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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/percpu.h> |
34 | #include <linux/seq_file.h> |
35 | #include <linux/slab.h> |
36 | #include <linux/proc_fs.h> |
37 | |
38 | #include "rds.h" |
39 | |
40 | /* |
41 | * This file implements a getsockopt() call which copies a set of fixed |
42 | * sized structs into a user-specified buffer as a means of providing |
43 | * read-only information about RDS. |
44 | * |
45 | * For a given information source there are a given number of fixed sized |
46 | * structs at a given time. The structs are only copied if the user-specified |
47 | * buffer is big enough. The destination pages that make up the buffer |
48 | * are pinned for the duration of the copy. |
49 | * |
50 | * This gives us the following benefits: |
51 | * |
52 | * - simple implementation, no copy "position" across multiple calls |
53 | * - consistent snapshot of an info source |
54 | * - atomic copy works well with whatever locking info source has |
55 | * - one portable tool to get rds info across implementations |
56 | * - long-lived tool can get info without allocating |
57 | * |
58 | * at the following costs: |
59 | * |
60 | * - info source copy must be pinned, may be "large" |
61 | */ |
62 | |
63 | struct rds_info_iterator { |
64 | struct page **pages; |
65 | void *addr; |
66 | unsigned long offset; |
67 | }; |
68 | |
69 | static DEFINE_SPINLOCK(rds_info_lock); |
70 | static rds_info_func rds_info_funcs[RDS_INFO_LAST - RDS_INFO_FIRST + 1]; |
71 | |
72 | void rds_info_register_func(int optname, rds_info_func func) |
73 | { |
74 | int offset = optname - RDS_INFO_FIRST; |
75 | |
76 | BUG_ON(optname < RDS_INFO_FIRST || optname > RDS_INFO_LAST); |
77 | |
78 | spin_lock(&rds_info_lock); |
79 | BUG_ON(rds_info_funcs[offset] != NULL); |
80 | rds_info_funcs[offset] = func; |
81 | spin_unlock(&rds_info_lock); |
82 | } |
83 | EXPORT_SYMBOL_GPL(rds_info_register_func); |
84 | |
85 | void rds_info_deregister_func(int optname, rds_info_func func) |
86 | { |
87 | int offset = optname - RDS_INFO_FIRST; |
88 | |
89 | BUG_ON(optname < RDS_INFO_FIRST || optname > RDS_INFO_LAST); |
90 | |
91 | spin_lock(&rds_info_lock); |
92 | BUG_ON(rds_info_funcs[offset] != func); |
93 | rds_info_funcs[offset] = NULL; |
94 | spin_unlock(&rds_info_lock); |
95 | } |
96 | EXPORT_SYMBOL_GPL(rds_info_deregister_func); |
97 | |
98 | /* |
99 | * Typically we hold an atomic kmap across multiple rds_info_copy() calls |
100 | * because the kmap is so expensive. This must be called before using blocking |
101 | * operations while holding the mapping and as the iterator is torn down. |
102 | */ |
103 | void rds_info_iter_unmap(struct rds_info_iterator *iter) |
104 | { |
105 | if (iter->addr != NULL) { |
106 | kunmap_atomic(iter->addr, KM_USER0); |
107 | iter->addr = NULL; |
108 | } |
109 | } |
110 | |
111 | /* |
112 | * get_user_pages() called flush_dcache_page() on the pages for us. |
113 | */ |
114 | void rds_info_copy(struct rds_info_iterator *iter, void *data, |
115 | unsigned long bytes) |
116 | { |
117 | unsigned long this; |
118 | |
119 | while (bytes) { |
120 | if (iter->addr == NULL) |
121 | iter->addr = kmap_atomic(*iter->pages, KM_USER0); |
122 | |
123 | this = min(bytes, PAGE_SIZE - iter->offset); |
124 | |
125 | rdsdebug("page %p addr %p offset %lu this %lu data %p " |
126 | "bytes %lu\n", *iter->pages, iter->addr, |
127 | iter->offset, this, data, bytes); |
128 | |
129 | memcpy(iter->addr + iter->offset, data, this); |
130 | |
131 | data += this; |
132 | bytes -= this; |
133 | iter->offset += this; |
134 | |
135 | if (iter->offset == PAGE_SIZE) { |
136 | kunmap_atomic(iter->addr, KM_USER0); |
137 | iter->addr = NULL; |
138 | iter->offset = 0; |
139 | iter->pages++; |
140 | } |
141 | } |
142 | } |
143 | EXPORT_SYMBOL_GPL(rds_info_copy); |
144 | |
145 | /* |
146 | * @optval points to the userspace buffer that the information snapshot |
147 | * will be copied into. |
148 | * |
149 | * @optlen on input is the size of the buffer in userspace. @optlen |
150 | * on output is the size of the requested snapshot in bytes. |
151 | * |
152 | * This function returns -errno if there is a failure, particularly -ENOSPC |
153 | * if the given userspace buffer was not large enough to fit the snapshot. |
154 | * On success it returns the positive number of bytes of each array element |
155 | * in the snapshot. |
156 | */ |
157 | int rds_info_getsockopt(struct socket *sock, int optname, char __user *optval, |
158 | int __user *optlen) |
159 | { |
160 | struct rds_info_iterator iter; |
161 | struct rds_info_lengths lens; |
162 | unsigned long nr_pages = 0; |
163 | unsigned long start; |
164 | unsigned long i; |
165 | rds_info_func func; |
166 | struct page **pages = NULL; |
167 | int ret; |
168 | int len; |
169 | int total; |
170 | |
171 | if (get_user(len, optlen)) { |
172 | ret = -EFAULT; |
173 | goto out; |
174 | } |
175 | |
176 | /* check for all kinds of wrapping and the like */ |
177 | start = (unsigned long)optval; |
178 | if (len < 0 || len + PAGE_SIZE - 1 < len || start + len < start) { |
179 | ret = -EINVAL; |
180 | goto out; |
181 | } |
182 | |
183 | /* a 0 len call is just trying to probe its length */ |
184 | if (len == 0) |
185 | goto call_func; |
186 | |
187 | nr_pages = (PAGE_ALIGN(start + len) - (start & PAGE_MASK)) |
188 | >> PAGE_SHIFT; |
189 | |
190 | pages = kmalloc(nr_pages * sizeof(struct page *), GFP_KERNEL); |
191 | if (pages == NULL) { |
192 | ret = -ENOMEM; |
193 | goto out; |
194 | } |
195 | ret = get_user_pages_fast(start, nr_pages, 1, pages); |
196 | if (ret != nr_pages) { |
197 | if (ret > 0) |
198 | nr_pages = ret; |
199 | else |
200 | nr_pages = 0; |
201 | ret = -EAGAIN; /* XXX ? */ |
202 | goto out; |
203 | } |
204 | |
205 | rdsdebug("len %d nr_pages %lu\n", len, nr_pages); |
206 | |
207 | call_func: |
208 | func = rds_info_funcs[optname - RDS_INFO_FIRST]; |
209 | if (func == NULL) { |
210 | ret = -ENOPROTOOPT; |
211 | goto out; |
212 | } |
213 | |
214 | iter.pages = pages; |
215 | iter.addr = NULL; |
216 | iter.offset = start & (PAGE_SIZE - 1); |
217 | |
218 | func(sock, len, &iter, &lens); |
219 | BUG_ON(lens.each == 0); |
220 | |
221 | total = lens.nr * lens.each; |
222 | |
223 | rds_info_iter_unmap(&iter); |
224 | |
225 | if (total > len) { |
226 | len = total; |
227 | ret = -ENOSPC; |
228 | } else { |
229 | len = total; |
230 | ret = lens.each; |
231 | } |
232 | |
233 | if (put_user(len, optlen)) |
234 | ret = -EFAULT; |
235 | |
236 | out: |
237 | for (i = 0; pages != NULL && i < nr_pages; i++) |
238 | put_page(pages[i]); |
239 | kfree(pages); |
240 | |
241 | return ret; |
242 | } |
243 |
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v2.6.34-rc5
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