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Linux/kernel/trace/trace_events_trigger.c

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

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