| 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 <fcntl.h> |
| 20 | #include <limits.h> |
| 21 | #include <stdlib.h> |
| 22 | #include <sys/types.h> |
| 23 | #include <sys/stat.h> |
| 24 | #include <unistd.h> |
| 25 | #include <config.h> |
| 26 | |
| 27 | #include <common/error.h> |
| 28 | #include <common/defaults.h> |
| 29 | |
| 30 | #include "poll.h" |
| 31 | |
| 32 | unsigned int poll_max_size; |
| 33 | |
| 34 | /* |
| 35 | * Create epoll set and allocate returned events structure. |
| 36 | */ |
| 37 | int compat_epoll_create(struct lttng_poll_event *events, int size, int flags) |
| 38 | { |
| 39 | int ret; |
| 40 | |
| 41 | if (events == NULL || size <= 0) { |
| 42 | goto error; |
| 43 | } |
| 44 | |
| 45 | /* Don't bust the limit here */ |
| 46 | if (size > poll_max_size && poll_max_size != 0) { |
| 47 | size = poll_max_size; |
| 48 | } |
| 49 | |
| 50 | ret = epoll_create1(flags); |
| 51 | if (ret < 0) { |
| 52 | /* At this point, every error is fatal */ |
| 53 | PERROR("epoll_create1"); |
| 54 | goto error; |
| 55 | } |
| 56 | |
| 57 | events->epfd = ret; |
| 58 | |
| 59 | /* This *must* be freed by using lttng_poll_free() */ |
| 60 | events->events = zmalloc(size * sizeof(struct epoll_event)); |
| 61 | if (events->events == NULL) { |
| 62 | PERROR("zmalloc epoll set"); |
| 63 | goto error_close; |
| 64 | } |
| 65 | |
| 66 | events->events_size = size; |
| 67 | events->nb_fd = 0; |
| 68 | |
| 69 | return 0; |
| 70 | |
| 71 | error_close: |
| 72 | ret = close(events->epfd); |
| 73 | if (ret) { |
| 74 | PERROR("close"); |
| 75 | } |
| 76 | error: |
| 77 | return -1; |
| 78 | } |
| 79 | |
| 80 | /* |
| 81 | * Add a fd to the epoll set with requesting events. |
| 82 | */ |
| 83 | int compat_epoll_add(struct lttng_poll_event *events, int fd, uint32_t req_events) |
| 84 | { |
| 85 | int ret, new_size; |
| 86 | struct epoll_event ev, *ptr; |
| 87 | |
| 88 | if (events == NULL || events->events == NULL || fd < 0) { |
| 89 | ERR("Bad compat epoll add arguments"); |
| 90 | goto error; |
| 91 | } |
| 92 | |
| 93 | ev.events = req_events; |
| 94 | ev.data.fd = fd; |
| 95 | |
| 96 | ret = epoll_ctl(events->epfd, EPOLL_CTL_ADD, fd, &ev); |
| 97 | if (ret < 0) { |
| 98 | switch (errno) { |
| 99 | case EEXIST: |
| 100 | /* If exist, it's OK. */ |
| 101 | goto end; |
| 102 | case ENOSPC: |
| 103 | case EPERM: |
| 104 | /* Print PERROR and goto end not failing. Show must go on. */ |
| 105 | PERROR("epoll_ctl ADD"); |
| 106 | goto end; |
| 107 | default: |
| 108 | PERROR("epoll_ctl ADD fatal"); |
| 109 | goto error; |
| 110 | } |
| 111 | } |
| 112 | |
| 113 | events->nb_fd++; |
| 114 | |
| 115 | if (events->nb_fd >= events->events_size) { |
| 116 | new_size = 2 * events->events_size; |
| 117 | ptr = realloc(events->events, new_size * sizeof(struct epoll_event)); |
| 118 | if (ptr == NULL) { |
| 119 | PERROR("realloc epoll add"); |
| 120 | goto error; |
| 121 | } |
| 122 | events->events = ptr; |
| 123 | events->events_size = new_size; |
| 124 | } |
| 125 | |
| 126 | end: |
| 127 | return 0; |
| 128 | |
| 129 | error: |
| 130 | return -1; |
| 131 | } |
| 132 | |
| 133 | /* |
| 134 | * Remove a fd from the epoll set. |
| 135 | */ |
| 136 | int compat_epoll_del(struct lttng_poll_event *events, int fd) |
| 137 | { |
| 138 | int ret; |
| 139 | |
| 140 | if (events == NULL || fd < 0) { |
| 141 | goto error; |
| 142 | } |
| 143 | |
| 144 | ret = epoll_ctl(events->epfd, EPOLL_CTL_DEL, fd, NULL); |
| 145 | if (ret < 0) { |
| 146 | switch (errno) { |
| 147 | case ENOENT: |
| 148 | case EPERM: |
| 149 | /* Print PERROR and goto end not failing. Show must go on. */ |
| 150 | PERROR("epoll_ctl DEL"); |
| 151 | goto end; |
| 152 | default: |
| 153 | PERROR("epoll_ctl DEL fatal"); |
| 154 | goto error; |
| 155 | } |
| 156 | PERROR("epoll_ctl del"); |
| 157 | goto error; |
| 158 | } |
| 159 | |
| 160 | events->nb_fd--; |
| 161 | |
| 162 | end: |
| 163 | return 0; |
| 164 | |
| 165 | error: |
| 166 | return -1; |
| 167 | } |
| 168 | |
| 169 | /* |
| 170 | * Wait on epoll set. This is a blocking call of timeout value. |
| 171 | */ |
| 172 | int compat_epoll_wait(struct lttng_poll_event *events, int timeout) |
| 173 | { |
| 174 | int ret; |
| 175 | |
| 176 | if (events == NULL || events->events == NULL || |
| 177 | events->events_size < events->nb_fd) { |
| 178 | ERR("Wrong arguments in compat_epoll_wait"); |
| 179 | goto error; |
| 180 | } |
| 181 | |
| 182 | do { |
| 183 | ret = epoll_wait(events->epfd, events->events, events->nb_fd, timeout); |
| 184 | } while (ret == -1 && errno == EINTR); |
| 185 | if (ret < 0) { |
| 186 | /* At this point, every error is fatal */ |
| 187 | PERROR("epoll_wait"); |
| 188 | goto error; |
| 189 | } |
| 190 | |
| 191 | /* |
| 192 | * Since the returned events are set sequentially in the "events" structure |
| 193 | * we only need to return the epoll_wait value and iterate over it. |
| 194 | */ |
| 195 | return ret; |
| 196 | |
| 197 | error: |
| 198 | return -1; |
| 199 | } |
| 200 | |
| 201 | /* |
| 202 | * Setup poll set maximum size. |
| 203 | */ |
| 204 | void compat_epoll_set_max_size(void) |
| 205 | { |
| 206 | int ret, fd; |
| 207 | char buf[64]; |
| 208 | |
| 209 | poll_max_size = DEFAULT_POLL_SIZE; |
| 210 | |
| 211 | fd = open(COMPAT_EPOLL_PROC_PATH, O_RDONLY); |
| 212 | if (fd < 0) { |
| 213 | return; |
| 214 | } |
| 215 | |
| 216 | ret = read(fd, buf, sizeof(buf)); |
| 217 | if (ret < 0) { |
| 218 | PERROR("read set max size"); |
| 219 | goto error; |
| 220 | } |
| 221 | |
| 222 | poll_max_size = atoi(buf); |
| 223 | if (poll_max_size <= 0) { |
| 224 | /* Extra precaution */ |
| 225 | poll_max_size = DEFAULT_POLL_SIZE; |
| 226 | } |
| 227 | |
| 228 | DBG("epoll set max size is %d", poll_max_size); |
| 229 | |
| 230 | error: |
| 231 | ret = close(fd); |
| 232 | if (ret) { |
| 233 | PERROR("close"); |
| 234 | } |
| 235 | } |