kernel/trace/trace_events_trigger.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * trace_events_trigger - trace event triggers
   4  *
   5  * Copyright (C) 2013 Tom Zanussi <tom.zanussi@linux.intel.com>
   6  */
   7
   8 #include <linux/security.h>
   9 #include <linux/module.h>
  10 #include <linux/ctype.h>
  11 #include <linux/mutex.h>
  12 #include <linux/slab.h>
  13 #include <linux/rculist.h>
  14
  15 #include "trace.h"
  16
  17 static LIST_HEAD(trigger_commands);
  18 static DEFINE_MUTEX(trigger_cmd_mutex);
  19
  20 void trigger_data_free(struct event_trigger_data *data)
  21 {
  22         if (data->cmd_ops->set_filter)
  23                 data->cmd_ops->set_filter(NULL, data, NULL);
  24
  25         /* make sure current triggers exit before free */
  26         tracepoint_synchronize_unregister();
  27
  28         kfree(data);
  29 }
  30
  31 /**
  32  * event_triggers_call - Call triggers associated with a trace event
  33  * @file: The trace_event_file associated with the event
  34  * @rec: The trace entry for the event, NULL for unconditional invocation
  35  *
  36  * For each trigger associated with an event, invoke the trigger
  37  * function registered with the associated trigger command.  If rec is
  38  * non-NULL, it means that the trigger requires further processing and
  39  * shouldn't be unconditionally invoked.  If rec is non-NULL and the
  40  * trigger has a filter associated with it, rec will checked against
  41  * the filter and if the record matches the trigger will be invoked.
  42  * If the trigger is a 'post_trigger', meaning it shouldn't be invoked
  43  * in any case until the current event is written, the trigger
  44  * function isn't invoked but the bit associated with the deferred
  45  * trigger is set in the return value.
  46  *
  47  * Returns an enum event_trigger_type value containing a set bit for
  48  * any trigger that should be deferred, ETT_NONE if nothing to defer.
  49  *
  50  * Called from tracepoint handlers (with rcu_read_lock_sched() held).
  51  *
  52  * Return: an enum event_trigger_type value containing a set bit for
  53  * any trigger that should be deferred, ETT_NONE if nothing to defer.
  54  */
  55 enum event_trigger_type
  56 event_triggers_call(struct trace_event_file *file, void *rec,
  57                     struct ring_buffer_event *event)
  58 {
  59         struct event_trigger_data *data;
  60         enum event_trigger_type tt = ETT_NONE;
  61         struct event_filter *filter;
  62
  63         if (list_empty(&file->triggers))
  64                 return tt;
  65
  66         list_for_each_entry_rcu(data, &file->triggers, list) {
  67                 if (data->paused)
  68                         continue;
  69                 if (!rec) {
  70                         data->ops->func(data, rec, event);
  71                         continue;
  72                 }
  73                 filter = rcu_dereference_sched(data->filter);
  74                 if (filter && !filter_match_preds(filter, rec))
  75                         continue;
  76                 if (event_command_post_trigger(data->cmd_ops)) {
  77                         tt |= data->cmd_ops->trigger_type;
  78                         continue;
  79                 }
  80                 data->ops->func(data, rec, event);
  81         }
  82         return tt;
  83 }
  84 EXPORT_SYMBOL_GPL(event_triggers_call);
  85
  86 /**
  87  * event_triggers_post_call - Call 'post_triggers' for a trace event
  88  * @file: The trace_event_file associated with the event
  89  * @tt: enum event_trigger_type containing a set bit for each trigger to invoke
  90  *
  91  * For each trigger associated with an event, invoke the trigger
  92  * function registered with the associated trigger command, if the
  93  * corresponding bit is set in the tt enum passed into this function.
  94  * See @event_triggers_call for details on how those bits are set.
  95  *
  96  * Called from tracepoint handlers (with rcu_read_lock_sched() held).
  97  */
  98 void
  99 event_triggers_post_call(struct trace_event_file *file,
 100                          enum event_trigger_type tt)
 101 {
 102         struct event_trigger_data *data;
 103
 104         list_for_each_entry_rcu(data, &file->triggers, list) {
 105                 if (data->paused)
 106                         continue;
 107                 if (data->cmd_ops->trigger_type & tt)
 108                         data->ops->func(data, NULL, NULL);
 109         }
 110 }
 111 EXPORT_SYMBOL_GPL(event_triggers_post_call);
 112
 113 #define SHOW_AVAILABLE_TRIGGERS (void *)(1UL)
 114
 115 static void *trigger_next(struct seq_file *m, void *t, loff_t *pos)
 116 {
 117         struct trace_event_file *event_file = event_file_data(m->private);
 118
 119         if (t == SHOW_AVAILABLE_TRIGGERS) {
 120                 (*pos)++;
 121                 return NULL;
 122         }
 123         return seq_list_next(t, &event_file->triggers, pos);
 124 }
 125
 126 static void *trigger_start(struct seq_file *m, loff_t *pos)
 127 {
 128         struct trace_event_file *event_file;
 129
 130         /* ->stop() is called even if ->start() fails */
 131         mutex_lock(&event_mutex);
 132         event_file = event_file_data(m->private);
 133         if (unlikely(!event_file))
 134                 return ERR_PTR(-ENODEV);
 135
 136         if (list_empty(&event_file->triggers))
 137                 return *pos == 0 ? SHOW_AVAILABLE_TRIGGERS : NULL;
 138
 139         return seq_list_start(&event_file->triggers, *pos);
 140 }
 141
 142 static void trigger_stop(struct seq_file *m, void *t)
 143 {
 144         mutex_unlock(&event_mutex);
 145 }
 146
 147 static int trigger_show(struct seq_file *m, void *v)
 148 {
 149         struct event_trigger_data *data;
 150         struct event_command *p;
 151
 152         if (v == SHOW_AVAILABLE_TRIGGERS) {
 153                 seq_puts(m, "# Available triggers:\n");
 154                 seq_putc(m, '#');
 155                 mutex_lock(&trigger_cmd_mutex);
 156                 list_for_each_entry_reverse(p, &trigger_commands, list)
 157                         seq_printf(m, " %s", p->name);
 158                 seq_putc(m, '\n');
 159                 mutex_unlock(&trigger_cmd_mutex);
 160                 return 0;
 161         }
 162
 163         data = list_entry(v, struct event_trigger_data, list);
 164         data->ops->print(m, data->ops, data);
 165
 166         return 0;
 167 }
 168
 169 static const struct seq_operations event_triggers_seq_ops = {
 170         .start = trigger_start,
 171         .next = trigger_next,
 172         .stop = trigger_stop,
 173         .show = trigger_show,
 174 };
 175
 176 static int event_trigger_regex_open(struct inode *inode, struct file *file)
 177 {
 178         int ret;
 179
 180         ret = security_locked_down(LOCKDOWN_TRACEFS);
 181         if (ret)
 182                 return ret;
 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_WRITE) &&
 192             (file->f_flags & O_TRUNC)) {
 193                 struct trace_event_file *event_file;
 194                 struct event_command *p;
 195
 196                 event_file = event_file_data(file);
 197
 198                 list_for_each_entry(p, &trigger_commands, list) {
 199                         if (p->unreg_all)
 200                                 p->unreg_all(event_file);
 201                 }
 202         }
 203
 204         if (file->f_mode & FMODE_READ) {
 205                 ret = seq_open(file, &event_triggers_seq_ops);
 206                 if (!ret) {
 207                         struct seq_file *m = file->private_data;
 208                         m->private = file;
 209                 }
 210         }
 211
 212         mutex_unlock(&event_mutex);
 213
 214         return ret;
 215 }
 216
 217 int trigger_process_regex(struct trace_event_file *file, char *buff)
 218 {
 219         char *command, *next;
 220         struct event_command *p;
 221         int ret = -EINVAL;
 222
 223         next = buff = skip_spaces(buff);
 224         command = strsep(&next, ": \t");
 225         if (next) {
 226                 next = skip_spaces(next);
 227                 if (!*next)
 228                         next = NULL;
 229         }
 230         command = (command[0] != '!') ? command : command + 1;
 231
 232         mutex_lock(&trigger_cmd_mutex);
 233         list_for_each_entry(p, &trigger_commands, list) {
 234                 if (strcmp(p->name, command) == 0) {
 235                         ret = p->func(p, file, buff, command, next);
 236                         goto out_unlock;
 237                 }
 238         }
 239  out_unlock:
 240         mutex_unlock(&trigger_cmd_mutex);
 241
 242         return ret;
 243 }
 244
 245 static ssize_t event_trigger_regex_write(struct file *file,
 246                                          const char __user *ubuf,
 247                                          size_t cnt, loff_t *ppos)
 248 {
 249         struct trace_event_file *event_file;
 250         ssize_t ret;
 251         char *buf;
 252
 253         if (!cnt)
 254                 return 0;
 255
 256         if (cnt >= PAGE_SIZE)
 257                 return -EINVAL;
 258
 259         buf = memdup_user_nul(ubuf, cnt);
 260         if (IS_ERR(buf))
 261                 return PTR_ERR(buf);
 262
 263         strim(buf);
 264
 265         mutex_lock(&event_mutex);
 266         event_file = event_file_data(file);
 267         if (unlikely(!event_file)) {
 268                 mutex_unlock(&event_mutex);
 269                 kfree(buf);
 270                 return -ENODEV;
 271         }
 272         ret = trigger_process_regex(event_file, buf);
 273         mutex_unlock(&event_mutex);
 274
 275         kfree(buf);
 276         if (ret < 0)
 277                 goto out;
 278
 279         *ppos += cnt;
 280         ret = cnt;
 281  out:
 282         return ret;
 283 }
 284
 285 static int event_trigger_regex_release(struct inode *inode, struct file *file)
 286 {
 287         mutex_lock(&event_mutex);
 288
 289         if (file->f_mode & FMODE_READ)
 290                 seq_release(inode, file);
 291
 292         mutex_unlock(&event_mutex);
 293
 294         return 0;
 295 }
 296
 297 static ssize_t
 298 event_trigger_write(struct file *filp, const char __user *ubuf,
 299                     size_t cnt, loff_t *ppos)
 300 {
 301         return event_trigger_regex_write(filp, ubuf, cnt, ppos);
 302 }
 303
 304 static int
 305 event_trigger_open(struct inode *inode, struct file *filp)
 306 {
 307         /* Checks for tracefs lockdown */
 308         return event_trigger_regex_open(inode, filp);
 309 }
 310
 311 static int
 312 event_trigger_release(struct inode *inode, struct file *file)
 313 {
 314         return event_trigger_regex_release(inode, file);
 315 }
 316
 317 const struct file_operations event_trigger_fops = {
 318         .open = event_trigger_open,
 319         .read = seq_read,
 320         .write = event_trigger_write,
 321         .llseek = tracing_lseek,
 322         .release = event_trigger_release,
 323 };
 324
 325 /*
 326  * Currently we only register event commands from __init, so mark this
 327  * __init too.
 328  */
 329 __init int register_event_command(struct event_command *cmd)
 330 {
 331         struct event_command *p;
 332         int ret = 0;
 333
 334         mutex_lock(&trigger_cmd_mutex);
 335         list_for_each_entry(p, &trigger_commands, list) {
 336                 if (strcmp(cmd->name, p->name) == 0) {
 337                         ret = -EBUSY;
 338                         goto out_unlock;
 339                 }
 340         }
 341         list_add(&cmd->list, &trigger_commands);
 342  out_unlock:
 343         mutex_unlock(&trigger_cmd_mutex);
 344
 345         return ret;
 346 }
 347
 348 /*
 349  * Currently we only unregister event commands from __init, so mark
 350  * this __init too.
 351  */
 352 __init int unregister_event_command(struct event_command *cmd)
 353 {
 354         struct event_command *p, *n;
 355         int ret = -ENODEV;
 356
 357         mutex_lock(&trigger_cmd_mutex);
 358         list_for_each_entry_safe(p, n, &trigger_commands, list) {
 359                 if (strcmp(cmd->name, p->name) == 0) {
 360                         ret = 0;
 361                         list_del_init(&p->list);
 362                         goto out_unlock;
 363                 }
 364         }
 365  out_unlock:
 366         mutex_unlock(&trigger_cmd_mutex);
 367
 368         return ret;
 369 }
 370
 371 /**
 372  * event_trigger_print - Generic event_trigger_ops @print implementation
 373  * @name: The name of the event trigger
 374  * @m: The seq_file being printed to
 375  * @data: Trigger-specific data
 376  * @filter_str: filter_str to print, if present
 377  *
 378  * Common implementation for event triggers to print themselves.
 379  *
 380  * Usually wrapped by a function that simply sets the @name of the
 381  * trigger command and then invokes this.
 382  *
 383  * Return: 0 on success, errno otherwise
 384  */
 385 static int
 386 event_trigger_print(const char *name, struct seq_file *m,
 387                     void *data, char *filter_str)
 388 {
 389         long count = (long)data;
 390
 391         seq_puts(m, name);
 392
 393         if (count == -1)
 394                 seq_puts(m, ":unlimited");
 395         else
 396                 seq_printf(m, ":count=%ld", count);
 397
 398         if (filter_str)
 399                 seq_printf(m, " if %s\n", filter_str);
 400         else
 401                 seq_putc(m, '\n');
 402
 403         return 0;
 404 }
 405
 406 /**
 407  * event_trigger_init - Generic event_trigger_ops @init implementation
 408  * @ops: The trigger ops associated with the trigger
 409  * @data: Trigger-specific data
 410  *
 411  * Common implementation of event trigger initialization.
 412  *
 413  * Usually used directly as the @init method in event trigger
 414  * implementations.
 415  *
 416  * Return: 0 on success, errno otherwise
 417  */
 418 int event_trigger_init(struct event_trigger_ops *ops,
 419                        struct event_trigger_data *data)
 420 {
 421         data->ref++;
 422         return 0;
 423 }
 424
 425 /**
 426  * event_trigger_free - Generic event_trigger_ops @free implementation
 427  * @ops: The trigger ops associated with the trigger
 428  * @data: Trigger-specific data
 429  *
 430  * Common implementation of event trigger de-initialization.
 431  *
 432  * Usually used directly as the @free method in event trigger
 433  * implementations.
 434  */
 435 static void
 436 event_trigger_free(struct event_trigger_ops *ops,
 437                    struct event_trigger_data *data)
 438 {
 439         if (WARN_ON_ONCE(data->ref <= 0))
 440                 return;
 441
 442         data->ref--;
 443         if (!data->ref)
 444                 trigger_data_free(data);
 445 }
 446
 447 int trace_event_trigger_enable_disable(struct trace_event_file *file,
 448                                        int trigger_enable)
 449 {
 450         int ret = 0;
 451
 452         if (trigger_enable) {
 453                 if (atomic_inc_return(&file->tm_ref) > 1)
 454                         return ret;
 455                 set_bit(EVENT_FILE_FL_TRIGGER_MODE_BIT, &file->flags);
 456                 ret = trace_event_enable_disable(file, 1, 1);
 457         } else {
 458                 if (atomic_dec_return(&file->tm_ref) > 0)
 459                         return ret;
 460                 clear_bit(EVENT_FILE_FL_TRIGGER_MODE_BIT, &file->flags);
 461                 ret = trace_event_enable_disable(file, 0, 1);
 462         }
 463
 464         return ret;
 465 }
 466
 467 /**
 468  * clear_event_triggers - Clear all triggers associated with a trace array
 469  * @tr: The trace array to clear
 470  *
 471  * For each trigger, the triggering event has its tm_ref decremented
 472  * via trace_event_trigger_enable_disable(), and any associated event
 473  * (in the case of enable/disable_event triggers) will have its sm_ref
 474  * decremented via free()->trace_event_enable_disable().  That
 475  * combination effectively reverses the soft-mode/trigger state added
 476  * by trigger registration.
 477  *
 478  * Must be called with event_mutex held.
 479  */
 480 void
 481 clear_event_triggers(struct trace_array *tr)
 482 {
 483         struct trace_event_file *file;
 484
 485         list_for_each_entry(file, &tr->events, list) {
 486                 struct event_trigger_data *data, *n;
 487                 list_for_each_entry_safe(data, n, &file->triggers, list) {
 488                         trace_event_trigger_enable_disable(file, 0);
 489                         list_del_rcu(&data->list);
 490                         if (data->ops->free)
 491                                 data->ops->free(data->ops, data);
 492                 }
 493         }
 494 }
 495
 496 /**
 497  * update_cond_flag - Set or reset the TRIGGER_COND bit
 498  * @file: The trace_event_file associated with the event
 499  *
 500  * If an event has triggers and any of those triggers has a filter or
 501  * a post_trigger, trigger invocation needs to be deferred until after
 502  * the current event has logged its data, and the event should have
 503  * its TRIGGER_COND bit set, otherwise the TRIGGER_COND bit should be
 504  * cleared.
 505  */
 506 void update_cond_flag(struct trace_event_file *file)
 507 {
 508         struct event_trigger_data *data;
 509         bool set_cond = false;
 510
 511         lockdep_assert_held(&event_mutex);
 512
 513         list_for_each_entry(data, &file->triggers, list) {
 514                 if (data->filter || event_command_post_trigger(data->cmd_ops) ||
 515                     event_command_needs_rec(data->cmd_ops)) {
 516                         set_cond = true;
 517                         break;
 518                 }
 519         }
 520
 521         if (set_cond)
 522                 set_bit(EVENT_FILE_FL_TRIGGER_COND_BIT, &file->flags);
 523         else
 524                 clear_bit(EVENT_FILE_FL_TRIGGER_COND_BIT, &file->flags);
 525 }
 526
 527 /**
 528  * register_trigger - Generic event_command @reg implementation
 529  * @glob: The raw string used to register the trigger
 530  * @ops: The trigger ops associated with the trigger
 531  * @data: Trigger-specific data to associate with the trigger
 532  * @file: The trace_event_file associated with the event
 533  *
 534  * Common implementation for event trigger registration.
 535  *
 536  * Usually used directly as the @reg method in event command
 537  * implementations.
 538  *
 539  * Return: 0 on success, errno otherwise
 540  */
 541 static int register_trigger(char *glob, struct event_trigger_ops *ops,
 542                             struct event_trigger_data *data,
 543                             struct trace_event_file *file)
 544 {
 545         struct event_trigger_data *test;
 546         int ret = 0;
 547
 548         lockdep_assert_held(&event_mutex);
 549
 550         list_for_each_entry(test, &file->triggers, list) {
 551                 if (test->cmd_ops->trigger_type == data->cmd_ops->trigger_type) {
 552                         ret = -EEXIST;
 553                         goto out;
 554                 }
 555         }
 556
 557         if (data->ops->init) {
 558                 ret = data->ops->init(data->ops, data);
 559                 if (ret < 0)
 560                         goto out;
 561         }
 562
 563         list_add_rcu(&data->list, &file->triggers);
 564         ret++;
 565
 566         update_cond_flag(file);
 567         if (trace_event_trigger_enable_disable(file, 1) < 0) {
 568                 list_del_rcu(&data->list);
 569                 update_cond_flag(file);
 570                 ret--;
 571         }
 572 out:
 573         return ret;
 574 }
 575
 576 /**
 577  * unregister_trigger - Generic event_command @unreg implementation
 578  * @glob: The raw string used to register the trigger
 579  * @ops: The trigger ops associated with the trigger
 580  * @test: Trigger-specific data used to find the trigger to remove
 581  * @file: The trace_event_file associated with the event
 582  *
 583  * Common implementation for event trigger unregistration.
 584  *
 585  * Usually used directly as the @unreg method in event command
 586  * implementations.
 587  */
 588 static void unregister_trigger(char *glob, struct event_trigger_ops *ops,
 589                                struct event_trigger_data *test,
 590                                struct trace_event_file *file)
 591 {
 592         struct event_trigger_data *data;
 593         bool unregistered = false;
 594
 595         lockdep_assert_held(&event_mutex);
 596
 597         list_for_each_entry(data, &file->triggers, list) {
 598                 if (data->cmd_ops->trigger_type == test->cmd_ops->trigger_type) {
 599                         unregistered = true;
 600                         list_del_rcu(&data->list);
 601                         trace_event_trigger_enable_disable(file, 0);
 602                         update_cond_flag(file);
 603                         break;
 604                 }
 605         }
 606
 607         if (unregistered && data->ops->free)
 608                 data->ops->free(data->ops, data);
 609 }
 610
 611 /**
 612  * event_trigger_callback - Generic event_command @func implementation
 613  * @cmd_ops: The command ops, used for trigger registration
 614  * @file: The trace_event_file associated with the event
 615  * @glob: The raw string used to register the trigger
 616  * @cmd: The cmd portion of the string used to register the trigger
 617  * @param: The params portion of the string used to register the trigger
 618  *
 619  * Common implementation for event command parsing and trigger
 620  * instantiation.
 621  *
 622  * Usually used directly as the @func method in event command
 623  * implementations.
 624  *
 625  * Return: 0 on success, errno otherwise
 626  */
 627 static int
 628 event_trigger_callback(struct event_command *cmd_ops,
 629                        struct trace_event_file *file,
 630                        char *glob, char *cmd, char *param)
 631 {
 632         struct event_trigger_data *trigger_data;
 633         struct event_trigger_ops *trigger_ops;
 634         char *trigger = NULL;
 635         char *number;
 636         int ret;
 637
 638         /* separate the trigger from the filter (t:n [if filter]) */
 639         if (param && isdigit(param[0])) {
 640                 trigger = strsep(&param, " \t");
 641                 if (param) {
 642                         param = skip_spaces(param);
 643                         if (!*param)
 644                                 param = NULL;
 645                 }
 646         }
 647
 648         trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
 649
 650         ret = -ENOMEM;
 651         trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
 652         if (!trigger_data)
 653                 goto out;
 654
 655         trigger_data->count = -1;
 656         trigger_data->ops = trigger_ops;
 657         trigger_data->cmd_ops = cmd_ops;
 658         trigger_data->private_data = file;
 659         INIT_LIST_HEAD(&trigger_data->list);
 660         INIT_LIST_HEAD(&trigger_data->named_list);
 661
 662         if (glob[0] == '!') {
 663                 cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
 664                 kfree(trigger_data);
 665                 ret = 0;
 666                 goto out;
 667         }
 668
 669         if (trigger) {
 670                 number = strsep(&trigger, ":");
 671
 672                 ret = -EINVAL;
 673                 if (!strlen(number))
 674                         goto out_free;
 675
 676                 /*
 677                  * We use the callback data field (which is a pointer)
 678                  * as our counter.
 679                  */
 680                 ret = kstrtoul(number, 0, &trigger_data->count);
 681                 if (ret)
 682                         goto out_free;
 683         }
 684
 685         if (!param) /* if param is non-empty, it's supposed to be a filter */
 686                 goto out_reg;
 687
 688         if (!cmd_ops->set_filter)
 689                 goto out_reg;
 690
 691         ret = cmd_ops->set_filter(param, trigger_data, file);
 692         if (ret < 0)
 693                 goto out_free;
 694
 695  out_reg:
 696         /* Up the trigger_data count to make sure reg doesn't free it on failure */
 697         event_trigger_init(trigger_ops, trigger_data);
 698         ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);
 699         /*
 700          * The above returns on success the # of functions enabled,
 701          * but if it didn't find any functions it returns zero.
 702          * Consider no functions a failure too.
 703          */
 704         if (!ret) {
 705                 cmd_ops->unreg(glob, trigger_ops, trigger_data, file);
 706                 ret = -ENOENT;
 707         } else if (ret > 0)
 708                 ret = 0;
 709
 710         /* Down the counter of trigger_data or free it if not used anymore */
 711         event_trigger_free(trigger_ops, trigger_data);
 712  out:
 713         return ret;
 714
 715  out_free:
 716         if (cmd_ops->set_filter)
 717                 cmd_ops->set_filter(NULL, trigger_data, NULL);
 718         kfree(trigger_data);
 719         goto out;
 720 }
 721
 722 /**
 723  * set_trigger_filter - Generic event_command @set_filter implementation
 724  * @filter_str: The filter string for the trigger, NULL to remove filter
 725  * @trigger_data: Trigger-specific data
 726  * @file: The trace_event_file associated with the event
 727  *
 728  * Common implementation for event command filter parsing and filter
 729  * instantiation.
 730  *
 731  * Usually used directly as the @set_filter method in event command
 732  * implementations.
 733  *
 734  * Also used to remove a filter (if filter_str = NULL).
 735  *
 736  * Return: 0 on success, errno otherwise
 737  */
 738 int set_trigger_filter(char *filter_str,
 739                        struct event_trigger_data *trigger_data,
 740                        struct trace_event_file *file)
 741 {
 742         struct event_trigger_data *data = trigger_data;
 743         struct event_filter *filter = NULL, *tmp;
 744         int ret = -EINVAL;
 745         char *s;
 746
 747         if (!filter_str) /* clear the current filter */
 748                 goto assign;
 749
 750         s = strsep(&filter_str, " \t");
 751
 752         if (!strlen(s) || strcmp(s, "if") != 0)
 753                 goto out;
 754
 755         if (!filter_str)
 756                 goto out;
 757
 758         /* The filter is for the 'trigger' event, not the triggered event */
 759         ret = create_event_filter(file->tr, file->event_call,
 760                                   filter_str, false, &filter);
 761         /*
 762          * If create_event_filter() fails, filter still needs to be freed.
 763          * Which the calling code will do with data->filter.
 764          */
 765  assign:
 766         tmp = rcu_access_pointer(data->filter);
 767
 768         rcu_assign_pointer(data->filter, filter);
 769
 770         if (tmp) {
 771                 /* Make sure the call is done with the filter */
 772                 tracepoint_synchronize_unregister();
 773                 free_event_filter(tmp);
 774         }
 775
 776         kfree(data->filter_str);
 777         data->filter_str = NULL;
 778
 779         if (filter_str) {
 780                 data->filter_str = kstrdup(filter_str, GFP_KERNEL);
 781                 if (!data->filter_str) {
 782                         free_event_filter(rcu_access_pointer(data->filter));
 783                         data->filter = NULL;
 784                         ret = -ENOMEM;
 785                 }
 786         }
 787  out:
 788         return ret;
 789 }
 790
 791 static LIST_HEAD(named_triggers);
 792
 793 /**
 794  * find_named_trigger - Find the common named trigger associated with @name
 795  * @name: The name of the set of named triggers to find the common data for
 796  *
 797  * Named triggers are sets of triggers that share a common set of
 798  * trigger data.  The first named trigger registered with a given name
 799  * owns the common trigger data that the others subsequently
 800  * registered with the same name will reference.  This function
 801  * returns the common trigger data associated with that first
 802  * registered instance.
 803  *
 804  * Return: the common trigger data for the given named trigger on
 805  * success, NULL otherwise.
 806  */
 807 struct event_trigger_data *find_named_trigger(const char *name)
 808 {
 809         struct event_trigger_data *data;
 810
 811         if (!name)
 812                 return NULL;
 813
 814         list_for_each_entry(data, &named_triggers, named_list) {
 815                 if (data->named_data)
 816                         continue;
 817                 if (strcmp(data->name, name) == 0)
 818                         return data;
 819         }
 820
 821         return NULL;
 822 }
 823
 824 /**
 825  * is_named_trigger - determine if a given trigger is a named trigger
 826  * @test: The trigger data to test
 827  *
 828  * Return: true if 'test' is a named trigger, false otherwise.
 829  */
 830 bool is_named_trigger(struct event_trigger_data *test)
 831 {
 832         struct event_trigger_data *data;
 833
 834         list_for_each_entry(data, &named_triggers, named_list) {
 835                 if (test == data)
 836                         return true;
 837         }
 838
 839         return false;
 840 }
 841
 842 /**
 843  * save_named_trigger - save the trigger in the named trigger list
 844  * @name: The name of the named trigger set
 845  * @data: The trigger data to save
 846  *
 847  * Return: 0 if successful, negative error otherwise.
 848  */
 849 int save_named_trigger(const char *name, struct event_trigger_data *data)
 850 {
 851         data->name = kstrdup(name, GFP_KERNEL);
 852         if (!data->name)
 853                 return -ENOMEM;
 854
 855         list_add(&data->named_list, &named_triggers);
 856
 857         return 0;
 858 }
 859
 860 /**
 861  * del_named_trigger - delete a trigger from the named trigger list
 862  * @data: The trigger data to delete
 863  */
 864 void del_named_trigger(struct event_trigger_data *data)
 865 {
 866         kfree(data->name);
 867         data->name = NULL;
 868
 869         list_del(&data->named_list);
 870 }
 871
 872 static void __pause_named_trigger(struct event_trigger_data *data, bool pause)
 873 {
 874         struct event_trigger_data *test;
 875
 876         list_for_each_entry(test, &named_triggers, named_list) {
 877                 if (strcmp(test->name, data->name) == 0) {
 878                         if (pause) {
 879                                 test->paused_tmp = test->paused;
 880                                 test->paused = true;
 881                         } else {
 882                                 test->paused = test->paused_tmp;
 883                         }
 884                 }
 885         }
 886 }
 887
 888 /**
 889  * pause_named_trigger - Pause all named triggers with the same name
 890  * @data: The trigger data of a named trigger to pause
 891  *
 892  * Pauses a named trigger along with all other triggers having the
 893  * same name.  Because named triggers share a common set of data,
 894  * pausing only one is meaningless, so pausing one named trigger needs
 895  * to pause all triggers with the same name.
 896  */
 897 void pause_named_trigger(struct event_trigger_data *data)
 898 {
 899         __pause_named_trigger(data, true);
 900 }
 901
 902 /**
 903  * unpause_named_trigger - Un-pause all named triggers with the same name
 904  * @data: The trigger data of a named trigger to unpause
 905  *
 906  * Un-pauses a named trigger along with all other triggers having the
 907  * same name.  Because named triggers share a common set of data,
 908  * unpausing only one is meaningless, so unpausing one named trigger
 909  * needs to unpause all triggers with the same name.
 910  */
 911 void unpause_named_trigger(struct event_trigger_data *data)
 912 {
 913         __pause_named_trigger(data, false);
 914 }
 915
 916 /**
 917  * set_named_trigger_data - Associate common named trigger data
 918  * @data: The trigger data of a named trigger to unpause
 919  *
 920  * Named triggers are sets of triggers that share a common set of
 921  * trigger data.  The first named trigger registered with a given name
 922  * owns the common trigger data that the others subsequently
 923  * registered with the same name will reference.  This function
 924  * associates the common trigger data from the first trigger with the
 925  * given trigger.
 926  */
 927 void set_named_trigger_data(struct event_trigger_data *data,
 928                             struct event_trigger_data *named_data)
 929 {
 930         data->named_data = named_data;
 931 }
 932
 933 struct event_trigger_data *
 934 get_named_trigger_data(struct event_trigger_data *data)
 935 {
 936         return data->named_data;
 937 }
 938
 939 static void
 940 traceon_trigger(struct event_trigger_data *data, void *rec,
 941                 struct ring_buffer_event *event)
 942 {
 943         if (tracing_is_on())
 944                 return;
 945
 946         tracing_on();
 947 }
 948
 949 static void
 950 traceon_count_trigger(struct event_trigger_data *data, void *rec,
 951                       struct ring_buffer_event *event)
 952 {
 953         if (tracing_is_on())
 954                 return;
 955
 956         if (!data->count)
 957                 return;
 958
 959         if (data->count != -1)
 960                 (data->count)--;
 961
 962         tracing_on();
 963 }
 964
 965 static void
 966 traceoff_trigger(struct event_trigger_data *data, void *rec,
 967                  struct ring_buffer_event *event)
 968 {
 969         if (!tracing_is_on())
 970                 return;
 971
 972         tracing_off();
 973 }
 974
 975 static void
 976 traceoff_count_trigger(struct event_trigger_data *data, void *rec,
 977                        struct ring_buffer_event *event)
 978 {
 979         if (!tracing_is_on())
 980                 return;
 981
 982         if (!data->count)
 983                 return;
 984
 985         if (data->count != -1)
 986                 (data->count)--;
 987
 988         tracing_off();
 989 }
 990
 991 static int
 992 traceon_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
 993                       struct event_trigger_data *data)
 994 {
 995         return event_trigger_print("traceon", m, (void *)data->count,
 996                                    data->filter_str);
 997 }
 998
 999 static int
1000 traceoff_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
1001                        struct event_trigger_data *data)
1002 {
1003         return event_trigger_print("traceoff", m, (void *)data->count,
1004                                    data->filter_str);
1005 }
1006
1007 static struct event_trigger_ops traceon_trigger_ops = {
1008         .func                   = traceon_trigger,
1009         .print                  = traceon_trigger_print,
1010         .init                   = event_trigger_init,
1011         .free                   = event_trigger_free,
1012 };
1013
1014 static struct event_trigger_ops traceon_count_trigger_ops = {
1015         .func                   = traceon_count_trigger,
1016         .print                  = traceon_trigger_print,
1017         .init                   = event_trigger_init,
1018         .free                   = event_trigger_free,
1019 };
1020
1021 static struct event_trigger_ops traceoff_trigger_ops = {
1022         .func                   = traceoff_trigger,
1023         .print                  = traceoff_trigger_print,
1024         .init                   = event_trigger_init,
1025         .free                   = event_trigger_free,
1026 };
1027
1028 static struct event_trigger_ops traceoff_count_trigger_ops = {
1029         .func                   = traceoff_count_trigger,
1030         .print                  = traceoff_trigger_print,
1031         .init                   = event_trigger_init,
1032         .free                   = event_trigger_free,
1033 };
1034
1035 static struct event_trigger_ops *
1036 onoff_get_trigger_ops(char *cmd, char *param)
1037 {
1038         struct event_trigger_ops *ops;
1039
1040         /* we register both traceon and traceoff to this callback */
1041         if (strcmp(cmd, "traceon") == 0)
1042                 ops = param ? &traceon_count_trigger_ops :
1043                         &traceon_trigger_ops;
1044         else
1045                 ops = param ? &traceoff_count_trigger_ops :
1046                         &traceoff_trigger_ops;
1047
1048         return ops;
1049 }
1050
1051 static struct event_command trigger_traceon_cmd = {
1052         .name                   = "traceon",
1053         .trigger_type           = ETT_TRACE_ONOFF,
1054         .func                   = event_trigger_callback,
1055         .reg                    = register_trigger,
1056         .unreg                  = unregister_trigger,
1057         .get_trigger_ops        = onoff_get_trigger_ops,
1058         .set_filter             = set_trigger_filter,
1059 };
1060
1061 static struct event_command trigger_traceoff_cmd = {
1062         .name                   = "traceoff",
1063         .trigger_type           = ETT_TRACE_ONOFF,
1064         .flags                  = EVENT_CMD_FL_POST_TRIGGER,
1065         .func                   = event_trigger_callback,
1066         .reg                    = register_trigger,
1067         .unreg                  = unregister_trigger,
1068         .get_trigger_ops        = onoff_get_trigger_ops,
1069         .set_filter             = set_trigger_filter,
1070 };
1071
1072 #ifdef CONFIG_TRACER_SNAPSHOT
1073 static void
1074 snapshot_trigger(struct event_trigger_data *data, void *rec,
1075                  struct ring_buffer_event *event)
1076 {
1077         struct trace_event_file *file = data->private_data;
1078
1079         if (file)
1080                 tracing_snapshot_instance(file->tr);
1081         else
1082                 tracing_snapshot();
1083 }
1084
1085 static void
1086 snapshot_count_trigger(struct event_trigger_data *data, void *rec,
1087                        struct ring_buffer_event *event)
1088 {
1089         if (!data->count)
1090                 return;
1091
1092         if (data->count != -1)
1093                 (data->count)--;
1094
1095         snapshot_trigger(data, rec, event);
1096 }
1097
1098 static int
1099 register_snapshot_trigger(char *glob, struct event_trigger_ops *ops,
1100                           struct event_trigger_data *data,
1101                           struct trace_event_file *file)
1102 {
1103         if (tracing_alloc_snapshot_instance(file->tr) != 0)
1104                 return 0;
1105
1106         return register_trigger(glob, ops, data, file);
1107 }
1108
1109 static int
1110 snapshot_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
1111                        struct event_trigger_data *data)
1112 {
1113         return event_trigger_print("snapshot", m, (void *)data->count,
1114                                    data->filter_str);
1115 }
1116
1117 static struct event_trigger_ops snapshot_trigger_ops = {
1118         .func                   = snapshot_trigger,
1119         .print                  = snapshot_trigger_print,
1120         .init                   = event_trigger_init,
1121         .free                   = event_trigger_free,
1122 };
1123
1124 static struct event_trigger_ops snapshot_count_trigger_ops = {
1125         .func                   = snapshot_count_trigger,
1126         .print                  = snapshot_trigger_print,
1127         .init                   = event_trigger_init,
1128         .free                   = event_trigger_free,
1129 };
1130
1131 static struct event_trigger_ops *
1132 snapshot_get_trigger_ops(char *cmd, char *param)
1133 {
1134         return param ? &snapshot_count_trigger_ops : &snapshot_trigger_ops;
1135 }
1136
1137 static struct event_command trigger_snapshot_cmd = {
1138         .name                   = "snapshot",
1139         .trigger_type           = ETT_SNAPSHOT,
1140         .func                   = event_trigger_callback,
1141         .reg                    = register_snapshot_trigger,
1142         .unreg                  = unregister_trigger,
1143         .get_trigger_ops        = snapshot_get_trigger_ops,
1144         .set_filter             = set_trigger_filter,
1145 };
1146
1147 static __init int register_trigger_snapshot_cmd(void)
1148 {
1149         int ret;
1150
1151         ret = register_event_command(&trigger_snapshot_cmd);
1152         WARN_ON(ret < 0);
1153
1154         return ret;
1155 }
1156 #else
1157 static __init int register_trigger_snapshot_cmd(void) { return 0; }
1158 #endif /* CONFIG_TRACER_SNAPSHOT */
1159
1160 #ifdef CONFIG_STACKTRACE
1161 #ifdef CONFIG_UNWINDER_ORC
1162 /* Skip 2:
1163  *   event_triggers_post_call()
1164  *   trace_event_raw_event_xxx()
1165  */
1166 # define STACK_SKIP 2
1167 #else
1168 /*
1169  * Skip 4:
1170  *   stacktrace_trigger()
1171  *   event_triggers_post_call()
1172  *   trace_event_buffer_commit()
1173  *   trace_event_raw_event_xxx()
1174  */
1175 #define STACK_SKIP 4
1176 #endif
1177
1178 static void
1179 stacktrace_trigger(struct event_trigger_data *data, void *rec,
1180                    struct ring_buffer_event *event)
1181 {
1182         trace_dump_stack(STACK_SKIP);
1183 }
1184
1185 static void
1186 stacktrace_count_trigger(struct event_trigger_data *data, void *rec,
1187                          struct ring_buffer_event *event)
1188 {
1189         if (!data->count)
1190                 return;
1191
1192         if (data->count != -1)
1193                 (data->count)--;
1194
1195         stacktrace_trigger(data, rec, event);
1196 }
1197
1198 static int
1199 stacktrace_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
1200                          struct event_trigger_data *data)
1201 {
1202         return event_trigger_print("stacktrace", m, (void *)data->count,
1203                                    data->filter_str);
1204 }
1205
1206 static struct event_trigger_ops stacktrace_trigger_ops = {
1207         .func                   = stacktrace_trigger,
1208         .print                  = stacktrace_trigger_print,
1209         .init                   = event_trigger_init,
1210         .free                   = event_trigger_free,
1211 };
1212
1213 static struct event_trigger_ops stacktrace_count_trigger_ops = {
1214         .func                   = stacktrace_count_trigger,
1215         .print                  = stacktrace_trigger_print,
1216         .init                   = event_trigger_init,
1217         .free                   = event_trigger_free,
1218 };
1219
1220 static struct event_trigger_ops *
1221 stacktrace_get_trigger_ops(char *cmd, char *param)
1222 {
1223         return param ? &stacktrace_count_trigger_ops : &stacktrace_trigger_ops;
1224 }
1225
1226 static struct event_command trigger_stacktrace_cmd = {
1227         .name                   = "stacktrace",
1228         .trigger_type           = ETT_STACKTRACE,
1229         .flags                  = EVENT_CMD_FL_POST_TRIGGER,
1230         .func                   = event_trigger_callback,
1231         .reg                    = register_trigger,
1232         .unreg                  = unregister_trigger,
1233         .get_trigger_ops        = stacktrace_get_trigger_ops,
1234         .set_filter             = set_trigger_filter,
1235 };
1236
1237 static __init int register_trigger_stacktrace_cmd(void)
1238 {
1239         int ret;
1240
1241         ret = register_event_command(&trigger_stacktrace_cmd);
1242         WARN_ON(ret < 0);
1243
1244         return ret;
1245 }
1246 #else
1247 static __init int register_trigger_stacktrace_cmd(void) { return 0; }
1248 #endif /* CONFIG_STACKTRACE */
1249
1250 static __init void unregister_trigger_traceon_traceoff_cmds(void)
1251 {
1252         unregister_event_command(&trigger_traceon_cmd);
1253         unregister_event_command(&trigger_traceoff_cmd);
1254 }
1255
1256 static void
1257 event_enable_trigger(struct event_trigger_data *data, void *rec,
1258                      struct ring_buffer_event *event)
1259 {
1260         struct enable_trigger_data *enable_data = data->private_data;
1261
1262         if (enable_data->enable)
1263                 clear_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
1264         else
1265                 set_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
1266 }
1267
1268 static void
1269 event_enable_count_trigger(struct event_trigger_data *data, void *rec,
1270                            struct ring_buffer_event *event)
1271 {
1272         struct enable_trigger_data *enable_data = data->private_data;
1273
1274         if (!data->count)
1275                 return;
1276
1277         /* Skip if the event is in a state we want to switch to */
1278         if (enable_data->enable == !(enable_data->file->flags & EVENT_FILE_FL_SOFT_DISABLED))
1279                 return;
1280
1281         if (data->count != -1)
1282                 (data->count)--;
1283
1284         event_enable_trigger(data, rec, event);
1285 }
1286
1287 int event_enable_trigger_print(struct seq_file *m,
1288                                struct event_trigger_ops *ops,
1289                                struct event_trigger_data *data)
1290 {
1291         struct enable_trigger_data *enable_data = data->private_data;
1292
1293         seq_printf(m, "%s:%s:%s",
1294                    enable_data->hist ?
1295                    (enable_data->enable ? ENABLE_HIST_STR : DISABLE_HIST_STR) :
1296                    (enable_data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR),
1297                    enable_data->file->event_call->class->system,
1298                    trace_event_name(enable_data->file->event_call));
1299
1300         if (data->count == -1)
1301                 seq_puts(m, ":unlimited");
1302         else
1303                 seq_printf(m, ":count=%ld", data->count);
1304
1305         if (data->filter_str)
1306                 seq_printf(m, " if %s\n", data->filter_str);
1307         else
1308                 seq_putc(m, '\n');
1309
1310         return 0;
1311 }
1312
1313 void event_enable_trigger_free(struct event_trigger_ops *ops,
1314                                struct event_trigger_data *data)
1315 {
1316         struct enable_trigger_data *enable_data = data->private_data;
1317
1318         if (WARN_ON_ONCE(data->ref <= 0))
1319                 return;
1320
1321         data->ref--;
1322         if (!data->ref) {
1323                 /* Remove the SOFT_MODE flag */
1324                 trace_event_enable_disable(enable_data->file, 0, 1);
1325                 module_put(enable_data->file->event_call->mod);
1326                 trigger_data_free(data);
1327                 kfree(enable_data);
1328         }
1329 }
1330
1331 static struct event_trigger_ops event_enable_trigger_ops = {
1332         .func                   = event_enable_trigger,
1333         .print                  = event_enable_trigger_print,
1334         .init                   = event_trigger_init,
1335         .free                   = event_enable_trigger_free,
1336 };
1337
1338 static struct event_trigger_ops event_enable_count_trigger_ops = {
1339         .func                   = event_enable_count_trigger,
1340         .print                  = event_enable_trigger_print,
1341         .init                   = event_trigger_init,
1342         .free                   = event_enable_trigger_free,
1343 };
1344
1345 static struct event_trigger_ops event_disable_trigger_ops = {
1346         .func                   = event_enable_trigger,
1347         .print                  = event_enable_trigger_print,
1348         .init                   = event_trigger_init,
1349         .free                   = event_enable_trigger_free,
1350 };
1351
1352 static struct event_trigger_ops event_disable_count_trigger_ops = {
1353         .func                   = event_enable_count_trigger,
1354         .print                  = event_enable_trigger_print,
1355         .init                   = event_trigger_init,
1356         .free                   = event_enable_trigger_free,
1357 };
1358
1359 int event_enable_trigger_func(struct event_command *cmd_ops,
1360                               struct trace_event_file *file,
1361                               char *glob, char *cmd, char *param)
1362 {
1363         struct trace_event_file *event_enable_file;
1364         struct enable_trigger_data *enable_data;
1365         struct event_trigger_data *trigger_data;
1366         struct event_trigger_ops *trigger_ops;
1367         struct trace_array *tr = file->tr;
1368         const char *system;
1369         const char *event;
1370         bool hist = false;
1371         char *trigger;
1372         char *number;
1373         bool enable;
1374         int ret;
1375
1376         if (!param)
1377                 return -EINVAL;
1378
1379         /* separate the trigger from the filter (s:e:n [if filter]) */
1380         trigger = strsep(&param, " \t");
1381         if (!trigger)
1382                 return -EINVAL;
1383         if (param) {
1384                 param = skip_spaces(param);
1385                 if (!*param)
1386                         param = NULL;
1387         }
1388
1389         system = strsep(&trigger, ":");
1390         if (!trigger)
1391                 return -EINVAL;
1392
1393         event = strsep(&trigger, ":");
1394
1395         ret = -EINVAL;
1396         event_enable_file = find_event_file(tr, system, event);
1397         if (!event_enable_file)
1398                 goto out;
1399
1400 #ifdef CONFIG_HIST_TRIGGERS
1401         hist = ((strcmp(cmd, ENABLE_HIST_STR) == 0) ||
1402                 (strcmp(cmd, DISABLE_HIST_STR) == 0));
1403
1404         enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
1405                   (strcmp(cmd, ENABLE_HIST_STR) == 0));
1406 #else
1407         enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
1408 #endif
1409         trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
1410
1411         ret = -ENOMEM;
1412         trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
1413         if (!trigger_data)
1414                 goto out;
1415
1416         enable_data = kzalloc(sizeof(*enable_data), GFP_KERNEL);
1417         if (!enable_data) {
1418                 kfree(trigger_data);
1419                 goto out;
1420         }
1421
1422         trigger_data->count = -1;
1423         trigger_data->ops = trigger_ops;
1424         trigger_data->cmd_ops = cmd_ops;
1425         INIT_LIST_HEAD(&trigger_data->list);
1426         RCU_INIT_POINTER(trigger_data->filter, NULL);
1427
1428         enable_data->hist = hist;
1429         enable_data->enable = enable;
1430         enable_data->file = event_enable_file;
1431         trigger_data->private_data = enable_data;
1432
1433         if (glob[0] == '!') {
1434                 cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
1435                 kfree(trigger_data);
1436                 kfree(enable_data);
1437                 ret = 0;
1438                 goto out;
1439         }
1440
1441         /* Up the trigger_data count to make sure nothing frees it on failure */
1442         event_trigger_init(trigger_ops, trigger_data);
1443
1444         if (trigger) {
1445                 number = strsep(&trigger, ":");
1446
1447                 ret = -EINVAL;
1448                 if (!strlen(number))
1449                         goto out_free;
1450
1451                 /*
1452                  * We use the callback data field (which is a pointer)
1453                  * as our counter.
1454                  */
1455                 ret = kstrtoul(number, 0, &trigger_data->count);
1456                 if (ret)
1457                         goto out_free;
1458         }
1459
1460         if (!param) /* if param is non-empty, it's supposed to be a filter */
1461                 goto out_reg;
1462
1463         if (!cmd_ops->set_filter)
1464                 goto out_reg;
1465
1466         ret = cmd_ops->set_filter(param, trigger_data, file);
1467         if (ret < 0)
1468                 goto out_free;
1469
1470  out_reg:
1471         /* Don't let event modules unload while probe registered */
1472         ret = try_module_get(event_enable_file->event_call->mod);
1473         if (!ret) {
1474                 ret = -EBUSY;
1475                 goto out_free;
1476         }
1477
1478         ret = trace_event_enable_disable(event_enable_file, 1, 1);
1479         if (ret < 0)
1480                 goto out_put;
1481         ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);
1482         /*
1483          * The above returns on success the # of functions enabled,
1484          * but if it didn't find any functions it returns zero.
1485          * Consider no functions a failure too.
1486          */
1487         if (!ret) {
1488                 ret = -ENOENT;
1489                 goto out_disable;
1490         } else if (ret < 0)
1491                 goto out_disable;
1492         /* Just return zero, not the number of enabled functions */
1493         ret = 0;
1494         event_trigger_free(trigger_ops, trigger_data);
1495  out:
1496         return ret;
1497
1498  out_disable:
1499         trace_event_enable_disable(event_enable_file, 0, 1);
1500  out_put:
1501         module_put(event_enable_file->event_call->mod);
1502  out_free:
1503         if (cmd_ops->set_filter)
1504                 cmd_ops->set_filter(NULL, trigger_data, NULL);
1505         event_trigger_free(trigger_ops, trigger_data);
1506         kfree(enable_data);
1507         goto out;
1508 }
1509
1510 int event_enable_register_trigger(char *glob,
1511                                   struct event_trigger_ops *ops,
1512                                   struct event_trigger_data *data,
1513                                   struct trace_event_file *file)
1514 {
1515         struct enable_trigger_data *enable_data = data->private_data;
1516         struct enable_trigger_data *test_enable_data;
1517         struct event_trigger_data *test;
1518         int ret = 0;
1519
1520         lockdep_assert_held(&event_mutex);
1521
1522         list_for_each_entry(test, &file->triggers, list) {
1523                 test_enable_data = test->private_data;
1524                 if (test_enable_data &&
1525                     (test->cmd_ops->trigger_type ==
1526                      data->cmd_ops->trigger_type) &&
1527                     (test_enable_data->file == enable_data->file)) {
1528                         ret = -EEXIST;
1529                         goto out;
1530                 }
1531         }
1532
1533         if (data->ops->init) {
1534                 ret = data->ops->init(data->ops, data);
1535                 if (ret < 0)
1536                         goto out;
1537         }
1538
1539         list_add_rcu(&data->list, &file->triggers);
1540         ret++;
1541
1542         update_cond_flag(file);
1543         if (trace_event_trigger_enable_disable(file, 1) < 0) {
1544                 list_del_rcu(&data->list);
1545                 update_cond_flag(file);
1546                 ret--;
1547         }
1548 out:
1549         return ret;
1550 }
1551
1552 void event_enable_unregister_trigger(char *glob,
1553                                      struct event_trigger_ops *ops,
1554                                      struct event_trigger_data *test,
1555                                      struct trace_event_file *file)
1556 {
1557         struct enable_trigger_data *test_enable_data = test->private_data;
1558         struct enable_trigger_data *enable_data;
1559         struct event_trigger_data *data;
1560         bool unregistered = false;
1561
1562         lockdep_assert_held(&event_mutex);
1563
1564         list_for_each_entry(data, &file->triggers, list) {
1565                 enable_data = data->private_data;
1566                 if (enable_data &&
1567                     (data->cmd_ops->trigger_type ==
1568                      test->cmd_ops->trigger_type) &&
1569                     (enable_data->file == test_enable_data->file)) {
1570                         unregistered = true;
1571                         list_del_rcu(&data->list);
1572                         trace_event_trigger_enable_disable(file, 0);
1573                         update_cond_flag(file);
1574                         break;
1575                 }
1576         }
1577
1578         if (unregistered && data->ops->free)
1579                 data->ops->free(data->ops, data);
1580 }
1581
1582 static struct event_trigger_ops *
1583 event_enable_get_trigger_ops(char *cmd, char *param)
1584 {
1585         struct event_trigger_ops *ops;
1586         bool enable;
1587
1588 #ifdef CONFIG_HIST_TRIGGERS
1589         enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
1590                   (strcmp(cmd, ENABLE_HIST_STR) == 0));
1591 #else
1592         enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
1593 #endif
1594         if (enable)
1595                 ops = param ? &event_enable_count_trigger_ops :
1596                         &event_enable_trigger_ops;
1597         else
1598                 ops = param ? &event_disable_count_trigger_ops :
1599                         &event_disable_trigger_ops;
1600
1601         return ops;
1602 }
1603
1604 static struct event_command trigger_enable_cmd = {
1605         .name                   = ENABLE_EVENT_STR,
1606         .trigger_type           = ETT_EVENT_ENABLE,
1607         .func                   = event_enable_trigger_func,
1608         .reg                    = event_enable_register_trigger,
1609         .unreg                  = event_enable_unregister_trigger,
1610         .get_trigger_ops        = event_enable_get_trigger_ops,
1611         .set_filter             = set_trigger_filter,
1612 };
1613
1614 static struct event_command trigger_disable_cmd = {
1615         .name                   = DISABLE_EVENT_STR,
1616         .trigger_type           = ETT_EVENT_ENABLE,
1617         .func                   = event_enable_trigger_func,
1618         .reg                    = event_enable_register_trigger,
1619         .unreg                  = event_enable_unregister_trigger,
1620         .get_trigger_ops        = event_enable_get_trigger_ops,
1621         .set_filter             = set_trigger_filter,
1622 };
1623
1624 static __init void unregister_trigger_enable_disable_cmds(void)
1625 {
1626         unregister_event_command(&trigger_enable_cmd);
1627         unregister_event_command(&trigger_disable_cmd);
1628 }
1629
1630 static __init int register_trigger_enable_disable_cmds(void)
1631 {
1632         int ret;
1633
1634         ret = register_event_command(&trigger_enable_cmd);
1635         if (WARN_ON(ret < 0))
1636                 return ret;
1637         ret = register_event_command(&trigger_disable_cmd);
1638         if (WARN_ON(ret < 0))
1639                 unregister_trigger_enable_disable_cmds();
1640
1641         return ret;
1642 }
1643
1644 static __init int register_trigger_traceon_traceoff_cmds(void)
1645 {
1646         int ret;
1647
1648         ret = register_event_command(&trigger_traceon_cmd);
1649         if (WARN_ON(ret < 0))
1650                 return ret;
1651         ret = register_event_command(&trigger_traceoff_cmd);
1652         if (WARN_ON(ret < 0))
1653                 unregister_trigger_traceon_traceoff_cmds();
1654
1655         return ret;
1656 }
1657
1658 __init int register_trigger_cmds(void)
1659 {
1660         register_trigger_traceon_traceoff_cmds();
1661         register_trigger_snapshot_cmd();
1662         register_trigger_stacktrace_cmd();
1663         register_trigger_enable_disable_cmds();
1664         register_trigger_hist_enable_disable_cmds();
1665         register_trigger_hist_cmd();
1666
1667         return 0;
1668 }