lttng-abi.c

   1 /*
   2  * lttng-abi.c
   3  *
   4  * Copyright 2010-2011 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * LTTng ABI
   7  *
   8  * Mimic system calls for:
   9  * - session creation, returns a file descriptor or failure.
  10  *   - channel creation, returns a file descriptor or failure.
  11  *     - Operates on a session file descriptor
  12  *     - Takes all channel options as parameters.
  13  *   - stream get, returns a file descriptor or failure.
  14  *     - Operates on a channel file descriptor.
  15  *   - stream notifier get, returns a file descriptor or failure.
  16  *     - Operates on a channel file descriptor.
  17  *   - event creation, returns a file descriptor or failure.
  18  *     - Operates on a channel file descriptor
  19  *     - Takes an event name as parameter
  20  *     - Takes an instrumentation source as parameter
  21  *       - e.g. tracepoints, dynamic_probes...
  22  *     - Takes instrumentation source specific arguments.
  23  *
  24  * Dual LGPL v2.1/GPL v2 license.
  25  */
  26
  27 #include <linux/module.h>
  28 #include <linux/proc_fs.h>
  29 #include <linux/anon_inodes.h>
  30 #include <linux/file.h>
  31 #include <linux/uaccess.h>
  32 #include <linux/slab.h>
  33 #include "wrapper/vmalloc.h"    /* for wrapper_vmalloc_sync_all() */
  34 #include "wrapper/ringbuffer/vfs.h"
  35 #include "wrapper/poll.h"
  36 #include "lttng-abi.h"
  37 #include "lttng-events.h"
  38 #include "lttng-tracer.h"
  39
  40 /*
  41  * This is LTTng's own personal way to create a system call as an external
  42  * module. We use ioctl() on /proc/lttng.
  43  */
  44
  45 static struct proc_dir_entry *lttng_proc_dentry;
  46 static const struct file_operations lttng_fops;
  47 static const struct file_operations lttng_session_fops;
  48 static const struct file_operations lttng_channel_fops;
  49 static const struct file_operations lttng_metadata_fops;
  50 static const struct file_operations lttng_event_fops;
  51
  52 /*
  53  * Teardown management: opened file descriptors keep a refcount on the module,
  54  * so it can only exit when all file descriptors are closed.
  55  */
  56
  57 enum channel_type {
  58         PER_CPU_CHANNEL,
  59         METADATA_CHANNEL,
  60 };
  61
  62 static
  63 int lttng_abi_create_session(void)
  64 {
  65         struct lttng_session *session;
  66         struct file *session_file;
  67         int session_fd, ret;
  68
  69         session = lttng_session_create();
  70         if (!session)
  71                 return -ENOMEM;
  72         session_fd = get_unused_fd();
  73         if (session_fd < 0) {
  74                 ret = session_fd;
  75                 goto fd_error;
  76         }
  77         session_file = anon_inode_getfile("[lttng_session]",
  78                                           &lttng_session_fops,
  79                                           session, O_RDWR);
  80         if (IS_ERR(session_file)) {
  81                 ret = PTR_ERR(session_file);
  82                 goto file_error;
  83         }
  84         session->file = session_file;
  85         fd_install(session_fd, session_file);
  86         return session_fd;
  87
  88 file_error:
  89         put_unused_fd(session_fd);
  90 fd_error:
  91         lttng_session_destroy(session);
  92         return ret;
  93 }
  94
  95 static
  96 int lttng_abi_tracepoint_list(void)
  97 {
  98         struct file *tracepoint_list_file;
  99         int file_fd, ret;
 100
 101         file_fd = get_unused_fd();
 102         if (file_fd < 0) {
 103                 ret = file_fd;
 104                 goto fd_error;
 105         }
 106
 107         tracepoint_list_file = anon_inode_getfile("[lttng_session]",
 108                                           &lttng_tracepoint_list_fops,
 109                                           NULL, O_RDWR);
 110         if (IS_ERR(tracepoint_list_file)) {
 111                 ret = PTR_ERR(tracepoint_list_file);
 112                 goto file_error;
 113         }
 114         ret = lttng_tracepoint_list_fops.open(NULL, tracepoint_list_file);
 115         if (ret < 0)
 116                 goto open_error;
 117         fd_install(file_fd, tracepoint_list_file);
 118         if (file_fd < 0) {
 119                 ret = file_fd;
 120                 goto fd_error;
 121         }
 122         return file_fd;
 123
 124 open_error:
 125         fput(tracepoint_list_file);
 126 file_error:
 127         put_unused_fd(file_fd);
 128 fd_error:
 129         return ret;
 130 }
 131
 132 static
 133 long lttng_abi_tracer_version(struct file *file,
 134         struct lttng_kernel_tracer_version __user *uversion_param)
 135 {
 136         struct lttng_kernel_tracer_version v;
 137
 138         v.version = LTTNG_VERSION;
 139         v.patchlevel = LTTNG_PATCHLEVEL;
 140         v.sublevel = LTTNG_SUBLEVEL;
 141
 142         if (copy_to_user(uversion_param, &v, sizeof(v)))
 143                 return -EFAULT;
 144         return 0;
 145 }
 146
 147 static
 148 long lttng_abi_add_context(struct file *file,
 149         struct lttng_kernel_context __user *ucontext_param,
 150         struct lttng_ctx **ctx, struct lttng_session *session)
 151 {
 152         struct lttng_kernel_context context_param;
 153
 154         if (session->been_active)
 155                 return -EPERM;
 156
 157         if (copy_from_user(&context_param, ucontext_param, sizeof(context_param)))
 158                 return -EFAULT;
 159
 160         switch (context_param.ctx) {
 161         case LTTNG_KERNEL_CONTEXT_PID:
 162                 return lttng_add_pid_to_ctx(ctx);
 163         case LTTNG_KERNEL_CONTEXT_PRIO:
 164                 return lttng_add_prio_to_ctx(ctx);
 165         case LTTNG_KERNEL_CONTEXT_NICE:
 166                 return lttng_add_nice_to_ctx(ctx);
 167         case LTTNG_KERNEL_CONTEXT_VPID:
 168                 return lttng_add_vpid_to_ctx(ctx);
 169         case LTTNG_KERNEL_CONTEXT_TID:
 170                 return lttng_add_tid_to_ctx(ctx);
 171         case LTTNG_KERNEL_CONTEXT_VTID:
 172                 return lttng_add_vtid_to_ctx(ctx);
 173         case LTTNG_KERNEL_CONTEXT_PPID:
 174                 return lttng_add_ppid_to_ctx(ctx);
 175         case LTTNG_KERNEL_CONTEXT_VPPID:
 176                 return lttng_add_vppid_to_ctx(ctx);
 177         case LTTNG_KERNEL_CONTEXT_PERF_COUNTER:
 178                 context_param.u.perf_counter.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 179                 return lttng_add_perf_counter_to_ctx(context_param.u.perf_counter.type,
 180                                 context_param.u.perf_counter.config,
 181                                 context_param.u.perf_counter.name,
 182                                 ctx);
 183         case LTTNG_KERNEL_CONTEXT_PROCNAME:
 184                 return lttng_add_procname_to_ctx(ctx);
 185         default:
 186                 return -EINVAL;
 187         }
 188 }
 189
 190 /**
 191  *      lttng_ioctl - lttng syscall through ioctl
 192  *
 193  *      @file: the file
 194  *      @cmd: the command
 195  *      @arg: command arg
 196  *
 197  *      This ioctl implements lttng commands:
 198  *      LTTNG_KERNEL_SESSION
 199  *              Returns a LTTng trace session file descriptor
 200  *      LTTNG_KERNEL_TRACER_VERSION
 201  *              Returns the LTTng kernel tracer version
 202  *      LTTNG_KERNEL_TRACEPOINT_LIST
 203  *              Returns a file descriptor listing available tracepoints
 204  *      LTTNG_KERNEL_WAIT_QUIESCENT
 205  *              Returns after all previously running probes have completed
 206  *
 207  * The returned session will be deleted when its file descriptor is closed.
 208  */
 209 static
 210 long lttng_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 211 {
 212         switch (cmd) {
 213         case LTTNG_KERNEL_SESSION:
 214                 return lttng_abi_create_session();
 215         case LTTNG_KERNEL_TRACER_VERSION:
 216                 return lttng_abi_tracer_version(file,
 217                                 (struct lttng_kernel_tracer_version __user *) arg);
 218         case LTTNG_KERNEL_TRACEPOINT_LIST:
 219                 return lttng_abi_tracepoint_list();
 220         case LTTNG_KERNEL_WAIT_QUIESCENT:
 221                 synchronize_trace();
 222                 return 0;
 223         case LTTNG_KERNEL_CALIBRATE:
 224         {
 225                 struct lttng_kernel_calibrate __user *ucalibrate =
 226                         (struct lttng_kernel_calibrate __user *) arg;
 227                 struct lttng_kernel_calibrate calibrate;
 228                 int ret;
 229
 230                 if (copy_from_user(&calibrate, ucalibrate, sizeof(calibrate)))
 231                         return -EFAULT;
 232                 ret = lttng_calibrate(&calibrate);
 233                 if (copy_to_user(ucalibrate, &calibrate, sizeof(calibrate)))
 234                         return -EFAULT;
 235                 return ret;
 236         }
 237         default:
 238                 return -ENOIOCTLCMD;
 239         }
 240 }
 241
 242 static const struct file_operations lttng_fops = {
 243         .owner = THIS_MODULE,
 244         .unlocked_ioctl = lttng_ioctl,
 245 #ifdef CONFIG_COMPAT
 246         .compat_ioctl = lttng_ioctl,
 247 #endif
 248 };
 249
 250 /*
 251  * We tolerate no failure in this function (if one happens, we print a dmesg
 252  * error, but cannot return any error, because the channel information is
 253  * invariant.
 254  */
 255 static
 256 void lttng_metadata_create_events(struct file *channel_file)
 257 {
 258         struct lttng_channel *channel = channel_file->private_data;
 259         static struct lttng_kernel_event metadata_params = {
 260                 .instrumentation = LTTNG_KERNEL_TRACEPOINT,
 261                 .name = "lttng_metadata",
 262         };
 263         struct lttng_event *event;
 264
 265         /*
 266          * We tolerate no failure path after event creation. It will stay
 267          * invariant for the rest of the session.
 268          */
 269         event = lttng_event_create(channel, &metadata_params, NULL, NULL);
 270         if (!event) {
 271                 goto create_error;
 272         }
 273         return;
 274
 275 create_error:
 276         WARN_ON(1);
 277         return;         /* not allowed to return error */
 278 }
 279
 280 static
 281 int lttng_abi_create_channel(struct file *session_file,
 282                              struct lttng_kernel_channel __user *uchan_param,
 283                              enum channel_type channel_type)
 284 {
 285         struct lttng_session *session = session_file->private_data;
 286         const struct file_operations *fops = NULL;
 287         const char *transport_name;
 288         struct lttng_channel *chan;
 289         struct file *chan_file;
 290         struct lttng_kernel_channel chan_param;
 291         int chan_fd;
 292         int ret = 0;
 293
 294         if (copy_from_user(&chan_param, uchan_param, sizeof(chan_param)))
 295                 return -EFAULT;
 296         chan_fd = get_unused_fd();
 297         if (chan_fd < 0) {
 298                 ret = chan_fd;
 299                 goto fd_error;
 300         }
 301         switch (channel_type) {
 302         case PER_CPU_CHANNEL:
 303                 fops = &lttng_channel_fops;
 304                 break;
 305         case METADATA_CHANNEL:
 306                 fops = &lttng_metadata_fops;
 307                 break;
 308         }
 309
 310         chan_file = anon_inode_getfile("[lttng_channel]",
 311                                        fops,
 312                                        NULL, O_RDWR);
 313         if (IS_ERR(chan_file)) {
 314                 ret = PTR_ERR(chan_file);
 315                 goto file_error;
 316         }
 317         switch (channel_type) {
 318         case PER_CPU_CHANNEL:
 319                 if (chan_param.output == LTTNG_KERNEL_SPLICE) {
 320                         transport_name = chan_param.overwrite ?
 321                                 "relay-overwrite" : "relay-discard";
 322                 } else if (chan_param.output == LTTNG_KERNEL_MMAP) {
 323                         transport_name = chan_param.overwrite ?
 324                                 "relay-overwrite-mmap" : "relay-discard-mmap";
 325                 } else {
 326                         return -EINVAL;
 327                 }
 328                 break;
 329         case METADATA_CHANNEL:
 330                 if (chan_param.output == LTTNG_KERNEL_SPLICE)
 331                         transport_name = "relay-metadata";
 332                 else if (chan_param.output == LTTNG_KERNEL_MMAP)
 333                         transport_name = "relay-metadata-mmap";
 334                 else
 335                         return -EINVAL;
 336                 break;
 337         default:
 338                 transport_name = "<unknown>";
 339                 break;
 340         }
 341         /*
 342          * We tolerate no failure path after channel creation. It will stay
 343          * invariant for the rest of the session.
 344          */
 345         chan = lttng_channel_create(session, transport_name, NULL,
 346                                   chan_param.subbuf_size,
 347                                   chan_param.num_subbuf,
 348                                   chan_param.switch_timer_interval,
 349                                   chan_param.read_timer_interval);
 350         if (!chan) {
 351                 ret = -EINVAL;
 352                 goto chan_error;
 353         }
 354         chan->file = chan_file;
 355         chan_file->private_data = chan;
 356         fd_install(chan_fd, chan_file);
 357         if (channel_type == METADATA_CHANNEL) {
 358                 session->metadata = chan;
 359                 lttng_metadata_create_events(chan_file);
 360         }
 361
 362         /* The channel created holds a reference on the session */
 363         atomic_long_inc(&session_file->f_count);
 364
 365         return chan_fd;
 366
 367 chan_error:
 368         fput(chan_file);
 369 file_error:
 370         put_unused_fd(chan_fd);
 371 fd_error:
 372         return ret;
 373 }
 374
 375 /**
 376  *      lttng_session_ioctl - lttng session fd ioctl
 377  *
 378  *      @file: the file
 379  *      @cmd: the command
 380  *      @arg: command arg
 381  *
 382  *      This ioctl implements lttng commands:
 383  *      LTTNG_KERNEL_CHANNEL
 384  *              Returns a LTTng channel file descriptor
 385  *      LTTNG_KERNEL_ENABLE
 386  *              Enables tracing for a session (weak enable)
 387  *      LTTNG_KERNEL_DISABLE
 388  *              Disables tracing for a session (strong disable)
 389  *      LTTNG_KERNEL_METADATA
 390  *              Returns a LTTng metadata file descriptor
 391  *
 392  * The returned channel will be deleted when its file descriptor is closed.
 393  */
 394 static
 395 long lttng_session_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 396 {
 397         struct lttng_session *session = file->private_data;
 398
 399         switch (cmd) {
 400         case LTTNG_KERNEL_CHANNEL:
 401                 return lttng_abi_create_channel(file,
 402                                 (struct lttng_kernel_channel __user *) arg,
 403                                 PER_CPU_CHANNEL);
 404         case LTTNG_KERNEL_SESSION_START:
 405         case LTTNG_KERNEL_ENABLE:
 406                 return lttng_session_enable(session);
 407         case LTTNG_KERNEL_SESSION_STOP:
 408         case LTTNG_KERNEL_DISABLE:
 409                 return lttng_session_disable(session);
 410         case LTTNG_KERNEL_METADATA:
 411                 return lttng_abi_create_channel(file,
 412                                 (struct lttng_kernel_channel __user *) arg,
 413                                 METADATA_CHANNEL);
 414         default:
 415                 return -ENOIOCTLCMD;
 416         }
 417 }
 418
 419 /*
 420  * Called when the last file reference is dropped.
 421  *
 422  * Big fat note: channels and events are invariant for the whole session after
 423  * their creation. So this session destruction also destroys all channel and
 424  * event structures specific to this session (they are not destroyed when their
 425  * individual file is released).
 426  */
 427 static
 428 int lttng_session_release(struct inode *inode, struct file *file)
 429 {
 430         struct lttng_session *session = file->private_data;
 431
 432         if (session)
 433                 lttng_session_destroy(session);
 434         return 0;
 435 }
 436
 437 static const struct file_operations lttng_session_fops = {
 438         .owner = THIS_MODULE,
 439         .release = lttng_session_release,
 440         .unlocked_ioctl = lttng_session_ioctl,
 441 #ifdef CONFIG_COMPAT
 442         .compat_ioctl = lttng_session_ioctl,
 443 #endif
 444 };
 445
 446 static
 447 int lttng_abi_open_stream(struct file *channel_file)
 448 {
 449         struct lttng_channel *channel = channel_file->private_data;
 450         struct lib_ring_buffer *buf;
 451         int stream_fd, ret;
 452         struct file *stream_file;
 453
 454         buf = channel->ops->buffer_read_open(channel->chan);
 455         if (!buf)
 456                 return -ENOENT;
 457
 458         stream_fd = get_unused_fd();
 459         if (stream_fd < 0) {
 460                 ret = stream_fd;
 461                 goto fd_error;
 462         }
 463         stream_file = anon_inode_getfile("[lttng_stream]",
 464                                          &lib_ring_buffer_file_operations,
 465                                          buf, O_RDWR);
 466         if (IS_ERR(stream_file)) {
 467                 ret = PTR_ERR(stream_file);
 468                 goto file_error;
 469         }
 470         /*
 471          * OPEN_FMODE, called within anon_inode_getfile/alloc_file, don't honor
 472          * FMODE_LSEEK, FMODE_PREAD nor FMODE_PWRITE. We need to read from this
 473          * file descriptor, so we set FMODE_PREAD here.
 474          */
 475         stream_file->f_mode |= FMODE_PREAD;
 476         fd_install(stream_fd, stream_file);
 477         /*
 478          * The stream holds a reference to the channel within the generic ring
 479          * buffer library, so no need to hold a refcount on the channel and
 480          * session files here.
 481          */
 482         return stream_fd;
 483
 484 file_error:
 485         put_unused_fd(stream_fd);
 486 fd_error:
 487         channel->ops->buffer_read_close(buf);
 488         return ret;
 489 }
 490
 491 static
 492 int lttng_abi_create_event(struct file *channel_file,
 493                            struct lttng_kernel_event __user *uevent_param)
 494 {
 495         struct lttng_channel *channel = channel_file->private_data;
 496         struct lttng_event *event;
 497         struct lttng_kernel_event event_param;
 498         int event_fd, ret;
 499         struct file *event_file;
 500
 501         if (copy_from_user(&event_param, uevent_param, sizeof(event_param)))
 502                 return -EFAULT;
 503         event_param.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 504         switch (event_param.instrumentation) {
 505         case LTTNG_KERNEL_KRETPROBE:
 506                 event_param.u.kretprobe.symbol_name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 507                 break;
 508         case LTTNG_KERNEL_KPROBE:
 509                 event_param.u.kprobe.symbol_name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 510                 break;
 511         case LTTNG_KERNEL_FUNCTION:
 512                 event_param.u.ftrace.symbol_name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 513                 break;
 514         default:
 515                 break;
 516         }
 517         switch (event_param.instrumentation) {
 518         default:
 519                 event_fd = get_unused_fd();
 520                 if (event_fd < 0) {
 521                         ret = event_fd;
 522                         goto fd_error;
 523                 }
 524                 event_file = anon_inode_getfile("[lttng_event]",
 525                                                 &lttng_event_fops,
 526                                                 NULL, O_RDWR);
 527                 if (IS_ERR(event_file)) {
 528                         ret = PTR_ERR(event_file);
 529                         goto file_error;
 530                 }
 531                 /*
 532                  * We tolerate no failure path after event creation. It
 533                  * will stay invariant for the rest of the session.
 534                  */
 535                 event = lttng_event_create(channel, &event_param, NULL, NULL);
 536                 if (!event) {
 537                         ret = -EINVAL;
 538                         goto event_error;
 539                 }
 540                 event_file->private_data = event;
 541                 fd_install(event_fd, event_file);
 542                 /* The event holds a reference on the channel */
 543                 atomic_long_inc(&channel_file->f_count);
 544                 break;
 545         case LTTNG_KERNEL_SYSCALL:
 546                 /*
 547                  * Only all-syscall tracing supported for now.
 548                  */
 549                 if (event_param.name[0] != '\0')
 550                         return -EINVAL;
 551                 ret = lttng_syscalls_register(channel, NULL);
 552                 if (ret)
 553                         goto fd_error;
 554                 event_fd = 0;
 555                 break;
 556         }
 557         return event_fd;
 558
 559 event_error:
 560         fput(event_file);
 561 file_error:
 562         put_unused_fd(event_fd);
 563 fd_error:
 564         return ret;
 565 }
 566
 567 /**
 568  *      lttng_channel_ioctl - lttng syscall through ioctl
 569  *
 570  *      @file: the file
 571  *      @cmd: the command
 572  *      @arg: command arg
 573  *
 574  *      This ioctl implements lttng commands:
 575  *      LTTNG_KERNEL_STREAM
 576  *              Returns an event stream file descriptor or failure.
 577  *              (typically, one event stream records events from one CPU)
 578  *      LTTNG_KERNEL_EVENT
 579  *              Returns an event file descriptor or failure.
 580  *      LTTNG_KERNEL_CONTEXT
 581  *              Prepend a context field to each event in the channel
 582  *      LTTNG_KERNEL_ENABLE
 583  *              Enable recording for events in this channel (weak enable)
 584  *      LTTNG_KERNEL_DISABLE
 585  *              Disable recording for events in this channel (strong disable)
 586  *
 587  * Channel and event file descriptors also hold a reference on the session.
 588  */
 589 static
 590 long lttng_channel_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 591 {
 592         struct lttng_channel *channel = file->private_data;
 593
 594         switch (cmd) {
 595         case LTTNG_KERNEL_STREAM:
 596                 return lttng_abi_open_stream(file);
 597         case LTTNG_KERNEL_EVENT:
 598                 return lttng_abi_create_event(file, (struct lttng_kernel_event __user *) arg);
 599         case LTTNG_KERNEL_CONTEXT:
 600                 return lttng_abi_add_context(file,
 601                                 (struct lttng_kernel_context __user *) arg,
 602                                 &channel->ctx, channel->session);
 603         case LTTNG_KERNEL_ENABLE:
 604                 return lttng_channel_enable(channel);
 605         case LTTNG_KERNEL_DISABLE:
 606                 return lttng_channel_disable(channel);
 607         default:
 608                 return -ENOIOCTLCMD;
 609         }
 610 }
 611
 612 /**
 613  *      lttng_metadata_ioctl - lttng syscall through ioctl
 614  *
 615  *      @file: the file
 616  *      @cmd: the command
 617  *      @arg: command arg
 618  *
 619  *      This ioctl implements lttng commands:
 620  *      LTTNG_KERNEL_STREAM
 621  *              Returns an event stream file descriptor or failure.
 622  *
 623  * Channel and event file descriptors also hold a reference on the session.
 624  */
 625 static
 626 long lttng_metadata_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 627 {
 628         switch (cmd) {
 629         case LTTNG_KERNEL_STREAM:
 630                 return lttng_abi_open_stream(file);
 631         default:
 632                 return -ENOIOCTLCMD;
 633         }
 634 }
 635
 636 /**
 637  *      lttng_channel_poll - lttng stream addition/removal monitoring
 638  *
 639  *      @file: the file
 640  *      @wait: poll table
 641  */
 642 unsigned int lttng_channel_poll(struct file *file, poll_table *wait)
 643 {
 644         struct lttng_channel *channel = file->private_data;
 645         unsigned int mask = 0;
 646
 647         if (file->f_mode & FMODE_READ) {
 648                 poll_wait_set_exclusive(wait);
 649                 poll_wait(file, channel->ops->get_hp_wait_queue(channel->chan),
 650                           wait);
 651
 652                 if (channel->ops->is_disabled(channel->chan))
 653                         return POLLERR;
 654                 if (channel->ops->is_finalized(channel->chan))
 655                         return POLLHUP;
 656                 if (channel->ops->buffer_has_read_closed_stream(channel->chan))
 657                         return POLLIN | POLLRDNORM;
 658                 return 0;
 659         }
 660         return mask;
 661
 662 }
 663
 664 static
 665 int lttng_channel_release(struct inode *inode, struct file *file)
 666 {
 667         struct lttng_channel *channel = file->private_data;
 668
 669         if (channel)
 670                 fput(channel->session->file);
 671         return 0;
 672 }
 673
 674 static const struct file_operations lttng_channel_fops = {
 675         .owner = THIS_MODULE,
 676         .release = lttng_channel_release,
 677         .poll = lttng_channel_poll,
 678         .unlocked_ioctl = lttng_channel_ioctl,
 679 #ifdef CONFIG_COMPAT
 680         .compat_ioctl = lttng_channel_ioctl,
 681 #endif
 682 };
 683
 684 static const struct file_operations lttng_metadata_fops = {
 685         .owner = THIS_MODULE,
 686         .release = lttng_channel_release,
 687         .unlocked_ioctl = lttng_metadata_ioctl,
 688 #ifdef CONFIG_COMPAT
 689         .compat_ioctl = lttng_metadata_ioctl,
 690 #endif
 691 };
 692
 693 /**
 694  *      lttng_event_ioctl - lttng syscall through ioctl
 695  *
 696  *      @file: the file
 697  *      @cmd: the command
 698  *      @arg: command arg
 699  *
 700  *      This ioctl implements lttng commands:
 701  *      LTTNG_KERNEL_CONTEXT
 702  *              Prepend a context field to each record of this event
 703  *      LTTNG_KERNEL_ENABLE
 704  *              Enable recording for this event (weak enable)
 705  *      LTTNG_KERNEL_DISABLE
 706  *              Disable recording for this event (strong disable)
 707  */
 708 static
 709 long lttng_event_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 710 {
 711         struct lttng_event *event = file->private_data;
 712
 713         switch (cmd) {
 714         case LTTNG_KERNEL_CONTEXT:
 715                 return lttng_abi_add_context(file,
 716                                 (struct lttng_kernel_context __user *) arg,
 717                                 &event->ctx, event->chan->session);
 718         case LTTNG_KERNEL_ENABLE:
 719                 return lttng_event_enable(event);
 720         case LTTNG_KERNEL_DISABLE:
 721                 return lttng_event_disable(event);
 722         default:
 723                 return -ENOIOCTLCMD;
 724         }
 725 }
 726
 727 static
 728 int lttng_event_release(struct inode *inode, struct file *file)
 729 {
 730         struct lttng_event *event = file->private_data;
 731
 732         if (event)
 733                 fput(event->chan->file);
 734         return 0;
 735 }
 736
 737 /* TODO: filter control ioctl */
 738 static const struct file_operations lttng_event_fops = {
 739         .owner = THIS_MODULE,
 740         .release = lttng_event_release,
 741         .unlocked_ioctl = lttng_event_ioctl,
 742 #ifdef CONFIG_COMPAT
 743         .compat_ioctl = lttng_event_ioctl,
 744 #endif
 745 };
 746
 747 int __init lttng_abi_init(void)
 748 {
 749         int ret = 0;
 750
 751         wrapper_vmalloc_sync_all();
 752         lttng_proc_dentry = proc_create_data("lttng", S_IWUSR, NULL,
 753                                         &lttng_fops, NULL);
 754
 755         if (!lttng_proc_dentry) {
 756                 printk(KERN_ERR "Error creating LTTng control file\n");
 757                 ret = -ENOMEM;
 758                 goto error;
 759         }
 760 error:
 761         return ret;
 762 }
 763
 764 void __exit lttng_abi_exit(void)
 765 {
 766         if (lttng_proc_dentry)
 767                 remove_proc_entry("lttng", NULL);
 768 }