src/bin/lttng-sessiond/notify-apps.cpp

   1 /*
   2  * Copyright (C) 2013 David Goulet <dgoulet@efficios.com>
   3  *
   4  * SPDX-License-Identifier: GPL-2.0-only
   5  *
   6  */
   7
   8 #define _LGPL_SOURCE
   9
  10 #include "fd-limit.hpp"
  11 #include "health-sessiond.hpp"
  12 #include "lttng-sessiond.hpp"
  13 #include "notify-apps.hpp"
  14 #include "testpoint.hpp"
  15 #include "thread.hpp"
  16 #include "utils.hpp"
  17
  18 #include <common/common.hpp>
  19 #include <common/utils.hpp>
  20
  21 #include <fcntl.h>
  22
  23 namespace {
  24 struct thread_notifiers {
  25         struct lttng_pipe *quit_pipe;
  26         int apps_cmd_notify_pipe_read_fd;
  27 };
  28 } /* namespace */
  29
  30 /*
  31  * This thread manage application notify communication.
  32  */
  33 static void *thread_application_notification(void *data)
  34 {
  35         int i, ret, err = -1;
  36         ssize_t size_ret;
  37         uint32_t nb_fd;
  38         struct lttng_poll_event events;
  39         struct thread_notifiers *notifiers = (thread_notifiers *) data;
  40         const auto thread_quit_pipe_fd = lttng_pipe_get_readfd(notifiers->quit_pipe);
  41
  42         DBG("[ust-thread] Manage application notify command");
  43
  44         rcu_register_thread();
  45         rcu_thread_online();
  46
  47         health_register(the_health_sessiond, HEALTH_SESSIOND_TYPE_APP_MANAGE_NOTIFY);
  48
  49         if (testpoint(sessiond_thread_app_manage_notify)) {
  50                 goto error_testpoint;
  51         }
  52
  53         health_code_update();
  54
  55         ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC);
  56         if (ret < 0) {
  57                 goto error_poll_create;
  58         }
  59
  60         /* Add notify pipe to the pollset. */
  61         ret = lttng_poll_add(
  62                 &events, notifiers->apps_cmd_notify_pipe_read_fd, LPOLLIN | LPOLLRDHUP);
  63         if (ret < 0) {
  64                 goto error;
  65         }
  66
  67         ret = lttng_poll_add(&events, thread_quit_pipe_fd, LPOLLIN);
  68         if (ret < 0) {
  69                 goto error;
  70         }
  71
  72         health_code_update();
  73
  74         while (true) {
  75                 DBG3("[ust-thread] Manage notify polling");
  76
  77                 /* Inifinite blocking call, waiting for transmission */
  78         restart:
  79                 health_poll_entry();
  80                 ret = lttng_poll_wait(&events, -1);
  81                 DBG3("[ust-thread] Manage notify return from poll on %d fds",
  82                      LTTNG_POLL_GETNB(&events));
  83                 health_poll_exit();
  84                 if (ret < 0) {
  85                         /*
  86                          * Restart interrupted system call.
  87                          */
  88                         if (errno == EINTR) {
  89                                 goto restart;
  90                         }
  91                         goto error;
  92                 }
  93
  94                 nb_fd = ret;
  95
  96                 for (i = 0; i < nb_fd; i++) {
  97                         health_code_update();
  98
  99                         /* Fetch once the poll data */
 100                         const auto revents = LTTNG_POLL_GETEV(&events, i);
 101                         const auto pollfd = LTTNG_POLL_GETFD(&events, i);
 102
 103                         /* Activity on thread quit pipe, exiting. */
 104                         if (pollfd == thread_quit_pipe_fd) {
 105                                 DBG("Activity on thread quit pipe");
 106                                 err = 0;
 107                                 goto exit;
 108                         }
 109
 110                         if (pollfd == notifiers->apps_cmd_notify_pipe_read_fd) {
 111                                 /* Inspect the apps cmd pipe */
 112                                 int sock;
 113
 114                                 if (revents & LPOLLIN) {
 115                                         /* Get socket from dispatch thread. */
 116                                         size_ret =
 117                                                 lttng_read(notifiers->apps_cmd_notify_pipe_read_fd,
 118                                                            &sock,
 119                                                            sizeof(sock));
 120                                         if (size_ret < sizeof(sock)) {
 121                                                 PERROR("read apps notify pipe");
 122                                                 goto error;
 123                                         }
 124                                         health_code_update();
 125
 126                                         ret = lttng_poll_add(&events, sock, LPOLLIN | LPOLLRDHUP);
 127                                         if (ret < 0) {
 128                                                 /*
 129                                                  * It's possible we've reached the max poll fd
 130                                                  * allowed. Let's close the socket but continue
 131                                                  * normal execution.
 132                                                  */
 133                                                 ret = close(sock);
 134                                                 if (ret) {
 135                                                         PERROR("close notify socket %d", sock);
 136                                                 }
 137                                                 lttng_fd_put(LTTNG_FD_APPS, 1);
 138                                                 continue;
 139                                         }
 140                                         DBG3("UST thread notify added sock %d to pollset", sock);
 141                                 } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 142                                         ERR("Apps notify command pipe error");
 143                                         goto error;
 144                                 } else {
 145                                         ERR("Unexpected poll events %u for sock %d",
 146                                             revents,
 147                                             pollfd);
 148                                         goto error;
 149                                 }
 150                         } else {
 151                                 /*
 152                                  * At this point, we know that a registered application
 153                                  * triggered the event.
 154                                  */
 155                                 if (revents & (LPOLLIN | LPOLLPRI)) {
 156                                         ret = ust_app_recv_notify(pollfd);
 157                                         if (ret < 0) {
 158                                                 /* Removing from the poll set */
 159                                                 ret = lttng_poll_del(&events, pollfd);
 160                                                 if (ret < 0) {
 161                                                         goto error;
 162                                                 }
 163
 164                                                 /* The socket is closed after a grace period here.
 165                                                  */
 166                                                 ust_app_notify_sock_unregister(pollfd);
 167                                         }
 168                                 } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 169                                         /* Removing from the poll set */
 170                                         ret = lttng_poll_del(&events, pollfd);
 171                                         if (ret < 0) {
 172                                                 goto error;
 173                                         }
 174
 175                                         /* The socket is closed after a grace period here. */
 176                                         ust_app_notify_sock_unregister(pollfd);
 177                                 } else {
 178                                         ERR("Unexpected poll events %u for sock %d",
 179                                             revents,
 180                                             pollfd);
 181                                         goto error;
 182                                 }
 183                                 health_code_update();
 184                         }
 185                 }
 186         }
 187
 188 exit:
 189 error:
 190         lttng_poll_clean(&events);
 191 error_poll_create:
 192 error_testpoint:
 193
 194         DBG("Application notify communication apps thread cleanup complete");
 195         if (err) {
 196                 health_error();
 197                 ERR("Health error occurred in %s", __func__);
 198         }
 199         health_unregister(the_health_sessiond);
 200         rcu_thread_offline();
 201         rcu_unregister_thread();
 202         return nullptr;
 203 }
 204
 205 static bool shutdown_application_notification_thread(void *data)
 206 {
 207         struct thread_notifiers *notifiers = (thread_notifiers *) data;
 208         const int write_fd = lttng_pipe_get_writefd(notifiers->quit_pipe);
 209
 210         return notify_thread_pipe(write_fd) == 1;
 211 }
 212
 213 static void cleanup_application_notification_thread(void *data)
 214 {
 215         struct thread_notifiers *notifiers = (thread_notifiers *) data;
 216
 217         lttng_pipe_destroy(notifiers->quit_pipe);
 218         free(notifiers);
 219 }
 220
 221 bool launch_application_notification_thread(int apps_cmd_notify_pipe_read_fd)
 222 {
 223         struct lttng_thread *thread;
 224         struct thread_notifiers *notifiers;
 225         struct lttng_pipe *quit_pipe;
 226
 227         notifiers = zmalloc<thread_notifiers>();
 228         if (!notifiers) {
 229                 goto error_alloc;
 230         }
 231         notifiers->apps_cmd_notify_pipe_read_fd = apps_cmd_notify_pipe_read_fd;
 232
 233         quit_pipe = lttng_pipe_open(FD_CLOEXEC);
 234         if (!quit_pipe) {
 235                 goto error;
 236         }
 237         notifiers->quit_pipe = quit_pipe;
 238
 239         thread = lttng_thread_create("Application notification",
 240                                      thread_application_notification,
 241                                      shutdown_application_notification_thread,
 242                                      cleanup_application_notification_thread,
 243                                      notifiers);
 244         if (!thread) {
 245                 goto error;
 246         }
 247         lttng_thread_put(thread);
 248         return true;
 249 error:
 250         cleanup_application_notification_thread(notifiers);
 251 error_alloc:
 252         return false;
 253 }