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

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