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]); 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) { 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) 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) { 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) { 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 && i < nr_pages; i++) 238 put_page(pages[i]); 239 kfree(pages); 240 241 return ret; 242 } 243