libust/tracer.c

   1 /*
   2  * tracer.c
   3  *
   4  * (C) Copyright        2005-2008 -
   5  *              Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca)
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with this library; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  20  *
  21  * Inspired from LTT :
  22  *  Karim Yaghmour (karim@opersys.com)
  23  *  Tom Zanussi (zanussi@us.ibm.com)
  24  *  Bob Wisniewski (bob@watson.ibm.com)
  25  * And from K42 :
  26  *  Bob Wisniewski (bob@watson.ibm.com)
  27  *
  28  * Changelog:
  29  *  22/09/06, Move to the marker/probes mechanism.
  30  *  19/10/05, Complete lockless mechanism.
  31  *  27/05/05, Modular redesign and rewrite.
  32  */
  33
  34 #include <urcu-bp.h>
  35 #include <urcu/rculist.h>
  36
  37 #include <ust/clock.h>
  38
  39 #include "tracercore.h"
  40 #include "tracer.h"
  41 #include "usterr.h"
  42
  43 //ust// static void async_wakeup(unsigned long data);
  44 //ust//
  45 //ust// static DEFINE_TIMER(ltt_async_wakeup_timer, async_wakeup, 0, 0);
  46
  47 /* Default callbacks for modules */
  48 notrace int ltt_filter_control_default(enum ltt_filter_control_msg msg,
  49                 struct ust_trace *trace)
  50 {
  51         return 0;
  52 }
  53
  54 int ltt_statedump_default(struct ust_trace *trace)
  55 {
  56         return 0;
  57 }
  58
  59 /* Callbacks for registered modules */
  60
  61 int (*ltt_filter_control_functor)
  62         (enum ltt_filter_control_msg msg, struct ust_trace *trace) =
  63                                         ltt_filter_control_default;
  64 struct module *ltt_filter_control_owner;
  65
  66 /* These function pointers are protected by a trace activation check */
  67 struct module *ltt_run_filter_owner;
  68 int (*ltt_statedump_functor)(struct ust_trace *trace) =
  69                                         ltt_statedump_default;
  70 struct module *ltt_statedump_owner;
  71
  72 struct chan_info_struct {
  73         const char *name;
  74         unsigned int def_subbufsize;
  75         unsigned int def_subbufcount;
  76 } chan_infos[] = {
  77         [LTT_CHANNEL_METADATA] = {
  78                 LTT_METADATA_CHANNEL,
  79                 LTT_DEFAULT_SUBBUF_SIZE_LOW,
  80                 LTT_DEFAULT_N_SUBBUFS_LOW,
  81         },
  82         [LTT_CHANNEL_UST] = {
  83                 LTT_UST_CHANNEL,
  84                 LTT_DEFAULT_SUBBUF_SIZE_HIGH,
  85                 LTT_DEFAULT_N_SUBBUFS_HIGH,
  86         },
  87 };
  88
  89 static enum ltt_channels get_channel_type_from_name(const char *name)
  90 {
  91         int i;
  92
  93         if (!name)
  94                 return LTT_CHANNEL_UST;
  95
  96         for (i = 0; i < ARRAY_SIZE(chan_infos); i++)
  97                 if (chan_infos[i].name && !strcmp(name, chan_infos[i].name))
  98                         return (enum ltt_channels)i;
  99
 100         return LTT_CHANNEL_UST;
 101 }
 102
 103 /**
 104  * ltt_module_register - LTT module registration
 105  * @name: module type
 106  * @function: callback to register
 107  * @owner: module which owns the callback
 108  *
 109  * The module calling this registration function must ensure that no
 110  * trap-inducing code will be executed by "function". E.g. vmalloc_sync_all()
 111  * must be called between a vmalloc and the moment the memory is made visible to
 112  * "function". This registration acts as a vmalloc_sync_all. Therefore, only if
 113  * the module allocates virtual memory after its registration must it
 114  * synchronize the TLBs.
 115  */
 116 //ust// int ltt_module_register(enum ltt_module_function name, void *function,
 117 //ust//                 struct module *owner)
 118 //ust// {
 119 //ust//         int ret = 0;
 120 //ust//
 121 //ust//         /*
 122 //ust//          * Make sure no page fault can be triggered by the module about to be
 123 //ust//          * registered. We deal with this here so we don't have to call
 124 //ust//          * vmalloc_sync_all() in each module's init.
 125 //ust//          */
 126 //ust//         vmalloc_sync_all();
 127 //ust//
 128 //ust//         switch (name) {
 129 //ust//         case LTT_FUNCTION_RUN_FILTER:
 130 //ust//                 if (ltt_run_filter_owner != NULL) {
 131 //ust//                         ret = -EEXIST;
 132 //ust//                         goto end;
 133 //ust//                 }
 134 //ust//                 ltt_filter_register((ltt_run_filter_functor)function);
 135 //ust//                 ltt_run_filter_owner = owner;
 136 //ust//                 break;
 137 //ust//         case LTT_FUNCTION_FILTER_CONTROL:
 138 //ust//                 if (ltt_filter_control_owner != NULL) {
 139 //ust//                         ret = -EEXIST;
 140 //ust//                         goto end;
 141 //ust//                 }
 142 //ust//                 ltt_filter_control_functor =
 143 //ust//                         (int (*)(enum ltt_filter_control_msg,
 144 //ust//                         struct ust_trace *))function;
 145 //ust//                 ltt_filter_control_owner = owner;
 146 //ust//                 break;
 147 //ust//         case LTT_FUNCTION_STATEDUMP:
 148 //ust//                 if (ltt_statedump_owner != NULL) {
 149 //ust//                         ret = -EEXIST;
 150 //ust//                         goto end;
 151 //ust//                 }
 152 //ust//                 ltt_statedump_functor =
 153 //ust//                         (int (*)(struct ust_trace *))function;
 154 //ust//                 ltt_statedump_owner = owner;
 155 //ust//                 break;
 156 //ust//         }
 157 //ust//
 158 //ust// end:
 159 //ust//
 160 //ust//         return ret;
 161 //ust// }
 162
 163 /**
 164  * ltt_module_unregister - LTT module unregistration
 165  * @name: module type
 166  */
 167 //ust// void ltt_module_unregister(enum ltt_module_function name)
 168 //ust// {
 169 //ust//         switch (name) {
 170 //ust//         case LTT_FUNCTION_RUN_FILTER:
 171 //ust//                 ltt_filter_unregister();
 172 //ust//                 ltt_run_filter_owner = NULL;
 173 //ust//                 /* Wait for preempt sections to finish */
 174 //ust//                 synchronize_sched();
 175 //ust//                 break;
 176 //ust//         case LTT_FUNCTION_FILTER_CONTROL:
 177 //ust//                 ltt_filter_control_functor = ltt_filter_control_default;
 178 //ust//                 ltt_filter_control_owner = NULL;
 179 //ust//                 break;
 180 //ust//         case LTT_FUNCTION_STATEDUMP:
 181 //ust//                 ltt_statedump_functor = ltt_statedump_default;
 182 //ust//                 ltt_statedump_owner = NULL;
 183 //ust//                 break;
 184 //ust//         }
 185 //ust//
 186 //ust// }
 187
 188 static LIST_HEAD(ltt_transport_list);
 189
 190 /**
 191  * ltt_transport_register - LTT transport registration
 192  * @transport: transport structure
 193  *
 194  * Registers a transport which can be used as output to extract the data out of
 195  * LTTng. The module calling this registration function must ensure that no
 196  * trap-inducing code will be executed by the transport functions. E.g.
 197  * vmalloc_sync_all() must be called between a vmalloc and the moment the memory
 198  * is made visible to the transport function. This registration acts as a
 199  * vmalloc_sync_all. Therefore, only if the module allocates virtual memory
 200  * after its registration must it synchronize the TLBs.
 201  */
 202 void ltt_transport_register(struct ltt_transport *transport)
 203 {
 204         /*
 205          * Make sure no page fault can be triggered by the module about to be
 206          * registered. We deal with this here so we don't have to call
 207          * vmalloc_sync_all() in each module's init.
 208          */
 209 //ust// vmalloc_sync_all();
 210
 211         ltt_lock_traces();
 212         list_add_tail(&transport->node, &ltt_transport_list);
 213         ltt_unlock_traces();
 214 }
 215
 216 /**
 217  * ltt_transport_unregister - LTT transport unregistration
 218  * @transport: transport structure
 219  */
 220 void ltt_transport_unregister(struct ltt_transport *transport)
 221 {
 222         ltt_lock_traces();
 223         list_del(&transport->node);
 224         ltt_unlock_traces();
 225 }
 226
 227 static inline int is_channel_overwrite(enum ltt_channels chan,
 228         enum trace_mode mode)
 229 {
 230         switch (mode) {
 231         case LTT_TRACE_NORMAL:
 232                 return 0;
 233         case LTT_TRACE_FLIGHT:
 234                 switch (chan) {
 235                 case LTT_CHANNEL_METADATA:
 236                         return 0;
 237                 default:
 238                         return 1;
 239                 }
 240         case LTT_TRACE_HYBRID:
 241                 switch (chan) {
 242                 case LTT_CHANNEL_METADATA:
 243                         return 0;
 244                 default:
 245                         return 1;
 246                 }
 247         default:
 248                 return 0;
 249         }
 250 }
 251
 252 static void trace_async_wakeup(struct ust_trace *trace)
 253 {
 254         int i;
 255         struct ust_channel *chan;
 256
 257         /* Must check each channel for pending read wakeup */
 258         for (i = 0; i < trace->nr_channels; i++) {
 259                 chan = &trace->channels[i];
 260                 if (chan->active)
 261                         trace->ops->wakeup_channel(chan);
 262         }
 263 }
 264
 265 //ust// /* Timer to send async wakeups to the readers */
 266 //ust// static void async_wakeup(unsigned long data)
 267 //ust// {
 268 //ust//         struct ust_trace *trace;
 269 //ust//
 270 //ust//         /*
 271 //ust//          * PREEMPT_RT does not allow spinlocks to be taken within preempt
 272 //ust//          * disable sections (spinlock taken in wake_up). However, mainline won't
 273 //ust//          * allow mutex to be taken in interrupt context. Ugly.
 274 //ust//          * A proper way to do this would be to turn the timer into a
 275 //ust//          * periodically woken up thread, but it adds to the footprint.
 276 //ust//          */
 277 //ust// #ifndef CONFIG_PREEMPT_RT
 278 //ust//         rcu_read_lock_sched();
 279 //ust// #else
 280 //ust//         ltt_lock_traces();
 281 //ust// #endif
 282 //ust//         list_for_each_entry_rcu(trace, &ltt_traces.head, list) {
 283 //ust//                 trace_async_wakeup(trace);
 284 //ust//         }
 285 //ust// #ifndef CONFIG_PREEMPT_RT
 286 //ust//         rcu_read_unlock_sched();
 287 //ust// #else
 288 //ust//         ltt_unlock_traces();
 289 //ust// #endif
 290 //ust//
 291 //ust//         mod_timer(&ltt_async_wakeup_timer, jiffies + LTT_PERCPU_TIMER_INTERVAL);
 292 //ust// }
 293
 294 /**
 295  * _ltt_trace_find - find a trace by given name.
 296  * trace_name: trace name
 297  *
 298  * Returns a pointer to the trace structure, NULL if not found.
 299  */
 300 struct ust_trace *_ltt_trace_find(const char *trace_name)
 301 {
 302         struct ust_trace *trace;
 303
 304         list_for_each_entry(trace, &ltt_traces.head, list)
 305                 if (!strncmp(trace->trace_name, trace_name, NAME_MAX))
 306                         return trace;
 307
 308         return NULL;
 309 }
 310
 311 /* _ltt_trace_find_setup :
 312  * find a trace in setup list by given name.
 313  *
 314  * Returns a pointer to the trace structure, NULL if not found.
 315  */
 316 struct ust_trace *_ltt_trace_find_setup(const char *trace_name)
 317 {
 318         struct ust_trace *trace;
 319
 320         list_for_each_entry(trace, &ltt_traces.setup_head, list)
 321                 if (!strncmp(trace->trace_name, trace_name, NAME_MAX))
 322                         return trace;
 323
 324         return NULL;
 325 }
 326
 327 /**
 328  * ltt_release_transport - Release an LTT transport
 329  * @kref : reference count on the transport
 330  */
 331 void ltt_release_transport(struct kref *kref)
 332 {
 333 //ust//         struct ust_trace *trace = container_of(kref,
 334 //ust//                         struct ust_trace, ltt_transport_kref);
 335 //ust//         trace->ops->remove_dirs(trace);
 336 }
 337
 338 /**
 339  * ltt_release_trace - Release a LTT trace
 340  * @kref : reference count on the trace
 341  */
 342 void ltt_release_trace(struct kref *kref)
 343 {
 344         struct ust_trace *trace = container_of(kref,
 345                         struct ust_trace, kref);
 346         ltt_channels_trace_free(trace->channels);
 347         free(trace);
 348 }
 349
 350 static inline void prepare_chan_size_num(unsigned int *subbuf_size,
 351                                          unsigned int *n_subbufs)
 352 {
 353         /* Make sure the subbuffer size is larger than a page */
 354         *subbuf_size = max_t(unsigned int, *subbuf_size, PAGE_SIZE);
 355
 356         /* round to next power of 2 */
 357         *subbuf_size = 1 << get_count_order(*subbuf_size);
 358         *n_subbufs = 1 << get_count_order(*n_subbufs);
 359
 360         /* Subbuf size and number must both be power of two */
 361         WARN_ON(hweight32(*subbuf_size) != 1);
 362         WARN_ON(hweight32(*n_subbufs) != 1);
 363 }
 364
 365 int _ltt_trace_setup(const char *trace_name)
 366 {
 367         int err = 0;
 368         struct ust_trace *new_trace = NULL;
 369         int metadata_index;
 370         unsigned int chan;
 371         enum ltt_channels chantype;
 372
 373         if (_ltt_trace_find_setup(trace_name)) {
 374                 ERR("Trace name %s already used", trace_name);
 375                 err = -EEXIST;
 376                 goto traces_error;
 377         }
 378
 379         if (_ltt_trace_find(trace_name)) {
 380                 ERR("Trace name %s already used", trace_name);
 381                 err = -EEXIST;
 382                 goto traces_error;
 383         }
 384
 385         new_trace = zmalloc(sizeof(struct ust_trace));
 386         if (!new_trace) {
 387                 ERR("Unable to allocate memory for trace %s", trace_name);
 388                 err = -ENOMEM;
 389                 goto traces_error;
 390         }
 391         strncpy(new_trace->trace_name, trace_name, NAME_MAX);
 392         new_trace->channels = ltt_channels_trace_alloc(&new_trace->nr_channels,
 393                                 ust_channels_overwrite_by_default,
 394                                 ust_channels_request_collection_by_default, 1);
 395         if (!new_trace->channels) {
 396                 ERR("Unable to allocate memory for chaninfo  %s\n", trace_name);
 397                 err = -ENOMEM;
 398                 goto trace_free;
 399         }
 400
 401         /*
 402          * Force metadata channel to active, no overwrite.
 403          */
 404         metadata_index = ltt_channels_get_index_from_name("metadata");
 405         WARN_ON(metadata_index < 0);
 406         new_trace->channels[metadata_index].overwrite = 0;
 407         new_trace->channels[metadata_index].active = 1;
 408
 409         /*
 410          * Set hardcoded tracer defaults for some channels
 411          */
 412         for (chan = 0; chan < new_trace->nr_channels; chan++) {
 413                 if (!(new_trace->channels[chan].active))
 414                         continue;
 415
 416                 chantype = get_channel_type_from_name(
 417                         ltt_channels_get_name_from_index(chan));
 418                 new_trace->channels[chan].subbuf_size =
 419                         chan_infos[chantype].def_subbufsize;
 420                 new_trace->channels[chan].subbuf_cnt =
 421                         chan_infos[chantype].def_subbufcount;
 422         }
 423
 424         list_add(&new_trace->list, &ltt_traces.setup_head);
 425         return 0;
 426
 427 trace_free:
 428         free(new_trace);
 429 traces_error:
 430         return err;
 431 }
 432
 433
 434 int ltt_trace_setup(const char *trace_name)
 435 {
 436         int ret;
 437         ltt_lock_traces();
 438         ret = _ltt_trace_setup(trace_name);
 439         ltt_unlock_traces();
 440         return ret;
 441 }
 442
 443 /* must be called from within a traces lock. */
 444 static void _ltt_trace_free(struct ust_trace *trace)
 445 {
 446         list_del(&trace->list);
 447         free(trace);
 448 }
 449
 450 int ltt_trace_set_type(const char *trace_name, const char *trace_type)
 451 {
 452         int err = 0;
 453         struct ust_trace *trace;
 454         struct ltt_transport *tran_iter, *transport = NULL;
 455
 456         ltt_lock_traces();
 457
 458         trace = _ltt_trace_find_setup(trace_name);
 459         if (!trace) {
 460                 ERR("Trace not found %s", trace_name);
 461                 err = -ENOENT;
 462                 goto traces_error;
 463         }
 464
 465         list_for_each_entry(tran_iter, &ltt_transport_list, node) {
 466                 if (!strcmp(tran_iter->name, trace_type)) {
 467                         transport = tran_iter;
 468                         break;
 469                 }
 470         }
 471         if (!transport) {
 472                 ERR("Transport %s is not present", trace_type);
 473                 err = -EINVAL;
 474                 goto traces_error;
 475         }
 476
 477         trace->transport = transport;
 478
 479 traces_error:
 480         ltt_unlock_traces();
 481         return err;
 482 }
 483
 484 int ltt_trace_set_channel_subbufsize(const char *trace_name,
 485                 const char *channel_name, unsigned int size)
 486 {
 487         int err = 0;
 488         struct ust_trace *trace;
 489         int index;
 490
 491         ltt_lock_traces();
 492
 493         trace = _ltt_trace_find_setup(trace_name);
 494         if (!trace) {
 495                 ERR("Trace not found %s", trace_name);
 496                 err = -ENOENT;
 497                 goto traces_error;
 498         }
 499
 500         index = ltt_channels_get_index_from_name(channel_name);
 501         if (index < 0) {
 502                 ERR("Channel %s not found", channel_name);
 503                 err = -ENOENT;
 504                 goto traces_error;
 505         }
 506         trace->channels[index].subbuf_size = size;
 507
 508 traces_error:
 509         ltt_unlock_traces();
 510         return err;
 511 }
 512
 513 int ltt_trace_set_channel_subbufcount(const char *trace_name,
 514                 const char *channel_name, unsigned int cnt)
 515 {
 516         int err = 0;
 517         struct ust_trace *trace;
 518         int index;
 519
 520         ltt_lock_traces();
 521
 522         trace = _ltt_trace_find_setup(trace_name);
 523         if (!trace) {
 524                 ERR("Trace not found %s", trace_name);
 525                 err = -ENOENT;
 526                 goto traces_error;
 527         }
 528
 529         index = ltt_channels_get_index_from_name(channel_name);
 530         if (index < 0) {
 531                 ERR("Channel %s not found", channel_name);
 532                 err = -ENOENT;
 533                 goto traces_error;
 534         }
 535         trace->channels[index].subbuf_cnt = cnt;
 536
 537 traces_error:
 538         ltt_unlock_traces();
 539         return err;
 540 }
 541
 542 int ltt_trace_set_channel_enable(const char *trace_name,
 543                 const char *channel_name, unsigned int enable)
 544 {
 545         int err = 0;
 546         struct ust_trace *trace;
 547         int index;
 548
 549         ltt_lock_traces();
 550
 551         trace = _ltt_trace_find_setup(trace_name);
 552         if (!trace) {
 553                 ERR("Trace not found %s", trace_name);
 554                 err = -ENOENT;
 555                 goto traces_error;
 556         }
 557
 558         /*
 559          * Datas in metadata channel(marker info) is necessary to be able to
 560          * read the trace, we always enable this channel.
 561          */
 562         if (!enable && !strcmp(channel_name, "metadata")) {
 563                 ERR("Trying to disable metadata channel");
 564                 err = -EINVAL;
 565                 goto traces_error;
 566         }
 567
 568         index = ltt_channels_get_index_from_name(channel_name);
 569         if (index < 0) {
 570                 ERR("Channel %s not found", channel_name);
 571                 err = -ENOENT;
 572                 goto traces_error;
 573         }
 574
 575         trace->channels[index].active = enable;
 576
 577 traces_error:
 578         ltt_unlock_traces();
 579         return err;
 580 }
 581
 582 int ltt_trace_set_channel_overwrite(const char *trace_name,
 583                 const char *channel_name, unsigned int overwrite)
 584 {
 585         int err = 0;
 586         struct ust_trace *trace;
 587         int index;
 588
 589         ltt_lock_traces();
 590
 591         trace = _ltt_trace_find_setup(trace_name);
 592         if (!trace) {
 593                 ERR("Trace not found %s", trace_name);
 594                 err = -ENOENT;
 595                 goto traces_error;
 596         }
 597
 598         /*
 599          * Always put the metadata channel in non-overwrite mode :
 600          * This is a very low traffic channel and it can't afford to have its
 601          * data overwritten : this data (marker info) is necessary to be
 602          * able to read the trace.
 603          */
 604         if (overwrite && !strcmp(channel_name, "metadata")) {
 605                 ERR("Trying to set metadata channel to overwrite mode");
 606                 err = -EINVAL;
 607                 goto traces_error;
 608         }
 609
 610         index = ltt_channels_get_index_from_name(channel_name);
 611         if (index < 0) {
 612                 ERR("Channel %s not found", channel_name);
 613                 err = -ENOENT;
 614                 goto traces_error;
 615         }
 616
 617         trace->channels[index].overwrite = overwrite;
 618
 619 traces_error:
 620         ltt_unlock_traces();
 621         return err;
 622 }
 623
 624 int ltt_trace_alloc(const char *trace_name)
 625 {
 626         int err = 0;
 627         struct ust_trace *trace;
 628         unsigned int subbuf_size, subbuf_cnt;
 629 //ust// unsigned long flags;
 630         int chan;
 631         const char *channel_name;
 632
 633         ltt_lock_traces();
 634
 635         if (_ltt_trace_find(trace_name)) { /* Trace already allocated */
 636                 err = 1;
 637                 goto traces_error;
 638         }
 639
 640         trace = _ltt_trace_find_setup(trace_name);
 641         if (!trace) {
 642                 ERR("Trace not found %s", trace_name);
 643                 err = -ENOENT;
 644                 goto traces_error;
 645         }
 646
 647         kref_init(&trace->kref);
 648         kref_init(&trace->ltt_transport_kref);
 649 //ust// init_waitqueue_head(&trace->kref_wq);
 650         trace->active = 0;
 651 //ust// get_trace_clock();
 652         trace->freq_scale = trace_clock_freq_scale();
 653
 654         if (!trace->transport) {
 655                 ERR("Transport is not set");
 656                 err = -EINVAL;
 657                 goto transport_error;
 658         }
 659 //ust// if (!try_module_get(trace->transport->owner)) {
 660 //ust//         ERR("Can't lock transport module");
 661 //ust//         err = -ENODEV;
 662 //ust//         goto transport_error;
 663 //ust// }
 664         trace->ops = &trace->transport->ops;
 665
 666 //ust// err = trace->ops->create_dirs(trace);
 667 //ust// if (err) {
 668 //ust//         ERR("Can't create dir for trace %s", trace_name);
 669 //ust//         goto dirs_error;
 670 //ust// }
 671
 672 //ust// local_irq_save(flags);
 673         trace->start_freq = trace_clock_frequency();
 674         trace->start_tsc = trace_clock_read64();
 675         gettimeofday(&trace->start_time, NULL); //ust// changed /* FIXME: is this ok? */
 676 //ust// local_irq_restore(flags);
 677
 678         for (chan = 0; chan < trace->nr_channels; chan++) {
 679                 if (!(trace->channels[chan].active))
 680                         continue;
 681
 682                 channel_name = ltt_channels_get_name_from_index(chan);
 683                 WARN_ON(!channel_name);
 684                 subbuf_size = trace->channels[chan].subbuf_size;
 685                 subbuf_cnt = trace->channels[chan].subbuf_cnt;
 686                 prepare_chan_size_num(&subbuf_size, &subbuf_cnt);
 687                 err = trace->ops->create_channel(trace_name, trace,
 688                                 channel_name,
 689                                 &trace->channels[chan],
 690                                 subbuf_size,
 691                                 subbuf_cnt,
 692                                 trace->channels[chan].overwrite);
 693                 if (err != 0) {
 694                         ERR("Cannot create channel %s", channel_name);
 695                         goto create_channel_error;
 696                 }
 697         }
 698
 699         list_del(&trace->list);
 700 //ust// if (list_empty(&ltt_traces.head)) {
 701 //ust//         mod_timer(&ltt_async_wakeup_timer,
 702 //ust//                         jiffies + LTT_PERCPU_TIMER_INTERVAL);
 703 //ust//         set_kernel_trace_flag_all_tasks();
 704 //ust// }
 705         list_add_rcu(&trace->list, &ltt_traces.head);
 706 //ust// synchronize_sched();
 707
 708         ltt_unlock_traces();
 709
 710         return 0;
 711
 712 create_channel_error:
 713         for (chan--; chan >= 0; chan--)
 714                 if (trace->channels[chan].active)
 715                         trace->ops->remove_channel(&trace->channels[chan]);
 716
 717 //ust// dirs_error:
 718 //ust// module_put(trace->transport->owner);
 719 transport_error:
 720 //ust// put_trace_clock();
 721 traces_error:
 722         ltt_unlock_traces();
 723         return err;
 724 }
 725
 726 /*
 727  * It is worked as a wrapper for current version of ltt_control.ko.
 728  * We will make a new ltt_control based on debugfs, and control each channel's
 729  * buffer.
 730  */
 731 //ust// static int ltt_trace_create(const char *trace_name, const char *trace_type,
 732 //ust//                 enum trace_mode mode,
 733 //ust//                 unsigned int subbuf_size_low, unsigned int n_subbufs_low,
 734 //ust//                 unsigned int subbuf_size_med, unsigned int n_subbufs_med,
 735 //ust//                 unsigned int subbuf_size_high, unsigned int n_subbufs_high)
 736 //ust// {
 737 //ust//         int err = 0;
 738 //ust//
 739 //ust//         err = ltt_trace_setup(trace_name);
 740 //ust//         if (IS_ERR_VALUE(err))
 741 //ust//                 return err;
 742 //ust//
 743 //ust//         err = ltt_trace_set_type(trace_name, trace_type);
 744 //ust//         if (IS_ERR_VALUE(err))
 745 //ust//                 return err;
 746 //ust//
 747 //ust//         err = ltt_trace_alloc(trace_name);
 748 //ust//         if (IS_ERR_VALUE(err))
 749 //ust//                 return err;
 750 //ust//
 751 //ust//         return err;
 752 //ust// }
 753
 754 /* Must be called while sure that trace is in the list. */
 755 static int _ltt_trace_destroy(struct ust_trace *trace)
 756 {
 757         int err = -EPERM;
 758
 759         if (trace == NULL) {
 760                 err = -ENOENT;
 761                 goto traces_error;
 762         }
 763         if (trace->active) {
 764                 ERR("Can't destroy trace %s : tracer is active", trace->trace_name);
 765                 err = -EBUSY;
 766                 goto active_error;
 767         }
 768         /* Everything went fine */
 769         list_del_rcu(&trace->list);
 770         synchronize_rcu();
 771         if (list_empty(&ltt_traces.head)) {
 772 //ust//         clear_kernel_trace_flag_all_tasks();
 773                 /*
 774                  * We stop the asynchronous delivery of reader wakeup, but
 775                  * we must make one last check for reader wakeups pending
 776                  * later in __ltt_trace_destroy.
 777                  */
 778 //ust//         del_timer_sync(&ltt_async_wakeup_timer);
 779         }
 780         return 0;
 781
 782         /* error handling */
 783 active_error:
 784 traces_error:
 785         return err;
 786 }
 787
 788 /* Sleepable part of the destroy */
 789 static void __ltt_trace_destroy(struct ust_trace *trace, int drop)
 790 {
 791         int i;
 792         struct ust_channel *chan;
 793
 794         if(!drop) {
 795                 for (i = 0; i < trace->nr_channels; i++) {
 796                         chan = &trace->channels[i];
 797                         if (chan->active)
 798                                 trace->ops->finish_channel(chan);
 799                 }
 800         }
 801
 802         return; /* FIXME: temporary for ust */
 803 //ust// flush_scheduled_work();
 804
 805         /*
 806          * The currently destroyed trace is not in the trace list anymore,
 807          * so it's safe to call the async wakeup ourself. It will deliver
 808          * the last subbuffers.
 809          */
 810         trace_async_wakeup(trace);
 811
 812         for (i = 0; i < trace->nr_channels; i++) {
 813                 chan = &trace->channels[i];
 814                 if (chan->active)
 815                         trace->ops->remove_channel(chan);
 816         }
 817
 818         kref_put(&trace->ltt_transport_kref, ltt_release_transport);
 819
 820 //ust// module_put(trace->transport->owner);
 821
 822         /*
 823          * Wait for lttd readers to release the files, therefore making sure
 824          * the last subbuffers have been read.
 825          */
 826 //ust// if (atomic_read(&trace->kref.refcount) > 1) {
 827 //ust//         int ret = 0;
 828 //ust//         __wait_event_interruptible(trace->kref_wq,
 829 //ust//                 (atomic_read(&trace->kref.refcount) == 1), ret);
 830 //ust// }
 831         kref_put(&trace->kref, ltt_release_trace);
 832 }
 833
 834 int ltt_trace_destroy(const char *trace_name, int drop)
 835 {
 836         int err = 0;
 837         struct ust_trace *trace;
 838
 839         ltt_lock_traces();
 840
 841         trace = _ltt_trace_find(trace_name);
 842         if (trace) {
 843                 err = _ltt_trace_destroy(trace);
 844                 if (err)
 845                         goto error;
 846
 847                 ltt_unlock_traces();
 848
 849                 __ltt_trace_destroy(trace, drop);
 850 //ust//         put_trace_clock();
 851
 852                 return 0;
 853         }
 854
 855         trace = _ltt_trace_find_setup(trace_name);
 856         if (trace) {
 857                 _ltt_trace_free(trace);
 858                 ltt_unlock_traces();
 859                 return 0;
 860         }
 861
 862         err = -ENOENT;
 863
 864         /* Error handling */
 865 error:
 866         ltt_unlock_traces();
 867         return err;
 868 }
 869
 870 /* must be called from within a traces lock. */
 871 static int _ltt_trace_start(struct ust_trace *trace)
 872 {
 873         int err = 0;
 874
 875         if (trace == NULL) {
 876                 err = -ENOENT;
 877                 goto traces_error;
 878         }
 879         if (trace->active)
 880                 DBG("Tracing already active for trace %s", trace->trace_name);
 881 //ust// if (!try_module_get(ltt_run_filter_owner)) {
 882 //ust//         err = -ENODEV;
 883 //ust//         ERR("Cannot lock filter module");
 884 //ust//         goto get_ltt_run_filter_error;
 885 //ust// }
 886         trace->active = 1;
 887         /* Read by trace points without protection : be careful */
 888         ltt_traces.num_active_traces++;
 889         return err;
 890
 891         /* error handling */
 892 //ust// get_ltt_run_filter_error:
 893 traces_error:
 894         return err;
 895 }
 896
 897 int ltt_trace_start(const char *trace_name)
 898 {
 899         int err = 0;
 900         struct ust_trace *trace;
 901
 902         ltt_lock_traces();
 903
 904         trace = _ltt_trace_find(trace_name);
 905         err = _ltt_trace_start(trace);
 906         if (err)
 907                 goto no_trace;
 908
 909         ltt_unlock_traces();
 910
 911         /*
 912          * Call the kernel state dump.
 913          * Events will be mixed with real kernel events, it's ok.
 914          * Notice that there is no protection on the trace : that's exactly
 915          * why we iterate on the list and check for trace equality instead of
 916          * directly using this trace handle inside the logging function.
 917          */
 918
 919         ltt_dump_marker_state(trace);
 920
 921 //ust// if (!try_module_get(ltt_statedump_owner)) {
 922 //ust//         err = -ENODEV;
 923 //ust//         ERR("Cannot lock state dump module");
 924 //ust// } else {
 925                 ltt_statedump_functor(trace);
 926 //ust//         module_put(ltt_statedump_owner);
 927 //ust// }
 928
 929         return err;
 930
 931         /* Error handling */
 932 no_trace:
 933         ltt_unlock_traces();
 934         return err;
 935 }
 936
 937 /* must be called from within traces lock */
 938 static int _ltt_trace_stop(struct ust_trace *trace)
 939 {
 940         int err = -EPERM;
 941
 942         if (trace == NULL) {
 943                 err = -ENOENT;
 944                 goto traces_error;
 945         }
 946         if (!trace->active)
 947                 DBG("LTT : Tracing not active for trace %s", trace->trace_name);
 948         if (trace->active) {
 949                 trace->active = 0;
 950                 ltt_traces.num_active_traces--;
 951 //ust//         synchronize_sched(); /* Wait for each tracing to be finished */
 952         }
 953 //ust// module_put(ltt_run_filter_owner);
 954         /* Everything went fine */
 955         return 0;
 956
 957         /* Error handling */
 958 traces_error:
 959         return err;
 960 }
 961
 962 int ltt_trace_stop(const char *trace_name)
 963 {
 964         int err = 0;
 965         struct ust_trace *trace;
 966
 967         ltt_lock_traces();
 968         trace = _ltt_trace_find(trace_name);
 969         err = _ltt_trace_stop(trace);
 970         ltt_unlock_traces();
 971         return err;
 972 }
 973
 974 /**
 975  * ltt_filter_control - Trace filter control in-kernel API
 976  * @msg: Action to perform on the filter
 977  * @trace_name: Trace on which the action must be done
 978  */
 979 int ltt_filter_control(enum ltt_filter_control_msg msg, const char *trace_name)
 980 {
 981         int err;
 982         struct ust_trace *trace;
 983
 984         DBG("ltt_filter_control : trace %s", trace_name);
 985         ltt_lock_traces();
 986         trace = _ltt_trace_find(trace_name);
 987         if (trace == NULL) {
 988                 ERR("Trace does not exist. Cannot proxy control request");
 989                 err = -ENOENT;
 990                 goto trace_error;
 991         }
 992 //ust// if (!try_module_get(ltt_filter_control_owner)) {
 993 //ust//         err = -ENODEV;
 994 //ust//         goto get_module_error;
 995 //ust// }
 996         switch (msg) {
 997         case LTT_FILTER_DEFAULT_ACCEPT:
 998                 DBG("Proxy filter default accept %s", trace_name);
 999                 err = (*ltt_filter_control_functor)(msg, trace);
1000                 break;
1001         case LTT_FILTER_DEFAULT_REJECT:
1002                 DBG("Proxy filter default reject %s", trace_name);
1003                 err = (*ltt_filter_control_functor)(msg, trace);
1004                 break;
1005         default:
1006                 err = -EPERM;
1007         }
1008 //ust// module_put(ltt_filter_control_owner);
1009
1010 //ust// get_module_error:
1011 trace_error:
1012         ltt_unlock_traces();
1013         return err;
1014 }