ARM: tegra: dvfs: Add GPU scaling trip-points interfaces
[linux-3.10.git] / kernel / tracepoint.c
1 /*
2  * Copyright (C) 2008 Mathieu Desnoyers
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 #include <linux/module.h>
19 #include <linux/mutex.h>
20 #include <linux/types.h>
21 #include <linux/jhash.h>
22 #include <linux/list.h>
23 #include <linux/rcupdate.h>
24 #include <linux/tracepoint.h>
25 #include <linux/err.h>
26 #include <linux/slab.h>
27 #include <linux/sched.h>
28 #include <linux/static_key.h>
29
30 extern struct tracepoint * const __start___tracepoints_ptrs[];
31 extern struct tracepoint * const __stop___tracepoints_ptrs[];
32
33 /* Set to 1 to enable tracepoint debug output */
34 static const int tracepoint_debug;
35
36 /*
37  * Tracepoints mutex protects the builtin and module tracepoints and the hash
38  * table, as well as the local module list.
39  */
40 static DEFINE_MUTEX(tracepoints_mutex);
41
42 #ifdef CONFIG_MODULES
43 /* Local list of struct module */
44 static LIST_HEAD(tracepoint_module_list);
45 #endif /* CONFIG_MODULES */
46
47 /*
48  * Tracepoint hash table, containing the active tracepoints.
49  * Protected by tracepoints_mutex.
50  */
51 #define TRACEPOINT_HASH_BITS 6
52 #define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS)
53 static struct hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE];
54
55 /*
56  * Note about RCU :
57  * It is used to delay the free of multiple probes array until a quiescent
58  * state is reached.
59  * Tracepoint entries modifications are protected by the tracepoints_mutex.
60  */
61 struct tracepoint_entry {
62         struct hlist_node hlist;
63         struct tracepoint_func *funcs;
64         int refcount;   /* Number of times armed. 0 if disarmed. */
65         char name[0];
66 };
67
68 struct tp_probes {
69         union {
70                 struct rcu_head rcu;
71                 struct list_head list;
72         } u;
73         struct tracepoint_func probes[0];
74 };
75
76 static inline void *allocate_probes(int count)
77 {
78         struct tp_probes *p  = kmalloc(count * sizeof(struct tracepoint_func)
79                         + sizeof(struct tp_probes), GFP_KERNEL);
80         return p == NULL ? NULL : p->probes;
81 }
82
83 static void rcu_free_old_probes(struct rcu_head *head)
84 {
85         kfree(container_of(head, struct tp_probes, u.rcu));
86 }
87
88 static inline void release_probes(struct tracepoint_func *old)
89 {
90         if (old) {
91                 struct tp_probes *tp_probes = container_of(old,
92                         struct tp_probes, probes[0]);
93                 call_rcu_sched(&tp_probes->u.rcu, rcu_free_old_probes);
94         }
95 }
96
97 static void debug_print_probes(struct tracepoint_entry *entry)
98 {
99         int i;
100
101         if (!tracepoint_debug || !entry->funcs)
102                 return;
103
104         for (i = 0; entry->funcs[i].func; i++)
105                 printk(KERN_DEBUG "Probe %d : %p\n", i, entry->funcs[i].func);
106 }
107
108 static struct tracepoint_func *
109 tracepoint_entry_add_probe(struct tracepoint_entry *entry,
110                            void *probe, void *data)
111 {
112         int nr_probes = 0;
113         struct tracepoint_func *old, *new;
114
115         if (WARN_ON(!probe))
116                 return ERR_PTR(-EINVAL);
117
118         debug_print_probes(entry);
119         old = entry->funcs;
120         if (old) {
121                 /* (N -> N+1), (N != 0, 1) probes */
122                 for (nr_probes = 0; old[nr_probes].func; nr_probes++)
123                         if (old[nr_probes].func == probe &&
124                             old[nr_probes].data == data)
125                                 return ERR_PTR(-EEXIST);
126         }
127         /* + 2 : one for new probe, one for NULL func */
128         new = allocate_probes(nr_probes + 2);
129         if (new == NULL)
130                 return ERR_PTR(-ENOMEM);
131         if (old)
132                 memcpy(new, old, nr_probes * sizeof(struct tracepoint_func));
133         new[nr_probes].func = probe;
134         new[nr_probes].data = data;
135         new[nr_probes + 1].func = NULL;
136         entry->refcount = nr_probes + 1;
137         entry->funcs = new;
138         debug_print_probes(entry);
139         return old;
140 }
141
142 static void *
143 tracepoint_entry_remove_probe(struct tracepoint_entry *entry,
144                               void *probe, void *data)
145 {
146         int nr_probes = 0, nr_del = 0, i;
147         struct tracepoint_func *old, *new;
148
149         old = entry->funcs;
150
151         if (!old)
152                 return ERR_PTR(-ENOENT);
153
154         debug_print_probes(entry);
155         /* (N -> M), (N > 1, M >= 0) probes */
156         if (probe) {
157                 for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
158                         if (old[nr_probes].func == probe &&
159                              old[nr_probes].data == data)
160                                 nr_del++;
161                 }
162         }
163
164         /*
165          * If probe is NULL, then nr_probes = nr_del = 0, and then the
166          * entire entry will be removed.
167          */
168         if (nr_probes - nr_del == 0) {
169                 /* N -> 0, (N > 1) */
170                 entry->funcs = NULL;
171                 entry->refcount = 0;
172                 debug_print_probes(entry);
173                 return old;
174         } else {
175                 int j = 0;
176                 /* N -> M, (N > 1, M > 0) */
177                 /* + 1 for NULL */
178                 new = allocate_probes(nr_probes - nr_del + 1);
179                 if (new == NULL)
180                         return ERR_PTR(-ENOMEM);
181                 for (i = 0; old[i].func; i++)
182                         if (old[i].func != probe || old[i].data != data)
183                                 new[j++] = old[i];
184                 new[nr_probes - nr_del].func = NULL;
185                 entry->refcount = nr_probes - nr_del;
186                 entry->funcs = new;
187         }
188         debug_print_probes(entry);
189         return old;
190 }
191
192 /*
193  * Get tracepoint if the tracepoint is present in the tracepoint hash table.
194  * Must be called with tracepoints_mutex held.
195  * Returns NULL if not present.
196  */
197 static struct tracepoint_entry *get_tracepoint(const char *name)
198 {
199         struct hlist_head *head;
200         struct tracepoint_entry *e;
201         u32 hash = jhash(name, strlen(name), 0);
202
203         head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
204         hlist_for_each_entry(e, head, hlist) {
205                 if (!strcmp(name, e->name))
206                         return e;
207         }
208         return NULL;
209 }
210
211 /*
212  * Add the tracepoint to the tracepoint hash table. Must be called with
213  * tracepoints_mutex held.
214  */
215 static struct tracepoint_entry *add_tracepoint(const char *name)
216 {
217         struct hlist_head *head;
218         struct tracepoint_entry *e;
219         size_t name_len = strlen(name) + 1;
220         u32 hash = jhash(name, name_len-1, 0);
221
222         head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
223         hlist_for_each_entry(e, head, hlist) {
224                 if (!strcmp(name, e->name)) {
225                         printk(KERN_NOTICE
226                                 "tracepoint %s busy\n", name);
227                         return ERR_PTR(-EEXIST);        /* Already there */
228                 }
229         }
230         /*
231          * Using kmalloc here to allocate a variable length element. Could
232          * cause some memory fragmentation if overused.
233          */
234         e = kmalloc(sizeof(struct tracepoint_entry) + name_len, GFP_KERNEL);
235         if (!e)
236                 return ERR_PTR(-ENOMEM);
237         memcpy(&e->name[0], name, name_len);
238         e->funcs = NULL;
239         e->refcount = 0;
240         hlist_add_head(&e->hlist, head);
241         return e;
242 }
243
244 /*
245  * Remove the tracepoint from the tracepoint hash table. Must be called with
246  * mutex_lock held.
247  */
248 static inline void remove_tracepoint(struct tracepoint_entry *e)
249 {
250         hlist_del(&e->hlist);
251         kfree(e);
252 }
253
254 /*
255  * Sets the probe callback corresponding to one tracepoint.
256  */
257 static void set_tracepoint(struct tracepoint_entry **entry,
258         struct tracepoint *elem, int active)
259 {
260         WARN_ON(strcmp((*entry)->name, elem->name) != 0);
261
262         if (elem->regfunc && !static_key_enabled(&elem->key) && active)
263                 elem->regfunc();
264         else if (elem->unregfunc && static_key_enabled(&elem->key) && !active)
265                 elem->unregfunc();
266
267         /*
268          * rcu_assign_pointer has a smp_wmb() which makes sure that the new
269          * probe callbacks array is consistent before setting a pointer to it.
270          * This array is referenced by __DO_TRACE from
271          * include/linux/tracepoints.h. A matching smp_read_barrier_depends()
272          * is used.
273          */
274         rcu_assign_pointer(elem->funcs, (*entry)->funcs);
275         if (active && !static_key_enabled(&elem->key))
276                 static_key_slow_inc(&elem->key);
277         else if (!active && static_key_enabled(&elem->key))
278                 static_key_slow_dec(&elem->key);
279 }
280
281 /*
282  * Disable a tracepoint and its probe callback.
283  * Note: only waiting an RCU period after setting elem->call to the empty
284  * function insures that the original callback is not used anymore. This insured
285  * by preempt_disable around the call site.
286  */
287 static void disable_tracepoint(struct tracepoint *elem)
288 {
289         if (elem->unregfunc && static_key_enabled(&elem->key))
290                 elem->unregfunc();
291
292         if (static_key_enabled(&elem->key))
293                 static_key_slow_dec(&elem->key);
294         rcu_assign_pointer(elem->funcs, NULL);
295 }
296
297 /**
298  * tracepoint_update_probe_range - Update a probe range
299  * @begin: beginning of the range
300  * @end: end of the range
301  *
302  * Updates the probe callback corresponding to a range of tracepoints.
303  * Called with tracepoints_mutex held.
304  */
305 static void tracepoint_update_probe_range(struct tracepoint * const *begin,
306                                           struct tracepoint * const *end)
307 {
308         struct tracepoint * const *iter;
309         struct tracepoint_entry *mark_entry;
310
311         if (!begin)
312                 return;
313
314         for (iter = begin; iter < end; iter++) {
315                 mark_entry = get_tracepoint((*iter)->name);
316                 if (mark_entry) {
317                         set_tracepoint(&mark_entry, *iter,
318                                         !!mark_entry->refcount);
319                 } else {
320                         disable_tracepoint(*iter);
321                 }
322         }
323 }
324
325 #ifdef CONFIG_MODULES
326 void module_update_tracepoints(void)
327 {
328         struct tp_module *tp_mod;
329
330         list_for_each_entry(tp_mod, &tracepoint_module_list, list)
331                 tracepoint_update_probe_range(tp_mod->tracepoints_ptrs,
332                         tp_mod->tracepoints_ptrs + tp_mod->num_tracepoints);
333 }
334 #else /* CONFIG_MODULES */
335 void module_update_tracepoints(void)
336 {
337 }
338 #endif /* CONFIG_MODULES */
339
340
341 /*
342  * Update probes, removing the faulty probes.
343  * Called with tracepoints_mutex held.
344  */
345 static void tracepoint_update_probes(void)
346 {
347         /* Core kernel tracepoints */
348         tracepoint_update_probe_range(__start___tracepoints_ptrs,
349                 __stop___tracepoints_ptrs);
350         /* tracepoints in modules. */
351         module_update_tracepoints();
352 }
353
354 static struct tracepoint_func *
355 tracepoint_add_probe(const char *name, void *probe, void *data)
356 {
357         struct tracepoint_entry *entry;
358         struct tracepoint_func *old;
359
360         entry = get_tracepoint(name);
361         if (!entry) {
362                 entry = add_tracepoint(name);
363                 if (IS_ERR(entry))
364                         return (struct tracepoint_func *)entry;
365         }
366         old = tracepoint_entry_add_probe(entry, probe, data);
367         if (IS_ERR(old) && !entry->refcount)
368                 remove_tracepoint(entry);
369         return old;
370 }
371
372 /**
373  * tracepoint_probe_register -  Connect a probe to a tracepoint
374  * @name: tracepoint name
375  * @probe: probe handler
376  *
377  * Returns 0 if ok, error value on error.
378  * The probe address must at least be aligned on the architecture pointer size.
379  */
380 int tracepoint_probe_register(const char *name, void *probe, void *data)
381 {
382         struct tracepoint_func *old;
383
384         mutex_lock(&tracepoints_mutex);
385         old = tracepoint_add_probe(name, probe, data);
386         if (IS_ERR(old)) {
387                 mutex_unlock(&tracepoints_mutex);
388                 return PTR_ERR(old);
389         }
390         tracepoint_update_probes();             /* may update entry */
391         mutex_unlock(&tracepoints_mutex);
392         release_probes(old);
393         return 0;
394 }
395 EXPORT_SYMBOL_GPL(tracepoint_probe_register);
396
397 static struct tracepoint_func *
398 tracepoint_remove_probe(const char *name, void *probe, void *data)
399 {
400         struct tracepoint_entry *entry;
401         struct tracepoint_func *old;
402
403         entry = get_tracepoint(name);
404         if (!entry)
405                 return ERR_PTR(-ENOENT);
406         old = tracepoint_entry_remove_probe(entry, probe, data);
407         if (IS_ERR(old))
408                 return old;
409         if (!entry->refcount)
410                 remove_tracepoint(entry);
411         return old;
412 }
413
414 /**
415  * tracepoint_probe_unregister -  Disconnect a probe from a tracepoint
416  * @name: tracepoint name
417  * @probe: probe function pointer
418  *
419  * We do not need to call a synchronize_sched to make sure the probes have
420  * finished running before doing a module unload, because the module unload
421  * itself uses stop_machine(), which insures that every preempt disabled section
422  * have finished.
423  */
424 int tracepoint_probe_unregister(const char *name, void *probe, void *data)
425 {
426         struct tracepoint_func *old;
427
428         mutex_lock(&tracepoints_mutex);
429         old = tracepoint_remove_probe(name, probe, data);
430         if (IS_ERR(old)) {
431                 mutex_unlock(&tracepoints_mutex);
432                 return PTR_ERR(old);
433         }
434         tracepoint_update_probes();             /* may update entry */
435         mutex_unlock(&tracepoints_mutex);
436         release_probes(old);
437         return 0;
438 }
439 EXPORT_SYMBOL_GPL(tracepoint_probe_unregister);
440
441 static LIST_HEAD(old_probes);
442 static int need_update;
443
444 static void tracepoint_add_old_probes(void *old)
445 {
446         need_update = 1;
447         if (old) {
448                 struct tp_probes *tp_probes = container_of(old,
449                         struct tp_probes, probes[0]);
450                 list_add(&tp_probes->u.list, &old_probes);
451         }
452 }
453
454 /**
455  * tracepoint_probe_register_noupdate -  register a probe but not connect
456  * @name: tracepoint name
457  * @probe: probe handler
458  *
459  * caller must call tracepoint_probe_update_all()
460  */
461 int tracepoint_probe_register_noupdate(const char *name, void *probe,
462                                        void *data)
463 {
464         struct tracepoint_func *old;
465
466         mutex_lock(&tracepoints_mutex);
467         old = tracepoint_add_probe(name, probe, data);
468         if (IS_ERR(old)) {
469                 mutex_unlock(&tracepoints_mutex);
470                 return PTR_ERR(old);
471         }
472         tracepoint_add_old_probes(old);
473         mutex_unlock(&tracepoints_mutex);
474         return 0;
475 }
476 EXPORT_SYMBOL_GPL(tracepoint_probe_register_noupdate);
477
478 /**
479  * tracepoint_probe_unregister_noupdate -  remove a probe but not disconnect
480  * @name: tracepoint name
481  * @probe: probe function pointer
482  *
483  * caller must call tracepoint_probe_update_all()
484  */
485 int tracepoint_probe_unregister_noupdate(const char *name, void *probe,
486                                          void *data)
487 {
488         struct tracepoint_func *old;
489
490         mutex_lock(&tracepoints_mutex);
491         old = tracepoint_remove_probe(name, probe, data);
492         if (IS_ERR(old)) {
493                 mutex_unlock(&tracepoints_mutex);
494                 return PTR_ERR(old);
495         }
496         tracepoint_add_old_probes(old);
497         mutex_unlock(&tracepoints_mutex);
498         return 0;
499 }
500 EXPORT_SYMBOL_GPL(tracepoint_probe_unregister_noupdate);
501
502 /**
503  * tracepoint_probe_update_all -  update tracepoints
504  */
505 void tracepoint_probe_update_all(void)
506 {
507         LIST_HEAD(release_probes);
508         struct tp_probes *pos, *next;
509
510         mutex_lock(&tracepoints_mutex);
511         if (!need_update) {
512                 mutex_unlock(&tracepoints_mutex);
513                 return;
514         }
515         if (!list_empty(&old_probes))
516                 list_replace_init(&old_probes, &release_probes);
517         need_update = 0;
518         tracepoint_update_probes();
519         mutex_unlock(&tracepoints_mutex);
520         list_for_each_entry_safe(pos, next, &release_probes, u.list) {
521                 list_del(&pos->u.list);
522                 call_rcu_sched(&pos->u.rcu, rcu_free_old_probes);
523         }
524 }
525 EXPORT_SYMBOL_GPL(tracepoint_probe_update_all);
526
527 /**
528  * tracepoint_get_iter_range - Get a next tracepoint iterator given a range.
529  * @tracepoint: current tracepoints (in), next tracepoint (out)
530  * @begin: beginning of the range
531  * @end: end of the range
532  *
533  * Returns whether a next tracepoint has been found (1) or not (0).
534  * Will return the first tracepoint in the range if the input tracepoint is
535  * NULL.
536  */
537 static int tracepoint_get_iter_range(struct tracepoint * const **tracepoint,
538         struct tracepoint * const *begin, struct tracepoint * const *end)
539 {
540         if (!*tracepoint && begin != end) {
541                 *tracepoint = begin;
542                 return 1;
543         }
544         if (*tracepoint >= begin && *tracepoint < end)
545                 return 1;
546         return 0;
547 }
548
549 #ifdef CONFIG_MODULES
550 static void tracepoint_get_iter(struct tracepoint_iter *iter)
551 {
552         int found = 0;
553         struct tp_module *iter_mod;
554
555         /* Core kernel tracepoints */
556         if (!iter->module) {
557                 found = tracepoint_get_iter_range(&iter->tracepoint,
558                                 __start___tracepoints_ptrs,
559                                 __stop___tracepoints_ptrs);
560                 if (found)
561                         goto end;
562         }
563         /* Tracepoints in modules */
564         mutex_lock(&tracepoints_mutex);
565         list_for_each_entry(iter_mod, &tracepoint_module_list, list) {
566                 /*
567                  * Sorted module list
568                  */
569                 if (iter_mod < iter->module)
570                         continue;
571                 else if (iter_mod > iter->module)
572                         iter->tracepoint = NULL;
573                 found = tracepoint_get_iter_range(&iter->tracepoint,
574                         iter_mod->tracepoints_ptrs,
575                         iter_mod->tracepoints_ptrs
576                                 + iter_mod->num_tracepoints);
577                 if (found) {
578                         iter->module = iter_mod;
579                         break;
580                 }
581         }
582         mutex_unlock(&tracepoints_mutex);
583 end:
584         if (!found)
585                 tracepoint_iter_reset(iter);
586 }
587 #else /* CONFIG_MODULES */
588 static void tracepoint_get_iter(struct tracepoint_iter *iter)
589 {
590         int found = 0;
591
592         /* Core kernel tracepoints */
593         found = tracepoint_get_iter_range(&iter->tracepoint,
594                         __start___tracepoints_ptrs,
595                         __stop___tracepoints_ptrs);
596         if (!found)
597                 tracepoint_iter_reset(iter);
598 }
599 #endif /* CONFIG_MODULES */
600
601 void tracepoint_iter_start(struct tracepoint_iter *iter)
602 {
603         tracepoint_get_iter(iter);
604 }
605 EXPORT_SYMBOL_GPL(tracepoint_iter_start);
606
607 void tracepoint_iter_next(struct tracepoint_iter *iter)
608 {
609         iter->tracepoint++;
610         /*
611          * iter->tracepoint may be invalid because we blindly incremented it.
612          * Make sure it is valid by marshalling on the tracepoints, getting the
613          * tracepoints from following modules if necessary.
614          */
615         tracepoint_get_iter(iter);
616 }
617 EXPORT_SYMBOL_GPL(tracepoint_iter_next);
618
619 void tracepoint_iter_stop(struct tracepoint_iter *iter)
620 {
621 }
622 EXPORT_SYMBOL_GPL(tracepoint_iter_stop);
623
624 void tracepoint_iter_reset(struct tracepoint_iter *iter)
625 {
626 #ifdef CONFIG_MODULES
627         iter->module = NULL;
628 #endif /* CONFIG_MODULES */
629         iter->tracepoint = NULL;
630 }
631 EXPORT_SYMBOL_GPL(tracepoint_iter_reset);
632
633 #ifdef CONFIG_MODULES
634 static int tracepoint_module_coming(struct module *mod)
635 {
636         struct tp_module *tp_mod, *iter;
637         int ret = 0;
638
639         /*
640          * We skip modules that taint the kernel, especially those with different
641          * module headers (for forced load), to make sure we don't cause a crash.
642          * Staging and out-of-tree GPL modules are fine.
643          */
644         if (mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP)))
645                 return 0;
646         mutex_lock(&tracepoints_mutex);
647         tp_mod = kmalloc(sizeof(struct tp_module), GFP_KERNEL);
648         if (!tp_mod) {
649                 ret = -ENOMEM;
650                 goto end;
651         }
652         tp_mod->num_tracepoints = mod->num_tracepoints;
653         tp_mod->tracepoints_ptrs = mod->tracepoints_ptrs;
654
655         /*
656          * tracepoint_module_list is kept sorted by struct module pointer
657          * address for iteration on tracepoints from a seq_file that can release
658          * the mutex between calls.
659          */
660         list_for_each_entry_reverse(iter, &tracepoint_module_list, list) {
661                 BUG_ON(iter == tp_mod); /* Should never be in the list twice */
662                 if (iter < tp_mod) {
663                         /* We belong to the location right after iter. */
664                         list_add(&tp_mod->list, &iter->list);
665                         goto module_added;
666                 }
667         }
668         /* We belong to the beginning of the list */
669         list_add(&tp_mod->list, &tracepoint_module_list);
670 module_added:
671         tracepoint_update_probe_range(mod->tracepoints_ptrs,
672                 mod->tracepoints_ptrs + mod->num_tracepoints);
673 end:
674         mutex_unlock(&tracepoints_mutex);
675         return ret;
676 }
677
678 static int tracepoint_module_going(struct module *mod)
679 {
680         struct tp_module *pos;
681
682         mutex_lock(&tracepoints_mutex);
683         tracepoint_update_probe_range(mod->tracepoints_ptrs,
684                 mod->tracepoints_ptrs + mod->num_tracepoints);
685         list_for_each_entry(pos, &tracepoint_module_list, list) {
686                 if (pos->tracepoints_ptrs == mod->tracepoints_ptrs) {
687                         list_del(&pos->list);
688                         kfree(pos);
689                         break;
690                 }
691         }
692         /*
693          * In the case of modules that were tainted at "coming", we'll simply
694          * walk through the list without finding it. We cannot use the "tainted"
695          * flag on "going", in case a module taints the kernel only after being
696          * loaded.
697          */
698         mutex_unlock(&tracepoints_mutex);
699         return 0;
700 }
701
702 int tracepoint_module_notify(struct notifier_block *self,
703                              unsigned long val, void *data)
704 {
705         struct module *mod = data;
706         int ret = 0;
707
708         switch (val) {
709         case MODULE_STATE_COMING:
710                 ret = tracepoint_module_coming(mod);
711                 break;
712         case MODULE_STATE_LIVE:
713                 break;
714         case MODULE_STATE_GOING:
715                 ret = tracepoint_module_going(mod);
716                 break;
717         }
718         return ret;
719 }
720
721 struct notifier_block tracepoint_module_nb = {
722         .notifier_call = tracepoint_module_notify,
723         .priority = 0,
724 };
725
726 static int init_tracepoints(void)
727 {
728         return register_module_notifier(&tracepoint_module_nb);
729 }
730 __initcall(init_tracepoints);
731 #endif /* CONFIG_MODULES */
732
733 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
734
735 /* NB: reg/unreg are called while guarded with the tracepoints_mutex */
736 static int sys_tracepoint_refcount;
737
738 void syscall_regfunc(void)
739 {
740         unsigned long flags;
741         struct task_struct *g, *t;
742
743         if (!sys_tracepoint_refcount) {
744                 read_lock_irqsave(&tasklist_lock, flags);
745                 do_each_thread(g, t) {
746                         /* Skip kernel threads. */
747                         if (t->mm)
748                                 set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
749                 } while_each_thread(g, t);
750                 read_unlock_irqrestore(&tasklist_lock, flags);
751         }
752         sys_tracepoint_refcount++;
753 }
754
755 void syscall_unregfunc(void)
756 {
757         unsigned long flags;
758         struct task_struct *g, *t;
759
760         sys_tracepoint_refcount--;
761         if (!sys_tracepoint_refcount) {
762                 read_lock_irqsave(&tasklist_lock, flags);
763                 do_each_thread(g, t) {
764                         clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
765                 } while_each_thread(g, t);
766                 read_unlock_irqrestore(&tasklist_lock, flags);
767         }
768 }
769 #endif