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 #include <linux/rculist.h>
  26
  27 #include "trace.h"
  28
  29 static LIST_HEAD(trigger_commands);
  30 static DEFINE_MUTEX(trigger_cmd_mutex);
  31
  32 void 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                     struct ring_buffer_event *event)
  68 {
  69         struct event_trigger_data *data;
  70         enum event_trigger_type tt = ETT_NONE;
  71         struct event_filter *filter;
  72
  73         if (list_empty(&file->triggers))
  74                 return tt;
  75
  76         list_for_each_entry_rcu(data, &file->triggers, list) {
  77                 if (data->paused)
  78                         continue;
  79                 if (!rec) {
  80                         data->ops->func(data, rec, event);
  81                         continue;
  82                 }
  83                 filter = rcu_dereference_sched(data->filter);
  84                 if (filter && !filter_match_preds(filter, rec))
  85                         continue;
  86                 if (event_command_post_trigger(data->cmd_ops)) {
  87                         tt |= data->cmd_ops->trigger_type;
  88                         continue;
  89                 }
  90                 data->ops->func(data, rec, event);
  91         }
  92         return tt;
  93 }
  94 EXPORT_SYMBOL_GPL(event_triggers_call);
  95
  96 /**
  97  * event_triggers_post_call - Call 'post_triggers' for a trace event
  98  * @file: The trace_event_file associated with the event
  99  * @tt: enum event_trigger_type containing a set bit for each trigger to invoke
 100  *
 101  * For each trigger associated with an event, invoke the trigger
 102  * function registered with the associated trigger command, if the
 103  * corresponding bit is set in the tt enum passed into this function.
 104  * See @event_triggers_call for details on how those bits are set.
 105  *
 106  * Called from tracepoint handlers (with rcu_read_lock_sched() held).
 107  */
 108 void
 109 event_triggers_post_call(struct trace_event_file *file,
 110                          enum event_trigger_type tt)
 111 {
 112         struct event_trigger_data *data;
 113
 114         list_for_each_entry_rcu(data, &file->triggers, list) {
 115                 if (data->paused)
 116                         continue;
 117                 if (data->cmd_ops->trigger_type & tt)
 118                         data->ops->func(data, NULL, NULL);
 119         }
 120 }
 121 EXPORT_SYMBOL_GPL(event_triggers_post_call);
 122
 123 #define SHOW_AVAILABLE_TRIGGERS (void *)(1UL)
 124
 125 static void *trigger_next(struct seq_file *m, void *t, loff_t *pos)
 126 {
 127         struct trace_event_file *event_file = event_file_data(m->private);
 128
 129         if (t == SHOW_AVAILABLE_TRIGGERS)
 130                 return NULL;
 131
 132         return seq_list_next(t, &event_file->triggers, pos);
 133 }
 134
 135 static void *trigger_start(struct seq_file *m, loff_t *pos)
 136 {
 137         struct trace_event_file *event_file;
 138
 139         /* ->stop() is called even if ->start() fails */
 140         mutex_lock(&event_mutex);
 141         event_file = event_file_data(m->private);
 142         if (unlikely(!event_file))
 143                 return ERR_PTR(-ENODEV);
 144
 145         if (list_empty(&event_file->triggers))
 146                 return *pos == 0 ? SHOW_AVAILABLE_TRIGGERS : NULL;
 147
 148         return seq_list_start(&event_file->triggers, *pos);
 149 }
 150
 151 static void trigger_stop(struct seq_file *m, void *t)
 152 {
 153         mutex_unlock(&event_mutex);
 154 }
 155
 156 static int trigger_show(struct seq_file *m, void *v)
 157 {
 158         struct event_trigger_data *data;
 159         struct event_command *p;
 160
 161         if (v == SHOW_AVAILABLE_TRIGGERS) {
 162                 seq_puts(m, "# Available triggers:\n");
 163                 seq_putc(m, '#');
 164                 mutex_lock(&trigger_cmd_mutex);
 165                 list_for_each_entry_reverse(p, &trigger_commands, list)
 166                         seq_printf(m, " %s", p->name);
 167                 seq_putc(m, '\n');
 168                 mutex_unlock(&trigger_cmd_mutex);
 169                 return 0;
 170         }
 171
 172         data = list_entry(v, struct event_trigger_data, list);
 173         data->ops->print(m, data->ops, data);
 174
 175         return 0;
 176 }
 177
 178 static const struct seq_operations event_triggers_seq_ops = {
 179         .start = trigger_start,
 180         .next = trigger_next,
 181         .stop = trigger_stop,
 182         .show = trigger_show,
 183 };
 184
 185 static int event_trigger_regex_open(struct inode *inode, struct file *file)
 186 {
 187         int ret = 0;
 188
 189         mutex_lock(&event_mutex);
 190
 191         if (unlikely(!event_file_data(file))) {
 192                 mutex_unlock(&event_mutex);
 193                 return -ENODEV;
 194         }
 195
 196         if ((file->f_mode & FMODE_WRITE) &&
 197             (file->f_flags & O_TRUNC)) {
 198                 struct trace_event_file *event_file;
 199                 struct event_command *p;
 200
 201                 event_file = event_file_data(file);
 202
 203                 list_for_each_entry(p, &trigger_commands, list) {
 204                         if (p->unreg_all)
 205                                 p->unreg_all(event_file);
 206                 }
 207         }
 208
 209         if (file->f_mode & FMODE_READ) {
 210                 ret = seq_open(file, &event_triggers_seq_ops);
 211                 if (!ret) {
 212                         struct seq_file *m = file->private_data;
 213                         m->private = file;
 214                 }
 215         }
 216
 217         mutex_unlock(&event_mutex);
 218
 219         return ret;
 220 }
 221
 222 static int trigger_process_regex(struct trace_event_file *file, char *buff)
 223 {
 224         char *command, *next = buff;
 225         struct event_command *p;
 226         int ret = -EINVAL;
 227
 228         command = strsep(&next, ": \t");
 229         command = (command[0] != '!') ? command : command + 1;
 230
 231         mutex_lock(&trigger_cmd_mutex);
 232         list_for_each_entry(p, &trigger_commands, list) {
 233                 if (strcmp(p->name, command) == 0) {
 234                         ret = p->func(p, file, buff, command, next);
 235                         goto out_unlock;
 236                 }
 237         }
 238  out_unlock:
 239         mutex_unlock(&trigger_cmd_mutex);
 240
 241         return ret;
 242 }
 243
 244 static ssize_t event_trigger_regex_write(struct file *file,
 245                                          const char __user *ubuf,
 246                                          size_t cnt, loff_t *ppos)
 247 {
 248         struct trace_event_file *event_file;
 249         ssize_t ret;
 250         char *buf;
 251
 252         if (!cnt)
 253                 return 0;
 254
 255         if (cnt >= PAGE_SIZE)
 256                 return -EINVAL;
 257
 258         buf = memdup_user_nul(ubuf, cnt);
 259         if (IS_ERR(buf))
 260                 return PTR_ERR(buf);
 261
 262         strim(buf);
 263
 264         mutex_lock(&event_mutex);
 265         event_file = event_file_data(file);
 266         if (unlikely(!event_file)) {
 267                 mutex_unlock(&event_mutex);
 268                 kfree(buf);
 269                 return -ENODEV;
 270         }
 271         ret = trigger_process_regex(event_file, buf);
 272         mutex_unlock(&event_mutex);
 273
 274         kfree(buf);
 275         if (ret < 0)
 276                 goto out;
 277
 278         *ppos += cnt;
 279         ret = cnt;
 280  out:
 281         return ret;
 282 }
 283
 284 static int event_trigger_regex_release(struct inode *inode, struct file *file)
 285 {
 286         mutex_lock(&event_mutex);
 287
 288         if (file->f_mode & FMODE_READ)
 289                 seq_release(inode, file);
 290
 291         mutex_unlock(&event_mutex);
 292
 293         return 0;
 294 }
 295
 296 static ssize_t
 297 event_trigger_write(struct file *filp, const char __user *ubuf,
 298                     size_t cnt, loff_t *ppos)
 299 {
 300         return event_trigger_regex_write(filp, ubuf, cnt, ppos);
 301 }
 302
 303 static int
 304 event_trigger_open(struct inode *inode, struct file *filp)
 305 {
 306         return event_trigger_regex_open(inode, filp);
 307 }
 308
 309 static int
 310 event_trigger_release(struct inode *inode, struct file *file)
 311 {
 312         return event_trigger_regex_release(inode, file);
 313 }
 314
 315 const struct file_operations event_trigger_fops = {
 316         .open = event_trigger_open,
 317         .read = seq_read,
 318         .write = event_trigger_write,
 319         .llseek = tracing_lseek,
 320         .release = event_trigger_release,
 321 };
 322
 323 /*
 324  * Currently we only register event commands from __init, so mark this
 325  * __init too.
 326  */
 327 __init int register_event_command(struct event_command *cmd)
 328 {
 329         struct event_command *p;
 330         int ret = 0;
 331
 332         mutex_lock(&trigger_cmd_mutex);
 333         list_for_each_entry(p, &trigger_commands, list) {
 334                 if (strcmp(cmd->name, p->name) == 0) {
 335                         ret = -EBUSY;
 336                         goto out_unlock;
 337                 }
 338         }
 339         list_add(&cmd->list, &trigger_commands);
 340  out_unlock:
 341         mutex_unlock(&trigger_cmd_mutex);
 342
 343         return ret;
 344 }
 345
 346 /*
 347  * Currently we only unregister event commands from __init, so mark
 348  * this __init too.
 349  */
 350 __init int unregister_event_command(struct event_command *cmd)
 351 {
 352         struct event_command *p, *n;
 353         int ret = -ENODEV;
 354
 355         mutex_lock(&trigger_cmd_mutex);
 356         list_for_each_entry_safe(p, n, &trigger_commands, list) {
 357                 if (strcmp(cmd->name, p->name) == 0) {
 358                         ret = 0;
 359                         list_del_init(&p->list);
 360                         goto out_unlock;
 361                 }
 362         }
 363  out_unlock:
 364         mutex_unlock(&trigger_cmd_mutex);
 365
 366         return ret;
 367 }
 368
 369 /**
 370  * event_trigger_print - Generic event_trigger_ops @print implementation
 371  * @name: The name of the event trigger
 372  * @m: The seq_file being printed to
 373  * @data: Trigger-specific data
 374  * @filter_str: filter_str to print, if present
 375  *
 376  * Common implementation for event triggers to print themselves.
 377  *
 378  * Usually wrapped by a function that simply sets the @name of the
 379  * trigger command and then invokes this.
 380  *
 381  * Return: 0 on success, errno otherwise
 382  */
 383 static int
 384 event_trigger_print(const char *name, struct seq_file *m,
 385                     void *data, char *filter_str)
 386 {
 387         long count = (long)data;
 388
 389         seq_puts(m, name);
 390
 391         if (count == -1)
 392                 seq_puts(m, ":unlimited");
 393         else
 394                 seq_printf(m, ":count=%ld", count);
 395
 396         if (filter_str)
 397                 seq_printf(m, " if %s\n", filter_str);
 398         else
 399                 seq_putc(m, '\n');
 400
 401         return 0;
 402 }
 403
 404 /**
 405  * event_trigger_init - Generic event_trigger_ops @init implementation
 406  * @ops: The trigger ops associated with the trigger
 407  * @data: Trigger-specific data
 408  *
 409  * Common implementation of event trigger initialization.
 410  *
 411  * Usually used directly as the @init method in event trigger
 412  * implementations.
 413  *
 414  * Return: 0 on success, errno otherwise
 415  */
 416 int event_trigger_init(struct event_trigger_ops *ops,
 417                        struct event_trigger_data *data)
 418 {
 419         data->ref++;
 420         return 0;
 421 }
 422
 423 /**
 424  * event_trigger_free - Generic event_trigger_ops @free implementation
 425  * @ops: The trigger ops associated with the trigger
 426  * @data: Trigger-specific data
 427  *
 428  * Common implementation of event trigger de-initialization.
 429  *
 430  * Usually used directly as the @free method in event trigger
 431  * implementations.
 432  */
 433 static void
 434 event_trigger_free(struct event_trigger_ops *ops,
 435                    struct event_trigger_data *data)
 436 {
 437         if (WARN_ON_ONCE(data->ref <= 0))
 438                 return;
 439
 440         data->ref--;
 441         if (!data->ref)
 442                 trigger_data_free(data);
 443 }
 444
 445 int trace_event_trigger_enable_disable(struct trace_event_file *file,
 446                                        int trigger_enable)
 447 {
 448         int ret = 0;
 449
 450         if (trigger_enable) {
 451                 if (atomic_inc_return(&file->tm_ref) > 1)
 452                         return ret;
 453                 set_bit(EVENT_FILE_FL_TRIGGER_MODE_BIT, &file->flags);
 454                 ret = trace_event_enable_disable(file, 1, 1);
 455         } else {
 456                 if (atomic_dec_return(&file->tm_ref) > 0)
 457                         return ret;
 458                 clear_bit(EVENT_FILE_FL_TRIGGER_MODE_BIT, &file->flags);
 459                 ret = trace_event_enable_disable(file, 0, 1);
 460         }
 461
 462         return ret;
 463 }
 464
 465 /**
 466  * clear_event_triggers - Clear all triggers associated with a trace array
 467  * @tr: The trace array to clear
 468  *
 469  * For each trigger, the triggering event has its tm_ref decremented
 470  * via trace_event_trigger_enable_disable(), and any associated event
 471  * (in the case of enable/disable_event triggers) will have its sm_ref
 472  * decremented via free()->trace_event_enable_disable().  That
 473  * combination effectively reverses the soft-mode/trigger state added
 474  * by trigger registration.
 475  *
 476  * Must be called with event_mutex held.
 477  */
 478 void
 479 clear_event_triggers(struct trace_array *tr)
 480 {
 481         struct trace_event_file *file;
 482
 483         list_for_each_entry(file, &tr->events, list) {
 484                 struct event_trigger_data *data, *n;
 485                 list_for_each_entry_safe(data, n, &file->triggers, list) {
 486                         trace_event_trigger_enable_disable(file, 0);
 487                         list_del_rcu(&data->list);
 488                         if (data->ops->free)
 489                                 data->ops->free(data->ops, data);
 490                 }
 491         }
 492 }
 493
 494 /**
 495  * update_cond_flag - Set or reset the TRIGGER_COND bit
 496  * @file: The trace_event_file associated with the event
 497  *
 498  * If an event has triggers and any of those triggers has a filter or
 499  * a post_trigger, trigger invocation needs to be deferred until after
 500  * the current event has logged its data, and the event should have
 501  * its TRIGGER_COND bit set, otherwise the TRIGGER_COND bit should be
 502  * cleared.
 503  */
 504 void update_cond_flag(struct trace_event_file *file)
 505 {
 506         struct event_trigger_data *data;
 507         bool set_cond = false;
 508
 509         list_for_each_entry_rcu(data, &file->triggers, list) {
 510                 if (data->filter || event_command_post_trigger(data->cmd_ops) ||
 511                     event_command_needs_rec(data->cmd_ops)) {
 512                         set_cond = true;
 513                         break;
 514                 }
 515         }
 516
 517         if (set_cond)
 518                 set_bit(EVENT_FILE_FL_TRIGGER_COND_BIT, &file->flags);
 519         else
 520                 clear_bit(EVENT_FILE_FL_TRIGGER_COND_BIT, &file->flags);
 521 }
 522
 523 /**
 524  * register_trigger - Generic event_command @reg implementation
 525  * @glob: The raw string used to register the trigger
 526  * @ops: The trigger ops associated with the trigger
 527  * @data: Trigger-specific data to associate with the trigger
 528  * @file: The trace_event_file associated with the event
 529  *
 530  * Common implementation for event trigger registration.
 531  *
 532  * Usually used directly as the @reg method in event command
 533  * implementations.
 534  *
 535  * Return: 0 on success, errno otherwise
 536  */
 537 static int register_trigger(char *glob, struct event_trigger_ops *ops,
 538                             struct event_trigger_data *data,
 539                             struct trace_event_file *file)
 540 {
 541         struct event_trigger_data *test;
 542         int ret = 0;
 543
 544         list_for_each_entry_rcu(test, &file->triggers, list) {
 545                 if (test->cmd_ops->trigger_type == data->cmd_ops->trigger_type) {
 546                         ret = -EEXIST;
 547                         goto out;
 548                 }
 549         }
 550
 551         if (data->ops->init) {
 552                 ret = data->ops->init(data->ops, data);
 553                 if (ret < 0)
 554                         goto out;
 555         }
 556
 557         list_add_rcu(&data->list, &file->triggers);
 558         ret++;
 559
 560         update_cond_flag(file);
 561         if (trace_event_trigger_enable_disable(file, 1) < 0) {
 562                 list_del_rcu(&data->list);
 563                 update_cond_flag(file);
 564                 ret--;
 565         }
 566 out:
 567         return ret;
 568 }
 569
 570 /**
 571  * unregister_trigger - Generic event_command @unreg implementation
 572  * @glob: The raw string used to register the trigger
 573  * @ops: The trigger ops associated with the trigger
 574  * @test: Trigger-specific data used to find the trigger to remove
 575  * @file: The trace_event_file associated with the event
 576  *
 577  * Common implementation for event trigger unregistration.
 578  *
 579  * Usually used directly as the @unreg method in event command
 580  * implementations.
 581  */
 582 void unregister_trigger(char *glob, struct event_trigger_ops *ops,
 583                         struct event_trigger_data *test,
 584                         struct trace_event_file *file)
 585 {
 586         struct event_trigger_data *data;
 587         bool unregistered = false;
 588
 589         list_for_each_entry_rcu(data, &file->triggers, list) {
 590                 if (data->cmd_ops->trigger_type == test->cmd_ops->trigger_type) {
 591                         unregistered = true;
 592                         list_del_rcu(&data->list);
 593                         trace_event_trigger_enable_disable(file, 0);
 594                         update_cond_flag(file);
 595                         break;
 596                 }
 597         }
 598
 599         if (unregistered && data->ops->free)
 600                 data->ops->free(data->ops, data);
 601 }
 602
 603 /**
 604  * event_trigger_callback - Generic event_command @func implementation
 605  * @cmd_ops: The command ops, used for trigger registration
 606  * @file: The trace_event_file associated with the event
 607  * @glob: The raw string used to register the trigger
 608  * @cmd: The cmd portion of the string used to register the trigger
 609  * @param: The params portion of the string used to register the trigger
 610  *
 611  * Common implementation for event command parsing and trigger
 612  * instantiation.
 613  *
 614  * Usually used directly as the @func method in event command
 615  * implementations.
 616  *
 617  * Return: 0 on success, errno otherwise
 618  */
 619 static int
 620 event_trigger_callback(struct event_command *cmd_ops,
 621                        struct trace_event_file *file,
 622                        char *glob, char *cmd, char *param)
 623 {
 624         struct event_trigger_data *trigger_data;
 625         struct event_trigger_ops *trigger_ops;
 626         char *trigger = NULL;
 627         char *number;
 628         int ret;
 629
 630         /* separate the trigger from the filter (t:n [if filter]) */
 631         if (param && isdigit(param[0]))
 632                 trigger = strsep(&param, " \t");
 633
 634         trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
 635
 636         ret = -ENOMEM;
 637         trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
 638         if (!trigger_data)
 639                 goto out;
 640
 641         trigger_data->count = -1;
 642         trigger_data->ops = trigger_ops;
 643         trigger_data->cmd_ops = cmd_ops;
 644         trigger_data->private_data = file;
 645         INIT_LIST_HEAD(&trigger_data->list);
 646         INIT_LIST_HEAD(&trigger_data->named_list);
 647
 648         if (glob[0] == '!') {
 649                 cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
 650                 kfree(trigger_data);
 651                 ret = 0;
 652                 goto out;
 653         }
 654
 655         if (trigger) {
 656                 number = strsep(&trigger, ":");
 657
 658                 ret = -EINVAL;
 659                 if (!strlen(number))
 660                         goto out_free;
 661
 662                 /*
 663                  * We use the callback data field (which is a pointer)
 664                  * as our counter.
 665                  */
 666                 ret = kstrtoul(number, 0, &trigger_data->count);
 667                 if (ret)
 668                         goto out_free;
 669         }
 670
 671         if (!param) /* if param is non-empty, it's supposed to be a filter */
 672                 goto out_reg;
 673
 674         if (!cmd_ops->set_filter)
 675                 goto out_reg;
 676
 677         ret = cmd_ops->set_filter(param, trigger_data, file);
 678         if (ret < 0)
 679                 goto out_free;
 680
 681  out_reg:
 682         ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);
 683         /*
 684          * The above returns on success the # of functions enabled,
 685          * but if it didn't find any functions it returns zero.
 686          * Consider no functions a failure too.
 687          */
 688         if (!ret) {
 689                 ret = -ENOENT;
 690                 goto out_free;
 691         } else if (ret < 0)
 692                 goto out_free;
 693         ret = 0;
 694  out:
 695         return ret;
 696
 697  out_free:
 698         if (cmd_ops->set_filter)
 699                 cmd_ops->set_filter(NULL, trigger_data, NULL);
 700         kfree(trigger_data);
 701         goto out;
 702 }
 703
 704 /**
 705  * set_trigger_filter - Generic event_command @set_filter implementation
 706  * @filter_str: The filter string for the trigger, NULL to remove filter
 707  * @trigger_data: Trigger-specific data
 708  * @file: The trace_event_file associated with the event
 709  *
 710  * Common implementation for event command filter parsing and filter
 711  * instantiation.
 712  *
 713  * Usually used directly as the @set_filter method in event command
 714  * implementations.
 715  *
 716  * Also used to remove a filter (if filter_str = NULL).
 717  *
 718  * Return: 0 on success, errno otherwise
 719  */
 720 int set_trigger_filter(char *filter_str,
 721                        struct event_trigger_data *trigger_data,
 722                        struct trace_event_file *file)
 723 {
 724         struct event_trigger_data *data = trigger_data;
 725         struct event_filter *filter = NULL, *tmp;
 726         int ret = -EINVAL;
 727         char *s;
 728
 729         if (!filter_str) /* clear the current filter */
 730                 goto assign;
 731
 732         s = strsep(&filter_str, " \t");
 733
 734         if (!strlen(s) || strcmp(s, "if") != 0)
 735                 goto out;
 736
 737         if (!filter_str)
 738                 goto out;
 739
 740         /* The filter is for the 'trigger' event, not the triggered event */
 741         ret = create_event_filter(file->event_call, filter_str, false, &filter);
 742         if (ret)
 743                 goto out;
 744  assign:
 745         tmp = rcu_access_pointer(data->filter);
 746
 747         rcu_assign_pointer(data->filter, filter);
 748
 749         if (tmp) {
 750                 /* Make sure the call is done with the filter */
 751                 synchronize_sched();
 752                 free_event_filter(tmp);
 753         }
 754
 755         kfree(data->filter_str);
 756         data->filter_str = NULL;
 757
 758         if (filter_str) {
 759                 data->filter_str = kstrdup(filter_str, GFP_KERNEL);
 760                 if (!data->filter_str) {
 761                         free_event_filter(rcu_access_pointer(data->filter));
 762                         data->filter = NULL;
 763                         ret = -ENOMEM;
 764                 }
 765         }
 766  out:
 767         return ret;
 768 }
 769
 770 static LIST_HEAD(named_triggers);
 771
 772 /**
 773  * find_named_trigger - Find the common named trigger associated with @name
 774  * @name: The name of the set of named triggers to find the common data for
 775  *
 776  * Named triggers are sets of triggers that share a common set of
 777  * trigger data.  The first named trigger registered with a given name
 778  * owns the common trigger data that the others subsequently
 779  * registered with the same name will reference.  This function
 780  * returns the common trigger data associated with that first
 781  * registered instance.
 782  *
 783  * Return: the common trigger data for the given named trigger on
 784  * success, NULL otherwise.
 785  */
 786 struct event_trigger_data *find_named_trigger(const char *name)
 787 {
 788         struct event_trigger_data *data;
 789
 790         if (!name)
 791                 return NULL;
 792
 793         list_for_each_entry(data, &named_triggers, named_list) {
 794                 if (data->named_data)
 795                         continue;
 796                 if (strcmp(data->name, name) == 0)
 797                         return data;
 798         }
 799
 800         return NULL;
 801 }
 802
 803 /**
 804  * is_named_trigger - determine if a given trigger is a named trigger
 805  * @test: The trigger data to test
 806  *
 807  * Return: true if 'test' is a named trigger, false otherwise.
 808  */
 809 bool is_named_trigger(struct event_trigger_data *test)
 810 {
 811         struct event_trigger_data *data;
 812
 813         list_for_each_entry(data, &named_triggers, named_list) {
 814                 if (test == data)
 815                         return true;
 816         }
 817
 818         return false;
 819 }
 820
 821 /**
 822  * save_named_trigger - save the trigger in the named trigger list
 823  * @name: The name of the named trigger set
 824  * @data: The trigger data to save
 825  *
 826  * Return: 0 if successful, negative error otherwise.
 827  */
 828 int save_named_trigger(const char *name, struct event_trigger_data *data)
 829 {
 830         data->name = kstrdup(name, GFP_KERNEL);
 831         if (!data->name)
 832                 return -ENOMEM;
 833
 834         list_add(&data->named_list, &named_triggers);
 835
 836         return 0;
 837 }
 838
 839 /**
 840  * del_named_trigger - delete a trigger from the named trigger list
 841  * @data: The trigger data to delete
 842  */
 843 void del_named_trigger(struct event_trigger_data *data)
 844 {
 845         kfree(data->name);
 846         data->name = NULL;
 847
 848         list_del(&data->named_list);
 849 }
 850
 851 static void __pause_named_trigger(struct event_trigger_data *data, bool pause)
 852 {
 853         struct event_trigger_data *test;
 854
 855         list_for_each_entry(test, &named_triggers, named_list) {
 856                 if (strcmp(test->name, data->name) == 0) {
 857                         if (pause) {
 858                                 test->paused_tmp = test->paused;
 859                                 test->paused = true;
 860                         } else {
 861                                 test->paused = test->paused_tmp;
 862                         }
 863                 }
 864         }
 865 }
 866
 867 /**
 868  * pause_named_trigger - Pause all named triggers with the same name
 869  * @data: The trigger data of a named trigger to pause
 870  *
 871  * Pauses a named trigger along with all other triggers having the
 872  * same name.  Because named triggers share a common set of data,
 873  * pausing only one is meaningless, so pausing one named trigger needs
 874  * to pause all triggers with the same name.
 875  */
 876 void pause_named_trigger(struct event_trigger_data *data)
 877 {
 878         __pause_named_trigger(data, true);
 879 }
 880
 881 /**
 882  * unpause_named_trigger - Un-pause all named triggers with the same name
 883  * @data: The trigger data of a named trigger to unpause
 884  *
 885  * Un-pauses a named trigger along with all other triggers having the
 886  * same name.  Because named triggers share a common set of data,
 887  * unpausing only one is meaningless, so unpausing one named trigger
 888  * needs to unpause all triggers with the same name.
 889  */
 890 void unpause_named_trigger(struct event_trigger_data *data)
 891 {
 892         __pause_named_trigger(data, false);
 893 }
 894
 895 /**
 896  * set_named_trigger_data - Associate common named trigger data
 897  * @data: The trigger data of a named trigger to unpause
 898  *
 899  * Named triggers are sets of triggers that share a common set of
 900  * trigger data.  The first named trigger registered with a given name
 901  * owns the common trigger data that the others subsequently
 902  * registered with the same name will reference.  This function
 903  * associates the common trigger data from the first trigger with the
 904  * given trigger.
 905  */
 906 void set_named_trigger_data(struct event_trigger_data *data,
 907                             struct event_trigger_data *named_data)
 908 {
 909         data->named_data = named_data;
 910 }
 911
 912 struct event_trigger_data *
 913 get_named_trigger_data(struct event_trigger_data *data)
 914 {
 915         return data->named_data;
 916 }
 917
 918 static void
 919 traceon_trigger(struct event_trigger_data *data, void *rec,
 920                 struct ring_buffer_event *event)
 921 {
 922         if (tracing_is_on())
 923                 return;
 924
 925         tracing_on();
 926 }
 927
 928 static void
 929 traceon_count_trigger(struct event_trigger_data *data, void *rec,
 930                       struct ring_buffer_event *event)
 931 {
 932         if (tracing_is_on())
 933                 return;
 934
 935         if (!data->count)
 936                 return;
 937
 938         if (data->count != -1)
 939                 (data->count)--;
 940
 941         tracing_on();
 942 }
 943
 944 static void
 945 traceoff_trigger(struct event_trigger_data *data, void *rec,
 946                  struct ring_buffer_event *event)
 947 {
 948         if (!tracing_is_on())
 949                 return;
 950
 951         tracing_off();
 952 }
 953
 954 static void
 955 traceoff_count_trigger(struct event_trigger_data *data, void *rec,
 956                        struct ring_buffer_event *event)
 957 {
 958         if (!tracing_is_on())
 959                 return;
 960
 961         if (!data->count)
 962                 return;
 963
 964         if (data->count != -1)
 965                 (data->count)--;
 966
 967         tracing_off();
 968 }
 969
 970 static int
 971 traceon_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
 972                       struct event_trigger_data *data)
 973 {
 974         return event_trigger_print("traceon", m, (void *)data->count,
 975                                    data->filter_str);
 976 }
 977
 978 static int
 979 traceoff_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
 980                        struct event_trigger_data *data)
 981 {
 982         return event_trigger_print("traceoff", m, (void *)data->count,
 983                                    data->filter_str);
 984 }
 985
 986 static struct event_trigger_ops traceon_trigger_ops = {
 987         .func                   = traceon_trigger,
 988         .print                  = traceon_trigger_print,
 989         .init                   = event_trigger_init,
 990         .free                   = event_trigger_free,
 991 };
 992
 993 static struct event_trigger_ops traceon_count_trigger_ops = {
 994         .func                   = traceon_count_trigger,
 995         .print                  = traceon_trigger_print,
 996         .init                   = event_trigger_init,
 997         .free                   = event_trigger_free,
 998 };
 999
1000 static struct event_trigger_ops traceoff_trigger_ops = {
1001         .func                   = traceoff_trigger,
1002         .print                  = traceoff_trigger_print,
1003         .init                   = event_trigger_init,
1004         .free                   = event_trigger_free,
1005 };
1006
1007 static struct event_trigger_ops traceoff_count_trigger_ops = {
1008         .func                   = traceoff_count_trigger,
1009         .print                  = traceoff_trigger_print,
1010         .init                   = event_trigger_init,
1011         .free                   = event_trigger_free,
1012 };
1013
1014 static struct event_trigger_ops *
1015 onoff_get_trigger_ops(char *cmd, char *param)
1016 {
1017         struct event_trigger_ops *ops;
1018
1019         /* we register both traceon and traceoff to this callback */
1020         if (strcmp(cmd, "traceon") == 0)
1021                 ops = param ? &traceon_count_trigger_ops :
1022                         &traceon_trigger_ops;
1023         else
1024                 ops = param ? &traceoff_count_trigger_ops :
1025                         &traceoff_trigger_ops;
1026
1027         return ops;
1028 }
1029
1030 static struct event_command trigger_traceon_cmd = {
1031         .name                   = "traceon",
1032         .trigger_type           = ETT_TRACE_ONOFF,
1033         .func                   = event_trigger_callback,
1034         .reg                    = register_trigger,
1035         .unreg                  = unregister_trigger,
1036         .get_trigger_ops        = onoff_get_trigger_ops,
1037         .set_filter             = set_trigger_filter,
1038 };
1039
1040 static struct event_command trigger_traceoff_cmd = {
1041         .name                   = "traceoff",
1042         .trigger_type           = ETT_TRACE_ONOFF,
1043         .flags                  = EVENT_CMD_FL_POST_TRIGGER,
1044         .func                   = event_trigger_callback,
1045         .reg                    = register_trigger,
1046         .unreg                  = unregister_trigger,
1047         .get_trigger_ops        = onoff_get_trigger_ops,
1048         .set_filter             = set_trigger_filter,
1049 };
1050
1051 #ifdef CONFIG_TRACER_SNAPSHOT
1052 static void
1053 snapshot_trigger(struct event_trigger_data *data, void *rec,
1054                  struct ring_buffer_event *event)
1055 {
1056         struct trace_event_file *file = data->private_data;
1057
1058         if (file)
1059                 tracing_snapshot_instance(file->tr);
1060         else
1061                 tracing_snapshot();
1062 }
1063
1064 static void
1065 snapshot_count_trigger(struct event_trigger_data *data, void *rec,
1066                        struct ring_buffer_event *event)
1067 {
1068         if (!data->count)
1069                 return;
1070
1071         if (data->count != -1)
1072                 (data->count)--;
1073
1074         snapshot_trigger(data, rec, event);
1075 }
1076
1077 static int
1078 register_snapshot_trigger(char *glob, struct event_trigger_ops *ops,
1079                           struct event_trigger_data *data,
1080                           struct trace_event_file *file)
1081 {
1082         int ret = register_trigger(glob, ops, data, file);
1083
1084         if (ret > 0 && tracing_alloc_snapshot_instance(file->tr) != 0) {
1085                 unregister_trigger(glob, ops, data, file);
1086                 ret = 0;
1087         }
1088
1089         return ret;
1090 }
1091
1092 static int
1093 snapshot_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
1094                        struct event_trigger_data *data)
1095 {
1096         return event_trigger_print("snapshot", m, (void *)data->count,
1097                                    data->filter_str);
1098 }
1099
1100 static struct event_trigger_ops snapshot_trigger_ops = {
1101         .func                   = snapshot_trigger,
1102         .print                  = snapshot_trigger_print,
1103         .init                   = event_trigger_init,
1104         .free                   = event_trigger_free,
1105 };
1106
1107 static struct event_trigger_ops snapshot_count_trigger_ops = {
1108         .func                   = snapshot_count_trigger,
1109         .print                  = snapshot_trigger_print,
1110         .init                   = event_trigger_init,
1111         .free                   = event_trigger_free,
1112 };
1113
1114 static struct event_trigger_ops *
1115 snapshot_get_trigger_ops(char *cmd, char *param)
1116 {
1117         return param ? &snapshot_count_trigger_ops : &snapshot_trigger_ops;
1118 }
1119
1120 static struct event_command trigger_snapshot_cmd = {
1121         .name                   = "snapshot",
1122         .trigger_type           = ETT_SNAPSHOT,
1123         .func                   = event_trigger_callback,
1124         .reg                    = register_snapshot_trigger,
1125         .unreg                  = unregister_trigger,
1126         .get_trigger_ops        = snapshot_get_trigger_ops,
1127         .set_filter             = set_trigger_filter,
1128 };
1129
1130 static __init int register_trigger_snapshot_cmd(void)
1131 {
1132         int ret;
1133
1134         ret = register_event_command(&trigger_snapshot_cmd);
1135         WARN_ON(ret < 0);
1136
1137         return ret;
1138 }
1139 #else
1140 static __init int register_trigger_snapshot_cmd(void) { return 0; }
1141 #endif /* CONFIG_TRACER_SNAPSHOT */
1142
1143 #ifdef CONFIG_STACKTRACE
1144 #ifdef CONFIG_UNWINDER_ORC
1145 /* Skip 2:
1146  *   event_triggers_post_call()
1147  *   trace_event_raw_event_xxx()
1148  */
1149 # define STACK_SKIP 2
1150 #else
1151 /*
1152  * Skip 4:
1153  *   stacktrace_trigger()
1154  *   event_triggers_post_call()
1155  *   trace_event_buffer_commit()
1156  *   trace_event_raw_event_xxx()
1157  */
1158 #define STACK_SKIP 4
1159 #endif
1160
1161 static void
1162 stacktrace_trigger(struct event_trigger_data *data, void *rec,
1163                    struct ring_buffer_event *event)
1164 {
1165         trace_dump_stack(STACK_SKIP);
1166 }
1167
1168 static void
1169 stacktrace_count_trigger(struct event_trigger_data *data, void *rec,
1170                          struct ring_buffer_event *event)
1171 {
1172         if (!data->count)
1173                 return;
1174
1175         if (data->count != -1)
1176                 (data->count)--;
1177
1178         stacktrace_trigger(data, rec, event);
1179 }
1180
1181 static int
1182 stacktrace_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
1183                          struct event_trigger_data *data)
1184 {
1185         return event_trigger_print("stacktrace", m, (void *)data->count,
1186                                    data->filter_str);
1187 }
1188
1189 static struct event_trigger_ops stacktrace_trigger_ops = {
1190         .func                   = stacktrace_trigger,
1191         .print                  = stacktrace_trigger_print,
1192         .init                   = event_trigger_init,
1193         .free                   = event_trigger_free,
1194 };
1195
1196 static struct event_trigger_ops stacktrace_count_trigger_ops = {
1197         .func                   = stacktrace_count_trigger,
1198         .print                  = stacktrace_trigger_print,
1199         .init                   = event_trigger_init,
1200         .free                   = event_trigger_free,
1201 };
1202
1203 static struct event_trigger_ops *
1204 stacktrace_get_trigger_ops(char *cmd, char *param)
1205 {
1206         return param ? &stacktrace_count_trigger_ops : &stacktrace_trigger_ops;
1207 }
1208
1209 static struct event_command trigger_stacktrace_cmd = {
1210         .name                   = "stacktrace",
1211         .trigger_type           = ETT_STACKTRACE,
1212         .flags                  = EVENT_CMD_FL_POST_TRIGGER,
1213         .func                   = event_trigger_callback,
1214         .reg                    = register_trigger,
1215         .unreg                  = unregister_trigger,
1216         .get_trigger_ops        = stacktrace_get_trigger_ops,
1217         .set_filter             = set_trigger_filter,
1218 };
1219
1220 static __init int register_trigger_stacktrace_cmd(void)
1221 {
1222         int ret;
1223
1224         ret = register_event_command(&trigger_stacktrace_cmd);
1225         WARN_ON(ret < 0);
1226
1227         return ret;
1228 }
1229 #else
1230 static __init int register_trigger_stacktrace_cmd(void) { return 0; }
1231 #endif /* CONFIG_STACKTRACE */
1232
1233 static __init void unregister_trigger_traceon_traceoff_cmds(void)
1234 {
1235         unregister_event_command(&trigger_traceon_cmd);
1236         unregister_event_command(&trigger_traceoff_cmd);
1237 }
1238
1239 static void
1240 event_enable_trigger(struct event_trigger_data *data, void *rec,
1241                      struct ring_buffer_event *event)
1242 {
1243         struct enable_trigger_data *enable_data = data->private_data;
1244
1245         if (enable_data->enable)
1246                 clear_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
1247         else
1248                 set_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
1249 }
1250
1251 static void
1252 event_enable_count_trigger(struct event_trigger_data *data, void *rec,
1253                            struct ring_buffer_event *event)
1254 {
1255         struct enable_trigger_data *enable_data = data->private_data;
1256
1257         if (!data->count)
1258                 return;
1259
1260         /* Skip if the event is in a state we want to switch to */
1261         if (enable_data->enable == !(enable_data->file->flags & EVENT_FILE_FL_SOFT_DISABLED))
1262                 return;
1263
1264         if (data->count != -1)
1265                 (data->count)--;
1266
1267         event_enable_trigger(data, rec, event);
1268 }
1269
1270 int event_enable_trigger_print(struct seq_file *m,
1271                                struct event_trigger_ops *ops,
1272                                struct event_trigger_data *data)
1273 {
1274         struct enable_trigger_data *enable_data = data->private_data;
1275
1276         seq_printf(m, "%s:%s:%s",
1277                    enable_data->hist ?
1278                    (enable_data->enable ? ENABLE_HIST_STR : DISABLE_HIST_STR) :
1279                    (enable_data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR),
1280                    enable_data->file->event_call->class->system,
1281                    trace_event_name(enable_data->file->event_call));
1282
1283         if (data->count == -1)
1284                 seq_puts(m, ":unlimited");
1285         else
1286                 seq_printf(m, ":count=%ld", data->count);
1287
1288         if (data->filter_str)
1289                 seq_printf(m, " if %s\n", data->filter_str);
1290         else
1291                 seq_putc(m, '\n');
1292
1293         return 0;
1294 }
1295
1296 void event_enable_trigger_free(struct event_trigger_ops *ops,
1297                                struct event_trigger_data *data)
1298 {
1299         struct enable_trigger_data *enable_data = data->private_data;
1300
1301         if (WARN_ON_ONCE(data->ref <= 0))
1302                 return;
1303
1304         data->ref--;
1305         if (!data->ref) {
1306                 /* Remove the SOFT_MODE flag */
1307                 trace_event_enable_disable(enable_data->file, 0, 1);
1308                 module_put(enable_data->file->event_call->mod);
1309                 trigger_data_free(data);
1310                 kfree(enable_data);
1311         }
1312 }
1313
1314 static struct event_trigger_ops event_enable_trigger_ops = {
1315         .func                   = event_enable_trigger,
1316         .print                  = event_enable_trigger_print,
1317         .init                   = event_trigger_init,
1318         .free                   = event_enable_trigger_free,
1319 };
1320
1321 static struct event_trigger_ops event_enable_count_trigger_ops = {
1322         .func                   = event_enable_count_trigger,
1323         .print                  = event_enable_trigger_print,
1324         .init                   = event_trigger_init,
1325         .free                   = event_enable_trigger_free,
1326 };
1327
1328 static struct event_trigger_ops event_disable_trigger_ops = {
1329         .func                   = event_enable_trigger,
1330         .print                  = event_enable_trigger_print,
1331         .init                   = event_trigger_init,
1332         .free                   = event_enable_trigger_free,
1333 };
1334
1335 static struct event_trigger_ops event_disable_count_trigger_ops = {
1336         .func                   = event_enable_count_trigger,
1337         .print                  = event_enable_trigger_print,
1338         .init                   = event_trigger_init,
1339         .free                   = event_enable_trigger_free,
1340 };
1341
1342 int event_enable_trigger_func(struct event_command *cmd_ops,
1343                               struct trace_event_file *file,
1344                               char *glob, char *cmd, char *param)
1345 {
1346         struct trace_event_file *event_enable_file;
1347         struct enable_trigger_data *enable_data;
1348         struct event_trigger_data *trigger_data;
1349         struct event_trigger_ops *trigger_ops;
1350         struct trace_array *tr = file->tr;
1351         const char *system;
1352         const char *event;
1353         bool hist = false;
1354         char *trigger;
1355         char *number;
1356         bool enable;
1357         int ret;
1358
1359         if (!param)
1360                 return -EINVAL;
1361
1362         /* separate the trigger from the filter (s:e:n [if filter]) */
1363         trigger = strsep(&param, " \t");
1364         if (!trigger)
1365                 return -EINVAL;
1366
1367         system = strsep(&trigger, ":");
1368         if (!trigger)
1369                 return -EINVAL;
1370
1371         event = strsep(&trigger, ":");
1372
1373         ret = -EINVAL;
1374         event_enable_file = find_event_file(tr, system, event);
1375         if (!event_enable_file)
1376                 goto out;
1377
1378 #ifdef CONFIG_HIST_TRIGGERS
1379         hist = ((strcmp(cmd, ENABLE_HIST_STR) == 0) ||
1380                 (strcmp(cmd, DISABLE_HIST_STR) == 0));
1381
1382         enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
1383                   (strcmp(cmd, ENABLE_HIST_STR) == 0));
1384 #else
1385         enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
1386 #endif
1387         trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
1388
1389         ret = -ENOMEM;
1390         trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
1391         if (!trigger_data)
1392                 goto out;
1393
1394         enable_data = kzalloc(sizeof(*enable_data), GFP_KERNEL);
1395         if (!enable_data) {
1396                 kfree(trigger_data);
1397                 goto out;
1398         }
1399
1400         trigger_data->count = -1;
1401         trigger_data->ops = trigger_ops;
1402         trigger_data->cmd_ops = cmd_ops;
1403         INIT_LIST_HEAD(&trigger_data->list);
1404         RCU_INIT_POINTER(trigger_data->filter, NULL);
1405
1406         enable_data->hist = hist;
1407         enable_data->enable = enable;
1408         enable_data->file = event_enable_file;
1409         trigger_data->private_data = enable_data;
1410
1411         if (glob[0] == '!') {
1412                 cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
1413                 kfree(trigger_data);
1414                 kfree(enable_data);
1415                 ret = 0;
1416                 goto out;
1417         }
1418
1419         if (trigger) {
1420                 number = strsep(&trigger, ":");
1421
1422                 ret = -EINVAL;
1423                 if (!strlen(number))
1424                         goto out_free;
1425
1426                 /*
1427                  * We use the callback data field (which is a pointer)
1428                  * as our counter.
1429                  */
1430                 ret = kstrtoul(number, 0, &trigger_data->count);
1431                 if (ret)
1432                         goto out_free;
1433         }
1434
1435         if (!param) /* if param is non-empty, it's supposed to be a filter */
1436                 goto out_reg;
1437
1438         if (!cmd_ops->set_filter)
1439                 goto out_reg;
1440
1441         ret = cmd_ops->set_filter(param, trigger_data, file);
1442         if (ret < 0)
1443                 goto out_free;
1444
1445  out_reg:
1446         /* Don't let event modules unload while probe registered */
1447         ret = try_module_get(event_enable_file->event_call->mod);
1448         if (!ret) {
1449                 ret = -EBUSY;
1450                 goto out_free;
1451         }
1452
1453         ret = trace_event_enable_disable(event_enable_file, 1, 1);
1454         if (ret < 0)
1455                 goto out_put;
1456         ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);
1457         /*
1458          * The above returns on success the # of functions enabled,
1459          * but if it didn't find any functions it returns zero.
1460          * Consider no functions a failure too.
1461          */
1462         if (!ret) {
1463                 ret = -ENOENT;
1464                 goto out_disable;
1465         } else if (ret < 0)
1466                 goto out_disable;
1467         /* Just return zero, not the number of enabled functions */
1468         ret = 0;
1469  out:
1470         return ret;
1471
1472  out_disable:
1473         trace_event_enable_disable(event_enable_file, 0, 1);
1474  out_put:
1475         module_put(event_enable_file->event_call->mod);
1476  out_free:
1477         if (cmd_ops->set_filter)
1478                 cmd_ops->set_filter(NULL, trigger_data, NULL);
1479         kfree(trigger_data);
1480         kfree(enable_data);
1481         goto out;
1482 }
1483
1484 int event_enable_register_trigger(char *glob,
1485                                   struct event_trigger_ops *ops,
1486                                   struct event_trigger_data *data,
1487                                   struct trace_event_file *file)
1488 {
1489         struct enable_trigger_data *enable_data = data->private_data;
1490         struct enable_trigger_data *test_enable_data;
1491         struct event_trigger_data *test;
1492         int ret = 0;
1493
1494         list_for_each_entry_rcu(test, &file->triggers, list) {
1495                 test_enable_data = test->private_data;
1496                 if (test_enable_data &&
1497                     (test->cmd_ops->trigger_type ==
1498                      data->cmd_ops->trigger_type) &&
1499                     (test_enable_data->file == enable_data->file)) {
1500                         ret = -EEXIST;
1501                         goto out;
1502                 }
1503         }
1504
1505         if (data->ops->init) {
1506                 ret = data->ops->init(data->ops, data);
1507                 if (ret < 0)
1508                         goto out;
1509         }
1510
1511         list_add_rcu(&data->list, &file->triggers);
1512         ret++;
1513
1514         update_cond_flag(file);
1515         if (trace_event_trigger_enable_disable(file, 1) < 0) {
1516                 list_del_rcu(&data->list);
1517                 update_cond_flag(file);
1518                 ret--;
1519         }
1520 out:
1521         return ret;
1522 }
1523
1524 void event_enable_unregister_trigger(char *glob,
1525                                      struct event_trigger_ops *ops,
1526                                      struct event_trigger_data *test,
1527                                      struct trace_event_file *file)
1528 {
1529         struct enable_trigger_data *test_enable_data = test->private_data;
1530         struct enable_trigger_data *enable_data;
1531         struct event_trigger_data *data;
1532         bool unregistered = false;
1533
1534         list_for_each_entry_rcu(data, &file->triggers, list) {
1535                 enable_data = data->private_data;
1536                 if (enable_data &&
1537                     (data->cmd_ops->trigger_type ==
1538                      test->cmd_ops->trigger_type) &&
1539                     (enable_data->file == test_enable_data->file)) {
1540                         unregistered = true;
1541                         list_del_rcu(&data->list);
1542                         trace_event_trigger_enable_disable(file, 0);
1543                         update_cond_flag(file);
1544                         break;
1545                 }
1546         }
1547
1548         if (unregistered && data->ops->free)
1549                 data->ops->free(data->ops, data);
1550 }
1551
1552 static struct event_trigger_ops *
1553 event_enable_get_trigger_ops(char *cmd, char *param)
1554 {
1555         struct event_trigger_ops *ops;
1556         bool enable;
1557
1558 #ifdef CONFIG_HIST_TRIGGERS
1559         enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
1560                   (strcmp(cmd, ENABLE_HIST_STR) == 0));
1561 #else
1562         enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
1563 #endif
1564         if (enable)
1565                 ops = param ? &event_enable_count_trigger_ops :
1566                         &event_enable_trigger_ops;
1567         else
1568                 ops = param ? &event_disable_count_trigger_ops :
1569                         &event_disable_trigger_ops;
1570
1571         return ops;
1572 }
1573
1574 static struct event_command trigger_enable_cmd = {
1575         .name                   = ENABLE_EVENT_STR,
1576         .trigger_type           = ETT_EVENT_ENABLE,
1577         .func                   = event_enable_trigger_func,
1578         .reg                    = event_enable_register_trigger,
1579         .unreg                  = event_enable_unregister_trigger,
1580         .get_trigger_ops        = event_enable_get_trigger_ops,
1581         .set_filter             = set_trigger_filter,
1582 };
1583
1584 static struct event_command trigger_disable_cmd = {
1585         .name                   = DISABLE_EVENT_STR,
1586         .trigger_type           = ETT_EVENT_ENABLE,
1587         .func                   = event_enable_trigger_func,
1588         .reg                    = event_enable_register_trigger,
1589         .unreg                  = event_enable_unregister_trigger,
1590         .get_trigger_ops        = event_enable_get_trigger_ops,
1591         .set_filter             = set_trigger_filter,
1592 };
1593
1594 static __init void unregister_trigger_enable_disable_cmds(void)
1595 {
1596         unregister_event_command(&trigger_enable_cmd);
1597         unregister_event_command(&trigger_disable_cmd);
1598 }
1599
1600 static __init int register_trigger_enable_disable_cmds(void)
1601 {
1602         int ret;
1603
1604         ret = register_event_command(&trigger_enable_cmd);
1605         if (WARN_ON(ret < 0))
1606                 return ret;
1607         ret = register_event_command(&trigger_disable_cmd);
1608         if (WARN_ON(ret < 0))
1609                 unregister_trigger_enable_disable_cmds();
1610
1611         return ret;
1612 }
1613
1614 static __init int register_trigger_traceon_traceoff_cmds(void)
1615 {
1616         int ret;
1617
1618         ret = register_event_command(&trigger_traceon_cmd);
1619         if (WARN_ON(ret < 0))
1620                 return ret;
1621         ret = register_event_command(&trigger_traceoff_cmd);
1622         if (WARN_ON(ret < 0))
1623                 unregister_trigger_traceon_traceoff_cmds();
1624
1625         return ret;
1626 }
1627
1628 __init int register_trigger_cmds(void)
1629 {
1630         register_trigger_traceon_traceoff_cmds();
1631         register_trigger_snapshot_cmd();
1632         register_trigger_stacktrace_cmd();
1633         register_trigger_enable_disable_cmds();
1634         register_trigger_hist_enable_disable_cmds();
1635         register_trigger_hist_cmd();
1636
1637         return 0;
1638 }