kernel/trace/trace_events_trigger.c

   1 /*
   2  * trace_events_trigger - trace event triggers
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17  *
  18  * Copyright (C) 2013 Tom Zanussi <tom.zanussi@linux.intel.com>
  19  */
  20
  21 #include <linux/module.h>
  22 #include <linux/ctype.h>
  23 #include <linux/mutex.h>
  24 #include <linux/slab.h>
  25
  26 #include "trace.h"
  27
  28 static LIST_HEAD(trigger_commands);
  29 static DEFINE_MUTEX(trigger_cmd_mutex);
  30
  31 static void
  32 trigger_data_free(struct event_trigger_data *data)
  33 {
  34         if (data->cmd_ops->set_filter)
  35                 data->cmd_ops->set_filter(NULL, data, NULL);
  36
  37         synchronize_sched(); /* make sure current triggers exit before free */
  38         kfree(data);
  39 }
  40
  41 /**
  42  * event_triggers_call - Call triggers associated with a trace event
  43  * @file: The trace_event_file associated with the event
  44  * @rec: The trace entry for the event, NULL for unconditional invocation
  45  *
  46  * For each trigger associated with an event, invoke the trigger
  47  * function registered with the associated trigger command.  If rec is
  48  * non-NULL, it means that the trigger requires further processing and
  49  * shouldn't be unconditionally invoked.  If rec is non-NULL and the
  50  * trigger has a filter associated with it, rec will checked against
  51  * the filter and if the record matches the trigger will be invoked.
  52  * If the trigger is a 'post_trigger', meaning it shouldn't be invoked
  53  * in any case until the current event is written, the trigger
  54  * function isn't invoked but the bit associated with the deferred
  55  * trigger is set in the return value.
  56  *
  57  * Returns an enum event_trigger_type value containing a set bit for
  58  * any trigger that should be deferred, ETT_NONE if nothing to defer.
  59  *
  60  * Called from tracepoint handlers (with rcu_read_lock_sched() held).
  61  *
  62  * Return: an enum event_trigger_type value containing a set bit for
  63  * any trigger that should be deferred, ETT_NONE if nothing to defer.
  64  */
  65 enum event_trigger_type
  66 event_triggers_call(struct trace_event_file *file, void *rec)
  67 {
  68         struct event_trigger_data *data;
  69         enum event_trigger_type tt = ETT_NONE;
  70         struct event_filter *filter;
  71
  72         if (list_empty(&file->triggers))
  73                 return tt;
  74
  75         list_for_each_entry_rcu(data, &file->triggers, list) {
  76                 if (!rec) {
  77                         data->ops->func(data);
  78                         continue;
  79                 }
  80                 filter = rcu_dereference_sched(data->filter);
  81                 if (filter && !filter_match_preds(filter, rec))
  82                         continue;
  83                 if (data->cmd_ops->post_trigger) {
  84                         tt |= data->cmd_ops->trigger_type;
  85                         continue;
  86                 }
  87                 data->ops->func(data);
  88         }
  89         return tt;
  90 }
  91 EXPORT_SYMBOL_GPL(event_triggers_call);
  92
  93 /**
  94  * event_triggers_post_call - Call 'post_triggers' for a trace event
  95  * @file: The trace_event_file associated with the event
  96  * @tt: enum event_trigger_type containing a set bit for each trigger to invoke
  97  *
  98  * For each trigger associated with an event, invoke the trigger
  99  * function registered with the associated trigger command, if the
 100  * corresponding bit is set in the tt enum passed into this function.
 101  * See @event_triggers_call for details on how those bits are set.
 102  *
 103  * Called from tracepoint handlers (with rcu_read_lock_sched() held).
 104  */
 105 void
 106 event_triggers_post_call(struct trace_event_file *file,
 107                          enum event_trigger_type tt)
 108 {
 109         struct event_trigger_data *data;
 110
 111         list_for_each_entry_rcu(data, &file->triggers, list) {
 112                 if (data->cmd_ops->trigger_type & tt)
 113                         data->ops->func(data);
 114         }
 115 }
 116 EXPORT_SYMBOL_GPL(event_triggers_post_call);
 117
 118 #define SHOW_AVAILABLE_TRIGGERS (void *)(1UL)
 119
 120 static void *trigger_next(struct seq_file *m, void *t, loff_t *pos)
 121 {
 122         struct trace_event_file *event_file = event_file_data(m->private);
 123
 124         if (t == SHOW_AVAILABLE_TRIGGERS)
 125                 return NULL;
 126
 127         return seq_list_next(t, &event_file->triggers, pos);
 128 }
 129
 130 static void *trigger_start(struct seq_file *m, loff_t *pos)
 131 {
 132         struct trace_event_file *event_file;
 133
 134         /* ->stop() is called even if ->start() fails */
 135         mutex_lock(&event_mutex);
 136         event_file = event_file_data(m->private);
 137         if (unlikely(!event_file))
 138                 return ERR_PTR(-ENODEV);
 139
 140         if (list_empty(&event_file->triggers))
 141                 return *pos == 0 ? SHOW_AVAILABLE_TRIGGERS : NULL;
 142
 143         return seq_list_start(&event_file->triggers, *pos);
 144 }
 145
 146 static void trigger_stop(struct seq_file *m, void *t)
 147 {
 148         mutex_unlock(&event_mutex);
 149 }
 150
 151 static int trigger_show(struct seq_file *m, void *v)
 152 {
 153         struct event_trigger_data *data;
 154         struct event_command *p;
 155
 156         if (v == SHOW_AVAILABLE_TRIGGERS) {
 157                 seq_puts(m, "# Available triggers:\n");
 158                 seq_putc(m, '#');
 159                 mutex_lock(&trigger_cmd_mutex);
 160                 list_for_each_entry_reverse(p, &trigger_commands, list)
 161                         seq_printf(m, " %s", p->name);
 162                 seq_putc(m, '\n');
 163                 mutex_unlock(&trigger_cmd_mutex);
 164                 return 0;
 165         }
 166
 167         data = list_entry(v, struct event_trigger_data, list);
 168         data->ops->print(m, data->ops, data);
 169
 170         return 0;
 171 }
 172
 173 static const struct seq_operations event_triggers_seq_ops = {
 174         .start = trigger_start,
 175         .next = trigger_next,
 176         .stop = trigger_stop,
 177         .show = trigger_show,
 178 };
 179
 180 static int event_trigger_regex_open(struct inode *inode, struct file *file)
 181 {
 182         int ret = 0;
 183
 184         mutex_lock(&event_mutex);
 185
 186         if (unlikely(!event_file_data(file))) {
 187                 mutex_unlock(&event_mutex);
 188                 return -ENODEV;
 189         }
 190
 191         if (file->f_mode & FMODE_READ) {
 192                 ret = seq_open(file, &event_triggers_seq_ops);
 193                 if (!ret) {
 194                         struct seq_file *m = file->private_data;
 195                         m->private = file;
 196                 }
 197         }
 198
 199         mutex_unlock(&event_mutex);
 200
 201         return ret;
 202 }
 203
 204 static int trigger_process_regex(struct trace_event_file *file, char *buff)
 205 {
 206         char *command, *next = buff;
 207         struct event_command *p;
 208         int ret = -EINVAL;
 209
 210         command = strsep(&next, ": \t");
 211         command = (command[0] != '!') ? command : command + 1;
 212
 213         mutex_lock(&trigger_cmd_mutex);
 214         list_for_each_entry(p, &trigger_commands, list) {
 215                 if (strcmp(p->name, command) == 0) {
 216                         ret = p->func(p, file, buff, command, next);
 217                         goto out_unlock;
 218                 }
 219         }
 220  out_unlock:
 221         mutex_unlock(&trigger_cmd_mutex);
 222
 223         return ret;
 224 }
 225
 226 static ssize_t event_trigger_regex_write(struct file *file,
 227                                          const char __user *ubuf,
 228                                          size_t cnt, loff_t *ppos)
 229 {
 230         struct trace_event_file *event_file;
 231         ssize_t ret;
 232         char *buf;
 233
 234         if (!cnt)
 235                 return 0;
 236
 237         if (cnt >= PAGE_SIZE)
 238                 return -EINVAL;
 239
 240         buf = memdup_user_nul(ubuf, cnt);
 241         if (IS_ERR(buf))
 242                 return PTR_ERR(buf);
 243
 244         strim(buf);
 245
 246         mutex_lock(&event_mutex);
 247         event_file = event_file_data(file);
 248         if (unlikely(!event_file)) {
 249                 mutex_unlock(&event_mutex);
 250                 kfree(buf);
 251                 return -ENODEV;
 252         }
 253         ret = trigger_process_regex(event_file, buf);
 254         mutex_unlock(&event_mutex);
 255
 256         kfree(buf);
 257         if (ret < 0)
 258                 goto out;
 259
 260         *ppos += cnt;
 261         ret = cnt;
 262  out:
 263         return ret;
 264 }
 265
 266 static int event_trigger_regex_release(struct inode *inode, struct file *file)
 267 {
 268         mutex_lock(&event_mutex);
 269
 270         if (file->f_mode & FMODE_READ)
 271                 seq_release(inode, file);
 272
 273         mutex_unlock(&event_mutex);
 274
 275         return 0;
 276 }
 277
 278 static ssize_t
 279 event_trigger_write(struct file *filp, const char __user *ubuf,
 280                     size_t cnt, loff_t *ppos)
 281 {
 282         return event_trigger_regex_write(filp, ubuf, cnt, ppos);
 283 }
 284
 285 static int
 286 event_trigger_open(struct inode *inode, struct file *filp)
 287 {
 288         return event_trigger_regex_open(inode, filp);
 289 }
 290
 291 static int
 292 event_trigger_release(struct inode *inode, struct file *file)
 293 {
 294         return event_trigger_regex_release(inode, file);
 295 }
 296
 297 const struct file_operations event_trigger_fops = {
 298         .open = event_trigger_open,
 299         .read = seq_read,
 300         .write = event_trigger_write,
 301         .llseek = tracing_lseek,
 302         .release = event_trigger_release,
 303 };
 304
 305 /*
 306  * Currently we only register event commands from __init, so mark this
 307  * __init too.
 308  */
 309 static __init int register_event_command(struct event_command *cmd)
 310 {
 311         struct event_command *p;
 312         int ret = 0;
 313
 314         mutex_lock(&trigger_cmd_mutex);
 315         list_for_each_entry(p, &trigger_commands, list) {
 316                 if (strcmp(cmd->name, p->name) == 0) {
 317                         ret = -EBUSY;
 318                         goto out_unlock;
 319                 }
 320         }
 321         list_add(&cmd->list, &trigger_commands);
 322  out_unlock:
 323         mutex_unlock(&trigger_cmd_mutex);
 324
 325         return ret;
 326 }
 327
 328 /*
 329  * Currently we only unregister event commands from __init, so mark
 330  * this __init too.
 331  */
 332 static __init int unregister_event_command(struct event_command *cmd)
 333 {
 334         struct event_command *p, *n;
 335         int ret = -ENODEV;
 336
 337         mutex_lock(&trigger_cmd_mutex);
 338         list_for_each_entry_safe(p, n, &trigger_commands, list) {
 339                 if (strcmp(cmd->name, p->name) == 0) {
 340                         ret = 0;
 341                         list_del_init(&p->list);
 342                         goto out_unlock;
 343                 }
 344         }
 345  out_unlock:
 346         mutex_unlock(&trigger_cmd_mutex);
 347
 348         return ret;
 349 }
 350
 351 /**
 352  * event_trigger_print - Generic event_trigger_ops @print implementation
 353  * @name: The name of the event trigger
 354  * @m: The seq_file being printed to
 355  * @data: Trigger-specific data
 356  * @filter_str: filter_str to print, if present
 357  *
 358  * Common implementation for event triggers to print themselves.
 359  *
 360  * Usually wrapped by a function that simply sets the @name of the
 361  * trigger command and then invokes this.
 362  *
 363  * Return: 0 on success, errno otherwise
 364  */
 365 static int
 366 event_trigger_print(const char *name, struct seq_file *m,
 367                     void *data, char *filter_str)
 368 {
 369         long count = (long)data;
 370
 371         seq_puts(m, name);
 372
 373         if (count == -1)
 374                 seq_puts(m, ":unlimited");
 375         else
 376                 seq_printf(m, ":count=%ld", count);
 377
 378         if (filter_str)
 379                 seq_printf(m, " if %s\n", filter_str);
 380         else
 381                 seq_putc(m, '\n');
 382
 383         return 0;
 384 }
 385
 386 /**
 387  * event_trigger_init - Generic event_trigger_ops @init implementation
 388  * @ops: The trigger ops associated with the trigger
 389  * @data: Trigger-specific data
 390  *
 391  * Common implementation of event trigger initialization.
 392  *
 393  * Usually used directly as the @init method in event trigger
 394  * implementations.
 395  *
 396  * Return: 0 on success, errno otherwise
 397  */
 398 static int
 399 event_trigger_init(struct event_trigger_ops *ops,
 400                    struct event_trigger_data *data)
 401 {
 402         data->ref++;
 403         return 0;
 404 }
 405
 406 /**
 407  * event_trigger_free - Generic event_trigger_ops @free implementation
 408  * @ops: The trigger ops associated with the trigger
 409  * @data: Trigger-specific data
 410  *
 411  * Common implementation of event trigger de-initialization.
 412  *
 413  * Usually used directly as the @free method in event trigger
 414  * implementations.
 415  */
 416 static void
 417 event_trigger_free(struct event_trigger_ops *ops,
 418                    struct event_trigger_data *data)
 419 {
 420         if (WARN_ON_ONCE(data->ref <= 0))
 421                 return;
 422
 423         data->ref--;
 424         if (!data->ref)
 425                 trigger_data_free(data);
 426 }
 427
 428 static int trace_event_trigger_enable_disable(struct trace_event_file *file,
 429                                               int trigger_enable)
 430 {
 431         int ret = 0;
 432
 433         if (trigger_enable) {
 434                 if (atomic_inc_return(&file->tm_ref) > 1)
 435                         return ret;
 436                 set_bit(EVENT_FILE_FL_TRIGGER_MODE_BIT, &file->flags);
 437                 ret = trace_event_enable_disable(file, 1, 1);
 438         } else {
 439                 if (atomic_dec_return(&file->tm_ref) > 0)
 440                         return ret;
 441                 clear_bit(EVENT_FILE_FL_TRIGGER_MODE_BIT, &file->flags);
 442                 ret = trace_event_enable_disable(file, 0, 1);
 443         }
 444
 445         return ret;
 446 }
 447
 448 /**
 449  * clear_event_triggers - Clear all triggers associated with a trace array
 450  * @tr: The trace array to clear
 451  *
 452  * For each trigger, the triggering event has its tm_ref decremented
 453  * via trace_event_trigger_enable_disable(), and any associated event
 454  * (in the case of enable/disable_event triggers) will have its sm_ref
 455  * decremented via free()->trace_event_enable_disable().  That
 456  * combination effectively reverses the soft-mode/trigger state added
 457  * by trigger registration.
 458  *
 459  * Must be called with event_mutex held.
 460  */
 461 void
 462 clear_event_triggers(struct trace_array *tr)
 463 {
 464         struct trace_event_file *file;
 465
 466         list_for_each_entry(file, &tr->events, list) {
 467                 struct event_trigger_data *data;
 468                 list_for_each_entry_rcu(data, &file->triggers, list) {
 469                         trace_event_trigger_enable_disable(file, 0);
 470                         if (data->ops->free)
 471                                 data->ops->free(data->ops, data);
 472                 }
 473         }
 474 }
 475
 476 /**
 477  * update_cond_flag - Set or reset the TRIGGER_COND bit
 478  * @file: The trace_event_file associated with the event
 479  *
 480  * If an event has triggers and any of those triggers has a filter or
 481  * a post_trigger, trigger invocation needs to be deferred until after
 482  * the current event has logged its data, and the event should have
 483  * its TRIGGER_COND bit set, otherwise the TRIGGER_COND bit should be
 484  * cleared.
 485  */
 486 static void update_cond_flag(struct trace_event_file *file)
 487 {
 488         struct event_trigger_data *data;
 489         bool set_cond = false;
 490
 491         list_for_each_entry_rcu(data, &file->triggers, list) {
 492                 if (data->filter || data->cmd_ops->post_trigger) {
 493                         set_cond = true;
 494                         break;
 495                 }
 496         }
 497
 498         if (set_cond)
 499                 set_bit(EVENT_FILE_FL_TRIGGER_COND_BIT, &file->flags);
 500         else
 501                 clear_bit(EVENT_FILE_FL_TRIGGER_COND_BIT, &file->flags);
 502 }
 503
 504 /**
 505  * register_trigger - Generic event_command @reg implementation
 506  * @glob: The raw string used to register the trigger
 507  * @ops: The trigger ops associated with the trigger
 508  * @data: Trigger-specific data to associate with the trigger
 509  * @file: The trace_event_file associated with the event
 510  *
 511  * Common implementation for event trigger registration.
 512  *
 513  * Usually used directly as the @reg method in event command
 514  * implementations.
 515  *
 516  * Return: 0 on success, errno otherwise
 517  */
 518 static int register_trigger(char *glob, struct event_trigger_ops *ops,
 519                             struct event_trigger_data *data,
 520                             struct trace_event_file *file)
 521 {
 522         struct event_trigger_data *test;
 523         int ret = 0;
 524
 525         list_for_each_entry_rcu(test, &file->triggers, list) {
 526                 if (test->cmd_ops->trigger_type == data->cmd_ops->trigger_type) {
 527                         ret = -EEXIST;
 528                         goto out;
 529                 }
 530         }
 531
 532         if (data->ops->init) {
 533                 ret = data->ops->init(data->ops, data);
 534                 if (ret < 0)
 535                         goto out;
 536         }
 537
 538         list_add_rcu(&data->list, &file->triggers);
 539         ret++;
 540
 541         if (trace_event_trigger_enable_disable(file, 1) < 0) {
 542                 list_del_rcu(&data->list);
 543                 ret--;
 544         }
 545         update_cond_flag(file);
 546 out:
 547         return ret;
 548 }
 549
 550 /**
 551  * unregister_trigger - Generic event_command @unreg implementation
 552  * @glob: The raw string used to register the trigger
 553  * @ops: The trigger ops associated with the trigger
 554  * @test: Trigger-specific data used to find the trigger to remove
 555  * @file: The trace_event_file associated with the event
 556  *
 557  * Common implementation for event trigger unregistration.
 558  *
 559  * Usually used directly as the @unreg method in event command
 560  * implementations.
 561  */
 562 static void unregister_trigger(char *glob, struct event_trigger_ops *ops,
 563                                struct event_trigger_data *test,
 564                                struct trace_event_file *file)
 565 {
 566         struct event_trigger_data *data;
 567         bool unregistered = false;
 568
 569         list_for_each_entry_rcu(data, &file->triggers, list) {
 570                 if (data->cmd_ops->trigger_type == test->cmd_ops->trigger_type) {
 571                         unregistered = true;
 572                         list_del_rcu(&data->list);
 573                         update_cond_flag(file);
 574                         trace_event_trigger_enable_disable(file, 0);
 575                         break;
 576                 }
 577         }
 578
 579         if (unregistered && data->ops->free)
 580                 data->ops->free(data->ops, data);
 581 }
 582
 583 /**
 584  * event_trigger_callback - Generic event_command @func implementation
 585  * @cmd_ops: The command ops, used for trigger registration
 586  * @file: The trace_event_file associated with the event
 587  * @glob: The raw string used to register the trigger
 588  * @cmd: The cmd portion of the string used to register the trigger
 589  * @param: The params portion of the string used to register the trigger
 590  *
 591  * Common implementation for event command parsing and trigger
 592  * instantiation.
 593  *
 594  * Usually used directly as the @func method in event command
 595  * implementations.
 596  *
 597  * Return: 0 on success, errno otherwise
 598  */
 599 static int
 600 event_trigger_callback(struct event_command *cmd_ops,
 601                        struct trace_event_file *file,
 602                        char *glob, char *cmd, char *param)
 603 {
 604         struct event_trigger_data *trigger_data;
 605         struct event_trigger_ops *trigger_ops;
 606         char *trigger = NULL;
 607         char *number;
 608         int ret;
 609
 610         /* separate the trigger from the filter (t:n [if filter]) */
 611         if (param && isdigit(param[0]))
 612                 trigger = strsep(&param, " \t");
 613
 614         trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
 615
 616         ret = -ENOMEM;
 617         trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
 618         if (!trigger_data)
 619                 goto out;
 620
 621         trigger_data->count = -1;
 622         trigger_data->ops = trigger_ops;
 623         trigger_data->cmd_ops = cmd_ops;
 624         INIT_LIST_HEAD(&trigger_data->list);
 625
 626         if (glob[0] == '!') {
 627                 cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
 628                 kfree(trigger_data);
 629                 ret = 0;
 630                 goto out;
 631         }
 632
 633         if (trigger) {
 634                 number = strsep(&trigger, ":");
 635
 636                 ret = -EINVAL;
 637                 if (!strlen(number))
 638                         goto out_free;
 639
 640                 /*
 641                  * We use the callback data field (which is a pointer)
 642                  * as our counter.
 643                  */
 644                 ret = kstrtoul(number, 0, &trigger_data->count);
 645                 if (ret)
 646                         goto out_free;
 647         }
 648
 649         if (!param) /* if param is non-empty, it's supposed to be a filter */
 650                 goto out_reg;
 651
 652         if (!cmd_ops->set_filter)
 653                 goto out_reg;
 654
 655         ret = cmd_ops->set_filter(param, trigger_data, file);
 656         if (ret < 0)
 657                 goto out_free;
 658
 659  out_reg:
 660         ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);
 661         /*
 662          * The above returns on success the # of functions enabled,
 663          * but if it didn't find any functions it returns zero.
 664          * Consider no functions a failure too.
 665          */
 666         if (!ret) {
 667                 ret = -ENOENT;
 668                 goto out_free;
 669         } else if (ret < 0)
 670                 goto out_free;
 671         ret = 0;
 672  out:
 673         return ret;
 674
 675  out_free:
 676         if (cmd_ops->set_filter)
 677                 cmd_ops->set_filter(NULL, trigger_data, NULL);
 678         kfree(trigger_data);
 679         goto out;
 680 }
 681
 682 /**
 683  * set_trigger_filter - Generic event_command @set_filter implementation
 684  * @filter_str: The filter string for the trigger, NULL to remove filter
 685  * @trigger_data: Trigger-specific data
 686  * @file: The trace_event_file associated with the event
 687  *
 688  * Common implementation for event command filter parsing and filter
 689  * instantiation.
 690  *
 691  * Usually used directly as the @set_filter method in event command
 692  * implementations.
 693  *
 694  * Also used to remove a filter (if filter_str = NULL).
 695  *
 696  * Return: 0 on success, errno otherwise
 697  */
 698 static int set_trigger_filter(char *filter_str,
 699                               struct event_trigger_data *trigger_data,
 700                               struct trace_event_file *file)
 701 {
 702         struct event_trigger_data *data = trigger_data;
 703         struct event_filter *filter = NULL, *tmp;
 704         int ret = -EINVAL;
 705         char *s;
 706
 707         if (!filter_str) /* clear the current filter */
 708                 goto assign;
 709
 710         s = strsep(&filter_str, " \t");
 711
 712         if (!strlen(s) || strcmp(s, "if") != 0)
 713                 goto out;
 714
 715         if (!filter_str)
 716                 goto out;
 717
 718         /* The filter is for the 'trigger' event, not the triggered event */
 719         ret = create_event_filter(file->event_call, filter_str, false, &filter);
 720         if (ret)
 721                 goto out;
 722  assign:
 723         tmp = rcu_access_pointer(data->filter);
 724
 725         rcu_assign_pointer(data->filter, filter);
 726
 727         if (tmp) {
 728                 /* Make sure the call is done with the filter */
 729                 synchronize_sched();
 730                 free_event_filter(tmp);
 731         }
 732
 733         kfree(data->filter_str);
 734         data->filter_str = NULL;
 735
 736         if (filter_str) {
 737                 data->filter_str = kstrdup(filter_str, GFP_KERNEL);
 738                 if (!data->filter_str) {
 739                         free_event_filter(rcu_access_pointer(data->filter));
 740                         data->filter = NULL;
 741                         ret = -ENOMEM;
 742                 }
 743         }
 744  out:
 745         return ret;
 746 }
 747
 748 static void
 749 traceon_trigger(struct event_trigger_data *data)
 750 {
 751         if (tracing_is_on())
 752                 return;
 753
 754         tracing_on();
 755 }
 756
 757 static void
 758 traceon_count_trigger(struct event_trigger_data *data)
 759 {
 760         if (tracing_is_on())
 761                 return;
 762
 763         if (!data->count)
 764                 return;
 765
 766         if (data->count != -1)
 767                 (data->count)--;
 768
 769         tracing_on();
 770 }
 771
 772 static void
 773 traceoff_trigger(struct event_trigger_data *data)
 774 {
 775         if (!tracing_is_on())
 776                 return;
 777
 778         tracing_off();
 779 }
 780
 781 static void
 782 traceoff_count_trigger(struct event_trigger_data *data)
 783 {
 784         if (!tracing_is_on())
 785                 return;
 786
 787         if (!data->count)
 788                 return;
 789
 790         if (data->count != -1)
 791                 (data->count)--;
 792
 793         tracing_off();
 794 }
 795
 796 static int
 797 traceon_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
 798                       struct event_trigger_data *data)
 799 {
 800         return event_trigger_print("traceon", m, (void *)data->count,
 801                                    data->filter_str);
 802 }
 803
 804 static int
 805 traceoff_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
 806                        struct event_trigger_data *data)
 807 {
 808         return event_trigger_print("traceoff", m, (void *)data->count,
 809                                    data->filter_str);
 810 }
 811
 812 static struct event_trigger_ops traceon_trigger_ops = {
 813         .func                   = traceon_trigger,
 814         .print                  = traceon_trigger_print,
 815         .init                   = event_trigger_init,
 816         .free                   = event_trigger_free,
 817 };
 818
 819 static struct event_trigger_ops traceon_count_trigger_ops = {
 820         .func                   = traceon_count_trigger,
 821         .print                  = traceon_trigger_print,
 822         .init                   = event_trigger_init,
 823         .free                   = event_trigger_free,
 824 };
 825
 826 static struct event_trigger_ops traceoff_trigger_ops = {
 827         .func                   = traceoff_trigger,
 828         .print                  = traceoff_trigger_print,
 829         .init                   = event_trigger_init,
 830         .free                   = event_trigger_free,
 831 };
 832
 833 static struct event_trigger_ops traceoff_count_trigger_ops = {
 834         .func                   = traceoff_count_trigger,
 835         .print                  = traceoff_trigger_print,
 836         .init                   = event_trigger_init,
 837         .free                   = event_trigger_free,
 838 };
 839
 840 static struct event_trigger_ops *
 841 onoff_get_trigger_ops(char *cmd, char *param)
 842 {
 843         struct event_trigger_ops *ops;
 844
 845         /* we register both traceon and traceoff to this callback */
 846         if (strcmp(cmd, "traceon") == 0)
 847                 ops = param ? &traceon_count_trigger_ops :
 848                         &traceon_trigger_ops;
 849         else
 850                 ops = param ? &traceoff_count_trigger_ops :
 851                         &traceoff_trigger_ops;
 852
 853         return ops;
 854 }
 855
 856 static struct event_command trigger_traceon_cmd = {
 857         .name                   = "traceon",
 858         .trigger_type           = ETT_TRACE_ONOFF,
 859         .func                   = event_trigger_callback,
 860         .reg                    = register_trigger,
 861         .unreg                  = unregister_trigger,
 862         .get_trigger_ops        = onoff_get_trigger_ops,
 863         .set_filter             = set_trigger_filter,
 864 };
 865
 866 static struct event_command trigger_traceoff_cmd = {
 867         .name                   = "traceoff",
 868         .trigger_type           = ETT_TRACE_ONOFF,
 869         .func                   = event_trigger_callback,
 870         .reg                    = register_trigger,
 871         .unreg                  = unregister_trigger,
 872         .get_trigger_ops        = onoff_get_trigger_ops,
 873         .set_filter             = set_trigger_filter,
 874 };
 875
 876 #ifdef CONFIG_TRACER_SNAPSHOT
 877 static void
 878 snapshot_trigger(struct event_trigger_data *data)
 879 {
 880         tracing_snapshot();
 881 }
 882
 883 static void
 884 snapshot_count_trigger(struct event_trigger_data *data)
 885 {
 886         if (!data->count)
 887                 return;
 888
 889         if (data->count != -1)
 890                 (data->count)--;
 891
 892         snapshot_trigger(data);
 893 }
 894
 895 static int
 896 register_snapshot_trigger(char *glob, struct event_trigger_ops *ops,
 897                           struct event_trigger_data *data,
 898                           struct trace_event_file *file)
 899 {
 900         int ret = register_trigger(glob, ops, data, file);
 901
 902         if (ret > 0 && tracing_alloc_snapshot() != 0) {
 903                 unregister_trigger(glob, ops, data, file);
 904                 ret = 0;
 905         }
 906
 907         return ret;
 908 }
 909
 910 static int
 911 snapshot_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
 912                        struct event_trigger_data *data)
 913 {
 914         return event_trigger_print("snapshot", m, (void *)data->count,
 915                                    data->filter_str);
 916 }
 917
 918 static struct event_trigger_ops snapshot_trigger_ops = {
 919         .func                   = snapshot_trigger,
 920         .print                  = snapshot_trigger_print,
 921         .init                   = event_trigger_init,
 922         .free                   = event_trigger_free,
 923 };
 924
 925 static struct event_trigger_ops snapshot_count_trigger_ops = {
 926         .func                   = snapshot_count_trigger,
 927         .print                  = snapshot_trigger_print,
 928         .init                   = event_trigger_init,
 929         .free                   = event_trigger_free,
 930 };
 931
 932 static struct event_trigger_ops *
 933 snapshot_get_trigger_ops(char *cmd, char *param)
 934 {
 935         return param ? &snapshot_count_trigger_ops : &snapshot_trigger_ops;
 936 }
 937
 938 static struct event_command trigger_snapshot_cmd = {
 939         .name                   = "snapshot",
 940         .trigger_type           = ETT_SNAPSHOT,
 941         .func                   = event_trigger_callback,
 942         .reg                    = register_snapshot_trigger,
 943         .unreg                  = unregister_trigger,
 944         .get_trigger_ops        = snapshot_get_trigger_ops,
 945         .set_filter             = set_trigger_filter,
 946 };
 947
 948 static __init int register_trigger_snapshot_cmd(void)
 949 {
 950         int ret;
 951
 952         ret = register_event_command(&trigger_snapshot_cmd);
 953         WARN_ON(ret < 0);
 954
 955         return ret;
 956 }
 957 #else
 958 static __init int register_trigger_snapshot_cmd(void) { return 0; }
 959 #endif /* CONFIG_TRACER_SNAPSHOT */
 960
 961 #ifdef CONFIG_STACKTRACE
 962 /*
 963  * Skip 3:
 964  *   stacktrace_trigger()
 965  *   event_triggers_post_call()
 966  *   trace_event_raw_event_xxx()
 967  */
 968 #define STACK_SKIP 3
 969
 970 static void
 971 stacktrace_trigger(struct event_trigger_data *data)
 972 {
 973         trace_dump_stack(STACK_SKIP);
 974 }
 975
 976 static void
 977 stacktrace_count_trigger(struct event_trigger_data *data)
 978 {
 979         if (!data->count)
 980                 return;
 981
 982         if (data->count != -1)
 983                 (data->count)--;
 984
 985         stacktrace_trigger(data);
 986 }
 987
 988 static int
 989 stacktrace_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
 990                          struct event_trigger_data *data)
 991 {
 992         return event_trigger_print("stacktrace", m, (void *)data->count,
 993                                    data->filter_str);
 994 }
 995
 996 static struct event_trigger_ops stacktrace_trigger_ops = {
 997         .func                   = stacktrace_trigger,
 998         .print                  = stacktrace_trigger_print,
 999         .init                   = event_trigger_init,
1000         .free                   = event_trigger_free,
1001 };
1002
1003 static struct event_trigger_ops stacktrace_count_trigger_ops = {
1004         .func                   = stacktrace_count_trigger,
1005         .print                  = stacktrace_trigger_print,
1006         .init                   = event_trigger_init,
1007         .free                   = event_trigger_free,
1008 };
1009
1010 static struct event_trigger_ops *
1011 stacktrace_get_trigger_ops(char *cmd, char *param)
1012 {
1013         return param ? &stacktrace_count_trigger_ops : &stacktrace_trigger_ops;
1014 }
1015
1016 static struct event_command trigger_stacktrace_cmd = {
1017         .name                   = "stacktrace",
1018         .trigger_type           = ETT_STACKTRACE,
1019         .post_trigger           = true,
1020         .func                   = event_trigger_callback,
1021         .reg                    = register_trigger,
1022         .unreg                  = unregister_trigger,
1023         .get_trigger_ops        = stacktrace_get_trigger_ops,
1024         .set_filter             = set_trigger_filter,
1025 };
1026
1027 static __init int register_trigger_stacktrace_cmd(void)
1028 {
1029         int ret;
1030
1031         ret = register_event_command(&trigger_stacktrace_cmd);
1032         WARN_ON(ret < 0);
1033
1034         return ret;
1035 }
1036 #else
1037 static __init int register_trigger_stacktrace_cmd(void) { return 0; }
1038 #endif /* CONFIG_STACKTRACE */
1039
1040 static __init void unregister_trigger_traceon_traceoff_cmds(void)
1041 {
1042         unregister_event_command(&trigger_traceon_cmd);
1043         unregister_event_command(&trigger_traceoff_cmd);
1044 }
1045
1046 /* Avoid typos */
1047 #define ENABLE_EVENT_STR        "enable_event"
1048 #define DISABLE_EVENT_STR       "disable_event"
1049
1050 struct enable_trigger_data {
1051         struct trace_event_file         *file;
1052         bool                            enable;
1053 };
1054
1055 static void
1056 event_enable_trigger(struct event_trigger_data *data)
1057 {
1058         struct enable_trigger_data *enable_data = data->private_data;
1059
1060         if (enable_data->enable)
1061                 clear_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
1062         else
1063                 set_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
1064 }
1065
1066 static void
1067 event_enable_count_trigger(struct event_trigger_data *data)
1068 {
1069         struct enable_trigger_data *enable_data = data->private_data;
1070
1071         if (!data->count)
1072                 return;
1073
1074         /* Skip if the event is in a state we want to switch to */
1075         if (enable_data->enable == !(enable_data->file->flags & EVENT_FILE_FL_SOFT_DISABLED))
1076                 return;
1077
1078         if (data->count != -1)
1079                 (data->count)--;
1080
1081         event_enable_trigger(data);
1082 }
1083
1084 static int
1085 event_enable_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
1086                            struct event_trigger_data *data)
1087 {
1088         struct enable_trigger_data *enable_data = data->private_data;
1089
1090         seq_printf(m, "%s:%s:%s",
1091                    enable_data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR,
1092                    enable_data->file->event_call->class->system,
1093                    trace_event_name(enable_data->file->event_call));
1094
1095         if (data->count == -1)
1096                 seq_puts(m, ":unlimited");
1097         else
1098                 seq_printf(m, ":count=%ld", data->count);
1099
1100         if (data->filter_str)
1101                 seq_printf(m, " if %s\n", data->filter_str);
1102         else
1103                 seq_putc(m, '\n');
1104
1105         return 0;
1106 }
1107
1108 static void
1109 event_enable_trigger_free(struct event_trigger_ops *ops,
1110                           struct event_trigger_data *data)
1111 {
1112         struct enable_trigger_data *enable_data = data->private_data;
1113
1114         if (WARN_ON_ONCE(data->ref <= 0))
1115                 return;
1116
1117         data->ref--;
1118         if (!data->ref) {
1119                 /* Remove the SOFT_MODE flag */
1120                 trace_event_enable_disable(enable_data->file, 0, 1);
1121                 module_put(enable_data->file->event_call->mod);
1122                 trigger_data_free(data);
1123                 kfree(enable_data);
1124         }
1125 }
1126
1127 static struct event_trigger_ops event_enable_trigger_ops = {
1128         .func                   = event_enable_trigger,
1129         .print                  = event_enable_trigger_print,
1130         .init                   = event_trigger_init,
1131         .free                   = event_enable_trigger_free,
1132 };
1133
1134 static struct event_trigger_ops event_enable_count_trigger_ops = {
1135         .func                   = event_enable_count_trigger,
1136         .print                  = event_enable_trigger_print,
1137         .init                   = event_trigger_init,
1138         .free                   = event_enable_trigger_free,
1139 };
1140
1141 static struct event_trigger_ops event_disable_trigger_ops = {
1142         .func                   = event_enable_trigger,
1143         .print                  = event_enable_trigger_print,
1144         .init                   = event_trigger_init,
1145         .free                   = event_enable_trigger_free,
1146 };
1147
1148 static struct event_trigger_ops event_disable_count_trigger_ops = {
1149         .func                   = event_enable_count_trigger,
1150         .print                  = event_enable_trigger_print,
1151         .init                   = event_trigger_init,
1152         .free                   = event_enable_trigger_free,
1153 };
1154
1155 static int
1156 event_enable_trigger_func(struct event_command *cmd_ops,
1157                           struct trace_event_file *file,
1158                           char *glob, char *cmd, char *param)
1159 {
1160         struct trace_event_file *event_enable_file;
1161         struct enable_trigger_data *enable_data;
1162         struct event_trigger_data *trigger_data;
1163         struct event_trigger_ops *trigger_ops;
1164         struct trace_array *tr = file->tr;
1165         const char *system;
1166         const char *event;
1167         char *trigger;
1168         char *number;
1169         bool enable;
1170         int ret;
1171
1172         if (!param)
1173                 return -EINVAL;
1174
1175         /* separate the trigger from the filter (s:e:n [if filter]) */
1176         trigger = strsep(&param, " \t");
1177         if (!trigger)
1178                 return -EINVAL;
1179
1180         system = strsep(&trigger, ":");
1181         if (!trigger)
1182                 return -EINVAL;
1183
1184         event = strsep(&trigger, ":");
1185
1186         ret = -EINVAL;
1187         event_enable_file = find_event_file(tr, system, event);
1188         if (!event_enable_file)
1189                 goto out;
1190
1191         enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
1192
1193         trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
1194
1195         ret = -ENOMEM;
1196         trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
1197         if (!trigger_data)
1198                 goto out;
1199
1200         enable_data = kzalloc(sizeof(*enable_data), GFP_KERNEL);
1201         if (!enable_data) {
1202                 kfree(trigger_data);
1203                 goto out;
1204         }
1205
1206         trigger_data->count = -1;
1207         trigger_data->ops = trigger_ops;
1208         trigger_data->cmd_ops = cmd_ops;
1209         INIT_LIST_HEAD(&trigger_data->list);
1210         RCU_INIT_POINTER(trigger_data->filter, NULL);
1211
1212         enable_data->enable = enable;
1213         enable_data->file = event_enable_file;
1214         trigger_data->private_data = enable_data;
1215
1216         if (glob[0] == '!') {
1217                 cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
1218                 kfree(trigger_data);
1219                 kfree(enable_data);
1220                 ret = 0;
1221                 goto out;
1222         }
1223
1224         if (trigger) {
1225                 number = strsep(&trigger, ":");
1226
1227                 ret = -EINVAL;
1228                 if (!strlen(number))
1229                         goto out_free;
1230
1231                 /*
1232                  * We use the callback data field (which is a pointer)
1233                  * as our counter.
1234                  */
1235                 ret = kstrtoul(number, 0, &trigger_data->count);
1236                 if (ret)
1237                         goto out_free;
1238         }
1239
1240         if (!param) /* if param is non-empty, it's supposed to be a filter */
1241                 goto out_reg;
1242
1243         if (!cmd_ops->set_filter)
1244                 goto out_reg;
1245
1246         ret = cmd_ops->set_filter(param, trigger_data, file);
1247         if (ret < 0)
1248                 goto out_free;
1249
1250  out_reg:
1251         /* Don't let event modules unload while probe registered */
1252         ret = try_module_get(event_enable_file->event_call->mod);
1253         if (!ret) {
1254                 ret = -EBUSY;
1255                 goto out_free;
1256         }
1257
1258         ret = trace_event_enable_disable(event_enable_file, 1, 1);
1259         if (ret < 0)
1260                 goto out_put;
1261         ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);
1262         /*
1263          * The above returns on success the # of functions enabled,
1264          * but if it didn't find any functions it returns zero.
1265          * Consider no functions a failure too.
1266          */
1267         if (!ret) {
1268                 ret = -ENOENT;
1269                 goto out_disable;
1270         } else if (ret < 0)
1271                 goto out_disable;
1272         /* Just return zero, not the number of enabled functions */
1273         ret = 0;
1274  out:
1275         return ret;
1276
1277  out_disable:
1278         trace_event_enable_disable(event_enable_file, 0, 1);
1279  out_put:
1280         module_put(event_enable_file->event_call->mod);
1281  out_free:
1282         if (cmd_ops->set_filter)
1283                 cmd_ops->set_filter(NULL, trigger_data, NULL);
1284         kfree(trigger_data);
1285         kfree(enable_data);
1286         goto out;
1287 }
1288
1289 static int event_enable_register_trigger(char *glob,
1290                                          struct event_trigger_ops *ops,
1291                                          struct event_trigger_data *data,
1292                                          struct trace_event_file *file)
1293 {
1294         struct enable_trigger_data *enable_data = data->private_data;
1295         struct enable_trigger_data *test_enable_data;
1296         struct event_trigger_data *test;
1297         int ret = 0;
1298
1299         list_for_each_entry_rcu(test, &file->triggers, list) {
1300                 test_enable_data = test->private_data;
1301                 if (test_enable_data &&
1302                     (test_enable_data->file == enable_data->file)) {
1303                         ret = -EEXIST;
1304                         goto out;
1305                 }
1306         }
1307
1308         if (data->ops->init) {
1309                 ret = data->ops->init(data->ops, data);
1310                 if (ret < 0)
1311                         goto out;
1312         }
1313
1314         list_add_rcu(&data->list, &file->triggers);
1315         ret++;
1316
1317         if (trace_event_trigger_enable_disable(file, 1) < 0) {
1318                 list_del_rcu(&data->list);
1319                 ret--;
1320         }
1321         update_cond_flag(file);
1322 out:
1323         return ret;
1324 }
1325
1326 static void event_enable_unregister_trigger(char *glob,
1327                                             struct event_trigger_ops *ops,
1328                                             struct event_trigger_data *test,
1329                                             struct trace_event_file *file)
1330 {
1331         struct enable_trigger_data *test_enable_data = test->private_data;
1332         struct enable_trigger_data *enable_data;
1333         struct event_trigger_data *data;
1334         bool unregistered = false;
1335
1336         list_for_each_entry_rcu(data, &file->triggers, list) {
1337                 enable_data = data->private_data;
1338                 if (enable_data &&
1339                     (enable_data->file == test_enable_data->file)) {
1340                         unregistered = true;
1341                         list_del_rcu(&data->list);
1342                         update_cond_flag(file);
1343                         trace_event_trigger_enable_disable(file, 0);
1344                         break;
1345                 }
1346         }
1347
1348         if (unregistered && data->ops->free)
1349                 data->ops->free(data->ops, data);
1350 }
1351
1352 static struct event_trigger_ops *
1353 event_enable_get_trigger_ops(char *cmd, char *param)
1354 {
1355         struct event_trigger_ops *ops;
1356         bool enable;
1357
1358         enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
1359
1360         if (enable)
1361                 ops = param ? &event_enable_count_trigger_ops :
1362                         &event_enable_trigger_ops;
1363         else
1364                 ops = param ? &event_disable_count_trigger_ops :
1365                         &event_disable_trigger_ops;
1366
1367         return ops;
1368 }
1369
1370 static struct event_command trigger_enable_cmd = {
1371         .name                   = ENABLE_EVENT_STR,
1372         .trigger_type           = ETT_EVENT_ENABLE,
1373         .func                   = event_enable_trigger_func,
1374         .reg                    = event_enable_register_trigger,
1375         .unreg                  = event_enable_unregister_trigger,
1376         .get_trigger_ops        = event_enable_get_trigger_ops,
1377         .set_filter             = set_trigger_filter,
1378 };
1379
1380 static struct event_command trigger_disable_cmd = {
1381         .name                   = DISABLE_EVENT_STR,
1382         .trigger_type           = ETT_EVENT_ENABLE,
1383         .func                   = event_enable_trigger_func,
1384         .reg                    = event_enable_register_trigger,
1385         .unreg                  = event_enable_unregister_trigger,
1386         .get_trigger_ops        = event_enable_get_trigger_ops,
1387         .set_filter             = set_trigger_filter,
1388 };
1389
1390 static __init void unregister_trigger_enable_disable_cmds(void)
1391 {
1392         unregister_event_command(&trigger_enable_cmd);
1393         unregister_event_command(&trigger_disable_cmd);
1394 }
1395
1396 static __init int register_trigger_enable_disable_cmds(void)
1397 {
1398         int ret;
1399
1400         ret = register_event_command(&trigger_enable_cmd);
1401         if (WARN_ON(ret < 0))
1402                 return ret;
1403         ret = register_event_command(&trigger_disable_cmd);
1404         if (WARN_ON(ret < 0))
1405                 unregister_trigger_enable_disable_cmds();
1406
1407         return ret;
1408 }
1409
1410 static __init int register_trigger_traceon_traceoff_cmds(void)
1411 {
1412         int ret;
1413
1414         ret = register_event_command(&trigger_traceon_cmd);
1415         if (WARN_ON(ret < 0))
1416                 return ret;
1417         ret = register_event_command(&trigger_traceoff_cmd);
1418         if (WARN_ON(ret < 0))
1419                 unregister_trigger_traceon_traceoff_cmds();
1420
1421         return ret;
1422 }
1423
1424 __init int register_trigger_cmds(void)
1425 {
1426         register_trigger_traceon_traceoff_cmds();
1427         register_trigger_snapshot_cmd();
1428         register_trigger_stacktrace_cmd();
1429         register_trigger_enable_disable_cmds();
1430
1431         return 0;
1432 }