu ret %d %p %u %u\n", bytes, ret, | |
183 | ret ? NULL : sg_page(scat), ret ? 0 : scat->offset, | |
184 | ret ? 0 : scat->length); | |
185 | return ret; | |
186 | } | |
187 | ||
188 | static int rds_page_remainder_cpu_notify(struct notifier_block *self, | |
189 | unsigned long action, void *hcpu) | |
190 | { | |
191 | struct rds_page_remainder *rem; | |
192 | long cpu = (long)hcpu; | |
193 | ||
194 | rem = &per_cpu(rds_page_remainders, cpu); | |
195 | ||
196 | rdsdebug("cpu %ld action 0x%lx\n", cpu, action); | |
197 | ||
198 | switch (action) { | |
199 | case CPU_DEAD: | |
200 | if (rem->r_page) | |
201 | __free_page(rem->r_page); | |
202 | rem->r_page = NULL; | |
203 | break; | |
204 | } | |
205 | ||
206 | return 0; | |
207 | } | |
208 | ||
209 | static struct notifier_block rds_page_remainder_nb = { | |
210 | .notifier_call = rds_page_remainder_cpu_notify, | |
211 | }; | |
212 | ||
213 | void rds_page_exit(void) | |
214 | { | |
215 | int i; | |
216 | ||
217 | for_each_possible_cpu(i) | |
218 | rds_page_remainder_cpu_notify(&rds_page_remainder_nb, | |
219 | (unsigned long)CPU_DEAD, | |
220 | (void *)(long)i); | |
221 | } |