src/bin/lttng-sessiond/agent-thread.c

   1 /*
   2  * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License, version 2 only, as
   6  * 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 with
  14  * this program; if not, write to the Free Software Foundation, Inc., 51
  15  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _GNU_SOURCE
  19 #define _LGPL_SOURCE
  20 #include <assert.h>
  21
  22 #include <common/common.h>
  23 #include <common/sessiond-comm/sessiond-comm.h>
  24 #include <common/uri.h>
  25 #include <common/utils.h>
  26
  27 #include <common/compat/endian.h>
  28
  29 #include "fd-limit.h"
  30 #include "agent-thread.h"
  31 #include "agent.h"
  32 #include "lttng-sessiond.h"
  33 #include "session.h"
  34 #include "utils.h"
  35
  36 /*
  37  * Note that there is not port here. It's set after this URI is parsed so we
  38  * can let the user define a custom one. However, localhost is ALWAYS the
  39  * default listening address.
  40  */
  41 static const char *default_reg_uri =
  42         "tcp://" DEFAULT_NETWORK_VIEWER_BIND_ADDRESS;
  43
  44 /*
  45  * Update agent application using the given socket. This is done just after
  46  * registration was successful.
  47  *
  48  * This is a quite heavy call in terms of locking since the session list lock
  49  * AND session lock are acquired.
  50  */
  51 static void update_agent_app(struct agent_app *app)
  52 {
  53         struct ltt_session *session, *stmp;
  54         struct ltt_session_list *list;
  55
  56         list = session_get_list();
  57         assert(list);
  58
  59         session_lock_list();
  60         cds_list_for_each_entry_safe(session, stmp, &list->head, list) {
  61                 session_lock(session);
  62                 if (session->ust_session) {
  63                         struct agent *agt;
  64
  65                         rcu_read_lock();
  66                         agt = trace_ust_find_agent(session->ust_session, app->domain);
  67                         if (agt) {
  68                                 agent_update(agt, app->sock->fd);
  69                         }
  70                         rcu_read_unlock();
  71                 }
  72                 session_unlock(session);
  73         }
  74         session_unlock_list();
  75 }
  76
  77 /*
  78  * Create and init socket from uri.
  79  */
  80 static struct lttcomm_sock *init_tcp_socket(void)
  81 {
  82         int ret;
  83         struct lttng_uri *uri = NULL;
  84         struct lttcomm_sock *sock = NULL;
  85
  86         /*
  87          * This should never fail since the URI is hardcoded and the port is set
  88          * before this thread is launched.
  89          */
  90         ret = uri_parse(default_reg_uri, &uri);
  91         assert(ret);
  92         assert(agent_tcp_port);
  93         uri->port = agent_tcp_port;
  94
  95         sock = lttcomm_alloc_sock_from_uri(uri);
  96         uri_free(uri);
  97         if (sock == NULL) {
  98                 ERR("[agent-thread] agent allocating TCP socket");
  99                 goto error;
 100         }
 101
 102         ret = lttcomm_create_sock(sock);
 103         if (ret < 0) {
 104                 goto error;
 105         }
 106
 107         ret = sock->ops->bind(sock);
 108         if (ret < 0) {
 109                 WARN("Another session daemon is using this agent port. Agent support "
 110                                 "will be deactivated to prevent interfering with the tracing.");
 111                 goto error;
 112         }
 113
 114         ret = sock->ops->listen(sock, -1);
 115         if (ret < 0) {
 116                 goto error;
 117         }
 118
 119         DBG("[agent-thread] Listening on TCP port %u and socket %d",
 120                         agent_tcp_port, sock->fd);
 121
 122         return sock;
 123
 124 error:
 125         if (sock) {
 126                 lttcomm_destroy_sock(sock);
 127         }
 128         return NULL;
 129 }
 130
 131 /*
 132  * Close and destroy the given TCP socket.
 133  */
 134 static void destroy_tcp_socket(struct lttcomm_sock *sock)
 135 {
 136         assert(sock);
 137
 138         DBG3("[agent-thread] Destroy TCP socket on port %u", agent_tcp_port);
 139
 140         /* This will return gracefully if fd is invalid. */
 141         sock->ops->close(sock);
 142         lttcomm_destroy_sock(sock);
 143 }
 144
 145 /*
 146  * Handle a new agent registration using the reg socket. After that, a new
 147  * agent application is added to the global hash table and attach to an UST app
 148  * object. If r_app is not NULL, the created app is set to the pointer.
 149  *
 150  * Return the new FD created upon accept() on success or else a negative errno
 151  * value.
 152  */
 153 static int handle_registration(struct lttcomm_sock *reg_sock,
 154                 struct agent_app **r_app)
 155 {
 156         int ret;
 157         pid_t pid;
 158         uint32_t major_version, minor_version;
 159         ssize_t size;
 160         enum lttng_domain_type domain;
 161         struct agent_app *app;
 162         struct agent_register_msg msg;
 163         struct lttcomm_sock *new_sock;
 164
 165         assert(reg_sock);
 166
 167         new_sock = reg_sock->ops->accept(reg_sock);
 168         if (!new_sock) {
 169                 ret = -ENOTCONN;
 170                 goto error;
 171         }
 172
 173         size = new_sock->ops->recvmsg(new_sock, &msg, sizeof(msg), 0);
 174         if (size < sizeof(msg)) {
 175                 ret = -EINVAL;
 176                 goto error_socket;
 177         }
 178         domain = be32toh(msg.domain);
 179         pid = be32toh(msg.pid);
 180         major_version = be32toh(msg.major_version);
 181         minor_version = be32toh(msg.minor_version);
 182
 183         /* Test communication protocol version of the registring agent. */
 184         if (major_version != AGENT_MAJOR_VERSION) {
 185                 ret = -EINVAL;
 186                 goto error_socket;
 187         }
 188         if (minor_version != AGENT_MINOR_VERSION) {
 189                 ret = -EINVAL;
 190                 goto error_socket;
 191         }
 192
 193         DBG2("[agent-thread] New registration for pid %d domain %d on socket %d",
 194                         pid, domain, new_sock->fd);
 195
 196         app = agent_create_app(pid, domain, new_sock);
 197         if (!app) {
 198                 ret = -ENOMEM;
 199                 goto error_socket;
 200         }
 201
 202         /*
 203          * Add before assigning the socket value to the UST app so it can be found
 204          * concurrently.
 205          */
 206         agent_add_app(app);
 207
 208         /*
 209          * We don't need to attach the agent app to the app. If we ever do so, we
 210          * should consider both registration order of agent before app and app
 211          * before agent.
 212          */
 213
 214         if (r_app) {
 215                 *r_app = app;
 216         }
 217
 218         return new_sock->fd;
 219
 220 error_socket:
 221         new_sock->ops->close(new_sock);
 222         lttcomm_destroy_sock(new_sock);
 223 error:
 224         return ret;
 225 }
 226
 227 /*
 228  * This thread manage application notify communication.
 229  */
 230 void *agent_thread_manage_registration(void *data)
 231 {
 232         int i, ret, pollfd;
 233         uint32_t revents, nb_fd;
 234         struct lttng_poll_event events;
 235         struct lttcomm_sock *reg_sock;
 236
 237         DBG("[agent-thread] Manage agent application registration.");
 238
 239         rcu_register_thread();
 240         rcu_thread_online();
 241
 242         /* Agent initialization call MUST be called before starting the thread. */
 243         assert(agent_apps_ht_by_sock);
 244
 245         /* Create pollset with size 2, quit pipe and socket. */
 246         ret = sessiond_set_thread_pollset(&events, 2);
 247         if (ret < 0) {
 248                 goto error_poll_create;
 249         }
 250
 251         reg_sock = init_tcp_socket();
 252         if (!reg_sock) {
 253                 goto error_tcp_socket;
 254         }
 255
 256         /* Add create valid TCP socket to poll set. */
 257         ret = lttng_poll_add(&events, reg_sock->fd,
 258                         LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP);
 259         if (ret < 0) {
 260                 goto error;
 261         }
 262
 263         while (1) {
 264                 DBG3("[agent-thread] Manage agent polling");
 265
 266                 /* Inifinite blocking call, waiting for transmission */
 267 restart:
 268                 ret = lttng_poll_wait(&events, -1);
 269                 DBG3("[agent-thread] Manage agent return from poll on %d fds",
 270                                 LTTNG_POLL_GETNB(&events));
 271                 if (ret < 0) {
 272                         /*
 273                          * Restart interrupted system call.
 274                          */
 275                         if (errno == EINTR) {
 276                                 goto restart;
 277                         }
 278                         goto error;
 279                 }
 280                 nb_fd = ret;
 281                 DBG3("[agent-thread] %d fd ready", nb_fd);
 282
 283                 for (i = 0; i < nb_fd; i++) {
 284                         /* Fetch once the poll data */
 285                         revents = LTTNG_POLL_GETEV(&events, i);
 286                         pollfd = LTTNG_POLL_GETFD(&events, i);
 287
 288                         if (!revents) {
 289                                 /* No activity for this FD (poll implementation). */
 290                                 continue;
 291                         }
 292
 293                         /* Thread quit pipe has been closed. Killing thread. */
 294                         ret = sessiond_check_thread_quit_pipe(pollfd, revents);
 295                         if (ret) {
 296                                 goto exit;
 297                         }
 298
 299                         /*
 300                          * Check first if this is a POLLERR since POLLIN is also included
 301                          * in an error value thus checking first.
 302                          */
 303                         if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 304                                 /* Removing from the poll set */
 305                                 ret = lttng_poll_del(&events, pollfd);
 306                                 if (ret < 0) {
 307                                         goto error;
 308                                 }
 309
 310                                 agent_destroy_app_by_sock(pollfd);
 311                         } else if (revents & (LPOLLIN)) {
 312                                 int new_fd;
 313                                 struct agent_app *app = NULL;
 314
 315                                 /* Pollin event of agent app socket should NEVER happen. */
 316                                 assert(pollfd == reg_sock->fd);
 317
 318                                 new_fd = handle_registration(reg_sock, &app);
 319                                 if (new_fd < 0) {
 320                                         WARN("[agent-thread] agent registration failed. Ignoring.");
 321                                         /* Somehow the communication failed. Just continue. */
 322                                         continue;
 323                                 }
 324                                 /* Should not have a NULL app on success. */
 325                                 assert(app);
 326
 327                                 /* Only add poll error event to only detect shutdown. */
 328                                 ret = lttng_poll_add(&events, new_fd,
 329                                                 LPOLLERR | LPOLLHUP | LPOLLRDHUP);
 330                                 if (ret < 0) {
 331                                         agent_destroy_app_by_sock(new_fd);
 332                                         continue;
 333                                 }
 334
 335                                 /* Update newly registered app. */
 336                                 update_agent_app(app);
 337
 338                                 /* On failure, the poll will detect it and clean it up. */
 339                                 (void) agent_send_registration_done(app);
 340                         } else {
 341                                 ERR("Unknown poll events %u for sock %d", revents, pollfd);
 342                                 continue;
 343                         }
 344                 }
 345         }
 346
 347 exit:
 348         /* Whatever happens, try to delete it and exit. */
 349         (void) lttng_poll_del(&events, reg_sock->fd);
 350 error:
 351         destroy_tcp_socket(reg_sock);
 352 error_tcp_socket:
 353         lttng_poll_clean(&events);
 354 error_poll_create:
 355         DBG("[agent-thread] is cleaning up and stopping.");
 356
 357         rcu_thread_offline();
 358         rcu_unregister_thread();
 359         return NULL;
 360 }