| 1 | /* |
| 2 | * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca> |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License, version 2 only, |
| 6 | * as published by the Free Software Foundation. |
| 7 | * |
| 8 | * This program is distributed in the hope that it will be useful, but WITHOUT |
| 9 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 10 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
| 11 | * more details. |
| 12 | * |
| 13 | * You should have received a copy of the GNU General Public License along |
| 14 | * with this program; if not, write to the Free Software Foundation, Inc., |
| 15 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
| 16 | */ |
| 17 | |
| 18 | #define _GNU_SOURCE |
| 19 | #include <assert.h> |
| 20 | #include <fcntl.h> |
| 21 | #include <limits.h> |
| 22 | #include <stdlib.h> |
| 23 | #include <sys/types.h> |
| 24 | #include <sys/stat.h> |
| 25 | #include <unistd.h> |
| 26 | #include <config.h> |
| 27 | |
| 28 | #include <common/error.h> |
| 29 | #include <common/defaults.h> |
| 30 | #include <common/macros.h> |
| 31 | #include <common/utils.h> |
| 32 | |
| 33 | #include "poll.h" |
| 34 | |
| 35 | unsigned int poll_max_size; |
| 36 | |
| 37 | /* |
| 38 | * Resize the epoll events structure of the new size. |
| 39 | * |
| 40 | * Return 0 on success or else -1 with the current events pointer untouched. |
| 41 | */ |
| 42 | static int resize_poll_event(struct lttng_poll_event *events, |
| 43 | uint32_t new_size) |
| 44 | { |
| 45 | struct epoll_event *ptr; |
| 46 | |
| 47 | assert(events); |
| 48 | |
| 49 | ptr = realloc(events->events, new_size * sizeof(*ptr)); |
| 50 | if (ptr == NULL) { |
| 51 | PERROR("realloc epoll add"); |
| 52 | goto error; |
| 53 | } |
| 54 | if (new_size > events->alloc_size) { |
| 55 | /* Zero newly allocated memory */ |
| 56 | memset(ptr + events->alloc_size, 0, |
| 57 | (new_size - events->alloc_size) * sizeof(*ptr)); |
| 58 | } |
| 59 | events->events = ptr; |
| 60 | events->alloc_size = new_size; |
| 61 | |
| 62 | return 0; |
| 63 | |
| 64 | error: |
| 65 | return -1; |
| 66 | } |
| 67 | |
| 68 | /* |
| 69 | * Create epoll set and allocate returned events structure. |
| 70 | */ |
| 71 | int compat_epoll_create(struct lttng_poll_event *events, int size, int flags) |
| 72 | { |
| 73 | int ret; |
| 74 | |
| 75 | if (events == NULL || size <= 0) { |
| 76 | goto error; |
| 77 | } |
| 78 | |
| 79 | /* Don't bust the limit here */ |
| 80 | if (size > poll_max_size && poll_max_size != 0) { |
| 81 | size = poll_max_size; |
| 82 | } |
| 83 | |
| 84 | ret = epoll_create1(flags); |
| 85 | if (ret < 0) { |
| 86 | /* At this point, every error is fatal */ |
| 87 | PERROR("epoll_create1"); |
| 88 | goto error; |
| 89 | } |
| 90 | |
| 91 | events->epfd = ret; |
| 92 | |
| 93 | /* This *must* be freed by using lttng_poll_free() */ |
| 94 | events->events = zmalloc(size * sizeof(struct epoll_event)); |
| 95 | if (events->events == NULL) { |
| 96 | PERROR("zmalloc epoll set"); |
| 97 | goto error_close; |
| 98 | } |
| 99 | |
| 100 | events->alloc_size = events->init_size = size; |
| 101 | events->nb_fd = 0; |
| 102 | |
| 103 | return 0; |
| 104 | |
| 105 | error_close: |
| 106 | ret = close(events->epfd); |
| 107 | if (ret) { |
| 108 | PERROR("close"); |
| 109 | } |
| 110 | error: |
| 111 | return -1; |
| 112 | } |
| 113 | |
| 114 | /* |
| 115 | * Add a fd to the epoll set with requesting events. |
| 116 | */ |
| 117 | int compat_epoll_add(struct lttng_poll_event *events, int fd, uint32_t req_events) |
| 118 | { |
| 119 | int ret; |
| 120 | struct epoll_event ev; |
| 121 | |
| 122 | if (events == NULL || events->events == NULL || fd < 0) { |
| 123 | ERR("Bad compat epoll add arguments"); |
| 124 | goto error; |
| 125 | } |
| 126 | |
| 127 | /* |
| 128 | * Zero struct epoll_event to ensure all representations of its |
| 129 | * union are zeroed. |
| 130 | */ |
| 131 | memset(&ev, 0, sizeof(ev)); |
| 132 | ev.events = req_events; |
| 133 | ev.data.fd = fd; |
| 134 | |
| 135 | ret = epoll_ctl(events->epfd, EPOLL_CTL_ADD, fd, &ev); |
| 136 | if (ret < 0) { |
| 137 | switch (errno) { |
| 138 | case EEXIST: |
| 139 | /* If exist, it's OK. */ |
| 140 | goto end; |
| 141 | case ENOSPC: |
| 142 | case EPERM: |
| 143 | /* Print PERROR and goto end not failing. Show must go on. */ |
| 144 | PERROR("epoll_ctl ADD"); |
| 145 | goto end; |
| 146 | default: |
| 147 | PERROR("epoll_ctl ADD fatal"); |
| 148 | goto error; |
| 149 | } |
| 150 | } |
| 151 | |
| 152 | events->nb_fd++; |
| 153 | |
| 154 | end: |
| 155 | return 0; |
| 156 | |
| 157 | error: |
| 158 | return -1; |
| 159 | } |
| 160 | |
| 161 | /* |
| 162 | * Remove a fd from the epoll set. |
| 163 | */ |
| 164 | int compat_epoll_del(struct lttng_poll_event *events, int fd) |
| 165 | { |
| 166 | int ret; |
| 167 | |
| 168 | if (events == NULL || fd < 0) { |
| 169 | goto error; |
| 170 | } |
| 171 | |
| 172 | ret = epoll_ctl(events->epfd, EPOLL_CTL_DEL, fd, NULL); |
| 173 | if (ret < 0) { |
| 174 | switch (errno) { |
| 175 | case ENOENT: |
| 176 | case EPERM: |
| 177 | /* Print PERROR and goto end not failing. Show must go on. */ |
| 178 | PERROR("epoll_ctl DEL"); |
| 179 | goto end; |
| 180 | default: |
| 181 | PERROR("epoll_ctl DEL fatal"); |
| 182 | goto error; |
| 183 | } |
| 184 | } |
| 185 | |
| 186 | events->nb_fd--; |
| 187 | |
| 188 | end: |
| 189 | return 0; |
| 190 | |
| 191 | error: |
| 192 | return -1; |
| 193 | } |
| 194 | |
| 195 | /* |
| 196 | * Wait on epoll set. This is a blocking call of timeout value. |
| 197 | */ |
| 198 | int compat_epoll_wait(struct lttng_poll_event *events, int timeout) |
| 199 | { |
| 200 | int ret; |
| 201 | uint32_t new_size; |
| 202 | |
| 203 | if (events == NULL || events->events == NULL) { |
| 204 | ERR("Wrong arguments in compat_epoll_wait"); |
| 205 | goto error; |
| 206 | } |
| 207 | |
| 208 | /* |
| 209 | * Resize if needed before waiting. We could either expand the array or |
| 210 | * shrink it down. It's important to note that after this step, we are |
| 211 | * ensured that the events argument of the epoll_wait call will be large |
| 212 | * enough to hold every possible returned events. |
| 213 | */ |
| 214 | if (events->nb_fd > events->alloc_size) { |
| 215 | /* Expand if the nb_fd is higher than the actual size. */ |
| 216 | new_size = max_t(uint32_t, |
| 217 | 1U << utils_get_count_order_u32(events->nb_fd), |
| 218 | events->alloc_size << 1UL); |
| 219 | } else if ((events->nb_fd << 1UL) <= events->alloc_size && |
| 220 | events->nb_fd >= events->init_size) { |
| 221 | /* Shrink if nb_fd multiplied by two is <= than the actual size. */ |
| 222 | new_size = max_t(uint32_t, |
| 223 | utils_get_count_order_u32(events->nb_fd) >> 1U, |
| 224 | events->alloc_size >> 1U); |
| 225 | } else { |
| 226 | /* Indicate that we don't want to resize. */ |
| 227 | new_size = 0; |
| 228 | } |
| 229 | |
| 230 | if (new_size) { |
| 231 | ret = resize_poll_event(events, new_size); |
| 232 | if (ret < 0) { |
| 233 | /* ENOMEM problem at this point. */ |
| 234 | goto error; |
| 235 | } |
| 236 | } |
| 237 | |
| 238 | do { |
| 239 | ret = epoll_wait(events->epfd, events->events, events->nb_fd, timeout); |
| 240 | } while (ret == -1 && errno == EINTR); |
| 241 | if (ret < 0) { |
| 242 | /* At this point, every error is fatal */ |
| 243 | PERROR("epoll_wait"); |
| 244 | goto error; |
| 245 | } |
| 246 | |
| 247 | /* |
| 248 | * Since the returned events are set sequentially in the "events" structure |
| 249 | * we only need to return the epoll_wait value and iterate over it. |
| 250 | */ |
| 251 | return ret; |
| 252 | |
| 253 | error: |
| 254 | return -1; |
| 255 | } |
| 256 | |
| 257 | /* |
| 258 | * Setup poll set maximum size. |
| 259 | */ |
| 260 | void compat_epoll_set_max_size(void) |
| 261 | { |
| 262 | int ret, fd; |
| 263 | ssize_t size_ret; |
| 264 | char buf[64]; |
| 265 | |
| 266 | poll_max_size = DEFAULT_POLL_SIZE; |
| 267 | |
| 268 | fd = open(COMPAT_EPOLL_PROC_PATH, O_RDONLY); |
| 269 | if (fd < 0) { |
| 270 | return; |
| 271 | } |
| 272 | |
| 273 | size_ret = lttng_read(fd, buf, sizeof(buf)); |
| 274 | /* |
| 275 | * Allow reading a file smaller than buf, but keep space for |
| 276 | * final \0. |
| 277 | */ |
| 278 | if (size_ret < 0 || size_ret >= sizeof(buf)) { |
| 279 | PERROR("read set max size"); |
| 280 | goto error; |
| 281 | } |
| 282 | buf[size_ret] = '\0'; |
| 283 | |
| 284 | poll_max_size = atoi(buf); |
| 285 | if (poll_max_size == 0) { |
| 286 | /* Extra precaution */ |
| 287 | poll_max_size = DEFAULT_POLL_SIZE; |
| 288 | } |
| 289 | |
| 290 | DBG("epoll set max size is %d", poll_max_size); |
| 291 | |
| 292 | error: |
| 293 | ret = close(fd); |
| 294 | if (ret) { |
| 295 | PERROR("close"); |
| 296 | } |
| 297 | } |