| 1 | /* |
| 2 | * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca> |
| 3 | * Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 4 | * 2013 - Jérémie Galarneau <jeremie.galarneau@efficios.com> |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify |
| 7 | * it under the terms of the GNU General Public License, version 2 only, |
| 8 | * as published by the Free Software Foundation. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | * GNU General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU General Public License along |
| 16 | * with this program; if not, write to the Free Software Foundation, Inc., |
| 17 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
| 18 | */ |
| 19 | |
| 20 | #include "lttng-sessiond.h" |
| 21 | #include "utils.h" |
| 22 | #include <common/utils.h> |
| 23 | #include <pthread.h> |
| 24 | |
| 25 | /* |
| 26 | * Quit pipe for all threads. This permits a single cancellation point |
| 27 | * for all threads when receiving an event on the pipe. |
| 28 | */ |
| 29 | static int thread_quit_pipe[2] = { -1, -1 }; |
| 30 | |
| 31 | /* |
| 32 | * Init thread quit pipe. |
| 33 | * |
| 34 | * Return -1 on error or 0 if all pipes are created. |
| 35 | */ |
| 36 | static int __init_thread_quit_pipe(int *a_pipe) |
| 37 | { |
| 38 | int ret, i; |
| 39 | |
| 40 | ret = pipe(a_pipe); |
| 41 | if (ret < 0) { |
| 42 | PERROR("thread quit pipe"); |
| 43 | goto error; |
| 44 | } |
| 45 | |
| 46 | for (i = 0; i < 2; i++) { |
| 47 | ret = fcntl(a_pipe[i], F_SETFD, FD_CLOEXEC); |
| 48 | if (ret < 0) { |
| 49 | PERROR("fcntl"); |
| 50 | goto error; |
| 51 | } |
| 52 | } |
| 53 | |
| 54 | error: |
| 55 | return ret; |
| 56 | } |
| 57 | |
| 58 | int sessiond_init_thread_quit_pipe(void) |
| 59 | { |
| 60 | return __init_thread_quit_pipe(thread_quit_pipe); |
| 61 | } |
| 62 | |
| 63 | int sessiond_check_thread_quit_pipe(int fd, uint32_t events) |
| 64 | { |
| 65 | return (fd == thread_quit_pipe[0] && (events & LPOLLIN)); |
| 66 | } |
| 67 | |
| 68 | /* |
| 69 | * Wait for a notification on the quit pipe (with a timeout). |
| 70 | * |
| 71 | * A timeout value of -1U means no timeout. |
| 72 | * |
| 73 | * Returns 1 if the caller should quit, 0 if the timeout was reached, and |
| 74 | * -1 if an error was encountered. |
| 75 | */ |
| 76 | int sessiond_wait_for_quit_pipe(unsigned int timeout_us) |
| 77 | { |
| 78 | int ret; |
| 79 | fd_set read_fds; |
| 80 | struct timeval timeout; |
| 81 | |
| 82 | FD_ZERO(&read_fds); |
| 83 | FD_SET(thread_quit_pipe[0], &read_fds); |
| 84 | memset(&timeout, 0, sizeof(timeout)); |
| 85 | timeout.tv_sec = timeout_us / USEC_PER_SEC; |
| 86 | timeout.tv_usec = timeout_us % USEC_PER_SEC; |
| 87 | |
| 88 | while (true) { |
| 89 | ret = select(thread_quit_pipe[0] + 1, &read_fds, NULL, NULL, |
| 90 | timeout_us != -1U ? &timeout : NULL); |
| 91 | if (ret < 0 && errno == EINTR) { |
| 92 | /* Retry on interrupt. */ |
| 93 | continue; |
| 94 | } else { |
| 95 | break; |
| 96 | } |
| 97 | } |
| 98 | |
| 99 | if (ret > 0) { |
| 100 | /* Should quit. */ |
| 101 | ret = 1; |
| 102 | } else if (ret < 0 && errno != EINTR) { |
| 103 | /* Unknown error. */ |
| 104 | PERROR("Failed to select() thread quit pipe"); |
| 105 | ret = -1; |
| 106 | } else { |
| 107 | /* Timeout reached. */ |
| 108 | ret = 0; |
| 109 | } |
| 110 | |
| 111 | return ret; |
| 112 | } |
| 113 | |
| 114 | int sessiond_notify_quit_pipe(void) |
| 115 | { |
| 116 | return notify_thread_pipe(thread_quit_pipe[1]); |
| 117 | } |
| 118 | |
| 119 | void sessiond_close_quit_pipe(void) |
| 120 | { |
| 121 | utils_close_pipe(thread_quit_pipe); |
| 122 | } |
| 123 | |
| 124 | static |
| 125 | int __sessiond_set_thread_pollset(struct lttng_poll_event *events, size_t size, |
| 126 | int *a_pipe) |
| 127 | { |
| 128 | int ret; |
| 129 | |
| 130 | assert(events); |
| 131 | |
| 132 | ret = lttng_poll_create(events, size, LTTNG_CLOEXEC); |
| 133 | if (ret < 0) { |
| 134 | goto error; |
| 135 | } |
| 136 | |
| 137 | /* Add quit pipe */ |
| 138 | ret = lttng_poll_add(events, a_pipe[0], LPOLLIN | LPOLLERR); |
| 139 | if (ret < 0) { |
| 140 | goto error; |
| 141 | } |
| 142 | |
| 143 | return 0; |
| 144 | |
| 145 | error: |
| 146 | return ret; |
| 147 | } |
| 148 | |
| 149 | /* |
| 150 | * Create a poll set with O_CLOEXEC and add the thread quit pipe to the set. |
| 151 | */ |
| 152 | int sessiond_set_thread_pollset(struct lttng_poll_event *events, size_t size) |
| 153 | { |
| 154 | return __sessiond_set_thread_pollset(events, size, thread_quit_pipe); |
| 155 | } |