]>
Commit | Line | Data |
---|---|---|
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 | ||
b9bf3121 | 43 | DEFINE_PER_CPU_SHARED_ALIGNED(struct rds_page_remainder, rds_page_remainders); |
7875e18e AG |
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 | ||
799c1055 LT |
60 | addr = kmap(page); |
61 | if (to_user) { | |
7875e18e | 62 | rds_stats_add(s_copy_to_user, bytes); |
799c1055 LT |
63 | ret = copy_to_user(ptr, addr + offset, bytes); |
64 | } else { | |
7875e18e | 65 | rds_stats_add(s_copy_from_user, bytes); |
799c1055 | 66 | ret = copy_from_user(addr + offset, ptr, bytes); |
7875e18e | 67 | } |
799c1055 | 68 | kunmap(page); |
7875e18e | 69 | |
799c1055 | 70 | return ret ? -EFAULT : 0; |
7875e18e | 71 | } |
616b757a | 72 | EXPORT_SYMBOL_GPL(rds_page_copy_user); |
7875e18e AG |
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 | } |