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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> | |
5a0e3ad6 | 34 | #include <linux/gfp.h> |
7875e18e AG |
35 | |
36 | #include "rds.h" | |
37 | ||
38 | struct rds_page_remainder { | |
39 | struct page *r_page; | |
40 | unsigned long r_offset; | |
41 | }; | |
42 | ||
ff51bf84 | 43 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct rds_page_remainder, |
44 | rds_page_remainders); | |
7875e18e AG |
45 | |
46 | /* | |
47 | * returns 0 on success or -errno on failure. | |
48 | * | |
49 | * We don't have to worry about flush_dcache_page() as this only works | |
50 | * with private pages. If, say, we were to do directed receive to pinned | |
51 | * user pages we'd have to worry more about cache coherence. (Though | |
52 | * the flush_dcache_page() in get_user_pages() would probably be enough). | |
53 | */ | |
54 | int rds_page_copy_user(struct page *page, unsigned long offset, | |
55 | void __user *ptr, unsigned long bytes, | |
56 | int to_user) | |
57 | { | |
58 | unsigned long ret; | |
59 | void *addr; | |
60 | ||
799c1055 LT |
61 | addr = kmap(page); |
62 | if (to_user) { | |
7875e18e | 63 | rds_stats_add(s_copy_to_user, bytes); |
799c1055 LT |
64 | ret = copy_to_user(ptr, addr + offset, bytes); |
65 | } else { | |
7875e18e | 66 | rds_stats_add(s_copy_from_user, bytes); |
799c1055 | 67 | ret = copy_from_user(addr + offset, ptr, bytes); |
7875e18e | 68 | } |
799c1055 | 69 | kunmap(page); |
7875e18e | 70 | |
799c1055 | 71 | return ret ? -EFAULT : 0; |
7875e18e | 72 | } |
616b757a | 73 | EXPORT_SYMBOL_GPL(rds_page_copy_user); |
7875e18e AG |
74 | |
75 | /* | |
76 | * Message allocation uses this to build up regions of a message. | |
77 | * | |
78 | * @bytes - the number of bytes needed. | |
79 | * @gfp - the waiting behaviour of the allocation | |
80 | * | |
81 | * @gfp is always ored with __GFP_HIGHMEM. Callers must be prepared to | |
82 | * kmap the pages, etc. | |
83 | * | |
84 | * If @bytes is at least a full page then this just returns a page from | |
85 | * alloc_page(). | |
86 | * | |
87 | * If @bytes is a partial page then this stores the unused region of the | |
88 | * page in a per-cpu structure. Future partial-page allocations may be | |
89 | * satisfied from that cached region. This lets us waste less memory on | |
90 | * small allocations with minimal complexity. It works because the transmit | |
91 | * path passes read-only page regions down to devices. They hold a page | |
92 | * reference until they are done with the region. | |
93 | */ | |
94 | int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes, | |
95 | gfp_t gfp) | |
96 | { | |
97 | struct rds_page_remainder *rem; | |
98 | unsigned long flags; | |
99 | struct page *page; | |
100 | int ret; | |
101 | ||
102 | gfp |= __GFP_HIGHMEM; | |
103 | ||
104 | /* jump straight to allocation if we're trying for a huge page */ | |
105 | if (bytes >= PAGE_SIZE) { | |
106 | page = alloc_page(gfp); | |
8690bfa1 | 107 | if (!page) { |
7875e18e AG |
108 | ret = -ENOMEM; |
109 | } else { | |
110 | sg_set_page(scat, page, PAGE_SIZE, 0); | |
111 | ret = 0; | |
112 | } | |
113 | goto out; | |
114 | } | |
115 | ||
116 | rem = &per_cpu(rds_page_remainders, get_cpu()); | |
117 | local_irq_save(flags); | |
118 | ||
119 | while (1) { | |
120 | /* avoid a tiny region getting stuck by tossing it */ | |
121 | if (rem->r_page && bytes > (PAGE_SIZE - rem->r_offset)) { | |
122 | rds_stats_inc(s_page_remainder_miss); | |
123 | __free_page(rem->r_page); | |
124 | rem->r_page = NULL; | |
125 | } | |
126 | ||
127 | /* hand out a fragment from the cached page */ | |
128 | if (rem->r_page && bytes <= (PAGE_SIZE - rem->r_offset)) { | |
129 | sg_set_page(scat, rem->r_page, bytes, rem->r_offset); | |
130 | get_page(sg_page(scat)); | |
131 | ||
132 | if (rem->r_offset != 0) | |
133 | rds_stats_inc(s_page_remainder_hit); | |
134 | ||
135 | rem->r_offset += bytes; | |
136 | if (rem->r_offset == PAGE_SIZE) { | |
137 | __free_page(rem->r_page); | |
138 | rem->r_page = NULL; | |
139 | } | |
140 | ret = 0; | |
141 | break; | |
142 | } | |
143 | ||
144 | /* alloc if there is nothing for us to use */ | |
145 | local_irq_restore(flags); | |
146 | put_cpu(); | |
147 | ||
148 | page = alloc_page(gfp); | |
149 | ||
150 | rem = &per_cpu(rds_page_remainders, get_cpu()); | |
151 | local_irq_save(flags); | |
152 | ||
8690bfa1 | 153 | if (!page) { |
7875e18e AG |
154 | ret = -ENOMEM; |
155 | break; | |
156 | } | |
157 | ||
158 | /* did someone race to fill the remainder before us? */ | |
159 | if (rem->r_page) { | |
160 | __free_page(page); | |
161 | continue; | |
162 | } | |
163 | ||
164 | /* otherwise install our page and loop around to alloc */ | |
165 | rem->r_page = page; | |
166 | rem->r_offset = 0; | |
167 | } | |
168 | ||
169 | local_irq_restore(flags); | |
170 | put_cpu(); | |
171 | out: | |
172 | rdsdebug("bytes %lu ret %d %p %u %u\n", bytes, ret, | |
173 | ret ? NULL : sg_page(scat), ret ? 0 : scat->offset, | |
174 | ret ? 0 : scat->length); | |
175 | return ret; | |
176 | } | |
0b088e00 | 177 | EXPORT_SYMBOL_GPL(rds_page_remainder_alloc); |
7875e18e AG |
178 | |
179 | static int rds_page_remainder_cpu_notify(struct notifier_block *self, | |
180 | unsigned long action, void *hcpu) | |
181 | { | |
182 | struct rds_page_remainder *rem; | |
183 | long cpu = (long)hcpu; | |
184 | ||
185 | rem = &per_cpu(rds_page_remainders, cpu); | |
186 | ||
187 | rdsdebug("cpu %ld action 0x%lx\n", cpu, action); | |
188 | ||
189 | switch (action) { | |
190 | case CPU_DEAD: | |
191 | if (rem->r_page) | |
192 | __free_page(rem->r_page); | |
193 | rem->r_page = NULL; | |
194 | break; | |
195 | } | |
196 | ||
197 | return 0; | |
198 | } | |
199 | ||
200 | static struct notifier_block rds_page_remainder_nb = { | |
201 | .notifier_call = rds_page_remainder_cpu_notify, | |
202 | }; | |
203 | ||
204 | void rds_page_exit(void) | |
205 | { | |
206 | int i; | |
207 | ||
208 | for_each_possible_cpu(i) | |
209 | rds_page_remainder_cpu_notify(&rds_page_remainder_nb, | |
210 | (unsigned long)CPU_DEAD, | |
211 | (void *)(long)i); | |
212 | } |