lttng-abi.c

   1 /*
   2  * lttng-abi.c
   3  *
   4  * LTTng ABI
   5  *
   6  * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  *
  22  *
  23  * Mimic system calls for:
  24  * - session creation, returns a file descriptor or failure.
  25  *   - channel creation, returns a file descriptor or failure.
  26  *     - Operates on a session file descriptor
  27  *     - Takes all channel options as parameters.
  28  *   - stream get, returns a file descriptor or failure.
  29  *     - Operates on a channel file descriptor.
  30  *   - stream notifier get, returns a file descriptor or failure.
  31  *     - Operates on a channel file descriptor.
  32  *   - event creation, returns a file descriptor or failure.
  33  *     - Operates on a channel file descriptor
  34  *     - Takes an event name as parameter
  35  *     - Takes an instrumentation source as parameter
  36  *       - e.g. tracepoints, dynamic_probes...
  37  *     - Takes instrumentation source specific arguments.
  38  */
  39
  40 #include <linux/module.h>
  41 #include <linux/proc_fs.h>
  42 #include <linux/anon_inodes.h>
  43 #include <linux/file.h>
  44 #include <linux/uaccess.h>
  45 #include <linux/slab.h>
  46 #include "wrapper/vmalloc.h"    /* for wrapper_vmalloc_sync_all() */
  47 #include "wrapper/ringbuffer/vfs.h"
  48 #include "wrapper/poll.h"
  49 #include "lttng-abi.h"
  50 #include "lttng-events.h"
  51 #include "lttng-tracer.h"
  52
  53 /*
  54  * This is LTTng's own personal way to create a system call as an external
  55  * module. We use ioctl() on /proc/lttng.
  56  */
  57
  58 static struct proc_dir_entry *lttng_proc_dentry;
  59 static const struct file_operations lttng_fops;
  60 static const struct file_operations lttng_session_fops;
  61 static const struct file_operations lttng_channel_fops;
  62 static const struct file_operations lttng_metadata_fops;
  63 static const struct file_operations lttng_event_fops;
  64
  65 /*
  66  * Teardown management: opened file descriptors keep a refcount on the module,
  67  * so it can only exit when all file descriptors are closed.
  68  */
  69
  70 enum channel_type {
  71         PER_CPU_CHANNEL,
  72         METADATA_CHANNEL,
  73 };
  74
  75 static
  76 int lttng_abi_create_session(void)
  77 {
  78         struct lttng_session *session;
  79         struct file *session_file;
  80         int session_fd, ret;
  81
  82         session = lttng_session_create();
  83         if (!session)
  84                 return -ENOMEM;
  85         session_fd = get_unused_fd();
  86         if (session_fd < 0) {
  87                 ret = session_fd;
  88                 goto fd_error;
  89         }
  90         session_file = anon_inode_getfile("[lttng_session]",
  91                                           &lttng_session_fops,
  92                                           session, O_RDWR);
  93         if (IS_ERR(session_file)) {
  94                 ret = PTR_ERR(session_file);
  95                 goto file_error;
  96         }
  97         session->file = session_file;
  98         fd_install(session_fd, session_file);
  99         return session_fd;
 100
 101 file_error:
 102         put_unused_fd(session_fd);
 103 fd_error:
 104         lttng_session_destroy(session);
 105         return ret;
 106 }
 107
 108 static
 109 int lttng_abi_tracepoint_list(void)
 110 {
 111         struct file *tracepoint_list_file;
 112         int file_fd, ret;
 113
 114         file_fd = get_unused_fd();
 115         if (file_fd < 0) {
 116                 ret = file_fd;
 117                 goto fd_error;
 118         }
 119
 120         tracepoint_list_file = anon_inode_getfile("[lttng_session]",
 121                                           &lttng_tracepoint_list_fops,
 122                                           NULL, O_RDWR);
 123         if (IS_ERR(tracepoint_list_file)) {
 124                 ret = PTR_ERR(tracepoint_list_file);
 125                 goto file_error;
 126         }
 127         ret = lttng_tracepoint_list_fops.open(NULL, tracepoint_list_file);
 128         if (ret < 0)
 129                 goto open_error;
 130         fd_install(file_fd, tracepoint_list_file);
 131         if (file_fd < 0) {
 132                 ret = file_fd;
 133                 goto fd_error;
 134         }
 135         return file_fd;
 136
 137 open_error:
 138         fput(tracepoint_list_file);
 139 file_error:
 140         put_unused_fd(file_fd);
 141 fd_error:
 142         return ret;
 143 }
 144
 145 static
 146 long lttng_abi_tracer_version(struct file *file,
 147         struct lttng_kernel_tracer_version __user *uversion_param)
 148 {
 149         struct lttng_kernel_tracer_version v;
 150
 151         v.major = LTTNG_MODULES_MAJOR_VERSION;
 152         v.minor = LTTNG_MODULES_MINOR_VERSION;
 153         v.patchlevel = LTTNG_MODULES_PATCHLEVEL_VERSION;
 154
 155         if (copy_to_user(uversion_param, &v, sizeof(v)))
 156                 return -EFAULT;
 157         return 0;
 158 }
 159
 160 static
 161 long lttng_abi_add_context(struct file *file,
 162         struct lttng_kernel_context __user *ucontext_param,
 163         struct lttng_ctx **ctx, struct lttng_session *session)
 164 {
 165         struct lttng_kernel_context context_param;
 166
 167         if (session->been_active)
 168                 return -EPERM;
 169
 170         if (copy_from_user(&context_param, ucontext_param, sizeof(context_param)))
 171                 return -EFAULT;
 172
 173         switch (context_param.ctx) {
 174         case LTTNG_KERNEL_CONTEXT_PID:
 175                 return lttng_add_pid_to_ctx(ctx);
 176         case LTTNG_KERNEL_CONTEXT_PRIO:
 177                 return lttng_add_prio_to_ctx(ctx);
 178         case LTTNG_KERNEL_CONTEXT_NICE:
 179                 return lttng_add_nice_to_ctx(ctx);
 180         case LTTNG_KERNEL_CONTEXT_VPID:
 181                 return lttng_add_vpid_to_ctx(ctx);
 182         case LTTNG_KERNEL_CONTEXT_TID:
 183                 return lttng_add_tid_to_ctx(ctx);
 184         case LTTNG_KERNEL_CONTEXT_VTID:
 185                 return lttng_add_vtid_to_ctx(ctx);
 186         case LTTNG_KERNEL_CONTEXT_PPID:
 187                 return lttng_add_ppid_to_ctx(ctx);
 188         case LTTNG_KERNEL_CONTEXT_VPPID:
 189                 return lttng_add_vppid_to_ctx(ctx);
 190         case LTTNG_KERNEL_CONTEXT_PERF_COUNTER:
 191                 context_param.u.perf_counter.name[LTTNG_KERNEL_SYM_NAME_LEN - 1] = '\0';
 192                 return lttng_add_perf_counter_to_ctx(context_param.u.perf_counter.type,
 193                                 context_param.u.perf_counter.config,
 194                                 context_param.u.perf_counter.name,
 195                                 ctx);
 196         case LTTNG_KERNEL_CONTEXT_PROCNAME:
 197                 return lttng_add_procname_to_ctx(ctx);
 198         default:
 199                 return -EINVAL;
 200         }
 201 }
 202
 203 /**
 204  *      lttng_ioctl - lttng syscall through ioctl
 205  *
 206  *      @file: the file
 207  *      @cmd: the command
 208  *      @arg: command arg
 209  *
 210  *      This ioctl implements lttng commands:
 211  *      LTTNG_KERNEL_SESSION
 212  *              Returns a LTTng trace session file descriptor
 213  *      LTTNG_KERNEL_TRACER_VERSION
 214  *              Returns the LTTng kernel tracer version
 215  *      LTTNG_KERNEL_TRACEPOINT_LIST
 216  *              Returns a file descriptor listing available tracepoints
 217  *      LTTNG_KERNEL_WAIT_QUIESCENT
 218  *              Returns after all previously running probes have completed
 219  *
 220  * The returned session will be deleted when its file descriptor is closed.
 221  */
 222 static
 223 long lttng_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 224 {
 225         switch (cmd) {
 226         case LTTNG_KERNEL_SESSION:
 227                 return lttng_abi_create_session();
 228         case LTTNG_KERNEL_TRACER_VERSION:
 229                 return lttng_abi_tracer_version(file,
 230                                 (struct lttng_kernel_tracer_version __user *) arg);
 231         case LTTNG_KERNEL_TRACEPOINT_LIST:
 232                 return lttng_abi_tracepoint_list();
 233         case LTTNG_KERNEL_WAIT_QUIESCENT:
 234                 synchronize_trace();
 235                 return 0;
 236         case LTTNG_KERNEL_CALIBRATE:
 237         {
 238                 struct lttng_kernel_calibrate __user *ucalibrate =
 239                         (struct lttng_kernel_calibrate __user *) arg;
 240                 struct lttng_kernel_calibrate calibrate;
 241                 int ret;
 242
 243                 if (copy_from_user(&calibrate, ucalibrate, sizeof(calibrate)))
 244                         return -EFAULT;
 245                 ret = lttng_calibrate(&calibrate);
 246                 if (copy_to_user(ucalibrate, &calibrate, sizeof(calibrate)))
 247                         return -EFAULT;
 248                 return ret;
 249         }
 250         default:
 251                 return -ENOIOCTLCMD;
 252         }
 253 }
 254
 255 static const struct file_operations lttng_fops = {
 256         .owner = THIS_MODULE,
 257         .unlocked_ioctl = lttng_ioctl,
 258 #ifdef CONFIG_COMPAT
 259         .compat_ioctl = lttng_ioctl,
 260 #endif
 261 };
 262
 263 /*
 264  * We tolerate no failure in this function (if one happens, we print a dmesg
 265  * error, but cannot return any error, because the channel information is
 266  * invariant.
 267  */
 268 static
 269 void lttng_metadata_create_events(struct file *channel_file)
 270 {
 271         struct lttng_channel *channel = channel_file->private_data;
 272         static struct lttng_kernel_event metadata_params = {
 273                 .instrumentation = LTTNG_KERNEL_TRACEPOINT,
 274                 .name = "lttng_metadata",
 275         };
 276         struct lttng_event *event;
 277
 278         /*
 279          * We tolerate no failure path after event creation. It will stay
 280          * invariant for the rest of the session.
 281          */
 282         event = lttng_event_create(channel, &metadata_params, NULL, NULL);
 283         if (!event) {
 284                 goto create_error;
 285         }
 286         return;
 287
 288 create_error:
 289         WARN_ON(1);
 290         return;         /* not allowed to return error */
 291 }
 292
 293 static
 294 int lttng_abi_create_channel(struct file *session_file,
 295                              struct lttng_kernel_channel __user *uchan_param,
 296                              enum channel_type channel_type)
 297 {
 298         struct lttng_session *session = session_file->private_data;
 299         const struct file_operations *fops = NULL;
 300         const char *transport_name;
 301         struct lttng_channel *chan;
 302         struct file *chan_file;
 303         struct lttng_kernel_channel chan_param;
 304         int chan_fd;
 305         int ret = 0;
 306
 307         if (copy_from_user(&chan_param, uchan_param, sizeof(chan_param)))
 308                 return -EFAULT;
 309         chan_fd = get_unused_fd();
 310         if (chan_fd < 0) {
 311                 ret = chan_fd;
 312                 goto fd_error;
 313         }
 314         switch (channel_type) {
 315         case PER_CPU_CHANNEL:
 316                 fops = &lttng_channel_fops;
 317                 break;
 318         case METADATA_CHANNEL:
 319                 fops = &lttng_metadata_fops;
 320                 break;
 321         }
 322
 323         chan_file = anon_inode_getfile("[lttng_channel]",
 324                                        fops,
 325                                        NULL, O_RDWR);
 326         if (IS_ERR(chan_file)) {
 327                 ret = PTR_ERR(chan_file);
 328                 goto file_error;
 329         }
 330         switch (channel_type) {
 331         case PER_CPU_CHANNEL:
 332                 if (chan_param.output == LTTNG_KERNEL_SPLICE) {
 333                         transport_name = chan_param.overwrite ?
 334                                 "relay-overwrite" : "relay-discard";
 335                 } else if (chan_param.output == LTTNG_KERNEL_MMAP) {
 336                         transport_name = chan_param.overwrite ?
 337                                 "relay-overwrite-mmap" : "relay-discard-mmap";
 338                 } else {
 339                         return -EINVAL;
 340                 }
 341                 break;
 342         case METADATA_CHANNEL:
 343                 if (chan_param.output == LTTNG_KERNEL_SPLICE)
 344                         transport_name = "relay-metadata";
 345                 else if (chan_param.output == LTTNG_KERNEL_MMAP)
 346                         transport_name = "relay-metadata-mmap";
 347                 else
 348                         return -EINVAL;
 349                 break;
 350         default:
 351                 transport_name = "<unknown>";
 352                 break;
 353         }
 354         /*
 355          * We tolerate no failure path after channel creation. It will stay
 356          * invariant for the rest of the session.
 357          */
 358         chan = lttng_channel_create(session, transport_name, NULL,
 359                                   chan_param.subbuf_size,
 360                                   chan_param.num_subbuf,
 361                                   chan_param.switch_timer_interval,
 362                                   chan_param.read_timer_interval);
 363         if (!chan) {
 364                 ret = -EINVAL;
 365                 goto chan_error;
 366         }
 367         chan->file = chan_file;
 368         chan_file->private_data = chan;
 369         fd_install(chan_fd, chan_file);
 370         if (channel_type == METADATA_CHANNEL) {
 371                 session->metadata = chan;
 372                 lttng_metadata_create_events(chan_file);
 373         }
 374
 375         /* The channel created holds a reference on the session */
 376         atomic_long_inc(&session_file->f_count);
 377
 378         return chan_fd;
 379
 380 chan_error:
 381         fput(chan_file);
 382 file_error:
 383         put_unused_fd(chan_fd);
 384 fd_error:
 385         return ret;
 386 }
 387
 388 /**
 389  *      lttng_session_ioctl - lttng session fd ioctl
 390  *
 391  *      @file: the file
 392  *      @cmd: the command
 393  *      @arg: command arg
 394  *
 395  *      This ioctl implements lttng commands:
 396  *      LTTNG_KERNEL_CHANNEL
 397  *              Returns a LTTng channel file descriptor
 398  *      LTTNG_KERNEL_ENABLE
 399  *              Enables tracing for a session (weak enable)
 400  *      LTTNG_KERNEL_DISABLE
 401  *              Disables tracing for a session (strong disable)
 402  *      LTTNG_KERNEL_METADATA
 403  *              Returns a LTTng metadata file descriptor
 404  *
 405  * The returned channel will be deleted when its file descriptor is closed.
 406  */
 407 static
 408 long lttng_session_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 409 {
 410         struct lttng_session *session = file->private_data;
 411
 412         switch (cmd) {
 413         case LTTNG_KERNEL_CHANNEL:
 414                 return lttng_abi_create_channel(file,
 415                                 (struct lttng_kernel_channel __user *) arg,
 416                                 PER_CPU_CHANNEL);
 417         case LTTNG_KERNEL_SESSION_START:
 418         case LTTNG_KERNEL_ENABLE:
 419                 return lttng_session_enable(session);
 420         case LTTNG_KERNEL_SESSION_STOP:
 421         case LTTNG_KERNEL_DISABLE:
 422                 return lttng_session_disable(session);
 423         case LTTNG_KERNEL_METADATA:
 424                 return lttng_abi_create_channel(file,
 425                                 (struct lttng_kernel_channel __user *) arg,
 426                                 METADATA_CHANNEL);
 427         default:
 428                 return -ENOIOCTLCMD;
 429         }
 430 }
 431
 432 /*
 433  * Called when the last file reference is dropped.
 434  *
 435  * Big fat note: channels and events are invariant for the whole session after
 436  * their creation. So this session destruction also destroys all channel and
 437  * event structures specific to this session (they are not destroyed when their
 438  * individual file is released).
 439  */
 440 static
 441 int lttng_session_release(struct inode *inode, struct file *file)
 442 {
 443         struct lttng_session *session = file->private_data;
 444
 445         if (session)
 446                 lttng_session_destroy(session);
 447         return 0;
 448 }
 449
 450 static const struct file_operations lttng_session_fops = {
 451         .owner = THIS_MODULE,
 452         .release = lttng_session_release,
 453         .unlocked_ioctl = lttng_session_ioctl,
 454 #ifdef CONFIG_COMPAT
 455         .compat_ioctl = lttng_session_ioctl,
 456 #endif
 457 };
 458
 459 static
 460 int lttng_abi_open_stream(struct file *channel_file)
 461 {
 462         struct lttng_channel *channel = channel_file->private_data;
 463         struct lib_ring_buffer *buf;
 464         int stream_fd, ret;
 465         struct file *stream_file;
 466
 467         buf = channel->ops->buffer_read_open(channel->chan);
 468         if (!buf)
 469                 return -ENOENT;
 470
 471         stream_fd = get_unused_fd();
 472         if (stream_fd < 0) {
 473                 ret = stream_fd;
 474                 goto fd_error;
 475         }
 476         stream_file = anon_inode_getfile("[lttng_stream]",
 477                                          &lib_ring_buffer_file_operations,
 478                                          buf, O_RDWR);
 479         if (IS_ERR(stream_file)) {
 480                 ret = PTR_ERR(stream_file);
 481                 goto file_error;
 482         }
 483         /*
 484          * OPEN_FMODE, called within anon_inode_getfile/alloc_file, don't honor
 485          * FMODE_LSEEK, FMODE_PREAD nor FMODE_PWRITE. We need to read from this
 486          * file descriptor, so we set FMODE_PREAD here.
 487          */
 488         stream_file->f_mode |= FMODE_PREAD;
 489         fd_install(stream_fd, stream_file);
 490         /*
 491          * The stream holds a reference to the channel within the generic ring
 492          * buffer library, so no need to hold a refcount on the channel and
 493          * session files here.
 494          */
 495         return stream_fd;
 496
 497 file_error:
 498         put_unused_fd(stream_fd);
 499 fd_error:
 500         channel->ops->buffer_read_close(buf);
 501         return ret;
 502 }
 503
 504 static
 505 int lttng_abi_create_event(struct file *channel_file,
 506                            struct lttng_kernel_event __user *uevent_param)
 507 {
 508         struct lttng_channel *channel = channel_file->private_data;
 509         struct lttng_event *event;
 510         struct lttng_kernel_event event_param;
 511         int event_fd, ret;
 512         struct file *event_file;
 513
 514         if (copy_from_user(&event_param, uevent_param, sizeof(event_param)))
 515                 return -EFAULT;
 516         event_param.name[LTTNG_KERNEL_SYM_NAME_LEN - 1] = '\0';
 517         switch (event_param.instrumentation) {
 518         case LTTNG_KERNEL_KRETPROBE:
 519                 event_param.u.kretprobe.symbol_name[LTTNG_KERNEL_SYM_NAME_LEN - 1] = '\0';
 520                 break;
 521         case LTTNG_KERNEL_KPROBE:
 522                 event_param.u.kprobe.symbol_name[LTTNG_KERNEL_SYM_NAME_LEN - 1] = '\0';
 523                 break;
 524         case LTTNG_KERNEL_FUNCTION:
 525                 event_param.u.ftrace.symbol_name[LTTNG_KERNEL_SYM_NAME_LEN - 1] = '\0';
 526                 break;
 527         default:
 528                 break;
 529         }
 530         switch (event_param.instrumentation) {
 531         default:
 532                 event_fd = get_unused_fd();
 533                 if (event_fd < 0) {
 534                         ret = event_fd;
 535                         goto fd_error;
 536                 }
 537                 event_file = anon_inode_getfile("[lttng_event]",
 538                                                 &lttng_event_fops,
 539                                                 NULL, O_RDWR);
 540                 if (IS_ERR(event_file)) {
 541                         ret = PTR_ERR(event_file);
 542                         goto file_error;
 543                 }
 544                 /*
 545                  * We tolerate no failure path after event creation. It
 546                  * will stay invariant for the rest of the session.
 547                  */
 548                 event = lttng_event_create(channel, &event_param, NULL, NULL);
 549                 if (!event) {
 550                         ret = -EINVAL;
 551                         goto event_error;
 552                 }
 553                 event_file->private_data = event;
 554                 fd_install(event_fd, event_file);
 555                 /* The event holds a reference on the channel */
 556                 atomic_long_inc(&channel_file->f_count);
 557                 break;
 558         case LTTNG_KERNEL_SYSCALL:
 559                 /*
 560                  * Only all-syscall tracing supported for now.
 561                  */
 562                 if (event_param.name[0] != '\0')
 563                         return -EINVAL;
 564                 ret = lttng_syscalls_register(channel, NULL);
 565                 if (ret)
 566                         goto fd_error;
 567                 event_fd = 0;
 568                 break;
 569         }
 570         return event_fd;
 571
 572 event_error:
 573         fput(event_file);
 574 file_error:
 575         put_unused_fd(event_fd);
 576 fd_error:
 577         return ret;
 578 }
 579
 580 /**
 581  *      lttng_channel_ioctl - lttng syscall through ioctl
 582  *
 583  *      @file: the file
 584  *      @cmd: the command
 585  *      @arg: command arg
 586  *
 587  *      This ioctl implements lttng commands:
 588  *      LTTNG_KERNEL_STREAM
 589  *              Returns an event stream file descriptor or failure.
 590  *              (typically, one event stream records events from one CPU)
 591  *      LTTNG_KERNEL_EVENT
 592  *              Returns an event file descriptor or failure.
 593  *      LTTNG_KERNEL_CONTEXT
 594  *              Prepend a context field to each event in the channel
 595  *      LTTNG_KERNEL_ENABLE
 596  *              Enable recording for events in this channel (weak enable)
 597  *      LTTNG_KERNEL_DISABLE
 598  *              Disable recording for events in this channel (strong disable)
 599  *
 600  * Channel and event file descriptors also hold a reference on the session.
 601  */
 602 static
 603 long lttng_channel_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 604 {
 605         struct lttng_channel *channel = file->private_data;
 606
 607         switch (cmd) {
 608         case LTTNG_KERNEL_STREAM:
 609                 return lttng_abi_open_stream(file);
 610         case LTTNG_KERNEL_EVENT:
 611                 return lttng_abi_create_event(file, (struct lttng_kernel_event __user *) arg);
 612         case LTTNG_KERNEL_CONTEXT:
 613                 return lttng_abi_add_context(file,
 614                                 (struct lttng_kernel_context __user *) arg,
 615                                 &channel->ctx, channel->session);
 616         case LTTNG_KERNEL_ENABLE:
 617                 return lttng_channel_enable(channel);
 618         case LTTNG_KERNEL_DISABLE:
 619                 return lttng_channel_disable(channel);
 620         default:
 621                 return -ENOIOCTLCMD;
 622         }
 623 }
 624
 625 /**
 626  *      lttng_metadata_ioctl - lttng syscall through ioctl
 627  *
 628  *      @file: the file
 629  *      @cmd: the command
 630  *      @arg: command arg
 631  *
 632  *      This ioctl implements lttng commands:
 633  *      LTTNG_KERNEL_STREAM
 634  *              Returns an event stream file descriptor or failure.
 635  *
 636  * Channel and event file descriptors also hold a reference on the session.
 637  */
 638 static
 639 long lttng_metadata_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 640 {
 641         switch (cmd) {
 642         case LTTNG_KERNEL_STREAM:
 643                 return lttng_abi_open_stream(file);
 644         default:
 645                 return -ENOIOCTLCMD;
 646         }
 647 }
 648
 649 /**
 650  *      lttng_channel_poll - lttng stream addition/removal monitoring
 651  *
 652  *      @file: the file
 653  *      @wait: poll table
 654  */
 655 unsigned int lttng_channel_poll(struct file *file, poll_table *wait)
 656 {
 657         struct lttng_channel *channel = file->private_data;
 658         unsigned int mask = 0;
 659
 660         if (file->f_mode & FMODE_READ) {
 661                 poll_wait_set_exclusive(wait);
 662                 poll_wait(file, channel->ops->get_hp_wait_queue(channel->chan),
 663                           wait);
 664
 665                 if (channel->ops->is_disabled(channel->chan))
 666                         return POLLERR;
 667                 if (channel->ops->is_finalized(channel->chan))
 668                         return POLLHUP;
 669                 if (channel->ops->buffer_has_read_closed_stream(channel->chan))
 670                         return POLLIN | POLLRDNORM;
 671                 return 0;
 672         }
 673         return mask;
 674
 675 }
 676
 677 static
 678 int lttng_channel_release(struct inode *inode, struct file *file)
 679 {
 680         struct lttng_channel *channel = file->private_data;
 681
 682         if (channel)
 683                 fput(channel->session->file);
 684         return 0;
 685 }
 686
 687 static const struct file_operations lttng_channel_fops = {
 688         .owner = THIS_MODULE,
 689         .release = lttng_channel_release,
 690         .poll = lttng_channel_poll,
 691         .unlocked_ioctl = lttng_channel_ioctl,
 692 #ifdef CONFIG_COMPAT
 693         .compat_ioctl = lttng_channel_ioctl,
 694 #endif
 695 };
 696
 697 static const struct file_operations lttng_metadata_fops = {
 698         .owner = THIS_MODULE,
 699         .release = lttng_channel_release,
 700         .unlocked_ioctl = lttng_metadata_ioctl,
 701 #ifdef CONFIG_COMPAT
 702         .compat_ioctl = lttng_metadata_ioctl,
 703 #endif
 704 };
 705
 706 /**
 707  *      lttng_event_ioctl - lttng syscall through ioctl
 708  *
 709  *      @file: the file
 710  *      @cmd: the command
 711  *      @arg: command arg
 712  *
 713  *      This ioctl implements lttng commands:
 714  *      LTTNG_KERNEL_CONTEXT
 715  *              Prepend a context field to each record of this event
 716  *      LTTNG_KERNEL_ENABLE
 717  *              Enable recording for this event (weak enable)
 718  *      LTTNG_KERNEL_DISABLE
 719  *              Disable recording for this event (strong disable)
 720  */
 721 static
 722 long lttng_event_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 723 {
 724         struct lttng_event *event = file->private_data;
 725
 726         switch (cmd) {
 727         case LTTNG_KERNEL_CONTEXT:
 728                 return lttng_abi_add_context(file,
 729                                 (struct lttng_kernel_context __user *) arg,
 730                                 &event->ctx, event->chan->session);
 731         case LTTNG_KERNEL_ENABLE:
 732                 return lttng_event_enable(event);
 733         case LTTNG_KERNEL_DISABLE:
 734                 return lttng_event_disable(event);
 735         default:
 736                 return -ENOIOCTLCMD;
 737         }
 738 }
 739
 740 static
 741 int lttng_event_release(struct inode *inode, struct file *file)
 742 {
 743         struct lttng_event *event = file->private_data;
 744
 745         if (event)
 746                 fput(event->chan->file);
 747         return 0;
 748 }
 749
 750 /* TODO: filter control ioctl */
 751 static const struct file_operations lttng_event_fops = {
 752         .owner = THIS_MODULE,
 753         .release = lttng_event_release,
 754         .unlocked_ioctl = lttng_event_ioctl,
 755 #ifdef CONFIG_COMPAT
 756         .compat_ioctl = lttng_event_ioctl,
 757 #endif
 758 };
 759
 760 int __init lttng_abi_init(void)
 761 {
 762         int ret = 0;
 763
 764         wrapper_vmalloc_sync_all();
 765         lttng_proc_dentry = proc_create_data("lttng", S_IRUSR | S_IWUSR, NULL,
 766                                         &lttng_fops, NULL);
 767
 768         if (!lttng_proc_dentry) {
 769                 printk(KERN_ERR "Error creating LTTng control file\n");
 770                 ret = -ENOMEM;
 771                 goto error;
 772         }
 773 error:
 774         return ret;
 775 }
 776
 777 void __exit lttng_abi_exit(void)
 778 {
 779         if (lttng_proc_dentry)
 780                 remove_proc_entry("lttng", NULL);
 781 }