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
   6  * modify it under the terms of the GNU General Public License
   7  * as published by the Free Software Foundation; only version 2
   8  * of the License.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  18  */
  19
  20 #define _GNU_SOURCE
  21 #include <assert.h>
  22 #include <fcntl.h>
  23 #include <poll.h>
  24 #include <pthread.h>
  25 #include <stdlib.h>
  26 #include <string.h>
  27 #include <sys/mman.h>
  28 #include <sys/socket.h>
  29 #include <sys/types.h>
  30 #include <unistd.h>
  31
  32 #include <common/kernel-ctl/kernel-ctl.h>
  33 #include <common/lttngerr.h>
  34 #include <common/runas.h>
  35 #include <common/sessiond-comm/sessiond-comm.h>
  36
  37 #include "kernel-consumer.h"
  38
  39 extern struct lttng_consumer_global_data consumer_data;
  40 extern int consumer_poll_timeout;
  41 extern volatile int consumer_quit;
  42
  43 /*
  44  * Mmap the ring buffer, read it and write the data to the tracefile.
  45  *
  46  * Returns the number of bytes written
  47  */
  48 int lttng_kconsumer_on_read_subbuffer_mmap(
  49                 struct lttng_consumer_local_data *ctx,
  50                 struct lttng_consumer_stream *stream, unsigned long len)
  51 {
  52         unsigned long mmap_offset;
  53         long ret = 0;
  54         off_t orig_offset = stream->out_fd_offset;
  55         int fd = stream->wait_fd;
  56         int outfd = stream->out_fd;
  57
  58         /* get the offset inside the fd to mmap */
  59         ret = kernctl_get_mmap_read_offset(fd, &mmap_offset);
  60         if (ret != 0) {
  61                 ret = -errno;
  62                 perror("kernctl_get_mmap_read_offset");
  63                 goto end;
  64         }
  65
  66         while (len > 0) {
  67                 ret = write(outfd, stream->mmap_base + mmap_offset, len);
  68                 if (ret >= len) {
  69                         len = 0;
  70                 } else if (ret < 0) {
  71                         ret = -errno;
  72                         perror("Error in file write");
  73                         goto end;
  74                 }
  75                 /* This won't block, but will start writeout asynchronously */
  76                 sync_file_range(outfd, stream->out_fd_offset, ret,
  77                                 SYNC_FILE_RANGE_WRITE);
  78                 stream->out_fd_offset += ret;
  79         }
  80
  81         lttng_consumer_sync_trace_file(stream, orig_offset);
  82
  83         goto end;
  84
  85 end:
  86         return ret;
  87 }
  88
  89 /*
  90  * Splice the data from the ring buffer to the tracefile.
  91  *
  92  * Returns the number of bytes spliced.
  93  */
  94 int lttng_kconsumer_on_read_subbuffer_splice(
  95                 struct lttng_consumer_local_data *ctx,
  96                 struct lttng_consumer_stream *stream, unsigned long len)
  97 {
  98         long ret = 0;
  99         loff_t offset = 0;
 100         off_t orig_offset = stream->out_fd_offset;
 101         int fd = stream->wait_fd;
 102         int outfd = stream->out_fd;
 103
 104         while (len > 0) {
 105                 DBG("splice chan to pipe offset %lu (fd : %d)",
 106                                 (unsigned long)offset, fd);
 107                 ret = splice(fd, &offset, ctx->consumer_thread_pipe[1], NULL, len,
 108                                 SPLICE_F_MOVE | SPLICE_F_MORE);
 109                 DBG("splice chan to pipe ret %ld", ret);
 110                 if (ret < 0) {
 111                         ret = errno;
 112                         perror("Error in relay splice");
 113                         goto splice_error;
 114                 }
 115
 116                 ret = splice(ctx->consumer_thread_pipe[0], NULL, outfd, NULL, ret,
 117                                 SPLICE_F_MOVE | SPLICE_F_MORE);
 118                 DBG("splice pipe to file %ld", ret);
 119                 if (ret < 0) {
 120                         ret = errno;
 121                         perror("Error in file splice");
 122                         goto splice_error;
 123                 }
 124                 len -= ret;
 125                 /* This won't block, but will start writeout asynchronously */
 126                 sync_file_range(outfd, stream->out_fd_offset, ret,
 127                                 SYNC_FILE_RANGE_WRITE);
 128                 stream->out_fd_offset += ret;
 129         }
 130         lttng_consumer_sync_trace_file(stream, orig_offset);
 131
 132         goto end;
 133
 134 splice_error:
 135         /* send the appropriate error description to sessiond */
 136         switch(ret) {
 137         case EBADF:
 138                 lttng_consumer_send_error(ctx, CONSUMERD_SPLICE_EBADF);
 139                 break;
 140         case EINVAL:
 141                 lttng_consumer_send_error(ctx, CONSUMERD_SPLICE_EINVAL);
 142                 break;
 143         case ENOMEM:
 144                 lttng_consumer_send_error(ctx, CONSUMERD_SPLICE_ENOMEM);
 145                 break;
 146         case ESPIPE:
 147                 lttng_consumer_send_error(ctx, CONSUMERD_SPLICE_ESPIPE);
 148                 break;
 149         }
 150
 151 end:
 152         return ret;
 153 }
 154
 155 /*
 156  * Take a snapshot for a specific fd
 157  *
 158  * Returns 0 on success, < 0 on error
 159  */
 160 int lttng_kconsumer_take_snapshot(struct lttng_consumer_local_data *ctx,
 161                 struct lttng_consumer_stream *stream)
 162 {
 163         int ret = 0;
 164         int infd = stream->wait_fd;
 165
 166         ret = kernctl_snapshot(infd);
 167         if (ret != 0) {
 168                 ret = errno;
 169                 perror("Getting sub-buffer snapshot.");
 170         }
 171
 172         return ret;
 173 }
 174
 175 /*
 176  * Get the produced position
 177  *
 178  * Returns 0 on success, < 0 on error
 179  */
 180 int lttng_kconsumer_get_produced_snapshot(
 181                 struct lttng_consumer_local_data *ctx,
 182                 struct lttng_consumer_stream *stream,
 183                 unsigned long *pos)
 184 {
 185         int ret;
 186         int infd = stream->wait_fd;
 187
 188         ret = kernctl_snapshot_get_produced(infd, pos);
 189         if (ret != 0) {
 190                 ret = errno;
 191                 perror("kernctl_snapshot_get_produced");
 192         }
 193
 194         return ret;
 195 }
 196
 197 int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 198                 int sock, struct pollfd *consumer_sockpoll)
 199 {
 200         ssize_t ret;
 201         struct lttcomm_consumer_msg msg;
 202
 203         ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
 204         if (ret != sizeof(msg)) {
 205                 lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_CMD);
 206                 return ret;
 207         }
 208         if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
 209                 return -ENOENT;
 210         }
 211
 212         switch (msg.cmd_type) {
 213         case LTTNG_CONSUMER_ADD_CHANNEL:
 214         {
 215                 struct lttng_consumer_channel *new_channel;
 216
 217                 DBG("consumer_add_channel %d", msg.u.channel.channel_key);
 218                 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
 219                                 -1, -1,
 220                                 msg.u.channel.mmap_len,
 221                                 msg.u.channel.max_sb_size);
 222                 if (new_channel == NULL) {
 223                         lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
 224                         goto end_nosignal;
 225                 }
 226                 if (ctx->on_recv_channel != NULL) {
 227                         ret = ctx->on_recv_channel(new_channel);
 228                         if (ret == 0) {
 229                                 consumer_add_channel(new_channel);
 230                         } else if (ret < 0) {
 231                                 goto end_nosignal;
 232                         }
 233                 } else {
 234                         consumer_add_channel(new_channel);
 235                 }
 236                 goto end_nosignal;
 237         }
 238         case LTTNG_CONSUMER_ADD_STREAM:
 239         {
 240                 struct lttng_consumer_stream *new_stream;
 241                 int fd;
 242
 243                 /* block */
 244                 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 245                         return -EINTR;
 246                 }
 247                 ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
 248                 if (ret != sizeof(fd)) {
 249                         lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
 250                         return ret;
 251                 }
 252
 253                 DBG("consumer_add_stream %s (%d)", msg.u.stream.path_name,
 254                         fd);
 255                 new_stream = consumer_allocate_stream(msg.u.stream.channel_key,
 256                                 msg.u.stream.stream_key,
 257                                 fd, fd,
 258                                 msg.u.stream.state,
 259                                 msg.u.stream.mmap_len,
 260                                 msg.u.stream.output,
 261                                 msg.u.stream.path_name,
 262                                 msg.u.stream.uid,
 263                                 msg.u.stream.gid);
 264                 if (new_stream == NULL) {
 265                         lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
 266                         goto end;
 267                 }
 268                 if (ctx->on_recv_stream != NULL) {
 269                         ret = ctx->on_recv_stream(new_stream);
 270                         if (ret == 0) {
 271                                 consumer_add_stream(new_stream);
 272                         } else if (ret < 0) {
 273                                 goto end;
 274                         }
 275                 } else {
 276                         consumer_add_stream(new_stream);
 277                 }
 278                 break;
 279         }
 280         case LTTNG_CONSUMER_UPDATE_STREAM:
 281         {
 282                 if (ctx->on_update_stream != NULL) {
 283                         ret = ctx->on_update_stream(msg.u.stream.stream_key, msg.u.stream.state);
 284                         if (ret == 0) {
 285                                 consumer_change_stream_state(msg.u.stream.stream_key, msg.u.stream.state);
 286                         } else if (ret < 0) {
 287                                 goto end;
 288                         }
 289                 } else {
 290                         consumer_change_stream_state(msg.u.stream.stream_key,
 291                                 msg.u.stream.state);
 292                 }
 293                 break;
 294         }
 295         default:
 296                 break;
 297         }
 298 end:
 299         /* signal the poll thread */
 300         ret = write(ctx->consumer_poll_pipe[1], "4", 1);
 301         if (ret < 0) {
 302                 perror("write consumer poll");
 303         }
 304 end_nosignal:
 305         return 0;
 306 }
 307
 308 /*
 309  * Consume data on a file descriptor and write it on a trace file.
 310  */
 311 int lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
 312                 struct lttng_consumer_local_data *ctx)
 313 {
 314         unsigned long len;
 315         int err;
 316         long ret = 0;
 317         int infd = stream->wait_fd;
 318
 319         DBG("In read_subbuffer (infd : %d)", infd);
 320         /* Get the next subbuffer */
 321         err = kernctl_get_next_subbuf(infd);
 322         if (err != 0) {
 323                 ret = errno;
 324                 /*
 325                  * This is a debug message even for single-threaded consumer,
 326                  * because poll() have more relaxed criterions than get subbuf,
 327                  * so get_subbuf may fail for short race windows where poll()
 328                  * would issue wakeups.
 329                  */
 330                 DBG("Reserving sub buffer failed (everything is normal, "
 331                                 "it is due to concurrency)");
 332                 goto end;
 333         }
 334
 335         switch (stream->output) {
 336                 case LTTNG_EVENT_SPLICE:
 337                         /* read the whole subbuffer */
 338                         err = kernctl_get_padded_subbuf_size(infd, &len);
 339                         if (err != 0) {
 340                                 ret = errno;
 341                                 perror("Getting sub-buffer len failed.");
 342                                 goto end;
 343                         }
 344
 345                         /* splice the subbuffer to the tracefile */
 346                         ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, len);
 347                         if (ret < 0) {
 348                                 /*
 349                                  * display the error but continue processing to try
 350                                  * to release the subbuffer
 351                                  */
 352                                 ERR("Error splicing to tracefile");
 353                         }
 354                         break;
 355                 case LTTNG_EVENT_MMAP:
 356                         /* read the used subbuffer size */
 357                         err = kernctl_get_padded_subbuf_size(infd, &len);
 358                         if (err != 0) {
 359                                 ret = errno;
 360                                 perror("Getting sub-buffer len failed.");
 361                                 goto end;
 362                         }
 363                         /* write the subbuffer to the tracefile */
 364                         ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len);
 365                         if (ret < 0) {
 366                                 /*
 367                                  * display the error but continue processing to try
 368                                  * to release the subbuffer
 369                                  */
 370                                 ERR("Error writing to tracefile");
 371                         }
 372                         break;
 373                 default:
 374                         ERR("Unknown output method");
 375                         ret = -1;
 376         }
 377
 378         err = kernctl_put_next_subbuf(infd);
 379         if (err != 0) {
 380                 ret = errno;
 381                 if (errno == EFAULT) {
 382                         perror("Error in unreserving sub buffer\n");
 383                 } else if (errno == EIO) {
 384                         /* Should never happen with newer LTTng versions */
 385                         perror("Reader has been pushed by the writer, last sub-buffer corrupted.");
 386                 }
 387                 goto end;
 388         }
 389
 390 end:
 391         return ret;
 392 }
 393
 394 int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
 395 {
 396         int ret;
 397
 398         /* Opening the tracefile in write mode */
 399         if (stream->path_name != NULL) {
 400                 ret = run_as_open(stream->path_name,
 401                                 O_WRONLY|O_CREAT|O_TRUNC,
 402                                 S_IRWXU|S_IRWXG|S_IRWXO,
 403                                 stream->uid, stream->gid);
 404                 if (ret < 0) {
 405                         ERR("Opening %s", stream->path_name);
 406                         perror("open");
 407                         goto error;
 408                 }
 409                 stream->out_fd = ret;
 410         }
 411
 412         if (stream->output == LTTNG_EVENT_MMAP) {
 413                 /* get the len of the mmap region */
 414                 unsigned long mmap_len;
 415
 416                 ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
 417                 if (ret != 0) {
 418                         ret = errno;
 419                         perror("kernctl_get_mmap_len");
 420                         goto error_close_fd;
 421                 }
 422                 stream->mmap_len = (size_t) mmap_len;
 423
 424                 stream->mmap_base = mmap(NULL, stream->mmap_len,
 425                                 PROT_READ, MAP_PRIVATE, stream->wait_fd, 0);
 426                 if (stream->mmap_base == MAP_FAILED) {
 427                         perror("Error mmaping");
 428                         ret = -1;
 429                         goto error_close_fd;
 430                 }
 431         }
 432
 433         /* we return 0 to let the library handle the FD internally */
 434         return 0;
 435
 436 error_close_fd:
 437         {
 438                 int err;
 439
 440                 err = close(stream->out_fd);
 441                 assert(!err);
 442         }
 443 error:
 444         return ret;
 445 }
 446