kernel/trace/trace_events_trigger.c

   1 /*
   2  * trace_events_trigger - trace event triggers
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17  *
  18  * Copyright (C) 2013 Tom Zanussi <tom.zanussi@linux.intel.com>
  19  */
  20
  21 #include <linux/module.h>
  22 #include <linux/ctype.h>
  23 #include <linux/mutex.h>
  24 #include <linux/slab.h>
  25
  26 #include "trace.h"
  27
  28 static LIST_HEAD(trigger_commands);
  29 static DEFINE_MUTEX(trigger_cmd_mutex);
  30
  31 void trigger_data_free(struct event_trigger_data *data)
  32 {
  33         if (data->cmd_ops->set_filter)
  34                 data->cmd_ops->set_filter(NULL, data, NULL);
  35
  36         synchronize_sched(); /* make sure current triggers exit before free */
  37         kfree(data);
  38 }
  39
  40 /**
  41  * event_triggers_call - Call triggers associated with a trace event
  42  * @file: The trace_event_file associated with the event
  43  * @rec: The trace entry for the event, NULL for unconditional invocation
  44  *
  45  * For each trigger associated with an event, invoke the trigger
  46  * function registered with the associated trigger command.  If rec is
  47  * non-NULL, it means that the trigger requires further processing and
  48  * shouldn't be unconditionally invoked.  If rec is non-NULL and the
  49  * trigger has a filter associated with it, rec will checked against
  50  * the filter and if the record matches the trigger will be invoked.
  51  * If the trigger is a 'post_trigger', meaning it shouldn't be invoked
  52  * in any case until the current event is written, the trigger
  53  * function isn't invoked but the bit associated with the deferred
  54  * trigger is set in the return value.
  55  *
  56  * Returns an enum event_trigger_type value containing a set bit for
  57  * any trigger that should be deferred, ETT_NONE if nothing to defer.
  58  *
  59  * Called from tracepoint handlers (with rcu_read_lock_sched() held).
  60  *
  61  * Return: an enum event_trigger_type value containing a set bit for
  62  * any trigger that should be deferred, ETT_NONE if nothing to defer.
  63  */
  64 enum event_trigger_type
  65 event_triggers_call(struct trace_event_file *file, void *rec)
  66 {
  67         struct event_trigger_data *data;
  68         enum event_trigger_type tt = ETT_NONE;
  69         struct event_filter *filter;
  70
  71         if (list_empty(&file->triggers))
  72                 return tt;
  73
  74         list_for_each_entry_rcu(data, &file->triggers, list) {
  75                 if (data->paused)
  76                         continue;
  77                 if (!rec) {
  78                         data->ops->func(data, rec);
  79                         continue;
  80                 }
  81                 filter = rcu_dereference_sched(data->filter);
  82                 if (filter && !filter_match_preds(filter, rec))
  83                         continue;
  84                 if (event_command_post_trigger(data->cmd_ops)) {
  85                         tt |= data->cmd_ops->trigger_type;
  86                         continue;
  87                 }
  88                 data->ops->func(data, rec);
  89         }
  90         return tt;
  91 }
  92 EXPORT_SYMBOL_GPL(event_triggers_call);
  93
  94 /**
  95  * event_triggers_post_call - Call 'post_triggers' for a trace event
  96  * @file: The trace_event_file associated with the event
  97  * @tt: enum event_trigger_type containing a set bit for each trigger to invoke
  98  * @rec: The trace entry for the event
  99  *
 100  * For each trigger associated with an event, invoke the trigger
 101  * function registered with the associated trigger command, if the
 102  * corresponding bit is set in the tt enum passed into this function.
 103  * See @event_triggers_call for details on how those bits are set.
 104  *
 105  * Called from tracepoint handlers (with rcu_read_lock_sched() held).
 106  */
 107 void
 108 event_triggers_post_call(struct trace_event_file *file,
 109                          enum event_trigger_type tt,
 110                          void *rec)
 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, rec);
 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 static __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;
 485                 list_for_each_entry_rcu(data, &file->triggers, list) {
 486                         trace_event_trigger_enable_disable(file, 0);
 487                         if (data->ops->free)
 488                                 data->ops->free(data->ops, data);
 489                 }
 490         }
 491 }
 492
 493 /**
 494  * update_cond_flag - Set or reset the TRIGGER_COND bit
 495  * @file: The trace_event_file associated with the event
 496  *
 497  * If an event has triggers and any of those triggers has a filter or
 498  * a post_trigger, trigger invocation needs to be deferred until after
 499  * the current event has logged its data, and the event should have
 500  * its TRIGGER_COND bit set, otherwise the TRIGGER_COND bit should be
 501  * cleared.
 502  */
 503 void update_cond_flag(struct trace_event_file *file)
 504 {
 505         struct event_trigger_data *data;
 506         bool set_cond = false;
 507
 508         list_for_each_entry_rcu(data, &file->triggers, list) {
 509                 if (data->filter || event_command_post_trigger(data->cmd_ops) ||
 510                     event_command_needs_rec(data->cmd_ops)) {
 511                         set_cond = true;
 512                         break;
 513                 }
 514         }
 515
 516         if (set_cond)
 517                 set_bit(EVENT_FILE_FL_TRIGGER_COND_BIT, &file->flags);
 518         else
 519                 clear_bit(EVENT_FILE_FL_TRIGGER_COND_BIT, &file->flags);
 520 }
 521
 522 /**
 523  * register_trigger - Generic event_command @reg implementation
 524  * @glob: The raw string used to register the trigger
 525  * @ops: The trigger ops associated with the trigger
 526  * @data: Trigger-specific data to associate with the trigger
 527  * @file: The trace_event_file associated with the event
 528  *
 529  * Common implementation for event trigger registration.
 530  *
 531  * Usually used directly as the @reg method in event command
 532  * implementations.
 533  *
 534  * Return: 0 on success, errno otherwise
 535  */
 536 static int register_trigger(char *glob, struct event_trigger_ops *ops,
 537                             struct event_trigger_data *data,
 538                             struct trace_event_file *file)
 539 {
 540         struct event_trigger_data *test;
 541         int ret = 0;
 542
 543         list_for_each_entry_rcu(test, &file->triggers, list) {
 544                 if (test->cmd_ops->trigger_type == data->cmd_ops->trigger_type) {
 545                         ret = -EEXIST;
 546                         goto out;
 547                 }
 548         }
 549
 550         if (data->ops->init) {
 551                 ret = data->ops->init(data->ops, data);
 552                 if (ret < 0)
 553                         goto out;
 554         }
 555
 556         list_add_rcu(&data->list, &file->triggers);
 557         ret++;
 558
 559         update_cond_flag(file);
 560         if (trace_event_trigger_enable_disable(file, 1) < 0) {
 561                 list_del_rcu(&data->list);
 562                 update_cond_flag(file);
 563                 ret--;
 564         }
 565 out:
 566         return ret;
 567 }
 568
 569 /**
 570  * unregister_trigger - Generic event_command @unreg implementation
 571  * @glob: The raw string used to register the trigger
 572  * @ops: The trigger ops associated with the trigger
 573  * @test: Trigger-specific data used to find the trigger to remove
 574  * @file: The trace_event_file associated with the event
 575  *
 576  * Common implementation for event trigger unregistration.
 577  *
 578  * Usually used directly as the @unreg method in event command
 579  * implementations.
 580  */
 581 void unregister_trigger(char *glob, struct event_trigger_ops *ops,
 582                         struct event_trigger_data *test,
 583                         struct trace_event_file *file)
 584 {
 585         struct event_trigger_data *data;
 586         bool unregistered = false;
 587
 588         list_for_each_entry_rcu(data, &file->triggers, list) {
 589                 if (data->cmd_ops->trigger_type == test->cmd_ops->trigger_type) {
 590                         unregistered = true;
 591                         list_del_rcu(&data->list);
 592                         trace_event_trigger_enable_disable(file, 0);
 593                         update_cond_flag(file);
 594                         break;
 595                 }
 596         }
 597
 598         if (unregistered && data->ops->free)
 599                 data->ops->free(data->ops, data);
 600 }
 601
 602 /**
 603  * event_trigger_callback - Generic event_command @func implementation
 604  * @cmd_ops: The command ops, used for trigger registration
 605  * @file: The trace_event_file associated with the event
 606  * @glob: The raw string used to register the trigger
 607  * @cmd: The cmd portion of the string used to register the trigger
 608  * @param: The params portion of the string used to register the trigger
 609  *
 610  * Common implementation for event command parsing and trigger
 611  * instantiation.
 612  *
 613  * Usually used directly as the @func method in event command
 614  * implementations.
 615  *
 616  * Return: 0 on success, errno otherwise
 617  */
 618 static int
 619 event_trigger_callback(struct event_command *cmd_ops,
 620                        struct trace_event_file *file,
 621                        char *glob, char *cmd, char *param)
 622 {
 623         struct event_trigger_data *trigger_data;
 624         struct event_trigger_ops *trigger_ops;
 625         char *trigger = NULL;
 626         char *number;
 627         int ret;
 628
 629         /* separate the trigger from the filter (t:n [if filter]) */
 630         if (param && isdigit(param[0]))
 631                 trigger = strsep(&param, " \t");
 632
 633         trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
 634
 635         ret = -ENOMEM;
 636         trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
 637         if (!trigger_data)
 638                 goto out;
 639
 640         trigger_data->count = -1;
 641         trigger_data->ops = trigger_ops;
 642         trigger_data->cmd_ops = cmd_ops;
 643         INIT_LIST_HEAD(&trigger_data->list);
 644
 645         if (glob[0] == '!') {
 646                 cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
 647                 kfree(trigger_data);
 648                 ret = 0;
 649                 goto out;
 650         }
 651
 652         if (trigger) {
 653                 number = strsep(&trigger, ":");
 654
 655                 ret = -EINVAL;
 656                 if (!strlen(number))
 657                         goto out_free;
 658
 659                 /*
 660                  * We use the callback data field (which is a pointer)
 661                  * as our counter.
 662                  */
 663                 ret = kstrtoul(number, 0, &trigger_data->count);
 664                 if (ret)
 665                         goto out_free;
 666         }
 667
 668         if (!param) /* if param is non-empty, it's supposed to be a filter */
 669                 goto out_reg;
 670
 671         if (!cmd_ops->set_filter)
 672                 goto out_reg;
 673
 674         ret = cmd_ops->set_filter(param, trigger_data, file);
 675         if (ret < 0)
 676                 goto out_free;
 677
 678  out_reg:
 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                 ret = -ENOENT;
 687                 goto out_free;
 688         } else if (ret < 0)
 689                 goto out_free;
 690         ret = 0;
 691  out:
 692         return ret;
 693
 694  out_free:
 695         if (cmd_ops->set_filter)
 696                 cmd_ops->set_filter(NULL, trigger_data, NULL);
 697         kfree(trigger_data);
 698         goto out;
 699 }
 700
 701 /**
 702  * set_trigger_filter - Generic event_command @set_filter implementation
 703  * @filter_str: The filter string for the trigger, NULL to remove filter
 704  * @trigger_data: Trigger-specific data
 705  * @file: The trace_event_file associated with the event
 706  *
 707  * Common implementation for event command filter parsing and filter
 708  * instantiation.
 709  *
 710  * Usually used directly as the @set_filter method in event command
 711  * implementations.
 712  *
 713  * Also used to remove a filter (if filter_str = NULL).
 714  *
 715  * Return: 0 on success, errno otherwise
 716  */
 717 int set_trigger_filter(char *filter_str,
 718                        struct event_trigger_data *trigger_data,
 719                        struct trace_event_file *file)
 720 {
 721         struct event_trigger_data *data = trigger_data;
 722         struct event_filter *filter = NULL, *tmp;
 723         int ret = -EINVAL;
 724         char *s;
 725
 726         if (!filter_str) /* clear the current filter */
 727                 goto assign;
 728
 729         s = strsep(&filter_str, " \t");
 730
 731         if (!strlen(s) || strcmp(s, "if") != 0)
 732                 goto out;
 733
 734         if (!filter_str)
 735                 goto out;
 736
 737         /* The filter is for the 'trigger' event, not the triggered event */
 738         ret = create_event_filter(file->event_call, filter_str, false, &filter);
 739         if (ret)
 740                 goto out;
 741  assign:
 742         tmp = rcu_access_pointer(data->filter);
 743
 744         rcu_assign_pointer(data->filter, filter);
 745
 746         if (tmp) {
 747                 /* Make sure the call is done with the filter */
 748                 synchronize_sched();
 749                 free_event_filter(tmp);
 750         }
 751
 752         kfree(data->filter_str);
 753         data->filter_str = NULL;
 754
 755         if (filter_str) {
 756                 data->filter_str = kstrdup(filter_str, GFP_KERNEL);
 757                 if (!data->filter_str) {
 758                         free_event_filter(rcu_access_pointer(data->filter));
 759                         data->filter = NULL;
 760                         ret = -ENOMEM;
 761                 }
 762         }
 763  out:
 764         return ret;
 765 }
 766
 767 static void
 768 traceon_trigger(struct event_trigger_data *data, void *rec)
 769 {
 770         if (tracing_is_on())
 771                 return;
 772
 773         tracing_on();
 774 }
 775
 776 static void
 777 traceon_count_trigger(struct event_trigger_data *data, void *rec)
 778 {
 779         if (tracing_is_on())
 780                 return;
 781
 782         if (!data->count)
 783                 return;
 784
 785         if (data->count != -1)
 786                 (data->count)--;
 787
 788         tracing_on();
 789 }
 790
 791 static void
 792 traceoff_trigger(struct event_trigger_data *data, void *rec)
 793 {
 794         if (!tracing_is_on())
 795                 return;
 796
 797         tracing_off();
 798 }
 799
 800 static void
 801 traceoff_count_trigger(struct event_trigger_data *data, void *rec)
 802 {
 803         if (!tracing_is_on())
 804                 return;
 805
 806         if (!data->count)
 807                 return;
 808
 809         if (data->count != -1)
 810                 (data->count)--;
 811
 812         tracing_off();
 813 }
 814
 815 static int
 816 traceon_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
 817                       struct event_trigger_data *data)
 818 {
 819         return event_trigger_print("traceon", m, (void *)data->count,
 820                                    data->filter_str);
 821 }
 822
 823 static int
 824 traceoff_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
 825                        struct event_trigger_data *data)
 826 {
 827         return event_trigger_print("traceoff", m, (void *)data->count,
 828                                    data->filter_str);
 829 }
 830
 831 static struct event_trigger_ops traceon_trigger_ops = {
 832         .func                   = traceon_trigger,
 833         .print                  = traceon_trigger_print,
 834         .init                   = event_trigger_init,
 835         .free                   = event_trigger_free,
 836 };
 837
 838 static struct event_trigger_ops traceon_count_trigger_ops = {
 839         .func                   = traceon_count_trigger,
 840         .print                  = traceon_trigger_print,
 841         .init                   = event_trigger_init,
 842         .free                   = event_trigger_free,
 843 };
 844
 845 static struct event_trigger_ops traceoff_trigger_ops = {
 846         .func                   = traceoff_trigger,
 847         .print                  = traceoff_trigger_print,
 848         .init                   = event_trigger_init,
 849         .free                   = event_trigger_free,
 850 };
 851
 852 static struct event_trigger_ops traceoff_count_trigger_ops = {
 853         .func                   = traceoff_count_trigger,
 854         .print                  = traceoff_trigger_print,
 855         .init                   = event_trigger_init,
 856         .free                   = event_trigger_free,
 857 };
 858
 859 static struct event_trigger_ops *
 860 onoff_get_trigger_ops(char *cmd, char *param)
 861 {
 862         struct event_trigger_ops *ops;
 863
 864         /* we register both traceon and traceoff to this callback */
 865         if (strcmp(cmd, "traceon") == 0)
 866                 ops = param ? &traceon_count_trigger_ops :
 867                         &traceon_trigger_ops;
 868         else
 869                 ops = param ? &traceoff_count_trigger_ops :
 870                         &traceoff_trigger_ops;
 871
 872         return ops;
 873 }
 874
 875 static struct event_command trigger_traceon_cmd = {
 876         .name                   = "traceon",
 877         .trigger_type           = ETT_TRACE_ONOFF,
 878         .func                   = event_trigger_callback,
 879         .reg                    = register_trigger,
 880         .unreg                  = unregister_trigger,
 881         .get_trigger_ops        = onoff_get_trigger_ops,
 882         .set_filter             = set_trigger_filter,
 883 };
 884
 885 static struct event_command trigger_traceoff_cmd = {
 886         .name                   = "traceoff",
 887         .trigger_type           = ETT_TRACE_ONOFF,
 888         .func                   = event_trigger_callback,
 889         .reg                    = register_trigger,
 890         .unreg                  = unregister_trigger,
 891         .get_trigger_ops        = onoff_get_trigger_ops,
 892         .set_filter             = set_trigger_filter,
 893 };
 894
 895 #ifdef CONFIG_TRACER_SNAPSHOT
 896 static void
 897 snapshot_trigger(struct event_trigger_data *data, void *rec)
 898 {
 899         tracing_snapshot();
 900 }
 901
 902 static void
 903 snapshot_count_trigger(struct event_trigger_data *data, void *rec)
 904 {
 905         if (!data->count)
 906                 return;
 907
 908         if (data->count != -1)
 909                 (data->count)--;
 910
 911         snapshot_trigger(data, rec);
 912 }
 913
 914 static int
 915 register_snapshot_trigger(char *glob, struct event_trigger_ops *ops,
 916                           struct event_trigger_data *data,
 917                           struct trace_event_file *file)
 918 {
 919         int ret = register_trigger(glob, ops, data, file);
 920
 921         if (ret > 0 && tracing_alloc_snapshot() != 0) {
 922                 unregister_trigger(glob, ops, data, file);
 923                 ret = 0;
 924         }
 925
 926         return ret;
 927 }
 928
 929 static int
 930 snapshot_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
 931                        struct event_trigger_data *data)
 932 {
 933         return event_trigger_print("snapshot", m, (void *)data->count,
 934                                    data->filter_str);
 935 }
 936
 937 static struct event_trigger_ops snapshot_trigger_ops = {
 938         .func                   = snapshot_trigger,
 939         .print                  = snapshot_trigger_print,
 940         .init                   = event_trigger_init,
 941         .free                   = event_trigger_free,
 942 };
 943
 944 static struct event_trigger_ops snapshot_count_trigger_ops = {
 945         .func                   = snapshot_count_trigger,
 946         .print                  = snapshot_trigger_print,
 947         .init                   = event_trigger_init,
 948         .free                   = event_trigger_free,
 949 };
 950
 951 static struct event_trigger_ops *
 952 snapshot_get_trigger_ops(char *cmd, char *param)
 953 {
 954         return param ? &snapshot_count_trigger_ops : &snapshot_trigger_ops;
 955 }
 956
 957 static struct event_command trigger_snapshot_cmd = {
 958         .name                   = "snapshot",
 959         .trigger_type           = ETT_SNAPSHOT,
 960         .func                   = event_trigger_callback,
 961         .reg                    = register_snapshot_trigger,
 962         .unreg                  = unregister_trigger,
 963         .get_trigger_ops        = snapshot_get_trigger_ops,
 964         .set_filter             = set_trigger_filter,
 965 };
 966
 967 static __init int register_trigger_snapshot_cmd(void)
 968 {
 969         int ret;
 970
 971         ret = register_event_command(&trigger_snapshot_cmd);
 972         WARN_ON(ret < 0);
 973
 974         return ret;
 975 }
 976 #else
 977 static __init int register_trigger_snapshot_cmd(void) { return 0; }
 978 #endif /* CONFIG_TRACER_SNAPSHOT */
 979
 980 #ifdef CONFIG_STACKTRACE
 981 /*
 982  * Skip 3:
 983  *   stacktrace_trigger()
 984  *   event_triggers_post_call()
 985  *   trace_event_raw_event_xxx()
 986  */
 987 #define STACK_SKIP 3
 988
 989 static void
 990 stacktrace_trigger(struct event_trigger_data *data, void *rec)
 991 {
 992         trace_dump_stack(STACK_SKIP);
 993 }
 994
 995 static void
 996 stacktrace_count_trigger(struct event_trigger_data *data, void *rec)
 997 {
 998         if (!data->count)
 999                 return;
1000
1001         if (data->count != -1)
1002                 (data->count)--;
1003
1004         stacktrace_trigger(data, rec);
1005 }
1006
1007 static int
1008 stacktrace_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
1009                          struct event_trigger_data *data)
1010 {
1011         return event_trigger_print("stacktrace", m, (void *)data->count,
1012                                    data->filter_str);
1013 }
1014
1015 static struct event_trigger_ops stacktrace_trigger_ops = {
1016         .func                   = stacktrace_trigger,
1017         .print                  = stacktrace_trigger_print,
1018         .init                   = event_trigger_init,
1019         .free                   = event_trigger_free,
1020 };
1021
1022 static struct event_trigger_ops stacktrace_count_trigger_ops = {
1023         .func                   = stacktrace_count_trigger,
1024         .print                  = stacktrace_trigger_print,
1025         .init                   = event_trigger_init,
1026         .free                   = event_trigger_free,
1027 };
1028
1029 static struct event_trigger_ops *
1030 stacktrace_get_trigger_ops(char *cmd, char *param)
1031 {
1032         return param ? &stacktrace_count_trigger_ops : &stacktrace_trigger_ops;
1033 }
1034
1035 static struct event_command trigger_stacktrace_cmd = {
1036         .name                   = "stacktrace",
1037         .trigger_type           = ETT_STACKTRACE,
1038         .flags                  = EVENT_CMD_FL_POST_TRIGGER,
1039         .func                   = event_trigger_callback,
1040         .reg                    = register_trigger,
1041         .unreg                  = unregister_trigger,
1042         .get_trigger_ops        = stacktrace_get_trigger_ops,
1043         .set_filter             = set_trigger_filter,
1044 };
1045
1046 static __init int register_trigger_stacktrace_cmd(void)
1047 {
1048         int ret;
1049
1050         ret = register_event_command(&trigger_stacktrace_cmd);
1051         WARN_ON(ret < 0);
1052
1053         return ret;
1054 }
1055 #else
1056 static __init int register_trigger_stacktrace_cmd(void) { return 0; }
1057 #endif /* CONFIG_STACKTRACE */
1058
1059 static __init void unregister_trigger_traceon_traceoff_cmds(void)
1060 {
1061         unregister_event_command(&trigger_traceon_cmd);
1062         unregister_event_command(&trigger_traceoff_cmd);
1063 }
1064
1065 /* Avoid typos */
1066 #define ENABLE_EVENT_STR        "enable_event"
1067 #define DISABLE_EVENT_STR       "disable_event"
1068
1069 struct enable_trigger_data {
1070         struct trace_event_file         *file;
1071         bool                            enable;
1072 };
1073
1074 static void
1075 event_enable_trigger(struct event_trigger_data *data, void *rec)
1076 {
1077         struct enable_trigger_data *enable_data = data->private_data;
1078
1079         if (enable_data->enable)
1080                 clear_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
1081         else
1082                 set_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
1083 }
1084
1085 static void
1086 event_enable_count_trigger(struct event_trigger_data *data, void *rec)
1087 {
1088         struct enable_trigger_data *enable_data = data->private_data;
1089
1090         if (!data->count)
1091                 return;
1092
1093         /* Skip if the event is in a state we want to switch to */
1094         if (enable_data->enable == !(enable_data->file->flags & EVENT_FILE_FL_SOFT_DISABLED))
1095                 return;
1096
1097         if (data->count != -1)
1098                 (data->count)--;
1099
1100         event_enable_trigger(data, rec);
1101 }
1102
1103 static int
1104 event_enable_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
1105                            struct event_trigger_data *data)
1106 {
1107         struct enable_trigger_data *enable_data = data->private_data;
1108
1109         seq_printf(m, "%s:%s:%s",
1110                    enable_data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR,
1111                    enable_data->file->event_call->class->system,
1112                    trace_event_name(enable_data->file->event_call));
1113
1114         if (data->count == -1)
1115                 seq_puts(m, ":unlimited");
1116         else
1117                 seq_printf(m, ":count=%ld", data->count);
1118
1119         if (data->filter_str)
1120                 seq_printf(m, " if %s\n", data->filter_str);
1121         else
1122                 seq_putc(m, '\n');
1123
1124         return 0;
1125 }
1126
1127 static void
1128 event_enable_trigger_free(struct event_trigger_ops *ops,
1129                           struct event_trigger_data *data)
1130 {
1131         struct enable_trigger_data *enable_data = data->private_data;
1132
1133         if (WARN_ON_ONCE(data->ref <= 0))
1134                 return;
1135
1136         data->ref--;
1137         if (!data->ref) {
1138                 /* Remove the SOFT_MODE flag */
1139                 trace_event_enable_disable(enable_data->file, 0, 1);
1140                 module_put(enable_data->file->event_call->mod);
1141                 trigger_data_free(data);
1142                 kfree(enable_data);
1143         }
1144 }
1145
1146 static struct event_trigger_ops event_enable_trigger_ops = {
1147         .func                   = event_enable_trigger,
1148         .print                  = event_enable_trigger_print,
1149         .init                   = event_trigger_init,
1150         .free                   = event_enable_trigger_free,
1151 };
1152
1153 static struct event_trigger_ops event_enable_count_trigger_ops = {
1154         .func                   = event_enable_count_trigger,
1155         .print                  = event_enable_trigger_print,
1156         .init                   = event_trigger_init,
1157         .free                   = event_enable_trigger_free,
1158 };
1159
1160 static struct event_trigger_ops event_disable_trigger_ops = {
1161         .func                   = event_enable_trigger,
1162         .print                  = event_enable_trigger_print,
1163         .init                   = event_trigger_init,
1164         .free                   = event_enable_trigger_free,
1165 };
1166
1167 static struct event_trigger_ops event_disable_count_trigger_ops = {
1168         .func                   = event_enable_count_trigger,
1169         .print                  = event_enable_trigger_print,
1170         .init                   = event_trigger_init,
1171         .free                   = event_enable_trigger_free,
1172 };
1173
1174 static int
1175 event_enable_trigger_func(struct event_command *cmd_ops,
1176                           struct trace_event_file *file,
1177                           char *glob, char *cmd, char *param)
1178 {
1179         struct trace_event_file *event_enable_file;
1180         struct enable_trigger_data *enable_data;
1181         struct event_trigger_data *trigger_data;
1182         struct event_trigger_ops *trigger_ops;
1183         struct trace_array *tr = file->tr;
1184         const char *system;
1185         const char *event;
1186         char *trigger;
1187         char *number;
1188         bool enable;
1189         int ret;
1190
1191         if (!param)
1192                 return -EINVAL;
1193
1194         /* separate the trigger from the filter (s:e:n [if filter]) */
1195         trigger = strsep(&param, " \t");
1196         if (!trigger)
1197                 return -EINVAL;
1198
1199         system = strsep(&trigger, ":");
1200         if (!trigger)
1201                 return -EINVAL;
1202
1203         event = strsep(&trigger, ":");
1204
1205         ret = -EINVAL;
1206         event_enable_file = find_event_file(tr, system, event);
1207         if (!event_enable_file)
1208                 goto out;
1209
1210         enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
1211
1212         trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
1213
1214         ret = -ENOMEM;
1215         trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
1216         if (!trigger_data)
1217                 goto out;
1218
1219         enable_data = kzalloc(sizeof(*enable_data), GFP_KERNEL);
1220         if (!enable_data) {
1221                 kfree(trigger_data);
1222                 goto out;
1223         }
1224
1225         trigger_data->count = -1;
1226         trigger_data->ops = trigger_ops;
1227         trigger_data->cmd_ops = cmd_ops;
1228         INIT_LIST_HEAD(&trigger_data->list);
1229         RCU_INIT_POINTER(trigger_data->filter, NULL);
1230
1231         enable_data->enable = enable;
1232         enable_data->file = event_enable_file;
1233         trigger_data->private_data = enable_data;
1234
1235         if (glob[0] == '!') {
1236                 cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
1237                 kfree(trigger_data);
1238                 kfree(enable_data);
1239                 ret = 0;
1240                 goto out;
1241         }
1242
1243         if (trigger) {
1244                 number = strsep(&trigger, ":");
1245
1246                 ret = -EINVAL;
1247                 if (!strlen(number))
1248                         goto out_free;
1249
1250                 /*
1251                  * We use the callback data field (which is a pointer)
1252                  * as our counter.
1253                  */
1254                 ret = kstrtoul(number, 0, &trigger_data->count);
1255                 if (ret)
1256                         goto out_free;
1257         }
1258
1259         if (!param) /* if param is non-empty, it's supposed to be a filter */
1260                 goto out_reg;
1261
1262         if (!cmd_ops->set_filter)
1263                 goto out_reg;
1264
1265         ret = cmd_ops->set_filter(param, trigger_data, file);
1266         if (ret < 0)
1267                 goto out_free;
1268
1269  out_reg:
1270         /* Don't let event modules unload while probe registered */
1271         ret = try_module_get(event_enable_file->event_call->mod);
1272         if (!ret) {
1273                 ret = -EBUSY;
1274                 goto out_free;
1275         }
1276
1277         ret = trace_event_enable_disable(event_enable_file, 1, 1);
1278         if (ret < 0)
1279                 goto out_put;
1280         ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);
1281         /*
1282          * The above returns on success the # of functions enabled,
1283          * but if it didn't find any functions it returns zero.
1284          * Consider no functions a failure too.
1285          */
1286         if (!ret) {
1287                 ret = -ENOENT;
1288                 goto out_disable;
1289         } else if (ret < 0)
1290                 goto out_disable;
1291         /* Just return zero, not the number of enabled functions */
1292         ret = 0;
1293  out:
1294         return ret;
1295
1296  out_disable:
1297         trace_event_enable_disable(event_enable_file, 0, 1);
1298  out_put:
1299         module_put(event_enable_file->event_call->mod);
1300  out_free:
1301         if (cmd_ops->set_filter)
1302                 cmd_ops->set_filter(NULL, trigger_data, NULL);
1303         kfree(trigger_data);
1304         kfree(enable_data);
1305         goto out;
1306 }
1307
1308 static int event_enable_register_trigger(char *glob,
1309                                          struct event_trigger_ops *ops,
1310                                          struct event_trigger_data *data,
1311                                          struct trace_event_file *file)
1312 {
1313         struct enable_trigger_data *enable_data = data->private_data;
1314         struct enable_trigger_data *test_enable_data;
1315         struct event_trigger_data *test;
1316         int ret = 0;
1317
1318         list_for_each_entry_rcu(test, &file->triggers, list) {
1319                 test_enable_data = test->private_data;
1320                 if (test_enable_data &&
1321                     (test_enable_data->file == enable_data->file)) {
1322                         ret = -EEXIST;
1323                         goto out;
1324                 }
1325         }
1326
1327         if (data->ops->init) {
1328                 ret = data->ops->init(data->ops, data);
1329                 if (ret < 0)
1330                         goto out;
1331         }
1332
1333         list_add_rcu(&data->list, &file->triggers);
1334         ret++;
1335
1336         update_cond_flag(file);
1337         if (trace_event_trigger_enable_disable(file, 1) < 0) {
1338                 list_del_rcu(&data->list);
1339                 update_cond_flag(file);
1340                 ret--;
1341         }
1342 out:
1343         return ret;
1344 }
1345
1346 static void event_enable_unregister_trigger(char *glob,
1347                                             struct event_trigger_ops *ops,
1348                                             struct event_trigger_data *test,
1349                                             struct trace_event_file *file)
1350 {
1351         struct enable_trigger_data *test_enable_data = test->private_data;
1352         struct enable_trigger_data *enable_data;
1353         struct event_trigger_data *data;
1354         bool unregistered = false;
1355
1356         list_for_each_entry_rcu(data, &file->triggers, list) {
1357                 enable_data = data->private_data;
1358                 if (enable_data &&
1359                     (enable_data->file == test_enable_data->file)) {
1360                         unregistered = true;
1361                         list_del_rcu(&data->list);
1362                         trace_event_trigger_enable_disable(file, 0);
1363                         update_cond_flag(file);
1364                         break;
1365                 }
1366         }
1367
1368         if (unregistered && data->ops->free)
1369                 data->ops->free(data->ops, data);
1370 }
1371
1372 static struct event_trigger_ops *
1373 event_enable_get_trigger_ops(char *cmd, char *param)
1374 {
1375         struct event_trigger_ops *ops;
1376         bool enable;
1377
1378         enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
1379
1380         if (enable)
1381                 ops = param ? &event_enable_count_trigger_ops :
1382                         &event_enable_trigger_ops;
1383         else
1384                 ops = param ? &event_disable_count_trigger_ops :
1385                         &event_disable_trigger_ops;
1386
1387         return ops;
1388 }
1389
1390 static struct event_command trigger_enable_cmd = {
1391         .name                   = ENABLE_EVENT_STR,
1392         .trigger_type           = ETT_EVENT_ENABLE,
1393         .func                   = event_enable_trigger_func,
1394         .reg                    = event_enable_register_trigger,
1395         .unreg                  = event_enable_unregister_trigger,
1396         .get_trigger_ops        = event_enable_get_trigger_ops,
1397         .set_filter             = set_trigger_filter,
1398 };
1399
1400 static struct event_command trigger_disable_cmd = {
1401         .name                   = DISABLE_EVENT_STR,
1402         .trigger_type           = ETT_EVENT_ENABLE,
1403         .func                   = event_enable_trigger_func,
1404         .reg                    = event_enable_register_trigger,
1405         .unreg                  = event_enable_unregister_trigger,
1406         .get_trigger_ops        = event_enable_get_trigger_ops,
1407         .set_filter             = set_trigger_filter,
1408 };
1409
1410 static __init void unregister_trigger_enable_disable_cmds(void)
1411 {
1412         unregister_event_command(&trigger_enable_cmd);
1413         unregister_event_command(&trigger_disable_cmd);
1414 }
1415
1416 static __init int register_trigger_enable_disable_cmds(void)
1417 {
1418         int ret;
1419
1420         ret = register_event_command(&trigger_enable_cmd);
1421         if (WARN_ON(ret < 0))
1422                 return ret;
1423         ret = register_event_command(&trigger_disable_cmd);
1424         if (WARN_ON(ret < 0))
1425                 unregister_trigger_enable_disable_cmds();
1426
1427         return ret;
1428 }
1429
1430 static __init int register_trigger_traceon_traceoff_cmds(void)
1431 {
1432         int ret;
1433
1434         ret = register_event_command(&trigger_traceon_cmd);
1435         if (WARN_ON(ret < 0))
1436                 return ret;
1437         ret = register_event_command(&trigger_traceoff_cmd);
1438         if (WARN_ON(ret < 0))
1439                 unregister_trigger_traceon_traceoff_cmds();
1440
1441         return ret;
1442 }
1443
1444 __init int register_trigger_cmds(void)
1445 {
1446         register_trigger_traceon_traceoff_cmds();
1447         register_trigger_snapshot_cmd();
1448         register_trigger_stacktrace_cmd();
1449         register_trigger_enable_disable_cmds();
1450
1451         return 0;
1452 }