ltt-debugfs-abi.c

   1 /*
   2  * ltt-debugfs-abi.c
   3  *
   4  * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * LTTng debugfs 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/debugfs.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 "ltt-debugfs-abi.h"
  37 #include "ltt-events.h"
  38 #include "ltt-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 /sys/kernel/debug/lttng.
  43  */
  44
  45 static struct dentry *lttng_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 ltt_session *session;
  66         struct file *session_file;
  67         int session_fd, ret;
  68
  69         session = ltt_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         ltt_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 ltt_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_COMM:
 184                 return lttng_add_comm_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 ltt_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 ltt_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 = ltt_event_create(channel, &metadata_params, 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 ltt_session *session = session_file->private_data;
 286         const struct file_operations *fops = NULL;
 287         const char *transport_name;
 288         struct ltt_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 = ltt_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 ltt_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 ltt_session_enable(session);
 407         case LTTNG_KERNEL_SESSION_STOP:
 408         case LTTNG_KERNEL_DISABLE:
 409                 return ltt_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 ltt_session *session = file->private_data;
 431
 432         if (session)
 433                 ltt_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 ltt_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 ltt_channel *channel = channel_file->private_data;
 496         struct ltt_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         event_fd = get_unused_fd();
 518         if (event_fd < 0) {
 519                 ret = event_fd;
 520                 goto fd_error;
 521         }
 522         event_file = anon_inode_getfile("[lttng_event]",
 523                                         &lttng_event_fops,
 524                                         NULL, O_RDWR);
 525         if (IS_ERR(event_file)) {
 526                 ret = PTR_ERR(event_file);
 527                 goto file_error;
 528         }
 529         /*
 530          * We tolerate no failure path after event creation. It will stay
 531          * invariant for the rest of the session.
 532          */
 533         event = ltt_event_create(channel, &event_param, NULL);
 534         if (!event) {
 535                 ret = -EINVAL;
 536                 goto event_error;
 537         }
 538         event_file->private_data = event;
 539         fd_install(event_fd, event_file);
 540         /* The event holds a reference on the channel */
 541         atomic_long_inc(&channel_file->f_count);
 542         return event_fd;
 543
 544 event_error:
 545         fput(event_file);
 546 file_error:
 547         put_unused_fd(event_fd);
 548 fd_error:
 549         return ret;
 550 }
 551
 552 /**
 553  *      lttng_channel_ioctl - lttng syscall through ioctl
 554  *
 555  *      @file: the file
 556  *      @cmd: the command
 557  *      @arg: command arg
 558  *
 559  *      This ioctl implements lttng commands:
 560  *      LTTNG_KERNEL_STREAM
 561  *              Returns an event stream file descriptor or failure.
 562  *              (typically, one event stream records events from one CPU)
 563  *      LTTNG_KERNEL_EVENT
 564  *              Returns an event file descriptor or failure.
 565  *      LTTNG_KERNEL_CONTEXT
 566  *              Prepend a context field to each event in the channel
 567  *      LTTNG_KERNEL_ENABLE
 568  *              Enable recording for events in this channel (weak enable)
 569  *      LTTNG_KERNEL_DISABLE
 570  *              Disable recording for events in this channel (strong disable)
 571  *
 572  * Channel and event file descriptors also hold a reference on the session.
 573  */
 574 static
 575 long lttng_channel_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 576 {
 577         struct ltt_channel *channel = file->private_data;
 578
 579         switch (cmd) {
 580         case LTTNG_KERNEL_STREAM:
 581                 return lttng_abi_open_stream(file);
 582         case LTTNG_KERNEL_EVENT:
 583                 return lttng_abi_create_event(file, (struct lttng_kernel_event __user *) arg);
 584         case LTTNG_KERNEL_CONTEXT:
 585                 return lttng_abi_add_context(file,
 586                                 (struct lttng_kernel_context __user *) arg,
 587                                 &channel->ctx, channel->session);
 588         case LTTNG_KERNEL_ENABLE:
 589                 return ltt_channel_enable(channel);
 590         case LTTNG_KERNEL_DISABLE:
 591                 return ltt_channel_disable(channel);
 592         default:
 593                 return -ENOIOCTLCMD;
 594         }
 595 }
 596
 597 /**
 598  *      lttng_metadata_ioctl - lttng syscall through ioctl
 599  *
 600  *      @file: the file
 601  *      @cmd: the command
 602  *      @arg: command arg
 603  *
 604  *      This ioctl implements lttng commands:
 605  *      LTTNG_KERNEL_STREAM
 606  *              Returns an event stream file descriptor or failure.
 607  *
 608  * Channel and event file descriptors also hold a reference on the session.
 609  */
 610 static
 611 long lttng_metadata_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 612 {
 613         switch (cmd) {
 614         case LTTNG_KERNEL_STREAM:
 615                 return lttng_abi_open_stream(file);
 616         default:
 617                 return -ENOIOCTLCMD;
 618         }
 619 }
 620
 621 /**
 622  *      lttng_channel_poll - lttng stream addition/removal monitoring
 623  *
 624  *      @file: the file
 625  *      @wait: poll table
 626  */
 627 unsigned int lttng_channel_poll(struct file *file, poll_table *wait)
 628 {
 629         struct ltt_channel *channel = file->private_data;
 630         unsigned int mask = 0;
 631
 632         if (file->f_mode & FMODE_READ) {
 633                 poll_wait_set_exclusive(wait);
 634                 poll_wait(file, channel->ops->get_hp_wait_queue(channel->chan),
 635                           wait);
 636
 637                 if (channel->ops->is_disabled(channel->chan))
 638                         return POLLERR;
 639                 if (channel->ops->is_finalized(channel->chan))
 640                         return POLLHUP;
 641                 if (channel->ops->buffer_has_read_closed_stream(channel->chan))
 642                         return POLLIN | POLLRDNORM;
 643                 return 0;
 644         }
 645         return mask;
 646
 647 }
 648
 649 static
 650 int lttng_channel_release(struct inode *inode, struct file *file)
 651 {
 652         struct ltt_channel *channel = file->private_data;
 653
 654         if (channel)
 655                 fput(channel->session->file);
 656         return 0;
 657 }
 658
 659 static const struct file_operations lttng_channel_fops = {
 660         .owner = THIS_MODULE,
 661         .release = lttng_channel_release,
 662         .poll = lttng_channel_poll,
 663         .unlocked_ioctl = lttng_channel_ioctl,
 664 #ifdef CONFIG_COMPAT
 665         .compat_ioctl = lttng_channel_ioctl,
 666 #endif
 667 };
 668
 669 static const struct file_operations lttng_metadata_fops = {
 670         .owner = THIS_MODULE,
 671         .release = lttng_channel_release,
 672         .unlocked_ioctl = lttng_metadata_ioctl,
 673 #ifdef CONFIG_COMPAT
 674         .compat_ioctl = lttng_metadata_ioctl,
 675 #endif
 676 };
 677
 678 /**
 679  *      lttng_event_ioctl - lttng syscall through ioctl
 680  *
 681  *      @file: the file
 682  *      @cmd: the command
 683  *      @arg: command arg
 684  *
 685  *      This ioctl implements lttng commands:
 686  *      LTTNG_KERNEL_CONTEXT
 687  *              Prepend a context field to each record of this event
 688  *      LTTNG_KERNEL_ENABLE
 689  *              Enable recording for this event (weak enable)
 690  *      LTTNG_KERNEL_DISABLE
 691  *              Disable recording for this event (strong disable)
 692  */
 693 static
 694 long lttng_event_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 695 {
 696         struct ltt_event *event = file->private_data;
 697
 698         switch (cmd) {
 699         case LTTNG_KERNEL_CONTEXT:
 700                 return lttng_abi_add_context(file,
 701                                 (struct lttng_kernel_context __user *) arg,
 702                                 &event->ctx, event->chan->session);
 703         case LTTNG_KERNEL_ENABLE:
 704                 return ltt_event_enable(event);
 705         case LTTNG_KERNEL_DISABLE:
 706                 return ltt_event_disable(event);
 707         default:
 708                 return -ENOIOCTLCMD;
 709         }
 710 }
 711
 712 static
 713 int lttng_event_release(struct inode *inode, struct file *file)
 714 {
 715         struct ltt_event *event = file->private_data;
 716
 717         if (event)
 718                 fput(event->chan->file);
 719         return 0;
 720 }
 721
 722 /* TODO: filter control ioctl */
 723 static const struct file_operations lttng_event_fops = {
 724         .owner = THIS_MODULE,
 725         .release = lttng_event_release,
 726         .unlocked_ioctl = lttng_event_ioctl,
 727 #ifdef CONFIG_COMPAT
 728         .compat_ioctl = lttng_event_ioctl,
 729 #endif
 730 };
 731
 732 int __init ltt_debugfs_abi_init(void)
 733 {
 734         int ret = 0;
 735
 736         wrapper_vmalloc_sync_all();
 737         lttng_dentry = debugfs_create_file("lttng", S_IWUSR, NULL, NULL,
 738                                            &lttng_fops);
 739         if (IS_ERR(lttng_dentry) || !lttng_dentry) {
 740                 printk(KERN_ERR "Error creating LTTng control file\n");
 741                 ret = -ENOMEM;
 742                 goto error;
 743         }
 744 error:
 745         return ret;
 746 }
 747
 748 void __exit ltt_debugfs_abi_exit(void)
 749 {
 750         debugfs_remove(lttng_dentry);
 751 }