src/bin/lttng-sessiond/health.c

   1 /*
   2  * Copyright (C) 2012 - David Goulet <dgoulet@efficios.com>
   3  * Copyright (C) 2018 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License, version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12  * more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along with
  15  * this program; if not, write to the Free Software Foundation, Inc., 51
  16  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #include "lttng-sessiond.h"
  20 #include "health-sessiond.h"
  21 #include <common/macros.h>
  22 #include <common/error.h>
  23 #include <common/utils.h>
  24 #include <common/pipe.h>
  25 #include <inttypes.h>
  26 #include <sys/stat.h>
  27 #include "utils.h"
  28 #include "thread.h"
  29
  30 struct thread_notifiers {
  31         struct lttng_pipe *quit_pipe;
  32         sem_t ready;
  33 };
  34
  35 static
  36 void mark_thread_as_ready(struct thread_notifiers *notifiers)
  37 {
  38         DBG("Marking health management thread as ready");
  39         sem_post(&notifiers->ready);
  40 }
  41
  42 static
  43 void wait_until_thread_is_ready(struct thread_notifiers *notifiers)
  44 {
  45         DBG("Waiting for health management thread to be ready");
  46         sem_wait(&notifiers->ready);
  47         DBG("Health management thread is ready");
  48 }
  49
  50 static void cleanup_health_management_thread(void *data)
  51 {
  52         struct thread_notifiers *notifiers = data;
  53
  54         lttng_pipe_destroy(notifiers->quit_pipe);
  55         sem_destroy(&notifiers->ready);
  56         free(notifiers);
  57 }
  58
  59 /*
  60  * Thread managing health check socket.
  61  */
  62 static void *thread_manage_health(void *data)
  63 {
  64         const bool is_root = (getuid() == 0);
  65         int sock = -1, new_sock = -1, ret, i, pollfd, err = -1;
  66         uint32_t revents, nb_fd;
  67         struct lttng_poll_event events;
  68         struct health_comm_msg msg;
  69         struct health_comm_reply reply;
  70         /* Thread-specific quit pipe. */
  71         struct thread_notifiers *notifiers = data;
  72         const int quit_pipe_read_fd = lttng_pipe_get_readfd(
  73                         notifiers->quit_pipe);
  74
  75         DBG("[thread] Manage health check started");
  76
  77         rcu_register_thread();
  78
  79         /*
  80          * Created with a size of two for:
  81          *   - client socket
  82          *   - thread quit pipe
  83          */
  84         ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC);
  85         if (ret < 0) {
  86                 goto error;
  87         }
  88
  89         /* Create unix socket */
  90         sock = lttcomm_create_unix_sock(config.health_unix_sock_path.value);
  91         if (sock < 0) {
  92                 ERR("Unable to create health check Unix socket");
  93                 goto error;
  94         }
  95
  96         if (is_root) {
  97                 /* lttng health client socket path permissions */
  98                 gid_t gid;
  99
 100                 ret = utils_get_group_id(config.tracing_group_name.value, true, &gid);
 101                 if (ret) {
 102                         /* Default to root group. */
 103                         gid = 0;
 104                 }
 105
 106                 ret = chown(config.health_unix_sock_path.value, 0, gid);
 107                 if (ret < 0) {
 108                         ERR("Unable to set group on %s", config.health_unix_sock_path.value);
 109                         PERROR("chown");
 110                         goto error;
 111                 }
 112
 113                 ret = chmod(config.health_unix_sock_path.value,
 114                                 S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
 115                 if (ret < 0) {
 116                         ERR("Unable to set permissions on %s", config.health_unix_sock_path.value);
 117                         PERROR("chmod");
 118                         goto error;
 119                 }
 120         }
 121
 122         /*
 123          * Set the CLOEXEC flag. Return code is useless because either way, the
 124          * show must go on.
 125          */
 126         (void) utils_set_fd_cloexec(sock);
 127
 128         ret = lttcomm_listen_unix_sock(sock);
 129         if (ret < 0) {
 130                 goto error;
 131         }
 132
 133         ret = lttng_poll_add(&events, quit_pipe_read_fd, LPOLLIN | LPOLLERR);
 134         if (ret < 0) {
 135                 goto error;
 136         }
 137
 138         /* Add the application registration socket */
 139         ret = lttng_poll_add(&events, sock, LPOLLIN | LPOLLPRI);
 140         if (ret < 0) {
 141                 goto error;
 142         }
 143
 144         mark_thread_as_ready(notifiers);
 145         while (1) {
 146                 DBG("Health check ready");
 147
 148                 /* Infinite blocking call, waiting for transmission */
 149 restart:
 150                 ret = lttng_poll_wait(&events, -1);
 151                 if (ret < 0) {
 152                         /*
 153                          * Restart interrupted system call.
 154                          */
 155                         if (errno == EINTR) {
 156                                 goto restart;
 157                         }
 158                         goto error;
 159                 }
 160
 161                 nb_fd = ret;
 162
 163                 for (i = 0; i < nb_fd; i++) {
 164                         /* Fetch once the poll data */
 165                         revents = LTTNG_POLL_GETEV(&events, i);
 166                         pollfd = LTTNG_POLL_GETFD(&events, i);
 167
 168                         /* Event on the registration socket */
 169                         if (pollfd == sock) {
 170                                 if (revents & LPOLLIN) {
 171                                         continue;
 172                                 } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 173                                         ERR("Health socket poll error");
 174                                         goto error;
 175                                 } else {
 176                                         ERR("Unexpected poll events %u for sock %d", revents, pollfd);
 177                                         goto error;
 178                                 }
 179                         } else {
 180                                 /* Event on the thread's quit pipe. */
 181                                 err = 0;
 182                                 goto exit;
 183                         }
 184                 }
 185
 186                 new_sock = lttcomm_accept_unix_sock(sock);
 187                 if (new_sock < 0) {
 188                         goto error;
 189                 }
 190
 191                 /*
 192                  * Set the CLOEXEC flag. Return code is useless because either way, the
 193                  * show must go on.
 194                  */
 195                 (void) utils_set_fd_cloexec(new_sock);
 196
 197                 DBG("Receiving data from client for health...");
 198                 ret = lttcomm_recv_unix_sock(new_sock, (void *)&msg, sizeof(msg));
 199                 if (ret <= 0) {
 200                         DBG("Nothing recv() from client... continuing");
 201                         ret = close(new_sock);
 202                         if (ret) {
 203                                 PERROR("close");
 204                         }
 205                         continue;
 206                 }
 207
 208                 rcu_thread_online();
 209
 210                 memset(&reply, 0, sizeof(reply));
 211                 for (i = 0; i < NR_HEALTH_SESSIOND_TYPES; i++) {
 212                         /*
 213                          * health_check_state returns 0 if health is
 214                          * bad.
 215                          */
 216                         if (!health_check_state(health_sessiond, i)) {
 217                                 reply.ret_code |= 1ULL << i;
 218                         }
 219                 }
 220
 221                 DBG2("Health check return value %" PRIx64, reply.ret_code);
 222
 223                 ret = lttcomm_send_unix_sock(new_sock, (void *) &reply,
 224                                 sizeof(reply));
 225                 if (ret < 0) {
 226                         ERR("Failed to send health data back to client");
 227                 }
 228
 229                 /* End of transmission */
 230                 ret = close(new_sock);
 231                 if (ret) {
 232                         PERROR("close");
 233                 }
 234         }
 235
 236 exit:
 237 error:
 238         if (err) {
 239                 ERR("Health error occurred in %s", __func__);
 240         }
 241         DBG("Health check thread dying");
 242         unlink(config.health_unix_sock_path.value);
 243         if (sock >= 0) {
 244                 ret = close(sock);
 245                 if (ret) {
 246                         PERROR("close");
 247                 }
 248         }
 249
 250         lttng_poll_clean(&events);
 251         rcu_unregister_thread();
 252         return NULL;
 253 }
 254
 255 static bool shutdown_health_management_thread(void *data)
 256 {
 257         struct thread_notifiers *notifiers = data;
 258         const int write_fd = lttng_pipe_get_writefd(notifiers->quit_pipe);
 259
 260         return notify_thread_pipe(write_fd) == 1;
 261 }
 262
 263 bool launch_health_management_thread(void)
 264 {
 265         struct thread_notifiers *notifiers;
 266         struct lttng_thread *thread;
 267
 268         notifiers = zmalloc(sizeof(*notifiers));
 269         if (!notifiers) {
 270                 goto error_alloc;
 271         }
 272
 273         sem_init(&notifiers->ready, 0, 0);
 274         notifiers->quit_pipe = lttng_pipe_open(FD_CLOEXEC);
 275         if (!notifiers->quit_pipe) {
 276                 goto error;
 277         }
 278         thread = lttng_thread_create("Health management",
 279                         thread_manage_health,
 280                         shutdown_health_management_thread,
 281                         cleanup_health_management_thread,
 282                         notifiers);
 283         if (!thread) {
 284                 goto error;
 285         }
 286
 287         wait_until_thread_is_ready(notifiers);
 288         lttng_thread_put(thread);
 289         return true;
 290 error:
 291         cleanup_health_management_thread(notifiers);
 292 error_alloc:
 293         return false;
 294 }