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         /* Up the trigger_data count to make sure reg doesn't free it on failure */
 683         event_trigger_init(trigger_ops, trigger_data);
 684         ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);
 685         /*
 686          * The above returns on success the # of functions enabled,
 687          * but if it didn't find any functions it returns zero.
 688          * Consider no functions a failure too.
 689          */
 690         if (!ret) {
 691                 cmd_ops->unreg(glob, trigger_ops, trigger_data, file);
 692                 ret = -ENOENT;
 693         } else if (ret > 0)
 694                 ret = 0;
 695
 696         /* Down the counter of trigger_data or free it if not used anymore */
 697         event_trigger_free(trigger_ops, trigger_data);
 698  out:
 699         return ret;
 700
 701  out_free:
 702         if (cmd_ops->set_filter)
 703                 cmd_ops->set_filter(NULL, trigger_data, NULL);
 704         kfree(trigger_data);
 705         goto out;
 706 }
 707
 708 /**
 709  * set_trigger_filter - Generic event_command @set_filter implementation
 710  * @filter_str: The filter string for the trigger, NULL to remove filter
 711  * @trigger_data: Trigger-specific data
 712  * @file: The trace_event_file associated with the event
 713  *
 714  * Common implementation for event command filter parsing and filter
 715  * instantiation.
 716  *
 717  * Usually used directly as the @set_filter method in event command
 718  * implementations.
 719  *
 720  * Also used to remove a filter (if filter_str = NULL).
 721  *
 722  * Return: 0 on success, errno otherwise
 723  */
 724 int set_trigger_filter(char *filter_str,
 725                        struct event_trigger_data *trigger_data,
 726                        struct trace_event_file *file)
 727 {
 728         struct event_trigger_data *data = trigger_data;
 729         struct event_filter *filter = NULL, *tmp;
 730         int ret = -EINVAL;
 731         char *s;
 732
 733         if (!filter_str) /* clear the current filter */
 734                 goto assign;
 735
 736         s = strsep(&filter_str, " \t");
 737
 738         if (!strlen(s) || strcmp(s, "if") != 0)
 739                 goto out;
 740
 741         if (!filter_str)
 742                 goto out;
 743
 744         /* The filter is for the 'trigger' event, not the triggered event */
 745         ret = create_event_filter(file->event_call, filter_str, false, &filter);
 746         if (ret)
 747                 goto out;
 748  assign:
 749         tmp = rcu_access_pointer(data->filter);
 750
 751         rcu_assign_pointer(data->filter, filter);
 752
 753         if (tmp) {
 754                 /* Make sure the call is done with the filter */
 755                 synchronize_sched();
 756                 free_event_filter(tmp);
 757         }
 758
 759         kfree(data->filter_str);
 760         data->filter_str = NULL;
 761
 762         if (filter_str) {
 763                 data->filter_str = kstrdup(filter_str, GFP_KERNEL);
 764                 if (!data->filter_str) {
 765                         free_event_filter(rcu_access_pointer(data->filter));
 766                         data->filter = NULL;
 767                         ret = -ENOMEM;
 768                 }
 769         }
 770  out:
 771         return ret;
 772 }
 773
 774 static LIST_HEAD(named_triggers);
 775
 776 /**
 777  * find_named_trigger - Find the common named trigger associated with @name
 778  * @name: The name of the set of named triggers to find the common data for
 779  *
 780  * Named triggers are sets of triggers that share a common set of
 781  * trigger data.  The first named trigger registered with a given name
 782  * owns the common trigger data that the others subsequently
 783  * registered with the same name will reference.  This function
 784  * returns the common trigger data associated with that first
 785  * registered instance.
 786  *
 787  * Return: the common trigger data for the given named trigger on
 788  * success, NULL otherwise.
 789  */
 790 struct event_trigger_data *find_named_trigger(const char *name)
 791 {
 792         struct event_trigger_data *data;
 793
 794         if (!name)
 795                 return NULL;
 796
 797         list_for_each_entry(data, &named_triggers, named_list) {
 798                 if (data->named_data)
 799                         continue;
 800                 if (strcmp(data->name, name) == 0)
 801                         return data;
 802         }
 803
 804         return NULL;
 805 }
 806
 807 /**
 808  * is_named_trigger - determine if a given trigger is a named trigger
 809  * @test: The trigger data to test
 810  *
 811  * Return: true if 'test' is a named trigger, false otherwise.
 812  */
 813 bool is_named_trigger(struct event_trigger_data *test)
 814 {
 815         struct event_trigger_data *data;
 816
 817         list_for_each_entry(data, &named_triggers, named_list) {
 818                 if (test == data)
 819                         return true;
 820         }
 821
 822         return false;
 823 }
 824
 825 /**
 826  * save_named_trigger - save the trigger in the named trigger list
 827  * @name: The name of the named trigger set
 828  * @data: The trigger data to save
 829  *
 830  * Return: 0 if successful, negative error otherwise.
 831  */
 832 int save_named_trigger(const char *name, struct event_trigger_data *data)
 833 {
 834         data->name = kstrdup(name, GFP_KERNEL);
 835         if (!data->name)
 836                 return -ENOMEM;
 837
 838         list_add(&data->named_list, &named_triggers);
 839
 840         return 0;
 841 }
 842
 843 /**
 844  * del_named_trigger - delete a trigger from the named trigger list
 845  * @data: The trigger data to delete
 846  */
 847 void del_named_trigger(struct event_trigger_data *data)
 848 {
 849         kfree(data->name);
 850         data->name = NULL;
 851
 852         list_del(&data->named_list);
 853 }
 854
 855 static void __pause_named_trigger(struct event_trigger_data *data, bool pause)
 856 {
 857         struct event_trigger_data *test;
 858
 859         list_for_each_entry(test, &named_triggers, named_list) {
 860                 if (strcmp(test->name, data->name) == 0) {
 861                         if (pause) {
 862                                 test->paused_tmp = test->paused;
 863                                 test->paused = true;
 864                         } else {
 865                                 test->paused = test->paused_tmp;
 866                         }
 867                 }
 868         }
 869 }
 870
 871 /**
 872  * pause_named_trigger - Pause all named triggers with the same name
 873  * @data: The trigger data of a named trigger to pause
 874  *
 875  * Pauses a named trigger along with all other triggers having the
 876  * same name.  Because named triggers share a common set of data,
 877  * pausing only one is meaningless, so pausing one named trigger needs
 878  * to pause all triggers with the same name.
 879  */
 880 void pause_named_trigger(struct event_trigger_data *data)
 881 {
 882         __pause_named_trigger(data, true);
 883 }
 884
 885 /**
 886  * unpause_named_trigger - Un-pause all named triggers with the same name
 887  * @data: The trigger data of a named trigger to unpause
 888  *
 889  * Un-pauses a named trigger along with all other triggers having the
 890  * same name.  Because named triggers share a common set of data,
 891  * unpausing only one is meaningless, so unpausing one named trigger
 892  * needs to unpause all triggers with the same name.
 893  */
 894 void unpause_named_trigger(struct event_trigger_data *data)
 895 {
 896         __pause_named_trigger(data, false);
 897 }
 898
 899 /**
 900  * set_named_trigger_data - Associate common named trigger data
 901  * @data: The trigger data of a named trigger to unpause
 902  *
 903  * Named triggers are sets of triggers that share a common set of
 904  * trigger data.  The first named trigger registered with a given name
 905  * owns the common trigger data that the others subsequently
 906  * registered with the same name will reference.  This function
 907  * associates the common trigger data from the first trigger with the
 908  * given trigger.
 909  */
 910 void set_named_trigger_data(struct event_trigger_data *data,
 911                             struct event_trigger_data *named_data)
 912 {
 913         data->named_data = named_data;
 914 }
 915
 916 struct event_trigger_data *
 917 get_named_trigger_data(struct event_trigger_data *data)
 918 {
 919         return data->named_data;
 920 }
 921
 922 static void
 923 traceon_trigger(struct event_trigger_data *data, void *rec,
 924                 struct ring_buffer_event *event)
 925 {
 926         if (tracing_is_on())
 927                 return;
 928
 929         tracing_on();
 930 }
 931
 932 static void
 933 traceon_count_trigger(struct event_trigger_data *data, void *rec,
 934                       struct ring_buffer_event *event)
 935 {
 936         if (tracing_is_on())
 937                 return;
 938
 939         if (!data->count)
 940                 return;
 941
 942         if (data->count != -1)
 943                 (data->count)--;
 944
 945         tracing_on();
 946 }
 947
 948 static void
 949 traceoff_trigger(struct event_trigger_data *data, void *rec,
 950                  struct ring_buffer_event *event)
 951 {
 952         if (!tracing_is_on())
 953                 return;
 954
 955         tracing_off();
 956 }
 957
 958 static void
 959 traceoff_count_trigger(struct event_trigger_data *data, void *rec,
 960                        struct ring_buffer_event *event)
 961 {
 962         if (!tracing_is_on())
 963                 return;
 964
 965         if (!data->count)
 966                 return;
 967
 968         if (data->count != -1)
 969                 (data->count)--;
 970
 971         tracing_off();
 972 }
 973
 974 static int
 975 traceon_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
 976                       struct event_trigger_data *data)
 977 {
 978         return event_trigger_print("traceon", m, (void *)data->count,
 979                                    data->filter_str);
 980 }
 981
 982 static int
 983 traceoff_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
 984                        struct event_trigger_data *data)
 985 {
 986         return event_trigger_print("traceoff", m, (void *)data->count,
 987                                    data->filter_str);
 988 }
 989
 990 static struct event_trigger_ops traceon_trigger_ops = {
 991         .func                   = traceon_trigger,
 992         .print                  = traceon_trigger_print,
 993         .init                   = event_trigger_init,
 994         .free                   = event_trigger_free,
 995 };
 996
 997 static struct event_trigger_ops traceon_count_trigger_ops = {
 998         .func                   = traceon_count_trigger,
 999         .print                  = traceon_trigger_print,
1000         .init                   = event_trigger_init,
1001         .free                   = event_trigger_free,
1002 };
1003
1004 static struct event_trigger_ops traceoff_trigger_ops = {
1005         .func                   = traceoff_trigger,
1006         .print                  = traceoff_trigger_print,
1007         .init                   = event_trigger_init,
1008         .free                   = event_trigger_free,
1009 };
1010
1011 static struct event_trigger_ops traceoff_count_trigger_ops = {
1012         .func                   = traceoff_count_trigger,
1013         .print                  = traceoff_trigger_print,
1014         .init                   = event_trigger_init,
1015         .free                   = event_trigger_free,
1016 };
1017
1018 static struct event_trigger_ops *
1019 onoff_get_trigger_ops(char *cmd, char *param)
1020 {
1021         struct event_trigger_ops *ops;
1022
1023         /* we register both traceon and traceoff to this callback */
1024         if (strcmp(cmd, "traceon") == 0)
1025                 ops = param ? &traceon_count_trigger_ops :
1026                         &traceon_trigger_ops;
1027         else
1028                 ops = param ? &traceoff_count_trigger_ops :
1029                         &traceoff_trigger_ops;
1030
1031         return ops;
1032 }
1033
1034 static struct event_command trigger_traceon_cmd = {
1035         .name                   = "traceon",
1036         .trigger_type           = ETT_TRACE_ONOFF,
1037         .func                   = event_trigger_callback,
1038         .reg                    = register_trigger,
1039         .unreg                  = unregister_trigger,
1040         .get_trigger_ops        = onoff_get_trigger_ops,
1041         .set_filter             = set_trigger_filter,
1042 };
1043
1044 static struct event_command trigger_traceoff_cmd = {
1045         .name                   = "traceoff",
1046         .trigger_type           = ETT_TRACE_ONOFF,
1047         .flags                  = EVENT_CMD_FL_POST_TRIGGER,
1048         .func                   = event_trigger_callback,
1049         .reg                    = register_trigger,
1050         .unreg                  = unregister_trigger,
1051         .get_trigger_ops        = onoff_get_trigger_ops,
1052         .set_filter             = set_trigger_filter,
1053 };
1054
1055 #ifdef CONFIG_TRACER_SNAPSHOT
1056 static void
1057 snapshot_trigger(struct event_trigger_data *data, void *rec,
1058                  struct ring_buffer_event *event)
1059 {
1060         struct trace_event_file *file = data->private_data;
1061
1062         if (file)
1063                 tracing_snapshot_instance(file->tr);
1064         else
1065                 tracing_snapshot();
1066 }
1067
1068 static void
1069 snapshot_count_trigger(struct event_trigger_data *data, void *rec,
1070                        struct ring_buffer_event *event)
1071 {
1072         if (!data->count)
1073                 return;
1074
1075         if (data->count != -1)
1076                 (data->count)--;
1077
1078         snapshot_trigger(data, rec, event);
1079 }
1080
1081 static int
1082 register_snapshot_trigger(char *glob, struct event_trigger_ops *ops,
1083                           struct event_trigger_data *data,
1084                           struct trace_event_file *file)
1085 {
1086         int ret = register_trigger(glob, ops, data, file);
1087
1088         if (ret > 0 && tracing_alloc_snapshot_instance(file->tr) != 0) {
1089                 unregister_trigger(glob, ops, data, file);
1090                 ret = 0;
1091         }
1092
1093         return ret;
1094 }
1095
1096 static int
1097 snapshot_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
1098                        struct event_trigger_data *data)
1099 {
1100         return event_trigger_print("snapshot", m, (void *)data->count,
1101                                    data->filter_str);
1102 }
1103
1104 static struct event_trigger_ops snapshot_trigger_ops = {
1105         .func                   = snapshot_trigger,
1106         .print                  = snapshot_trigger_print,
1107         .init                   = event_trigger_init,
1108         .free                   = event_trigger_free,
1109 };
1110
1111 static struct event_trigger_ops snapshot_count_trigger_ops = {
1112         .func                   = snapshot_count_trigger,
1113         .print                  = snapshot_trigger_print,
1114         .init                   = event_trigger_init,
1115         .free                   = event_trigger_free,
1116 };
1117
1118 static struct event_trigger_ops *
1119 snapshot_get_trigger_ops(char *cmd, char *param)
1120 {
1121         return param ? &snapshot_count_trigger_ops : &snapshot_trigger_ops;
1122 }
1123
1124 static struct event_command trigger_snapshot_cmd = {
1125         .name                   = "snapshot",
1126         .trigger_type           = ETT_SNAPSHOT,
1127         .func                   = event_trigger_callback,
1128         .reg                    = register_snapshot_trigger,
1129         .unreg                  = unregister_trigger,
1130         .get_trigger_ops        = snapshot_get_trigger_ops,
1131         .set_filter             = set_trigger_filter,
1132 };
1133
1134 static __init int register_trigger_snapshot_cmd(void)
1135 {
1136         int ret;
1137
1138         ret = register_event_command(&trigger_snapshot_cmd);
1139         WARN_ON(ret < 0);
1140
1141         return ret;
1142 }
1143 #else
1144 static __init int register_trigger_snapshot_cmd(void) { return 0; }
1145 #endif /* CONFIG_TRACER_SNAPSHOT */
1146
1147 #ifdef CONFIG_STACKTRACE
1148 #ifdef CONFIG_UNWINDER_ORC
1149 /* Skip 2:
1150  *   event_triggers_post_call()
1151  *   trace_event_raw_event_xxx()
1152  */
1153 # define STACK_SKIP 2
1154 #else
1155 /*
1156  * Skip 4:
1157  *   stacktrace_trigger()
1158  *   event_triggers_post_call()
1159  *   trace_event_buffer_commit()
1160  *   trace_event_raw_event_xxx()
1161  */
1162 #define STACK_SKIP 4
1163 #endif
1164
1165 static void
1166 stacktrace_trigger(struct event_trigger_data *data, void *rec,
1167                    struct ring_buffer_event *event)
1168 {
1169         trace_dump_stack(STACK_SKIP);
1170 }
1171
1172 static void
1173 stacktrace_count_trigger(struct event_trigger_data *data, void *rec,
1174                          struct ring_buffer_event *event)
1175 {
1176         if (!data->count)
1177                 return;
1178
1179         if (data->count != -1)
1180                 (data->count)--;
1181
1182         stacktrace_trigger(data, rec, event);
1183 }
1184
1185 static int
1186 stacktrace_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
1187                          struct event_trigger_data *data)
1188 {
1189         return event_trigger_print("stacktrace", m, (void *)data->count,
1190                                    data->filter_str);
1191 }
1192
1193 static struct event_trigger_ops stacktrace_trigger_ops = {
1194         .func                   = stacktrace_trigger,
1195         .print                  = stacktrace_trigger_print,
1196         .init                   = event_trigger_init,
1197         .free                   = event_trigger_free,
1198 };
1199
1200 static struct event_trigger_ops stacktrace_count_trigger_ops = {
1201         .func                   = stacktrace_count_trigger,
1202         .print                  = stacktrace_trigger_print,
1203         .init                   = event_trigger_init,
1204         .free                   = event_trigger_free,
1205 };
1206
1207 static struct event_trigger_ops *
1208 stacktrace_get_trigger_ops(char *cmd, char *param)
1209 {
1210         return param ? &stacktrace_count_trigger_ops : &stacktrace_trigger_ops;
1211 }
1212
1213 static struct event_command trigger_stacktrace_cmd = {
1214         .name                   = "stacktrace",
1215         .trigger_type           = ETT_STACKTRACE,
1216         .flags                  = EVENT_CMD_FL_POST_TRIGGER,
1217         .func                   = event_trigger_callback,
1218         .reg                    = register_trigger,
1219         .unreg                  = unregister_trigger,
1220         .get_trigger_ops        = stacktrace_get_trigger_ops,
1221         .set_filter             = set_trigger_filter,
1222 };
1223
1224 static __init int register_trigger_stacktrace_cmd(void)
1225 {
1226         int ret;
1227
1228         ret = register_event_command(&trigger_stacktrace_cmd);
1229         WARN_ON(ret < 0);
1230
1231         return ret;
1232 }
1233 #else
1234 static __init int register_trigger_stacktrace_cmd(void) { return 0; }
1235 #endif /* CONFIG_STACKTRACE */
1236
1237 static __init void unregister_trigger_traceon_traceoff_cmds(void)
1238 {
1239         unregister_event_command(&trigger_traceon_cmd);
1240         unregister_event_command(&trigger_traceoff_cmd);
1241 }
1242
1243 static void
1244 event_enable_trigger(struct event_trigger_data *data, void *rec,
1245                      struct ring_buffer_event *event)
1246 {
1247         struct enable_trigger_data *enable_data = data->private_data;
1248
1249         if (enable_data->enable)
1250                 clear_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
1251         else
1252                 set_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
1253 }
1254
1255 static void
1256 event_enable_count_trigger(struct event_trigger_data *data, void *rec,
1257                            struct ring_buffer_event *event)
1258 {
1259         struct enable_trigger_data *enable_data = data->private_data;
1260
1261         if (!data->count)
1262                 return;
1263
1264         /* Skip if the event is in a state we want to switch to */
1265         if (enable_data->enable == !(enable_data->file->flags & EVENT_FILE_FL_SOFT_DISABLED))
1266                 return;
1267
1268         if (data->count != -1)
1269                 (data->count)--;
1270
1271         event_enable_trigger(data, rec, event);
1272 }
1273
1274 int event_enable_trigger_print(struct seq_file *m,
1275                                struct event_trigger_ops *ops,
1276                                struct event_trigger_data *data)
1277 {
1278         struct enable_trigger_data *enable_data = data->private_data;
1279
1280         seq_printf(m, "%s:%s:%s",
1281                    enable_data->hist ?
1282                    (enable_data->enable ? ENABLE_HIST_STR : DISABLE_HIST_STR) :
1283                    (enable_data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR),
1284                    enable_data->file->event_call->class->system,
1285                    trace_event_name(enable_data->file->event_call));
1286
1287         if (data->count == -1)
1288                 seq_puts(m, ":unlimited");
1289         else
1290                 seq_printf(m, ":count=%ld", data->count);
1291
1292         if (data->filter_str)
1293                 seq_printf(m, " if %s\n", data->filter_str);
1294         else
1295                 seq_putc(m, '\n');
1296
1297         return 0;
1298 }
1299
1300 void event_enable_trigger_free(struct event_trigger_ops *ops,
1301                                struct event_trigger_data *data)
1302 {
1303         struct enable_trigger_data *enable_data = data->private_data;
1304
1305         if (WARN_ON_ONCE(data->ref <= 0))
1306                 return;
1307
1308         data->ref--;
1309         if (!data->ref) {
1310                 /* Remove the SOFT_MODE flag */
1311                 trace_event_enable_disable(enable_data->file, 0, 1);
1312                 module_put(enable_data->file->event_call->mod);
1313                 trigger_data_free(data);
1314                 kfree(enable_data);
1315         }
1316 }
1317
1318 static struct event_trigger_ops event_enable_trigger_ops = {
1319         .func                   = event_enable_trigger,
1320         .print                  = event_enable_trigger_print,
1321         .init                   = event_trigger_init,
1322         .free                   = event_enable_trigger_free,
1323 };
1324
1325 static struct event_trigger_ops event_enable_count_trigger_ops = {
1326         .func                   = event_enable_count_trigger,
1327         .print                  = event_enable_trigger_print,
1328         .init                   = event_trigger_init,
1329         .free                   = event_enable_trigger_free,
1330 };
1331
1332 static struct event_trigger_ops event_disable_trigger_ops = {
1333         .func                   = event_enable_trigger,
1334         .print                  = event_enable_trigger_print,
1335         .init                   = event_trigger_init,
1336         .free                   = event_enable_trigger_free,
1337 };
1338
1339 static struct event_trigger_ops event_disable_count_trigger_ops = {
1340         .func                   = event_enable_count_trigger,
1341         .print                  = event_enable_trigger_print,
1342         .init                   = event_trigger_init,
1343         .free                   = event_enable_trigger_free,
1344 };
1345
1346 int event_enable_trigger_func(struct event_command *cmd_ops,
1347                               struct trace_event_file *file,
1348                               char *glob, char *cmd, char *param)
1349 {
1350         struct trace_event_file *event_enable_file;
1351         struct enable_trigger_data *enable_data;
1352         struct event_trigger_data *trigger_data;
1353         struct event_trigger_ops *trigger_ops;
1354         struct trace_array *tr = file->tr;
1355         const char *system;
1356         const char *event;
1357         bool hist = false;
1358         char *trigger;
1359         char *number;
1360         bool enable;
1361         int ret;
1362
1363         if (!param)
1364                 return -EINVAL;
1365
1366         /* separate the trigger from the filter (s:e:n [if filter]) */
1367         trigger = strsep(&param, " \t");
1368         if (!trigger)
1369                 return -EINVAL;
1370
1371         system = strsep(&trigger, ":");
1372         if (!trigger)
1373                 return -EINVAL;
1374
1375         event = strsep(&trigger, ":");
1376
1377         ret = -EINVAL;
1378         event_enable_file = find_event_file(tr, system, event);
1379         if (!event_enable_file)
1380                 goto out;
1381
1382 #ifdef CONFIG_HIST_TRIGGERS
1383         hist = ((strcmp(cmd, ENABLE_HIST_STR) == 0) ||
1384                 (strcmp(cmd, DISABLE_HIST_STR) == 0));
1385
1386         enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
1387                   (strcmp(cmd, ENABLE_HIST_STR) == 0));
1388 #else
1389         enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
1390 #endif
1391         trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
1392
1393         ret = -ENOMEM;
1394         trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
1395         if (!trigger_data)
1396                 goto out;
1397
1398         enable_data = kzalloc(sizeof(*enable_data), GFP_KERNEL);
1399         if (!enable_data) {
1400                 kfree(trigger_data);
1401                 goto out;
1402         }
1403
1404         trigger_data->count = -1;
1405         trigger_data->ops = trigger_ops;
1406         trigger_data->cmd_ops = cmd_ops;
1407         INIT_LIST_HEAD(&trigger_data->list);
1408         RCU_INIT_POINTER(trigger_data->filter, NULL);
1409
1410         enable_data->hist = hist;
1411         enable_data->enable = enable;
1412         enable_data->file = event_enable_file;
1413         trigger_data->private_data = enable_data;
1414
1415         if (glob[0] == '!') {
1416                 cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
1417                 kfree(trigger_data);
1418                 kfree(enable_data);
1419                 ret = 0;
1420                 goto out;
1421         }
1422
1423         if (trigger) {
1424                 number = strsep(&trigger, ":");
1425
1426                 ret = -EINVAL;
1427                 if (!strlen(number))
1428                         goto out_free;
1429
1430                 /*
1431                  * We use the callback data field (which is a pointer)
1432                  * as our counter.
1433                  */
1434                 ret = kstrtoul(number, 0, &trigger_data->count);
1435                 if (ret)
1436                         goto out_free;
1437         }
1438
1439         if (!param) /* if param is non-empty, it's supposed to be a filter */
1440                 goto out_reg;
1441
1442         if (!cmd_ops->set_filter)
1443                 goto out_reg;
1444
1445         ret = cmd_ops->set_filter(param, trigger_data, file);
1446         if (ret < 0)
1447                 goto out_free;
1448
1449  out_reg:
1450         /* Don't let event modules unload while probe registered */
1451         ret = try_module_get(event_enable_file->event_call->mod);
1452         if (!ret) {
1453                 ret = -EBUSY;
1454                 goto out_free;
1455         }
1456
1457         ret = trace_event_enable_disable(event_enable_file, 1, 1);
1458         if (ret < 0)
1459                 goto out_put;
1460         ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);
1461         /*
1462          * The above returns on success the # of functions enabled,
1463          * but if it didn't find any functions it returns zero.
1464          * Consider no functions a failure too.
1465          */
1466         if (!ret) {
1467                 ret = -ENOENT;
1468                 goto out_disable;
1469         } else if (ret < 0)
1470                 goto out_disable;
1471         /* Just return zero, not the number of enabled functions */
1472         ret = 0;
1473  out:
1474         return ret;
1475
1476  out_disable:
1477         trace_event_enable_disable(event_enable_file, 0, 1);
1478  out_put:
1479         module_put(event_enable_file->event_call->mod);
1480  out_free:
1481         if (cmd_ops->set_filter)
1482                 cmd_ops->set_filter(NULL, trigger_data, NULL);
1483         kfree(trigger_data);
1484         kfree(enable_data);
1485         goto out;
1486 }
1487
1488 int event_enable_register_trigger(char *glob,
1489                                   struct event_trigger_ops *ops,
1490                                   struct event_trigger_data *data,
1491                                   struct trace_event_file *file)
1492 {
1493         struct enable_trigger_data *enable_data = data->private_data;
1494         struct enable_trigger_data *test_enable_data;
1495         struct event_trigger_data *test;
1496         int ret = 0;
1497
1498         list_for_each_entry_rcu(test, &file->triggers, list) {
1499                 test_enable_data = test->private_data;
1500                 if (test_enable_data &&
1501                     (test->cmd_ops->trigger_type ==
1502                      data->cmd_ops->trigger_type) &&
1503                     (test_enable_data->file == enable_data->file)) {
1504                         ret = -EEXIST;
1505                         goto out;
1506                 }
1507         }
1508
1509         if (data->ops->init) {
1510                 ret = data->ops->init(data->ops, data);
1511                 if (ret < 0)
1512                         goto out;
1513         }
1514
1515         list_add_rcu(&data->list, &file->triggers);
1516         ret++;
1517
1518         update_cond_flag(file);
1519         if (trace_event_trigger_enable_disable(file, 1) < 0) {
1520                 list_del_rcu(&data->list);
1521                 update_cond_flag(file);
1522                 ret--;
1523         }
1524 out:
1525         return ret;
1526 }
1527
1528 void event_enable_unregister_trigger(char *glob,
1529                                      struct event_trigger_ops *ops,
1530                                      struct event_trigger_data *test,
1531                                      struct trace_event_file *file)
1532 {
1533         struct enable_trigger_data *test_enable_data = test->private_data;
1534         struct enable_trigger_data *enable_data;
1535         struct event_trigger_data *data;
1536         bool unregistered = false;
1537
1538         list_for_each_entry_rcu(data, &file->triggers, list) {
1539                 enable_data = data->private_data;
1540                 if (enable_data &&
1541                     (data->cmd_ops->trigger_type ==
1542                      test->cmd_ops->trigger_type) &&
1543                     (enable_data->file == test_enable_data->file)) {
1544                         unregistered = true;
1545                         list_del_rcu(&data->list);
1546                         trace_event_trigger_enable_disable(file, 0);
1547                         update_cond_flag(file);
1548                         break;
1549                 }
1550         }
1551
1552         if (unregistered && data->ops->free)
1553                 data->ops->free(data->ops, data);
1554 }
1555
1556 static struct event_trigger_ops *
1557 event_enable_get_trigger_ops(char *cmd, char *param)
1558 {
1559         struct event_trigger_ops *ops;
1560         bool enable;
1561
1562 #ifdef CONFIG_HIST_TRIGGERS
1563         enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
1564                   (strcmp(cmd, ENABLE_HIST_STR) == 0));
1565 #else
1566         enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
1567 #endif
1568         if (enable)
1569                 ops = param ? &event_enable_count_trigger_ops :
1570                         &event_enable_trigger_ops;
1571         else
1572                 ops = param ? &event_disable_count_trigger_ops :
1573                         &event_disable_trigger_ops;
1574
1575         return ops;
1576 }
1577
1578 static struct event_command trigger_enable_cmd = {
1579         .name                   = ENABLE_EVENT_STR,
1580         .trigger_type           = ETT_EVENT_ENABLE,
1581         .func                   = event_enable_trigger_func,
1582         .reg                    = event_enable_register_trigger,
1583         .unreg                  = event_enable_unregister_trigger,
1584         .get_trigger_ops        = event_enable_get_trigger_ops,
1585         .set_filter             = set_trigger_filter,
1586 };
1587
1588 static struct event_command trigger_disable_cmd = {
1589         .name                   = DISABLE_EVENT_STR,
1590         .trigger_type           = ETT_EVENT_ENABLE,
1591         .func                   = event_enable_trigger_func,
1592         .reg                    = event_enable_register_trigger,
1593         .unreg                  = event_enable_unregister_trigger,
1594         .get_trigger_ops        = event_enable_get_trigger_ops,
1595         .set_filter             = set_trigger_filter,
1596 };
1597
1598 static __init void unregister_trigger_enable_disable_cmds(void)
1599 {
1600         unregister_event_command(&trigger_enable_cmd);
1601         unregister_event_command(&trigger_disable_cmd);
1602 }
1603
1604 static __init int register_trigger_enable_disable_cmds(void)
1605 {
1606         int ret;
1607
1608         ret = register_event_command(&trigger_enable_cmd);
1609         if (WARN_ON(ret < 0))
1610                 return ret;
1611         ret = register_event_command(&trigger_disable_cmd);
1612         if (WARN_ON(ret < 0))
1613                 unregister_trigger_enable_disable_cmds();
1614
1615         return ret;
1616 }
1617
1618 static __init int register_trigger_traceon_traceoff_cmds(void)
1619 {
1620         int ret;
1621
1622         ret = register_event_command(&trigger_traceon_cmd);
1623         if (WARN_ON(ret < 0))
1624                 return ret;
1625         ret = register_event_command(&trigger_traceoff_cmd);
1626         if (WARN_ON(ret < 0))
1627                 unregister_trigger_traceon_traceoff_cmds();
1628
1629         return ret;
1630 }
1631
1632 __init int register_trigger_cmds(void)
1633 {
1634         register_trigger_traceon_traceoff_cmds();
1635         register_trigger_snapshot_cmd();
1636         register_trigger_stacktrace_cmd();
1637         register_trigger_enable_disable_cmds();
1638         register_trigger_hist_enable_disable_cmds();
1639         register_trigger_hist_cmd();
1640
1641         return 0;
1642 }