kernel/trace/trace_events_trigger.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * trace_events_trigger - trace event triggers
   4  *
   5  * Copyright (C) 2013 Tom Zanussi <tom.zanussi@linux.intel.com>
   6  */
   7
   8 #include <linux/security.h>
   9 #include <linux/module.h>
  10 #include <linux/ctype.h>
  11 #include <linux/mutex.h>
  12 #include <linux/slab.h>
  13 #include <linux/rculist.h>
  14
  15 #include "trace.h"
  16
  17 static LIST_HEAD(trigger_commands);
  18 static DEFINE_MUTEX(trigger_cmd_mutex);
  19
  20 void trigger_data_free(struct event_trigger_data *data)
  21 {
  22         if (data->cmd_ops->set_filter)
  23                 data->cmd_ops->set_filter(NULL, data, NULL);
  24
  25         /* make sure current triggers exit before free */
  26         tracepoint_synchronize_unregister();
  27
  28         kfree(data);
  29 }
  30
  31 /**
  32  * event_triggers_call - Call triggers associated with a trace event
  33  * @file: The trace_event_file associated with the event
  34  * @rec: The trace entry for the event, NULL for unconditional invocation
  35  *
  36  * For each trigger associated with an event, invoke the trigger
  37  * function registered with the associated trigger command.  If rec is
  38  * non-NULL, it means that the trigger requires further processing and
  39  * shouldn't be unconditionally invoked.  If rec is non-NULL and the
  40  * trigger has a filter associated with it, rec will checked against
  41  * the filter and if the record matches the trigger will be invoked.
  42  * If the trigger is a 'post_trigger', meaning it shouldn't be invoked
  43  * in any case until the current event is written, the trigger
  44  * function isn't invoked but the bit associated with the deferred
  45  * trigger is set in the return value.
  46  *
  47  * Returns an enum event_trigger_type value containing a set bit for
  48  * any trigger that should be deferred, ETT_NONE if nothing to defer.
  49  *
  50  * Called from tracepoint handlers (with rcu_read_lock_sched() held).
  51  *
  52  * Return: an enum event_trigger_type value containing a set bit for
  53  * any trigger that should be deferred, ETT_NONE if nothing to defer.
  54  */
  55 enum event_trigger_type
  56 event_triggers_call(struct trace_event_file *file, void *rec,
  57                     struct ring_buffer_event *event)
  58 {
  59         struct event_trigger_data *data;
  60         enum event_trigger_type tt = ETT_NONE;
  61         struct event_filter *filter;
  62
  63         if (list_empty(&file->triggers))
  64                 return tt;
  65
  66         list_for_each_entry_rcu(data, &file->triggers, list) {
  67                 if (data->paused)
  68                         continue;
  69                 if (!rec) {
  70                         data->ops->func(data, rec, event);
  71                         continue;
  72                 }
  73                 filter = rcu_dereference_sched(data->filter);
  74                 if (filter && !filter_match_preds(filter, rec))
  75                         continue;
  76                 if (event_command_post_trigger(data->cmd_ops)) {
  77                         tt |= data->cmd_ops->trigger_type;
  78                         continue;
  79                 }
  80                 data->ops->func(data, rec, event);
  81         }
  82         return tt;
  83 }
  84 EXPORT_SYMBOL_GPL(event_triggers_call);
  85
  86 /**
  87  * event_triggers_post_call - Call 'post_triggers' for a trace event
  88  * @file: The trace_event_file associated with the event
  89  * @tt: enum event_trigger_type containing a set bit for each trigger to invoke
  90  *
  91  * For each trigger associated with an event, invoke the trigger
  92  * function registered with the associated trigger command, if the
  93  * corresponding bit is set in the tt enum passed into this function.
  94  * See @event_triggers_call for details on how those bits are set.
  95  *
  96  * Called from tracepoint handlers (with rcu_read_lock_sched() held).
  97  */
  98 void
  99 event_triggers_post_call(struct trace_event_file *file,
 100                          enum event_trigger_type tt)
 101 {
 102         struct event_trigger_data *data;
 103
 104         list_for_each_entry_rcu(data, &file->triggers, list) {
 105                 if (data->paused)
 106                         continue;
 107                 if (data->cmd_ops->trigger_type & tt)
 108                         data->ops->func(data, NULL, NULL);
 109         }
 110 }
 111 EXPORT_SYMBOL_GPL(event_triggers_post_call);
 112
 113 #define SHOW_AVAILABLE_TRIGGERS (void *)(1UL)
 114
 115 static void *trigger_next(struct seq_file *m, void *t, loff_t *pos)
 116 {
 117         struct trace_event_file *event_file = event_file_data(m->private);
 118
 119         if (t == SHOW_AVAILABLE_TRIGGERS)
 120                 return NULL;
 121
 122         return seq_list_next(t, &event_file->triggers, pos);
 123 }
 124
 125 static void *trigger_start(struct seq_file *m, loff_t *pos)
 126 {
 127         struct trace_event_file *event_file;
 128
 129         /* ->stop() is called even if ->start() fails */
 130         mutex_lock(&event_mutex);
 131         event_file = event_file_data(m->private);
 132         if (unlikely(!event_file))
 133                 return ERR_PTR(-ENODEV);
 134
 135         if (list_empty(&event_file->triggers))
 136                 return *pos == 0 ? SHOW_AVAILABLE_TRIGGERS : NULL;
 137
 138         return seq_list_start(&event_file->triggers, *pos);
 139 }
 140
 141 static void trigger_stop(struct seq_file *m, void *t)
 142 {
 143         mutex_unlock(&event_mutex);
 144 }
 145
 146 static int trigger_show(struct seq_file *m, void *v)
 147 {
 148         struct event_trigger_data *data;
 149         struct event_command *p;
 150
 151         if (v == SHOW_AVAILABLE_TRIGGERS) {
 152                 seq_puts(m, "# Available triggers:\n");
 153                 seq_putc(m, '#');
 154                 mutex_lock(&trigger_cmd_mutex);
 155                 list_for_each_entry_reverse(p, &trigger_commands, list)
 156                         seq_printf(m, " %s", p->name);
 157                 seq_putc(m, '\n');
 158                 mutex_unlock(&trigger_cmd_mutex);
 159                 return 0;
 160         }
 161
 162         data = list_entry(v, struct event_trigger_data, list);
 163         data->ops->print(m, data->ops, data);
 164
 165         return 0;
 166 }
 167
 168 static const struct seq_operations event_triggers_seq_ops = {
 169         .start = trigger_start,
 170         .next = trigger_next,
 171         .stop = trigger_stop,
 172         .show = trigger_show,
 173 };
 174
 175 static int event_trigger_regex_open(struct inode *inode, struct file *file)
 176 {
 177         int ret;
 178
 179         ret = security_locked_down(LOCKDOWN_TRACEFS);
 180         if (ret)
 181                 return ret;
 182
 183         mutex_lock(&event_mutex);
 184
 185         if (unlikely(!event_file_data(file))) {
 186                 mutex_unlock(&event_mutex);
 187                 return -ENODEV;
 188         }
 189
 190         if ((file->f_mode & FMODE_WRITE) &&
 191             (file->f_flags & O_TRUNC)) {
 192                 struct trace_event_file *event_file;
 193                 struct event_command *p;
 194
 195                 event_file = event_file_data(file);
 196
 197                 list_for_each_entry(p, &trigger_commands, list) {
 198                         if (p->unreg_all)
 199                                 p->unreg_all(event_file);
 200                 }
 201         }
 202
 203         if (file->f_mode & FMODE_READ) {
 204                 ret = seq_open(file, &event_triggers_seq_ops);
 205                 if (!ret) {
 206                         struct seq_file *m = file->private_data;
 207                         m->private = file;
 208                 }
 209         }
 210
 211         mutex_unlock(&event_mutex);
 212
 213         return ret;
 214 }
 215
 216 int trigger_process_regex(struct trace_event_file *file, char *buff)
 217 {
 218         char *command, *next = buff;
 219         struct event_command *p;
 220         int ret = -EINVAL;
 221
 222         command = strsep(&next, ": \t");
 223         command = (command[0] != '!') ? command : command + 1;
 224
 225         mutex_lock(&trigger_cmd_mutex);
 226         list_for_each_entry(p, &trigger_commands, list) {
 227                 if (strcmp(p->name, command) == 0) {
 228                         ret = p->func(p, file, buff, command, next);
 229                         goto out_unlock;
 230                 }
 231         }
 232  out_unlock:
 233         mutex_unlock(&trigger_cmd_mutex);
 234
 235         return ret;
 236 }
 237
 238 static ssize_t event_trigger_regex_write(struct file *file,
 239                                          const char __user *ubuf,
 240                                          size_t cnt, loff_t *ppos)
 241 {
 242         struct trace_event_file *event_file;
 243         ssize_t ret;
 244         char *buf;
 245
 246         if (!cnt)
 247                 return 0;
 248
 249         if (cnt >= PAGE_SIZE)
 250                 return -EINVAL;
 251
 252         buf = memdup_user_nul(ubuf, cnt);
 253         if (IS_ERR(buf))
 254                 return PTR_ERR(buf);
 255
 256         strim(buf);
 257
 258         mutex_lock(&event_mutex);
 259         event_file = event_file_data(file);
 260         if (unlikely(!event_file)) {
 261                 mutex_unlock(&event_mutex);
 262                 kfree(buf);
 263                 return -ENODEV;
 264         }
 265         ret = trigger_process_regex(event_file, buf);
 266         mutex_unlock(&event_mutex);
 267
 268         kfree(buf);
 269         if (ret < 0)
 270                 goto out;
 271
 272         *ppos += cnt;
 273         ret = cnt;
 274  out:
 275         return ret;
 276 }
 277
 278 static int event_trigger_regex_release(struct inode *inode, struct file *file)
 279 {
 280         mutex_lock(&event_mutex);
 281
 282         if (file->f_mode & FMODE_READ)
 283                 seq_release(inode, file);
 284
 285         mutex_unlock(&event_mutex);
 286
 287         return 0;
 288 }
 289
 290 static ssize_t
 291 event_trigger_write(struct file *filp, const char __user *ubuf,
 292                     size_t cnt, loff_t *ppos)
 293 {
 294         return event_trigger_regex_write(filp, ubuf, cnt, ppos);
 295 }
 296
 297 static int
 298 event_trigger_open(struct inode *inode, struct file *filp)
 299 {
 300         /* Checks for tracefs lockdown */
 301         return event_trigger_regex_open(inode, filp);
 302 }
 303
 304 static int
 305 event_trigger_release(struct inode *inode, struct file *file)
 306 {
 307         return event_trigger_regex_release(inode, file);
 308 }
 309
 310 const struct file_operations event_trigger_fops = {
 311         .open = event_trigger_open,
 312         .read = seq_read,
 313         .write = event_trigger_write,
 314         .llseek = tracing_lseek,
 315         .release = event_trigger_release,
 316 };
 317
 318 /*
 319  * Currently we only register event commands from __init, so mark this
 320  * __init too.
 321  */
 322 __init int register_event_command(struct event_command *cmd)
 323 {
 324         struct event_command *p;
 325         int ret = 0;
 326
 327         mutex_lock(&trigger_cmd_mutex);
 328         list_for_each_entry(p, &trigger_commands, list) {
 329                 if (strcmp(cmd->name, p->name) == 0) {
 330                         ret = -EBUSY;
 331                         goto out_unlock;
 332                 }
 333         }
 334         list_add(&cmd->list, &trigger_commands);
 335  out_unlock:
 336         mutex_unlock(&trigger_cmd_mutex);
 337
 338         return ret;
 339 }
 340
 341 /*
 342  * Currently we only unregister event commands from __init, so mark
 343  * this __init too.
 344  */
 345 __init int unregister_event_command(struct event_command *cmd)
 346 {
 347         struct event_command *p, *n;
 348         int ret = -ENODEV;
 349
 350         mutex_lock(&trigger_cmd_mutex);
 351         list_for_each_entry_safe(p, n, &trigger_commands, list) {
 352                 if (strcmp(cmd->name, p->name) == 0) {
 353                         ret = 0;
 354                         list_del_init(&p->list);
 355                         goto out_unlock;
 356                 }
 357         }
 358  out_unlock:
 359         mutex_unlock(&trigger_cmd_mutex);
 360
 361         return ret;
 362 }
 363
 364 /**
 365  * event_trigger_print - Generic event_trigger_ops @print implementation
 366  * @name: The name of the event trigger
 367  * @m: The seq_file being printed to
 368  * @data: Trigger-specific data
 369  * @filter_str: filter_str to print, if present
 370  *
 371  * Common implementation for event triggers to print themselves.
 372  *
 373  * Usually wrapped by a function that simply sets the @name of the
 374  * trigger command and then invokes this.
 375  *
 376  * Return: 0 on success, errno otherwise
 377  */
 378 static int
 379 event_trigger_print(const char *name, struct seq_file *m,
 380                     void *data, char *filter_str)
 381 {
 382         long count = (long)data;
 383
 384         seq_puts(m, name);
 385
 386         if (count == -1)
 387                 seq_puts(m, ":unlimited");
 388         else
 389                 seq_printf(m, ":count=%ld", count);
 390
 391         if (filter_str)
 392                 seq_printf(m, " if %s\n", filter_str);
 393         else
 394                 seq_putc(m, '\n');
 395
 396         return 0;
 397 }
 398
 399 /**
 400  * event_trigger_init - Generic event_trigger_ops @init implementation
 401  * @ops: The trigger ops associated with the trigger
 402  * @data: Trigger-specific data
 403  *
 404  * Common implementation of event trigger initialization.
 405  *
 406  * Usually used directly as the @init method in event trigger
 407  * implementations.
 408  *
 409  * Return: 0 on success, errno otherwise
 410  */
 411 int event_trigger_init(struct event_trigger_ops *ops,
 412                        struct event_trigger_data *data)
 413 {
 414         data->ref++;
 415         return 0;
 416 }
 417
 418 /**
 419  * event_trigger_free - Generic event_trigger_ops @free implementation
 420  * @ops: The trigger ops associated with the trigger
 421  * @data: Trigger-specific data
 422  *
 423  * Common implementation of event trigger de-initialization.
 424  *
 425  * Usually used directly as the @free method in event trigger
 426  * implementations.
 427  */
 428 static void
 429 event_trigger_free(struct event_trigger_ops *ops,
 430                    struct event_trigger_data *data)
 431 {
 432         if (WARN_ON_ONCE(data->ref <= 0))
 433                 return;
 434
 435         data->ref--;
 436         if (!data->ref)
 437                 trigger_data_free(data);
 438 }
 439
 440 int trace_event_trigger_enable_disable(struct trace_event_file *file,
 441                                        int trigger_enable)
 442 {
 443         int ret = 0;
 444
 445         if (trigger_enable) {
 446                 if (atomic_inc_return(&file->tm_ref) > 1)
 447                         return ret;
 448                 set_bit(EVENT_FILE_FL_TRIGGER_MODE_BIT, &file->flags);
 449                 ret = trace_event_enable_disable(file, 1, 1);
 450         } else {
 451                 if (atomic_dec_return(&file->tm_ref) > 0)
 452                         return ret;
 453                 clear_bit(EVENT_FILE_FL_TRIGGER_MODE_BIT, &file->flags);
 454                 ret = trace_event_enable_disable(file, 0, 1);
 455         }
 456
 457         return ret;
 458 }
 459
 460 /**
 461  * clear_event_triggers - Clear all triggers associated with a trace array
 462  * @tr: The trace array to clear
 463  *
 464  * For each trigger, the triggering event has its tm_ref decremented
 465  * via trace_event_trigger_enable_disable(), and any associated event
 466  * (in the case of enable/disable_event triggers) will have its sm_ref
 467  * decremented via free()->trace_event_enable_disable().  That
 468  * combination effectively reverses the soft-mode/trigger state added
 469  * by trigger registration.
 470  *
 471  * Must be called with event_mutex held.
 472  */
 473 void
 474 clear_event_triggers(struct trace_array *tr)
 475 {
 476         struct trace_event_file *file;
 477
 478         list_for_each_entry(file, &tr->events, list) {
 479                 struct event_trigger_data *data, *n;
 480                 list_for_each_entry_safe(data, n, &file->triggers, list) {
 481                         trace_event_trigger_enable_disable(file, 0);
 482                         list_del_rcu(&data->list);
 483                         if (data->ops->free)
 484                                 data->ops->free(data->ops, data);
 485                 }
 486         }
 487 }
 488
 489 /**
 490  * update_cond_flag - Set or reset the TRIGGER_COND bit
 491  * @file: The trace_event_file associated with the event
 492  *
 493  * If an event has triggers and any of those triggers has a filter or
 494  * a post_trigger, trigger invocation needs to be deferred until after
 495  * the current event has logged its data, and the event should have
 496  * its TRIGGER_COND bit set, otherwise the TRIGGER_COND bit should be
 497  * cleared.
 498  */
 499 void update_cond_flag(struct trace_event_file *file)
 500 {
 501         struct event_trigger_data *data;
 502         bool set_cond = false;
 503
 504         list_for_each_entry_rcu(data, &file->triggers, list) {
 505                 if (data->filter || event_command_post_trigger(data->cmd_ops) ||
 506                     event_command_needs_rec(data->cmd_ops)) {
 507                         set_cond = true;
 508                         break;
 509                 }
 510         }
 511
 512         if (set_cond)
 513                 set_bit(EVENT_FILE_FL_TRIGGER_COND_BIT, &file->flags);
 514         else
 515                 clear_bit(EVENT_FILE_FL_TRIGGER_COND_BIT, &file->flags);
 516 }
 517
 518 /**
 519  * register_trigger - Generic event_command @reg implementation
 520  * @glob: The raw string used to register the trigger
 521  * @ops: The trigger ops associated with the trigger
 522  * @data: Trigger-specific data to associate with the trigger
 523  * @file: The trace_event_file associated with the event
 524  *
 525  * Common implementation for event trigger registration.
 526  *
 527  * Usually used directly as the @reg method in event command
 528  * implementations.
 529  *
 530  * Return: 0 on success, errno otherwise
 531  */
 532 static int register_trigger(char *glob, struct event_trigger_ops *ops,
 533                             struct event_trigger_data *data,
 534                             struct trace_event_file *file)
 535 {
 536         struct event_trigger_data *test;
 537         int ret = 0;
 538
 539         list_for_each_entry_rcu(test, &file->triggers, list) {
 540                 if (test->cmd_ops->trigger_type == data->cmd_ops->trigger_type) {
 541                         ret = -EEXIST;
 542                         goto out;
 543                 }
 544         }
 545
 546         if (data->ops->init) {
 547                 ret = data->ops->init(data->ops, data);
 548                 if (ret < 0)
 549                         goto out;
 550         }
 551
 552         list_add_rcu(&data->list, &file->triggers);
 553         ret++;
 554
 555         update_cond_flag(file);
 556         if (trace_event_trigger_enable_disable(file, 1) < 0) {
 557                 list_del_rcu(&data->list);
 558                 update_cond_flag(file);
 559                 ret--;
 560         }
 561 out:
 562         return ret;
 563 }
 564
 565 /**
 566  * unregister_trigger - Generic event_command @unreg implementation
 567  * @glob: The raw string used to register the trigger
 568  * @ops: The trigger ops associated with the trigger
 569  * @test: Trigger-specific data used to find the trigger to remove
 570  * @file: The trace_event_file associated with the event
 571  *
 572  * Common implementation for event trigger unregistration.
 573  *
 574  * Usually used directly as the @unreg method in event command
 575  * implementations.
 576  */
 577 static void unregister_trigger(char *glob, struct event_trigger_ops *ops,
 578                                struct event_trigger_data *test,
 579                                struct trace_event_file *file)
 580 {
 581         struct event_trigger_data *data;
 582         bool unregistered = false;
 583
 584         list_for_each_entry_rcu(data, &file->triggers, list) {
 585                 if (data->cmd_ops->trigger_type == test->cmd_ops->trigger_type) {
 586                         unregistered = true;
 587                         list_del_rcu(&data->list);
 588                         trace_event_trigger_enable_disable(file, 0);
 589                         update_cond_flag(file);
 590                         break;
 591                 }
 592         }
 593
 594         if (unregistered && data->ops->free)
 595                 data->ops->free(data->ops, data);
 596 }
 597
 598 /**
 599  * event_trigger_callback - Generic event_command @func implementation
 600  * @cmd_ops: The command ops, used for trigger registration
 601  * @file: The trace_event_file associated with the event
 602  * @glob: The raw string used to register the trigger
 603  * @cmd: The cmd portion of the string used to register the trigger
 604  * @param: The params portion of the string used to register the trigger
 605  *
 606  * Common implementation for event command parsing and trigger
 607  * instantiation.
 608  *
 609  * Usually used directly as the @func method in event command
 610  * implementations.
 611  *
 612  * Return: 0 on success, errno otherwise
 613  */
 614 static int
 615 event_trigger_callback(struct event_command *cmd_ops,
 616                        struct trace_event_file *file,
 617                        char *glob, char *cmd, char *param)
 618 {
 619         struct event_trigger_data *trigger_data;
 620         struct event_trigger_ops *trigger_ops;
 621         char *trigger = NULL;
 622         char *number;
 623         int ret;
 624
 625         /* separate the trigger from the filter (t:n [if filter]) */
 626         if (param && isdigit(param[0]))
 627                 trigger = strsep(&param, " \t");
 628
 629         trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
 630
 631         ret = -ENOMEM;
 632         trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
 633         if (!trigger_data)
 634                 goto out;
 635
 636         trigger_data->count = -1;
 637         trigger_data->ops = trigger_ops;
 638         trigger_data->cmd_ops = cmd_ops;
 639         trigger_data->private_data = file;
 640         INIT_LIST_HEAD(&trigger_data->list);
 641         INIT_LIST_HEAD(&trigger_data->named_list);
 642
 643         if (glob[0] == '!') {
 644                 cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
 645                 kfree(trigger_data);
 646                 ret = 0;
 647                 goto out;
 648         }
 649
 650         if (trigger) {
 651                 number = strsep(&trigger, ":");
 652
 653                 ret = -EINVAL;
 654                 if (!strlen(number))
 655                         goto out_free;
 656
 657                 /*
 658                  * We use the callback data field (which is a pointer)
 659                  * as our counter.
 660                  */
 661                 ret = kstrtoul(number, 0, &trigger_data->count);
 662                 if (ret)
 663                         goto out_free;
 664         }
 665
 666         if (!param) /* if param is non-empty, it's supposed to be a filter */
 667                 goto out_reg;
 668
 669         if (!cmd_ops->set_filter)
 670                 goto out_reg;
 671
 672         ret = cmd_ops->set_filter(param, trigger_data, file);
 673         if (ret < 0)
 674                 goto out_free;
 675
 676  out_reg:
 677         /* Up the trigger_data count to make sure reg doesn't free it on failure */
 678         event_trigger_init(trigger_ops, trigger_data);
 679         ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);
 680         /*
 681          * The above returns on success the # of functions enabled,
 682          * but if it didn't find any functions it returns zero.
 683          * Consider no functions a failure too.
 684          */
 685         if (!ret) {
 686                 cmd_ops->unreg(glob, trigger_ops, trigger_data, file);
 687                 ret = -ENOENT;
 688         } else if (ret > 0)
 689                 ret = 0;
 690
 691         /* Down the counter of trigger_data or free it if not used anymore */
 692         event_trigger_free(trigger_ops, trigger_data);
 693  out:
 694         return ret;
 695
 696  out_free:
 697         if (cmd_ops->set_filter)
 698                 cmd_ops->set_filter(NULL, trigger_data, NULL);
 699         kfree(trigger_data);
 700         goto out;
 701 }
 702
 703 /**
 704  * set_trigger_filter - Generic event_command @set_filter implementation
 705  * @filter_str: The filter string for the trigger, NULL to remove filter
 706  * @trigger_data: Trigger-specific data
 707  * @file: The trace_event_file associated with the event
 708  *
 709  * Common implementation for event command filter parsing and filter
 710  * instantiation.
 711  *
 712  * Usually used directly as the @set_filter method in event command
 713  * implementations.
 714  *
 715  * Also used to remove a filter (if filter_str = NULL).
 716  *
 717  * Return: 0 on success, errno otherwise
 718  */
 719 int set_trigger_filter(char *filter_str,
 720                        struct event_trigger_data *trigger_data,
 721                        struct trace_event_file *file)
 722 {
 723         struct event_trigger_data *data = trigger_data;
 724         struct event_filter *filter = NULL, *tmp;
 725         int ret = -EINVAL;
 726         char *s;
 727
 728         if (!filter_str) /* clear the current filter */
 729                 goto assign;
 730
 731         s = strsep(&filter_str, " \t");
 732
 733         if (!strlen(s) || strcmp(s, "if") != 0)
 734                 goto out;
 735
 736         if (!filter_str)
 737                 goto out;
 738
 739         /* The filter is for the 'trigger' event, not the triggered event */
 740         ret = create_event_filter(file->tr, file->event_call,
 741                                   filter_str, false, &filter);
 742         /*
 743          * If create_event_filter() fails, filter still needs to be freed.
 744          * Which the calling code will do with data->filter.
 745          */
 746  assign:
 747         tmp = rcu_access_pointer(data->filter);
 748
 749         rcu_assign_pointer(data->filter, filter);
 750
 751         if (tmp) {
 752                 /* Make sure the call is done with the filter */
 753                 tracepoint_synchronize_unregister();
 754                 free_event_filter(tmp);
 755         }
 756
 757         kfree(data->filter_str);
 758         data->filter_str = NULL;
 759
 760         if (filter_str) {
 761                 data->filter_str = kstrdup(filter_str, GFP_KERNEL);
 762                 if (!data->filter_str) {
 763                         free_event_filter(rcu_access_pointer(data->filter));
 764                         data->filter = NULL;
 765                         ret = -ENOMEM;
 766                 }
 767         }
 768  out:
 769         return ret;
 770 }
 771
 772 static LIST_HEAD(named_triggers);
 773
 774 /**
 775  * find_named_trigger - Find the common named trigger associated with @name
 776  * @name: The name of the set of named triggers to find the common data for
 777  *
 778  * Named triggers are sets of triggers that share a common set of
 779  * trigger data.  The first named trigger registered with a given name
 780  * owns the common trigger data that the others subsequently
 781  * registered with the same name will reference.  This function
 782  * returns the common trigger data associated with that first
 783  * registered instance.
 784  *
 785  * Return: the common trigger data for the given named trigger on
 786  * success, NULL otherwise.
 787  */
 788 struct event_trigger_data *find_named_trigger(const char *name)
 789 {
 790         struct event_trigger_data *data;
 791
 792         if (!name)
 793                 return NULL;
 794
 795         list_for_each_entry(data, &named_triggers, named_list) {
 796                 if (data->named_data)
 797                         continue;
 798                 if (strcmp(data->name, name) == 0)
 799                         return data;
 800         }
 801
 802         return NULL;
 803 }
 804
 805 /**
 806  * is_named_trigger - determine if a given trigger is a named trigger
 807  * @test: The trigger data to test
 808  *
 809  * Return: true if 'test' is a named trigger, false otherwise.
 810  */
 811 bool is_named_trigger(struct event_trigger_data *test)
 812 {
 813         struct event_trigger_data *data;
 814
 815         list_for_each_entry(data, &named_triggers, named_list) {
 816                 if (test == data)
 817                         return true;
 818         }
 819
 820         return false;
 821 }
 822
 823 /**
 824  * save_named_trigger - save the trigger in the named trigger list
 825  * @name: The name of the named trigger set
 826  * @data: The trigger data to save
 827  *
 828  * Return: 0 if successful, negative error otherwise.
 829  */
 830 int save_named_trigger(const char *name, struct event_trigger_data *data)
 831 {
 832         data->name = kstrdup(name, GFP_KERNEL);
 833         if (!data->name)
 834                 return -ENOMEM;
 835
 836         list_add(&data->named_list, &named_triggers);
 837
 838         return 0;
 839 }
 840
 841 /**
 842  * del_named_trigger - delete a trigger from the named trigger list
 843  * @data: The trigger data to delete
 844  */
 845 void del_named_trigger(struct event_trigger_data *data)
 846 {
 847         kfree(data->name);
 848         data->name = NULL;
 849
 850         list_del(&data->named_list);
 851 }
 852
 853 static void __pause_named_trigger(struct event_trigger_data *data, bool pause)
 854 {
 855         struct event_trigger_data *test;
 856
 857         list_for_each_entry(test, &named_triggers, named_list) {
 858                 if (strcmp(test->name, data->name) == 0) {
 859                         if (pause) {
 860                                 test->paused_tmp = test->paused;
 861                                 test->paused = true;
 862                         } else {
 863                                 test->paused = test->paused_tmp;
 864                         }
 865                 }
 866         }
 867 }
 868
 869 /**
 870  * pause_named_trigger - Pause all named triggers with the same name
 871  * @data: The trigger data of a named trigger to pause
 872  *
 873  * Pauses a named trigger along with all other triggers having the
 874  * same name.  Because named triggers share a common set of data,
 875  * pausing only one is meaningless, so pausing one named trigger needs
 876  * to pause all triggers with the same name.
 877  */
 878 void pause_named_trigger(struct event_trigger_data *data)
 879 {
 880         __pause_named_trigger(data, true);
 881 }
 882
 883 /**
 884  * unpause_named_trigger - Un-pause all named triggers with the same name
 885  * @data: The trigger data of a named trigger to unpause
 886  *
 887  * Un-pauses a named trigger along with all other triggers having the
 888  * same name.  Because named triggers share a common set of data,
 889  * unpausing only one is meaningless, so unpausing one named trigger
 890  * needs to unpause all triggers with the same name.
 891  */
 892 void unpause_named_trigger(struct event_trigger_data *data)
 893 {
 894         __pause_named_trigger(data, false);
 895 }
 896
 897 /**
 898  * set_named_trigger_data - Associate common named trigger data
 899  * @data: The trigger data of a named trigger to unpause
 900  *
 901  * Named triggers are sets of triggers that share a common set of
 902  * trigger data.  The first named trigger registered with a given name
 903  * owns the common trigger data that the others subsequently
 904  * registered with the same name will reference.  This function
 905  * associates the common trigger data from the first trigger with the
 906  * given trigger.
 907  */
 908 void set_named_trigger_data(struct event_trigger_data *data,
 909                             struct event_trigger_data *named_data)
 910 {
 911         data->named_data = named_data;
 912 }
 913
 914 struct event_trigger_data *
 915 get_named_trigger_data(struct event_trigger_data *data)
 916 {
 917         return data->named_data;
 918 }
 919
 920 static void
 921 traceon_trigger(struct event_trigger_data *data, void *rec,
 922                 struct ring_buffer_event *event)
 923 {
 924         if (tracing_is_on())
 925                 return;
 926
 927         tracing_on();
 928 }
 929
 930 static void
 931 traceon_count_trigger(struct event_trigger_data *data, void *rec,
 932                       struct ring_buffer_event *event)
 933 {
 934         if (tracing_is_on())
 935                 return;
 936
 937         if (!data->count)
 938                 return;
 939
 940         if (data->count != -1)
 941                 (data->count)--;
 942
 943         tracing_on();
 944 }
 945
 946 static void
 947 traceoff_trigger(struct event_trigger_data *data, void *rec,
 948                  struct ring_buffer_event *event)
 949 {
 950         if (!tracing_is_on())
 951                 return;
 952
 953         tracing_off();
 954 }
 955
 956 static void
 957 traceoff_count_trigger(struct event_trigger_data *data, void *rec,
 958                        struct ring_buffer_event *event)
 959 {
 960         if (!tracing_is_on())
 961                 return;
 962
 963         if (!data->count)
 964                 return;
 965
 966         if (data->count != -1)
 967                 (data->count)--;
 968
 969         tracing_off();
 970 }
 971
 972 static int
 973 traceon_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
 974                       struct event_trigger_data *data)
 975 {
 976         return event_trigger_print("traceon", m, (void *)data->count,
 977                                    data->filter_str);
 978 }
 979
 980 static int
 981 traceoff_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
 982                        struct event_trigger_data *data)
 983 {
 984         return event_trigger_print("traceoff", m, (void *)data->count,
 985                                    data->filter_str);
 986 }
 987
 988 static struct event_trigger_ops traceon_trigger_ops = {
 989         .func                   = traceon_trigger,
 990         .print                  = traceon_trigger_print,
 991         .init                   = event_trigger_init,
 992         .free                   = event_trigger_free,
 993 };
 994
 995 static struct event_trigger_ops traceon_count_trigger_ops = {
 996         .func                   = traceon_count_trigger,
 997         .print                  = traceon_trigger_print,
 998         .init                   = event_trigger_init,
 999         .free                   = event_trigger_free,
1000 };
1001
1002 static struct event_trigger_ops traceoff_trigger_ops = {
1003         .func                   = traceoff_trigger,
1004         .print                  = traceoff_trigger_print,
1005         .init                   = event_trigger_init,
1006         .free                   = event_trigger_free,
1007 };
1008
1009 static struct event_trigger_ops traceoff_count_trigger_ops = {
1010         .func                   = traceoff_count_trigger,
1011         .print                  = traceoff_trigger_print,
1012         .init                   = event_trigger_init,
1013         .free                   = event_trigger_free,
1014 };
1015
1016 static struct event_trigger_ops *
1017 onoff_get_trigger_ops(char *cmd, char *param)
1018 {
1019         struct event_trigger_ops *ops;
1020
1021         /* we register both traceon and traceoff to this callback */
1022         if (strcmp(cmd, "traceon") == 0)
1023                 ops = param ? &traceon_count_trigger_ops :
1024                         &traceon_trigger_ops;
1025         else
1026                 ops = param ? &traceoff_count_trigger_ops :
1027                         &traceoff_trigger_ops;
1028
1029         return ops;
1030 }
1031
1032 static struct event_command trigger_traceon_cmd = {
1033         .name                   = "traceon",
1034         .trigger_type           = ETT_TRACE_ONOFF,
1035         .func                   = event_trigger_callback,
1036         .reg                    = register_trigger,
1037         .unreg                  = unregister_trigger,
1038         .get_trigger_ops        = onoff_get_trigger_ops,
1039         .set_filter             = set_trigger_filter,
1040 };
1041
1042 static struct event_command trigger_traceoff_cmd = {
1043         .name                   = "traceoff",
1044         .trigger_type           = ETT_TRACE_ONOFF,
1045         .flags                  = EVENT_CMD_FL_POST_TRIGGER,
1046         .func                   = event_trigger_callback,
1047         .reg                    = register_trigger,
1048         .unreg                  = unregister_trigger,
1049         .get_trigger_ops        = onoff_get_trigger_ops,
1050         .set_filter             = set_trigger_filter,
1051 };
1052
1053 #ifdef CONFIG_TRACER_SNAPSHOT
1054 static void
1055 snapshot_trigger(struct event_trigger_data *data, void *rec,
1056                  struct ring_buffer_event *event)
1057 {
1058         struct trace_event_file *file = data->private_data;
1059
1060         if (file)
1061                 tracing_snapshot_instance(file->tr);
1062         else
1063                 tracing_snapshot();
1064 }
1065
1066 static void
1067 snapshot_count_trigger(struct event_trigger_data *data, void *rec,
1068                        struct ring_buffer_event *event)
1069 {
1070         if (!data->count)
1071                 return;
1072
1073         if (data->count != -1)
1074                 (data->count)--;
1075
1076         snapshot_trigger(data, rec, event);
1077 }
1078
1079 static int
1080 register_snapshot_trigger(char *glob, struct event_trigger_ops *ops,
1081                           struct event_trigger_data *data,
1082                           struct trace_event_file *file)
1083 {
1084         int ret = register_trigger(glob, ops, data, file);
1085
1086         if (ret > 0 && tracing_alloc_snapshot_instance(file->tr) != 0) {
1087                 unregister_trigger(glob, ops, data, file);
1088                 ret = 0;
1089         }
1090
1091         return ret;
1092 }
1093
1094 static int
1095 snapshot_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
1096                        struct event_trigger_data *data)
1097 {
1098         return event_trigger_print("snapshot", m, (void *)data->count,
1099                                    data->filter_str);
1100 }
1101
1102 static struct event_trigger_ops snapshot_trigger_ops = {
1103         .func                   = snapshot_trigger,
1104         .print                  = snapshot_trigger_print,
1105         .init                   = event_trigger_init,
1106         .free                   = event_trigger_free,
1107 };
1108
1109 static struct event_trigger_ops snapshot_count_trigger_ops = {
1110         .func                   = snapshot_count_trigger,
1111         .print                  = snapshot_trigger_print,
1112         .init                   = event_trigger_init,
1113         .free                   = event_trigger_free,
1114 };
1115
1116 static struct event_trigger_ops *
1117 snapshot_get_trigger_ops(char *cmd, char *param)
1118 {
1119         return param ? &snapshot_count_trigger_ops : &snapshot_trigger_ops;
1120 }
1121
1122 static struct event_command trigger_snapshot_cmd = {
1123         .name                   = "snapshot",
1124         .trigger_type           = ETT_SNAPSHOT,
1125         .func                   = event_trigger_callback,
1126         .reg                    = register_snapshot_trigger,
1127         .unreg                  = unregister_trigger,
1128         .get_trigger_ops        = snapshot_get_trigger_ops,
1129         .set_filter             = set_trigger_filter,
1130 };
1131
1132 static __init int register_trigger_snapshot_cmd(void)
1133 {
1134         int ret;
1135
1136         ret = register_event_command(&trigger_snapshot_cmd);
1137         WARN_ON(ret < 0);
1138
1139         return ret;
1140 }
1141 #else
1142 static __init int register_trigger_snapshot_cmd(void) { return 0; }
1143 #endif /* CONFIG_TRACER_SNAPSHOT */
1144
1145 #ifdef CONFIG_STACKTRACE
1146 #ifdef CONFIG_UNWINDER_ORC
1147 /* Skip 2:
1148  *   event_triggers_post_call()
1149  *   trace_event_raw_event_xxx()
1150  */
1151 # define STACK_SKIP 2
1152 #else
1153 /*
1154  * Skip 4:
1155  *   stacktrace_trigger()
1156  *   event_triggers_post_call()
1157  *   trace_event_buffer_commit()
1158  *   trace_event_raw_event_xxx()
1159  */
1160 #define STACK_SKIP 4
1161 #endif
1162
1163 static void
1164 stacktrace_trigger(struct event_trigger_data *data, void *rec,
1165                    struct ring_buffer_event *event)
1166 {
1167         trace_dump_stack(STACK_SKIP);
1168 }
1169
1170 static void
1171 stacktrace_count_trigger(struct event_trigger_data *data, void *rec,
1172                          struct ring_buffer_event *event)
1173 {
1174         if (!data->count)
1175                 return;
1176
1177         if (data->count != -1)
1178                 (data->count)--;
1179
1180         stacktrace_trigger(data, rec, event);
1181 }
1182
1183 static int
1184 stacktrace_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
1185                          struct event_trigger_data *data)
1186 {
1187         return event_trigger_print("stacktrace", m, (void *)data->count,
1188                                    data->filter_str);
1189 }
1190
1191 static struct event_trigger_ops stacktrace_trigger_ops = {
1192         .func                   = stacktrace_trigger,
1193         .print                  = stacktrace_trigger_print,
1194         .init                   = event_trigger_init,
1195         .free                   = event_trigger_free,
1196 };
1197
1198 static struct event_trigger_ops stacktrace_count_trigger_ops = {
1199         .func                   = stacktrace_count_trigger,
1200         .print                  = stacktrace_trigger_print,
1201         .init                   = event_trigger_init,
1202         .free                   = event_trigger_free,
1203 };
1204
1205 static struct event_trigger_ops *
1206 stacktrace_get_trigger_ops(char *cmd, char *param)
1207 {
1208         return param ? &stacktrace_count_trigger_ops : &stacktrace_trigger_ops;
1209 }
1210
1211 static struct event_command trigger_stacktrace_cmd = {
1212         .name                   = "stacktrace",
1213         .trigger_type           = ETT_STACKTRACE,
1214         .flags                  = EVENT_CMD_FL_POST_TRIGGER,
1215         .func                   = event_trigger_callback,
1216         .reg                    = register_trigger,
1217         .unreg                  = unregister_trigger,
1218         .get_trigger_ops        = stacktrace_get_trigger_ops,
1219         .set_filter             = set_trigger_filter,
1220 };
1221
1222 static __init int register_trigger_stacktrace_cmd(void)
1223 {
1224         int ret;
1225
1226         ret = register_event_command(&trigger_stacktrace_cmd);
1227         WARN_ON(ret < 0);
1228
1229         return ret;
1230 }
1231 #else
1232 static __init int register_trigger_stacktrace_cmd(void) { return 0; }
1233 #endif /* CONFIG_STACKTRACE */
1234
1235 static __init void unregister_trigger_traceon_traceoff_cmds(void)
1236 {
1237         unregister_event_command(&trigger_traceon_cmd);
1238         unregister_event_command(&trigger_traceoff_cmd);
1239 }
1240
1241 static void
1242 event_enable_trigger(struct event_trigger_data *data, void *rec,
1243                      struct ring_buffer_event *event)
1244 {
1245         struct enable_trigger_data *enable_data = data->private_data;
1246
1247         if (enable_data->enable)
1248                 clear_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
1249         else
1250                 set_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
1251 }
1252
1253 static void
1254 event_enable_count_trigger(struct event_trigger_data *data, void *rec,
1255                            struct ring_buffer_event *event)
1256 {
1257         struct enable_trigger_data *enable_data = data->private_data;
1258
1259         if (!data->count)
1260                 return;
1261
1262         /* Skip if the event is in a state we want to switch to */
1263         if (enable_data->enable == !(enable_data->file->flags & EVENT_FILE_FL_SOFT_DISABLED))
1264                 return;
1265
1266         if (data->count != -1)
1267                 (data->count)--;
1268
1269         event_enable_trigger(data, rec, event);
1270 }
1271
1272 int event_enable_trigger_print(struct seq_file *m,
1273                                struct event_trigger_ops *ops,
1274                                struct event_trigger_data *data)
1275 {
1276         struct enable_trigger_data *enable_data = data->private_data;
1277
1278         seq_printf(m, "%s:%s:%s",
1279                    enable_data->hist ?
1280                    (enable_data->enable ? ENABLE_HIST_STR : DISABLE_HIST_STR) :
1281                    (enable_data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR),
1282                    enable_data->file->event_call->class->system,
1283                    trace_event_name(enable_data->file->event_call));
1284
1285         if (data->count == -1)
1286                 seq_puts(m, ":unlimited");
1287         else
1288                 seq_printf(m, ":count=%ld", data->count);
1289
1290         if (data->filter_str)
1291                 seq_printf(m, " if %s\n", data->filter_str);
1292         else
1293                 seq_putc(m, '\n');
1294
1295         return 0;
1296 }
1297
1298 void event_enable_trigger_free(struct event_trigger_ops *ops,
1299                                struct event_trigger_data *data)
1300 {
1301         struct enable_trigger_data *enable_data = data->private_data;
1302
1303         if (WARN_ON_ONCE(data->ref <= 0))
1304                 return;
1305
1306         data->ref--;
1307         if (!data->ref) {
1308                 /* Remove the SOFT_MODE flag */
1309                 trace_event_enable_disable(enable_data->file, 0, 1);
1310                 module_put(enable_data->file->event_call->mod);
1311                 trigger_data_free(data);
1312                 kfree(enable_data);
1313         }
1314 }
1315
1316 static struct event_trigger_ops event_enable_trigger_ops = {
1317         .func                   = event_enable_trigger,
1318         .print                  = event_enable_trigger_print,
1319         .init                   = event_trigger_init,
1320         .free                   = event_enable_trigger_free,
1321 };
1322
1323 static struct event_trigger_ops event_enable_count_trigger_ops = {
1324         .func                   = event_enable_count_trigger,
1325         .print                  = event_enable_trigger_print,
1326         .init                   = event_trigger_init,
1327         .free                   = event_enable_trigger_free,
1328 };
1329
1330 static struct event_trigger_ops event_disable_trigger_ops = {
1331         .func                   = event_enable_trigger,
1332         .print                  = event_enable_trigger_print,
1333         .init                   = event_trigger_init,
1334         .free                   = event_enable_trigger_free,
1335 };
1336
1337 static struct event_trigger_ops event_disable_count_trigger_ops = {
1338         .func                   = event_enable_count_trigger,
1339         .print                  = event_enable_trigger_print,
1340         .init                   = event_trigger_init,
1341         .free                   = event_enable_trigger_free,
1342 };
1343
1344 int event_enable_trigger_func(struct event_command *cmd_ops,
1345                               struct trace_event_file *file,
1346                               char *glob, char *cmd, char *param)
1347 {
1348         struct trace_event_file *event_enable_file;
1349         struct enable_trigger_data *enable_data;
1350         struct event_trigger_data *trigger_data;
1351         struct event_trigger_ops *trigger_ops;
1352         struct trace_array *tr = file->tr;
1353         const char *system;
1354         const char *event;
1355         bool hist = false;
1356         char *trigger;
1357         char *number;
1358         bool enable;
1359         int ret;
1360
1361         if (!param)
1362                 return -EINVAL;
1363
1364         /* separate the trigger from the filter (s:e:n [if filter]) */
1365         trigger = strsep(&param, " \t");
1366         if (!trigger)
1367                 return -EINVAL;
1368
1369         system = strsep(&trigger, ":");
1370         if (!trigger)
1371                 return -EINVAL;
1372
1373         event = strsep(&trigger, ":");
1374
1375         ret = -EINVAL;
1376         event_enable_file = find_event_file(tr, system, event);
1377         if (!event_enable_file)
1378                 goto out;
1379
1380 #ifdef CONFIG_HIST_TRIGGERS
1381         hist = ((strcmp(cmd, ENABLE_HIST_STR) == 0) ||
1382                 (strcmp(cmd, DISABLE_HIST_STR) == 0));
1383
1384         enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
1385                   (strcmp(cmd, ENABLE_HIST_STR) == 0));
1386 #else
1387         enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
1388 #endif
1389         trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
1390
1391         ret = -ENOMEM;
1392         trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
1393         if (!trigger_data)
1394                 goto out;
1395
1396         enable_data = kzalloc(sizeof(*enable_data), GFP_KERNEL);
1397         if (!enable_data) {
1398                 kfree(trigger_data);
1399                 goto out;
1400         }
1401
1402         trigger_data->count = -1;
1403         trigger_data->ops = trigger_ops;
1404         trigger_data->cmd_ops = cmd_ops;
1405         INIT_LIST_HEAD(&trigger_data->list);
1406         RCU_INIT_POINTER(trigger_data->filter, NULL);
1407
1408         enable_data->hist = hist;
1409         enable_data->enable = enable;
1410         enable_data->file = event_enable_file;
1411         trigger_data->private_data = enable_data;
1412
1413         if (glob[0] == '!') {
1414                 cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
1415                 kfree(trigger_data);
1416                 kfree(enable_data);
1417                 ret = 0;
1418                 goto out;
1419         }
1420
1421         /* Up the trigger_data count to make sure nothing frees it on failure */
1422         event_trigger_init(trigger_ops, trigger_data);
1423
1424         if (trigger) {
1425                 number = strsep(&trigger, ":");
1426
1427                 ret = -EINVAL;
1428                 if (!strlen(number))
1429                         goto out_free;
1430
1431                 /*
1432                  * We use the callback data field (which is a pointer)
1433                  * as our counter.
1434                  */
1435                 ret = kstrtoul(number, 0, &trigger_data->count);
1436                 if (ret)
1437                         goto out_free;
1438         }
1439
1440         if (!param) /* if param is non-empty, it's supposed to be a filter */
1441                 goto out_reg;
1442
1443         if (!cmd_ops->set_filter)
1444                 goto out_reg;
1445
1446         ret = cmd_ops->set_filter(param, trigger_data, file);
1447         if (ret < 0)
1448                 goto out_free;
1449
1450  out_reg:
1451         /* Don't let event modules unload while probe registered */
1452         ret = try_module_get(event_enable_file->event_call->mod);
1453         if (!ret) {
1454                 ret = -EBUSY;
1455                 goto out_free;
1456         }
1457
1458         ret = trace_event_enable_disable(event_enable_file, 1, 1);
1459         if (ret < 0)
1460                 goto out_put;
1461         ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);
1462         /*
1463          * The above returns on success the # of functions enabled,
1464          * but if it didn't find any functions it returns zero.
1465          * Consider no functions a failure too.
1466          */
1467         if (!ret) {
1468                 ret = -ENOENT;
1469                 goto out_disable;
1470         } else if (ret < 0)
1471                 goto out_disable;
1472         /* Just return zero, not the number of enabled functions */
1473         ret = 0;
1474         event_trigger_free(trigger_ops, trigger_data);
1475  out:
1476         return ret;
1477
1478  out_disable:
1479         trace_event_enable_disable(event_enable_file, 0, 1);
1480  out_put:
1481         module_put(event_enable_file->event_call->mod);
1482  out_free:
1483         if (cmd_ops->set_filter)
1484                 cmd_ops->set_filter(NULL, trigger_data, NULL);
1485         event_trigger_free(trigger_ops, trigger_data);
1486         kfree(enable_data);
1487         goto out;
1488 }
1489
1490 int event_enable_register_trigger(char *glob,
1491                                   struct event_trigger_ops *ops,
1492                                   struct event_trigger_data *data,
1493                                   struct trace_event_file *file)
1494 {
1495         struct enable_trigger_data *enable_data = data->private_data;
1496         struct enable_trigger_data *test_enable_data;
1497         struct event_trigger_data *test;
1498         int ret = 0;
1499
1500         list_for_each_entry_rcu(test, &file->triggers, list) {
1501                 test_enable_data = test->private_data;
1502                 if (test_enable_data &&
1503                     (test->cmd_ops->trigger_type ==
1504                      data->cmd_ops->trigger_type) &&
1505                     (test_enable_data->file == enable_data->file)) {
1506                         ret = -EEXIST;
1507                         goto out;
1508                 }
1509         }
1510
1511         if (data->ops->init) {
1512                 ret = data->ops->init(data->ops, data);
1513                 if (ret < 0)
1514                         goto out;
1515         }
1516
1517         list_add_rcu(&data->list, &file->triggers);
1518         ret++;
1519
1520         update_cond_flag(file);
1521         if (trace_event_trigger_enable_disable(file, 1) < 0) {
1522                 list_del_rcu(&data->list);
1523                 update_cond_flag(file);
1524                 ret--;
1525         }
1526 out:
1527         return ret;
1528 }
1529
1530 void event_enable_unregister_trigger(char *glob,
1531                                      struct event_trigger_ops *ops,
1532                                      struct event_trigger_data *test,
1533                                      struct trace_event_file *file)
1534 {
1535         struct enable_trigger_data *test_enable_data = test->private_data;
1536         struct enable_trigger_data *enable_data;
1537         struct event_trigger_data *data;
1538         bool unregistered = false;
1539
1540         list_for_each_entry_rcu(data, &file->triggers, list) {
1541                 enable_data = data->private_data;
1542                 if (enable_data &&
1543                     (data->cmd_ops->trigger_type ==
1544                      test->cmd_ops->trigger_type) &&
1545                     (enable_data->file == test_enable_data->file)) {
1546                         unregistered = true;
1547                         list_del_rcu(&data->list);
1548                         trace_event_trigger_enable_disable(file, 0);
1549                         update_cond_flag(file);
1550                         break;
1551                 }
1552         }
1553
1554         if (unregistered && data->ops->free)
1555                 data->ops->free(data->ops, data);
1556 }
1557
1558 static struct event_trigger_ops *
1559 event_enable_get_trigger_ops(char *cmd, char *param)
1560 {
1561         struct event_trigger_ops *ops;
1562         bool enable;
1563
1564 #ifdef CONFIG_HIST_TRIGGERS
1565         enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
1566                   (strcmp(cmd, ENABLE_HIST_STR) == 0));
1567 #else
1568         enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
1569 #endif
1570         if (enable)
1571                 ops = param ? &event_enable_count_trigger_ops :
1572                         &event_enable_trigger_ops;
1573         else
1574                 ops = param ? &event_disable_count_trigger_ops :
1575                         &event_disable_trigger_ops;
1576
1577         return ops;
1578 }
1579
1580 static struct event_command trigger_enable_cmd = {
1581         .name                   = ENABLE_EVENT_STR,
1582         .trigger_type           = ETT_EVENT_ENABLE,
1583         .func                   = event_enable_trigger_func,
1584         .reg                    = event_enable_register_trigger,
1585         .unreg                  = event_enable_unregister_trigger,
1586         .get_trigger_ops        = event_enable_get_trigger_ops,
1587         .set_filter             = set_trigger_filter,
1588 };
1589
1590 static struct event_command trigger_disable_cmd = {
1591         .name                   = DISABLE_EVENT_STR,
1592         .trigger_type           = ETT_EVENT_ENABLE,
1593         .func                   = event_enable_trigger_func,
1594         .reg                    = event_enable_register_trigger,
1595         .unreg                  = event_enable_unregister_trigger,
1596         .get_trigger_ops        = event_enable_get_trigger_ops,
1597         .set_filter             = set_trigger_filter,
1598 };
1599
1600 static __init void unregister_trigger_enable_disable_cmds(void)
1601 {
1602         unregister_event_command(&trigger_enable_cmd);
1603         unregister_event_command(&trigger_disable_cmd);
1604 }
1605
1606 static __init int register_trigger_enable_disable_cmds(void)
1607 {
1608         int ret;
1609
1610         ret = register_event_command(&trigger_enable_cmd);
1611         if (WARN_ON(ret < 0))
1612                 return ret;
1613         ret = register_event_command(&trigger_disable_cmd);
1614         if (WARN_ON(ret < 0))
1615                 unregister_trigger_enable_disable_cmds();
1616
1617         return ret;
1618 }
1619
1620 static __init int register_trigger_traceon_traceoff_cmds(void)
1621 {
1622         int ret;
1623
1624         ret = register_event_command(&trigger_traceon_cmd);
1625         if (WARN_ON(ret < 0))
1626                 return ret;
1627         ret = register_event_command(&trigger_traceoff_cmd);
1628         if (WARN_ON(ret < 0))
1629                 unregister_trigger_traceon_traceoff_cmds();
1630
1631         return ret;
1632 }
1633
1634 __init int register_trigger_cmds(void)
1635 {
1636         register_trigger_traceon_traceoff_cmds();
1637         register_trigger_snapshot_cmd();
1638         register_trigger_stacktrace_cmd();
1639         register_trigger_enable_disable_cmds();
1640         register_trigger_hist_enable_disable_cmds();
1641         register_trigger_hist_cmd();
1642
1643         return 0;
1644 }