src/common/kernel-consumer/kernel-consumer.c

   1 /*
   2  * Copyright (C) 2011 - Julien Desfossez <julien.desfossez@polymtl.ca>
   3  *                      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License, version 2 only,
   7  * as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #define _GNU_SOURCE
  20 #include <assert.h>
  21 #include <poll.h>
  22 #include <pthread.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <sys/mman.h>
  26 #include <sys/socket.h>
  27 #include <sys/types.h>
  28 #include <inttypes.h>
  29 #include <unistd.h>
  30 #include <sys/stat.h>
  31
  32 #include <common/common.h>
  33 #include <common/kernel-ctl/kernel-ctl.h>
  34 #include <common/sessiond-comm/sessiond-comm.h>
  35 #include <common/sessiond-comm/relayd.h>
  36 #include <common/compat/fcntl.h>
  37 #include <common/relayd/relayd.h>
  38
  39 #include "kernel-consumer.h"
  40
  41 extern struct lttng_consumer_global_data consumer_data;
  42 extern int consumer_poll_timeout;
  43 extern volatile int consumer_quit;
  44
  45 /*
  46  * Take a snapshot for a specific fd
  47  *
  48  * Returns 0 on success, < 0 on error
  49  */
  50 int lttng_kconsumer_take_snapshot(struct lttng_consumer_local_data *ctx,
  51                 struct lttng_consumer_stream *stream)
  52 {
  53         int ret = 0;
  54         int infd = stream->wait_fd;
  55
  56         ret = kernctl_snapshot(infd);
  57         if (ret != 0) {
  58                 errno = -ret;
  59                 perror("Getting sub-buffer snapshot.");
  60         }
  61
  62         return ret;
  63 }
  64
  65 /*
  66  * Get the produced position
  67  *
  68  * Returns 0 on success, < 0 on error
  69  */
  70 int lttng_kconsumer_get_produced_snapshot(
  71                 struct lttng_consumer_local_data *ctx,
  72                 struct lttng_consumer_stream *stream,
  73                 unsigned long *pos)
  74 {
  75         int ret;
  76         int infd = stream->wait_fd;
  77
  78         ret = kernctl_snapshot_get_produced(infd, pos);
  79         if (ret != 0) {
  80                 errno = -ret;
  81                 perror("kernctl_snapshot_get_produced");
  82         }
  83
  84         return ret;
  85 }
  86
  87 int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
  88                 int sock, struct pollfd *consumer_sockpoll)
  89 {
  90         ssize_t ret;
  91         struct lttcomm_consumer_msg msg;
  92
  93         ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
  94         if (ret != sizeof(msg)) {
  95                 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
  96                 return ret;
  97         }
  98         if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
  99                 return -ENOENT;
 100         }
 101
 102         /* relayd needs RCU read-side protection */
 103         rcu_read_lock();
 104
 105         switch (msg.cmd_type) {
 106         case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
 107         {
 108                 ret = consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
 109                                 msg.u.relayd_sock.type, ctx, sock, consumer_sockpoll,
 110                                 &msg.u.relayd_sock.sock);
 111                 goto end_nosignal;
 112         }
 113         case LTTNG_CONSUMER_ADD_CHANNEL:
 114         {
 115                 struct lttng_consumer_channel *new_channel;
 116
 117                 DBG("consumer_add_channel %d", msg.u.channel.channel_key);
 118                 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
 119                                 -1, -1,
 120                                 msg.u.channel.mmap_len,
 121                                 msg.u.channel.max_sb_size);
 122                 if (new_channel == NULL) {
 123                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 124                         goto end_nosignal;
 125                 }
 126                 if (ctx->on_recv_channel != NULL) {
 127                         ret = ctx->on_recv_channel(new_channel);
 128                         if (ret == 0) {
 129                                 consumer_add_channel(new_channel);
 130                         } else if (ret < 0) {
 131                                 goto end_nosignal;
 132                         }
 133                 } else {
 134                         consumer_add_channel(new_channel);
 135                 }
 136                 goto end_nosignal;
 137         }
 138         case LTTNG_CONSUMER_ADD_STREAM:
 139         {
 140                 int fd;
 141                 struct consumer_relayd_sock_pair *relayd = NULL;
 142                 struct lttng_consumer_stream *new_stream;
 143
 144                 /* block */
 145                 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 146                         rcu_read_unlock();
 147                         return -EINTR;
 148                 }
 149
 150                 /* Get stream file descriptor from socket */
 151                 ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
 152                 if (ret != sizeof(fd)) {
 153                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
 154                         rcu_read_unlock();
 155                         return ret;
 156                 }
 157
 158                 new_stream = consumer_allocate_stream(msg.u.stream.channel_key,
 159                                 msg.u.stream.stream_key,
 160                                 fd, fd,
 161                                 msg.u.stream.state,
 162                                 msg.u.stream.mmap_len,
 163                                 msg.u.stream.output,
 164                                 msg.u.stream.path_name,
 165                                 msg.u.stream.uid,
 166                                 msg.u.stream.gid,
 167                                 msg.u.stream.net_index,
 168                                 msg.u.stream.metadata_flag);
 169                 if (new_stream == NULL) {
 170                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 171                         goto end_nosignal;
 172                 }
 173
 174                 /* The stream is not metadata. Get relayd reference if exists. */
 175                 relayd = consumer_find_relayd(msg.u.stream.net_index);
 176                 if (relayd != NULL) {
 177                         /* Add stream on the relayd */
 178                         pthread_mutex_lock(&relayd->ctrl_sock_mutex);
 179                         ret = relayd_add_stream(&relayd->control_sock,
 180                                         msg.u.stream.name, msg.u.stream.path_name,
 181                                         &new_stream->relayd_stream_id);
 182                         pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
 183                         if (ret < 0) {
 184                                 goto end_nosignal;
 185                         }
 186                 } else if (msg.u.stream.net_index != -1) {
 187                         ERR("Network sequence index %d unknown. Not adding stream.",
 188                                         msg.u.stream.net_index);
 189                         free(new_stream);
 190                         goto end_nosignal;
 191                 }
 192
 193                 if (ctx->on_recv_stream != NULL) {
 194                         ret = ctx->on_recv_stream(new_stream);
 195                         if (ret == 0) {
 196                                 consumer_add_stream(new_stream);
 197                         } else if (ret < 0) {
 198                                 goto end_nosignal;
 199                         }
 200                 } else {
 201                         consumer_add_stream(new_stream);
 202                 }
 203
 204                 DBG("Kernel consumer_add_stream (%d)", fd);
 205                 break;
 206         }
 207         case LTTNG_CONSUMER_UPDATE_STREAM:
 208         {
 209                 rcu_read_unlock();
 210                 return -ENOSYS;
 211         }
 212         case LTTNG_CONSUMER_DESTROY_RELAYD:
 213         {
 214                 uint64_t index = msg.u.destroy_relayd.net_seq_idx;
 215                 struct consumer_relayd_sock_pair *relayd;
 216
 217                 DBG("Kernel consumer destroying relayd %" PRIu64, index);
 218
 219                 /* Get relayd reference if exists. */
 220                 relayd = consumer_find_relayd(index);
 221                 if (relayd == NULL) {
 222                         ERR("Unable to find relayd %" PRIu64, index);
 223                         goto end_nosignal;
 224                 }
 225
 226                 /*
 227                  * Each relayd socket pair has a refcount of stream attached to it
 228                  * which tells if the relayd is still active or not depending on the
 229                  * refcount value.
 230                  *
 231                  * This will set the destroy flag of the relayd object and destroy it
 232                  * if the refcount reaches zero when called.
 233                  *
 234                  * The destroy can happen either here or when a stream fd hangs up.
 235                  */
 236                 consumer_flag_relayd_for_destroy(relayd);
 237
 238                 goto end_nosignal;
 239         }
 240         default:
 241                 goto end_nosignal;
 242         }
 243
 244         /*
 245          * Wake-up the other end by writing a null byte in the pipe (non-blocking).
 246          * Important note: Because writing into the pipe is non-blocking (and
 247          * therefore we allow dropping wakeup data, as long as there is wakeup data
 248          * present in the pipe buffer to wake up the other end), the other end
 249          * should perform the following sequence for waiting:
 250          *
 251          * 1) empty the pipe (reads).
 252          * 2) perform update operation.
 253          * 3) wait on the pipe (poll).
 254          */
 255         do {
 256                 ret = write(ctx->consumer_poll_pipe[1], "", 1);
 257         } while (ret < 0 && errno == EINTR);
 258 end_nosignal:
 259         rcu_read_unlock();
 260
 261         /*
 262          * Return 1 to indicate success since the 0 value can be a socket
 263          * shutdown during the recv() or send() call.
 264          */
 265         return 1;
 266 }
 267
 268 /*
 269  * Consume data on a file descriptor and write it on a trace file.
 270  */
 271 ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
 272                 struct lttng_consumer_local_data *ctx)
 273 {
 274         unsigned long len;
 275         int err;
 276         ssize_t ret = 0;
 277         int infd = stream->wait_fd;
 278
 279         DBG("In read_subbuffer (infd : %d)", infd);
 280         /* Get the next subbuffer */
 281         err = kernctl_get_next_subbuf(infd);
 282         if (err != 0) {
 283                 /*
 284                  * This is a debug message even for single-threaded consumer,
 285                  * because poll() have more relaxed criterions than get subbuf,
 286                  * so get_subbuf may fail for short race windows where poll()
 287                  * would issue wakeups.
 288                  */
 289                 DBG("Reserving sub buffer failed (everything is normal, "
 290                                 "it is due to concurrency)");
 291                 goto end;
 292         }
 293
 294         switch (stream->output) {
 295                 case LTTNG_EVENT_SPLICE:
 296                         /* read the whole subbuffer */
 297                         err = kernctl_get_padded_subbuf_size(infd, &len);
 298                         if (err != 0) {
 299                                 errno = -ret;
 300                                 perror("Getting sub-buffer len failed.");
 301                                 goto end;
 302                         }
 303
 304                         /* splice the subbuffer to the tracefile */
 305                         ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, len);
 306                         if (ret != len) {
 307                                 /*
 308                                  * display the error but continue processing to try
 309                                  * to release the subbuffer
 310                                  */
 311                                 ERR("Error splicing to tracefile (ret: %zd != len: %lu)",
 312                                                 ret, len);
 313                         }
 314
 315                         break;
 316                 case LTTNG_EVENT_MMAP:
 317                         /* read the used subbuffer size */
 318                         err = kernctl_get_padded_subbuf_size(infd, &len);
 319                         if (err != 0) {
 320                                 errno = -ret;
 321                                 perror("Getting sub-buffer len failed.");
 322                                 goto end;
 323                         }
 324                         /* write the subbuffer to the tracefile */
 325                         ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len);
 326                         if (ret != len) {
 327                                 /*
 328                                  * display the error but continue processing to try
 329                                  * to release the subbuffer
 330                                  */
 331                                 ERR("Error writing to tracefile");
 332                         }
 333                         break;
 334                 default:
 335                         ERR("Unknown output method");
 336                         ret = -1;
 337         }
 338
 339         err = kernctl_put_next_subbuf(infd);
 340         if (err != 0) {
 341                 errno = -ret;
 342                 if (errno == EFAULT) {
 343                         perror("Error in unreserving sub buffer\n");
 344                 } else if (errno == EIO) {
 345                         /* Should never happen with newer LTTng versions */
 346                         perror("Reader has been pushed by the writer, last sub-buffer corrupted.");
 347                 }
 348                 goto end;
 349         }
 350
 351 end:
 352         return ret;
 353 }
 354
 355 int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
 356 {
 357         int ret;
 358
 359         /* Opening the tracefile in write mode */
 360         if (strlen(stream->path_name) > 0 && stream->net_seq_idx == -1) {
 361                 ret = run_as_open(stream->path_name,
 362                                 O_WRONLY|O_CREAT|O_TRUNC,
 363                                 S_IRWXU|S_IRWXG|S_IRWXO,
 364                                 stream->uid, stream->gid);
 365                 if (ret < 0) {
 366                         ERR("Opening %s", stream->path_name);
 367                         perror("open");
 368                         goto error;
 369                 }
 370                 stream->out_fd = ret;
 371         }
 372
 373         if (stream->output == LTTNG_EVENT_MMAP) {
 374                 /* get the len of the mmap region */
 375                 unsigned long mmap_len;
 376
 377                 ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
 378                 if (ret != 0) {
 379                         errno = -ret;
 380                         perror("kernctl_get_mmap_len");
 381                         goto error_close_fd;
 382                 }
 383                 stream->mmap_len = (size_t) mmap_len;
 384
 385                 stream->mmap_base = mmap(NULL, stream->mmap_len,
 386                                 PROT_READ, MAP_PRIVATE, stream->wait_fd, 0);
 387                 if (stream->mmap_base == MAP_FAILED) {
 388                         perror("Error mmaping");
 389                         ret = -1;
 390                         goto error_close_fd;
 391                 }
 392         }
 393
 394         /* we return 0 to let the library handle the FD internally */
 395         return 0;
 396
 397 error_close_fd:
 398         {
 399                 int err;
 400
 401                 err = close(stream->out_fd);
 402                 assert(!err);
 403         }
 404 error:
 405         return ret;
 406 }
 407