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