2 * Copyright (C) 2008-2011 Mathieu Desnoyers
3 * Copyright (C) 2009 Pierre-Marc Fournier
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation;
8 * version 2.1 of the License.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 * Ported to userspace by Pierre-Marc Fournier.
28 #include <urcu/arch.h>
29 #include <urcu/urcu-bp.h>
30 #include <urcu/hlist.h>
31 #include <urcu/uatomic.h>
32 #include <urcu/compiler.h>
33 #include <urcu/system.h>
35 #include <lttng/tracepoint.h>
36 #include <lttng/ust-abi.h> /* for LTTNG_UST_SYM_NAME_LEN */
38 #include <usterr-signal-safe.h>
41 #include "tracepoint-internal.h"
42 #include "lttng-tracer-core.h"
46 /* Test compiler support for weak symbols with hidden visibility. */
47 int __tracepoint_test_symbol1
__attribute__((weak
, visibility("hidden")));
48 void *__tracepoint_test_symbol2
__attribute__((weak
, visibility("hidden")));
51 } __tracepoint_test_symbol3
__attribute__((weak
, visibility("hidden")));
53 /* Set to 1 to enable tracepoint debug output */
54 static const int tracepoint_debug
;
55 static int initialized
;
58 * If tracepoint_destructors_state = 1, tracepoint destructors are
59 * enabled. They are disabled otherwise.
61 static int tracepoint_destructors_state
= 1;
64 * Expose the now deprecated symbol __tracepoints__disable_destructors for
65 * backward compatibility of applications built against old versions of
66 * lttng-ust. We need to keep __tracepoints__disable_destructors up to date
67 * within the new destructor disabling API because old applications read this
70 int __tracepoints__disable_destructors
__attribute__((weak
));
72 static void (*new_tracepoint_cb
)(struct lttng_ust_tracepoint
*);
75 * tracepoint_mutex nests inside UST mutex.
77 * Note about interaction with fork/clone: UST does not hold the
78 * tracepoint mutex across fork/clone because it is either:
79 * - nested within UST mutex, in which case holding the UST mutex across
81 * - taken by a library constructor, which should never race with a
82 * fork/clone if the application is expected to continue running with
83 * the same memory layout (no following exec()).
85 static pthread_mutex_t tracepoint_mutex
= PTHREAD_MUTEX_INITIALIZER
;
88 * libraries that contain tracepoints (struct tracepoint_lib).
89 * Protected by tracepoint mutex.
91 static CDS_LIST_HEAD(libs
);
94 * The tracepoint mutex protects the library tracepoints, the hash table, and
96 * All calls to the tracepoint API must be protected by the tracepoint mutex,
97 * excepts calls to tracepoint_register_lib and
98 * tracepoint_unregister_lib, which take the tracepoint mutex themselves.
102 * Tracepoint hash table, containing the active tracepoints.
103 * Protected by tracepoint mutex.
105 #define TRACEPOINT_HASH_BITS 12
106 #define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS)
107 static struct cds_hlist_head tracepoint_table
[TRACEPOINT_TABLE_SIZE
];
109 static CDS_LIST_HEAD(old_probes
);
110 static int need_update
;
112 static CDS_LIST_HEAD(release_queue
);
113 static int release_queue_need_update
;
117 * It is used to to delay the free of multiple probes array until a quiescent
119 * Tracepoint entries modifications are protected by the tracepoint mutex.
121 struct tracepoint_entry
{
122 struct cds_hlist_node hlist
;
123 struct lttng_ust_tracepoint_probe
*probes
;
124 int refcount
; /* Number of times armed. 0 if disarmed. */
125 int callsite_refcount
; /* how many libs use this tracepoint */
132 struct cds_list_head list
;
133 /* Field below only used for call_rcu scheme */
134 /* struct rcu_head head; */
136 struct lttng_ust_tracepoint_probe probes
[0];
140 * Callsite hash table, containing the tracepoint call sites.
141 * Protected by tracepoint mutex.
143 #define CALLSITE_HASH_BITS 12
144 #define CALLSITE_TABLE_SIZE (1 << CALLSITE_HASH_BITS)
145 static struct cds_hlist_head callsite_table
[CALLSITE_TABLE_SIZE
];
147 struct callsite_entry
{
148 struct cds_hlist_node hlist
; /* hash table node */
149 struct cds_list_head node
; /* lib list of callsites node */
150 struct lttng_ust_tracepoint
*tp
;
151 bool tp_entry_callsite_ref
; /* Has a tp_entry took a ref on this callsite */
154 /* coverity[+alloc] */
155 static void *allocate_probes(int count
)
157 struct tp_probes
*p
=
158 zmalloc(count
* sizeof(struct lttng_ust_tracepoint_probe
)
159 + sizeof(struct tp_probes
));
160 return p
== NULL
? NULL
: p
->probes
;
163 /* coverity[+free : arg-0] */
164 static void release_probes(void *old
)
167 struct tp_probes
*tp_probes
= caa_container_of(old
,
168 struct tp_probes
, probes
[0]);
169 urcu_bp_synchronize_rcu();
174 static void debug_print_probes(struct tracepoint_entry
*entry
)
178 if (!tracepoint_debug
|| !entry
->probes
)
181 for (i
= 0; entry
->probes
[i
].func
; i
++)
182 DBG("Probe %d : %p", i
, entry
->probes
[i
].func
);
186 tracepoint_entry_add_probe(struct tracepoint_entry
*entry
,
187 void (*probe
)(void), void *data
)
190 struct lttng_ust_tracepoint_probe
*old
, *new;
194 return ERR_PTR(-EINVAL
);
196 debug_print_probes(entry
);
199 /* (N -> N+1), (N != 0, 1) probes */
200 for (nr_probes
= 0; old
[nr_probes
].func
; nr_probes
++)
201 if (old
[nr_probes
].func
== probe
&&
202 old
[nr_probes
].data
== data
)
203 return ERR_PTR(-EEXIST
);
205 /* + 2 : one for new probe, one for NULL func */
206 new = allocate_probes(nr_probes
+ 2);
208 return ERR_PTR(-ENOMEM
);
211 nr_probes
* sizeof(struct lttng_ust_tracepoint_probe
));
212 new[nr_probes
].func
= probe
;
213 new[nr_probes
].data
= data
;
214 new[nr_probes
+ 1].func
= NULL
;
215 entry
->refcount
= nr_probes
+ 1;
217 debug_print_probes(entry
);
222 tracepoint_entry_remove_probe(struct tracepoint_entry
*entry
,
223 void (*probe
)(void), void *data
)
225 int nr_probes
= 0, nr_del
= 0, i
;
226 struct lttng_ust_tracepoint_probe
*old
, *new;
231 return ERR_PTR(-ENOENT
);
233 debug_print_probes(entry
);
234 /* (N -> M), (N > 1, M >= 0) probes */
236 for (nr_probes
= 0; old
[nr_probes
].func
; nr_probes
++) {
237 if (old
[nr_probes
].func
== probe
&&
238 old
[nr_probes
].data
== data
)
243 if (nr_probes
- nr_del
== 0) {
244 /* N -> 0, (N > 1) */
245 entry
->probes
= NULL
;
247 debug_print_probes(entry
);
251 /* N -> M, (N > 1, M > 0) */
253 new = allocate_probes(nr_probes
- nr_del
+ 1);
255 return ERR_PTR(-ENOMEM
);
256 for (i
= 0; old
[i
].func
; i
++)
257 if (old
[i
].func
!= probe
|| old
[i
].data
!= data
)
259 new[nr_probes
- nr_del
].func
= NULL
;
260 entry
->refcount
= nr_probes
- nr_del
;
263 debug_print_probes(entry
);
268 * Get tracepoint if the tracepoint is present in the tracepoint hash table.
269 * Must be called with tracepoint mutex held.
270 * Returns NULL if not present.
272 static struct tracepoint_entry
*get_tracepoint(const char *name
)
274 struct cds_hlist_head
*head
;
275 struct cds_hlist_node
*node
;
276 struct tracepoint_entry
*e
;
277 size_t name_len
= strlen(name
);
280 if (name_len
> LTTNG_UST_SYM_NAME_LEN
- 1) {
281 WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name
, LTTNG_UST_SYM_NAME_LEN
- 1);
282 name_len
= LTTNG_UST_SYM_NAME_LEN
- 1;
284 hash
= jhash(name
, name_len
, 0);
285 head
= &tracepoint_table
[hash
& (TRACEPOINT_TABLE_SIZE
- 1)];
286 cds_hlist_for_each_entry(e
, node
, head
, hlist
) {
287 if (!strncmp(name
, e
->name
, LTTNG_UST_SYM_NAME_LEN
- 1))
294 * Add the tracepoint to the tracepoint hash table. Must be called with
295 * tracepoint mutex held.
297 static struct tracepoint_entry
*add_tracepoint(const char *name
,
298 const char *signature
)
300 struct cds_hlist_head
*head
;
301 struct cds_hlist_node
*node
;
302 struct tracepoint_entry
*e
;
303 size_t name_len
= strlen(name
);
304 size_t sig_len
= strlen(signature
);
305 size_t sig_off
, name_off
;
308 if (name_len
> LTTNG_UST_SYM_NAME_LEN
- 1) {
309 WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name
, LTTNG_UST_SYM_NAME_LEN
- 1);
310 name_len
= LTTNG_UST_SYM_NAME_LEN
- 1;
312 hash
= jhash(name
, name_len
, 0);
313 head
= &tracepoint_table
[hash
& (TRACEPOINT_TABLE_SIZE
- 1)];
314 cds_hlist_for_each_entry(e
, node
, head
, hlist
) {
315 if (!strncmp(name
, e
->name
, LTTNG_UST_SYM_NAME_LEN
- 1)) {
316 DBG("tracepoint %s busy", name
);
317 return ERR_PTR(-EEXIST
); /* Already there */
322 * Using zmalloc here to allocate a variable length elements: name and
323 * signature. Could cause some memory fragmentation if overused.
325 name_off
= sizeof(struct tracepoint_entry
);
326 sig_off
= name_off
+ name_len
+ 1;
328 e
= zmalloc(sizeof(struct tracepoint_entry
) + name_len
+ 1 + sig_len
+ 1);
330 return ERR_PTR(-ENOMEM
);
331 e
->name
= (char *) e
+ name_off
;
332 memcpy(e
->name
, name
, name_len
+ 1);
333 e
->name
[name_len
] = '\0';
335 e
->signature
= (char *) e
+ sig_off
;
336 memcpy(e
->signature
, signature
, sig_len
+ 1);
337 e
->signature
[sig_len
] = '\0';
341 e
->callsite_refcount
= 0;
343 cds_hlist_add_head(&e
->hlist
, head
);
348 * Remove the tracepoint from the tracepoint hash table. Must be called with
349 * tracepoint mutex held.
351 static void remove_tracepoint(struct tracepoint_entry
*e
)
353 cds_hlist_del(&e
->hlist
);
358 * Sets the probe callback corresponding to one tracepoint.
360 static void set_tracepoint(struct tracepoint_entry
**entry
,
361 struct lttng_ust_tracepoint
*elem
, int active
)
363 WARN_ON(strncmp((*entry
)->name
, elem
->name
, LTTNG_UST_SYM_NAME_LEN
- 1) != 0);
365 * Check that signatures match before connecting a probe to a
366 * tracepoint. Warn the user if they don't.
368 if (strcmp(elem
->signature
, (*entry
)->signature
) != 0) {
369 static int warned
= 0;
371 /* Only print once, don't flood console. */
373 WARN("Tracepoint signature mismatch, not enabling one or more tracepoints. Ensure that the tracepoint probes prototypes match the application.");
374 WARN("Tracepoint \"%s\" signatures: call: \"%s\" vs probe: \"%s\".",
375 elem
->name
, elem
->signature
, (*entry
)->signature
);
378 /* Don't accept connecting non-matching signatures. */
383 * rcu_assign_pointer has a cmm_smp_wmb() which makes sure that the new
384 * probe callbacks array is consistent before setting a pointer to it.
385 * This array is referenced by __DO_TRACE from
386 * include/linux/tracepoints.h. A matching cmm_smp_read_barrier_depends()
389 rcu_assign_pointer(elem
->probes
, (*entry
)->probes
);
390 CMM_STORE_SHARED(elem
->state
, active
);
394 * Disable a tracepoint and its probe callback.
395 * Note: only waiting an RCU period after setting elem->call to the empty
396 * function insures that the original callback is not used anymore. This insured
397 * by preempt_disable around the call site.
399 static void disable_tracepoint(struct lttng_ust_tracepoint
*elem
)
401 CMM_STORE_SHARED(elem
->state
, 0);
402 rcu_assign_pointer(elem
->probes
, NULL
);
406 * Add the callsite to the callsite hash table. Must be called with
407 * tracepoint mutex held.
409 static void add_callsite(struct tracepoint_lib
* lib
, struct lttng_ust_tracepoint
*tp
)
411 struct cds_hlist_head
*head
;
412 struct callsite_entry
*e
;
413 const char *name
= tp
->name
;
414 size_t name_len
= strlen(name
);
416 struct tracepoint_entry
*tp_entry
;
418 if (name_len
> LTTNG_UST_SYM_NAME_LEN
- 1) {
419 WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name
, LTTNG_UST_SYM_NAME_LEN
- 1);
420 name_len
= LTTNG_UST_SYM_NAME_LEN
- 1;
422 hash
= jhash(name
, name_len
, 0);
423 head
= &callsite_table
[hash
& (CALLSITE_TABLE_SIZE
- 1)];
424 e
= zmalloc(sizeof(struct callsite_entry
));
426 PERROR("Unable to add callsite for tracepoint \"%s\"", name
);
429 cds_hlist_add_head(&e
->hlist
, head
);
431 cds_list_add(&e
->node
, &lib
->callsites
);
433 tp_entry
= get_tracepoint(name
);
436 tp_entry
->callsite_refcount
++;
437 e
->tp_entry_callsite_ref
= true;
441 * Remove the callsite from the callsite hash table and from lib
442 * callsite list. Must be called with tracepoint mutex held.
444 static void remove_callsite(struct callsite_entry
*e
)
446 struct tracepoint_entry
*tp_entry
;
448 tp_entry
= get_tracepoint(e
->tp
->name
);
450 if (e
->tp_entry_callsite_ref
)
451 tp_entry
->callsite_refcount
--;
452 if (tp_entry
->callsite_refcount
== 0)
453 disable_tracepoint(e
->tp
);
455 cds_hlist_del(&e
->hlist
);
456 cds_list_del(&e
->node
);
461 * Enable/disable all callsites based on the state of a specific
463 * Must be called with tracepoint mutex held.
465 static void tracepoint_sync_callsites(const char *name
)
467 struct cds_hlist_head
*head
;
468 struct cds_hlist_node
*node
;
469 struct callsite_entry
*e
;
470 size_t name_len
= strlen(name
);
472 struct tracepoint_entry
*tp_entry
;
474 tp_entry
= get_tracepoint(name
);
475 if (name_len
> LTTNG_UST_SYM_NAME_LEN
- 1) {
476 WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name
, LTTNG_UST_SYM_NAME_LEN
- 1);
477 name_len
= LTTNG_UST_SYM_NAME_LEN
- 1;
479 hash
= jhash(name
, name_len
, 0);
480 head
= &callsite_table
[hash
& (CALLSITE_TABLE_SIZE
- 1)];
481 cds_hlist_for_each_entry(e
, node
, head
, hlist
) {
482 struct lttng_ust_tracepoint
*tp
= e
->tp
;
484 if (strncmp(name
, tp
->name
, LTTNG_UST_SYM_NAME_LEN
- 1))
487 if (!e
->tp_entry_callsite_ref
) {
488 tp_entry
->callsite_refcount
++;
489 e
->tp_entry_callsite_ref
= true;
491 set_tracepoint(&tp_entry
, tp
,
492 !!tp_entry
->refcount
);
494 disable_tracepoint(tp
);
495 e
->tp_entry_callsite_ref
= false;
501 * tracepoint_update_probe_range - Update a probe range
502 * @begin: beginning of the range
503 * @end: end of the range
505 * Updates the probe callback corresponding to a range of tracepoints.
508 void tracepoint_update_probe_range(struct lttng_ust_tracepoint
* const *begin
,
509 struct lttng_ust_tracepoint
* const *end
)
511 struct lttng_ust_tracepoint
* const *iter
;
512 struct tracepoint_entry
*mark_entry
;
514 for (iter
= begin
; iter
< end
; iter
++) {
516 continue; /* skip dummy */
517 if (!(*iter
)->name
) {
518 disable_tracepoint(*iter
);
521 mark_entry
= get_tracepoint((*iter
)->name
);
523 set_tracepoint(&mark_entry
, *iter
,
524 !!mark_entry
->refcount
);
526 disable_tracepoint(*iter
);
531 static void lib_update_tracepoints(struct tracepoint_lib
*lib
)
533 tracepoint_update_probe_range(lib
->tracepoints_start
,
534 lib
->tracepoints_start
+ lib
->tracepoints_count
);
537 static void lib_register_callsites(struct tracepoint_lib
*lib
)
539 struct lttng_ust_tracepoint
* const *begin
;
540 struct lttng_ust_tracepoint
* const *end
;
541 struct lttng_ust_tracepoint
* const *iter
;
543 begin
= lib
->tracepoints_start
;
544 end
= lib
->tracepoints_start
+ lib
->tracepoints_count
;
546 for (iter
= begin
; iter
< end
; iter
++) {
548 continue; /* skip dummy */
549 if (!(*iter
)->name
) {
552 add_callsite(lib
, *iter
);
556 static void lib_unregister_callsites(struct tracepoint_lib
*lib
)
558 struct callsite_entry
*callsite
, *tmp
;
560 cds_list_for_each_entry_safe(callsite
, tmp
, &lib
->callsites
, node
)
561 remove_callsite(callsite
);
565 * Update probes, removing the faulty probes.
567 static void tracepoint_update_probes(void)
569 struct tracepoint_lib
*lib
;
571 /* tracepoints registered from libraries and executable. */
572 cds_list_for_each_entry(lib
, &libs
, list
)
573 lib_update_tracepoints(lib
);
576 static struct lttng_ust_tracepoint_probe
*
577 tracepoint_add_probe(const char *name
, void (*probe
)(void), void *data
,
578 const char *signature
)
580 struct tracepoint_entry
*entry
;
581 struct lttng_ust_tracepoint_probe
*old
;
583 entry
= get_tracepoint(name
);
585 if (strcmp(entry
->signature
, signature
) != 0) {
586 ERR("Tracepoint and probe signature do not match.");
587 return ERR_PTR(-EINVAL
);
590 entry
= add_tracepoint(name
, signature
);
592 return (struct lttng_ust_tracepoint_probe
*)entry
;
594 old
= tracepoint_entry_add_probe(entry
, probe
, data
);
595 if (IS_ERR(old
) && !entry
->refcount
)
596 remove_tracepoint(entry
);
600 static void tracepoint_release_queue_add_old_probes(void *old
)
602 release_queue_need_update
= 1;
604 struct tp_probes
*tp_probes
= caa_container_of(old
,
605 struct tp_probes
, probes
[0]);
606 cds_list_add(&tp_probes
->u
.list
, &release_queue
);
611 * __tracepoint_probe_register - Connect a probe to a tracepoint
612 * @name: tracepoint name
613 * @probe: probe handler
615 * Returns 0 if ok, error value on error.
616 * The probe address must at least be aligned on the architecture pointer size.
617 * Called with the tracepoint mutex held.
619 int __tracepoint_probe_register(const char *name
, void (*probe
)(void),
620 void *data
, const char *signature
)
625 DBG("Registering probe to tracepoint %s", name
);
627 pthread_mutex_lock(&tracepoint_mutex
);
628 old
= tracepoint_add_probe(name
, probe
, data
, signature
);
634 tracepoint_sync_callsites(name
);
637 pthread_mutex_unlock(&tracepoint_mutex
);
642 * Caller needs to invoke __tracepoint_probe_release_queue() after
643 * calling __tracepoint_probe_register_queue_release() one or multiple
644 * times to ensure it does not leak memory.
646 int __tracepoint_probe_register_queue_release(const char *name
,
647 void (*probe
)(void), void *data
, const char *signature
)
652 DBG("Registering probe to tracepoint %s. Queuing release.", name
);
654 pthread_mutex_lock(&tracepoint_mutex
);
655 old
= tracepoint_add_probe(name
, probe
, data
, signature
);
661 tracepoint_sync_callsites(name
);
662 tracepoint_release_queue_add_old_probes(old
);
664 pthread_mutex_unlock(&tracepoint_mutex
);
668 static void *tracepoint_remove_probe(const char *name
, void (*probe
)(void),
671 struct tracepoint_entry
*entry
;
674 entry
= get_tracepoint(name
);
676 return ERR_PTR(-ENOENT
);
677 old
= tracepoint_entry_remove_probe(entry
, probe
, data
);
680 if (!entry
->refcount
)
681 remove_tracepoint(entry
);
686 * tracepoint_probe_unregister - Disconnect a probe from a tracepoint
687 * @name: tracepoint name
688 * @probe: probe function pointer
689 * @probe: probe data pointer
691 int __tracepoint_probe_unregister(const char *name
, void (*probe
)(void),
697 DBG("Un-registering probe from tracepoint %s", name
);
699 pthread_mutex_lock(&tracepoint_mutex
);
700 old
= tracepoint_remove_probe(name
, probe
, data
);
705 tracepoint_sync_callsites(name
);
708 pthread_mutex_unlock(&tracepoint_mutex
);
713 * Caller needs to invoke __tracepoint_probe_release_queue() after
714 * calling __tracepoint_probe_unregister_queue_release() one or multiple
715 * times to ensure it does not leak memory.
717 int __tracepoint_probe_unregister_queue_release(const char *name
,
718 void (*probe
)(void), void *data
)
723 DBG("Un-registering probe from tracepoint %s. Queuing release.", name
);
725 pthread_mutex_lock(&tracepoint_mutex
);
726 old
= tracepoint_remove_probe(name
, probe
, data
);
731 tracepoint_sync_callsites(name
);
732 tracepoint_release_queue_add_old_probes(old
);
734 pthread_mutex_unlock(&tracepoint_mutex
);
738 void __tracepoint_probe_prune_release_queue(void)
740 CDS_LIST_HEAD(release_probes
);
741 struct tp_probes
*pos
, *next
;
743 DBG("Release queue of unregistered tracepoint probes.");
745 pthread_mutex_lock(&tracepoint_mutex
);
746 if (!release_queue_need_update
)
748 if (!cds_list_empty(&release_queue
))
749 cds_list_replace_init(&release_queue
, &release_probes
);
750 release_queue_need_update
= 0;
752 /* Wait for grace period between all sync_callsites and free. */
753 urcu_bp_synchronize_rcu();
755 cds_list_for_each_entry_safe(pos
, next
, &release_probes
, u
.list
) {
756 cds_list_del(&pos
->u
.list
);
760 pthread_mutex_unlock(&tracepoint_mutex
);
763 static void tracepoint_add_old_probes(void *old
)
767 struct tp_probes
*tp_probes
= caa_container_of(old
,
768 struct tp_probes
, probes
[0]);
769 cds_list_add(&tp_probes
->u
.list
, &old_probes
);
774 * tracepoint_probe_register_noupdate - register a probe but not connect
775 * @name: tracepoint name
776 * @probe: probe handler
778 * caller must call tracepoint_probe_update_all()
780 int tracepoint_probe_register_noupdate(const char *name
, void (*probe
)(void),
781 void *data
, const char *signature
)
786 pthread_mutex_lock(&tracepoint_mutex
);
787 old
= tracepoint_add_probe(name
, probe
, data
, signature
);
792 tracepoint_add_old_probes(old
);
794 pthread_mutex_unlock(&tracepoint_mutex
);
799 * tracepoint_probe_unregister_noupdate - remove a probe but not disconnect
800 * @name: tracepoint name
801 * @probe: probe function pointer
803 * caller must call tracepoint_probe_update_all()
804 * Called with the tracepoint mutex held.
806 int tracepoint_probe_unregister_noupdate(const char *name
, void (*probe
)(void),
812 DBG("Un-registering probe from tracepoint %s", name
);
814 pthread_mutex_lock(&tracepoint_mutex
);
815 old
= tracepoint_remove_probe(name
, probe
, data
);
820 tracepoint_add_old_probes(old
);
822 pthread_mutex_unlock(&tracepoint_mutex
);
827 * tracepoint_probe_update_all - update tracepoints
829 void tracepoint_probe_update_all(void)
831 CDS_LIST_HEAD(release_probes
);
832 struct tp_probes
*pos
, *next
;
834 pthread_mutex_lock(&tracepoint_mutex
);
838 if (!cds_list_empty(&old_probes
))
839 cds_list_replace_init(&old_probes
, &release_probes
);
842 tracepoint_update_probes();
843 /* Wait for grace period between update_probes and free. */
844 urcu_bp_synchronize_rcu();
845 cds_list_for_each_entry_safe(pos
, next
, &release_probes
, u
.list
) {
846 cds_list_del(&pos
->u
.list
);
850 pthread_mutex_unlock(&tracepoint_mutex
);
853 void tracepoint_set_new_tracepoint_cb(void (*cb
)(struct lttng_ust_tracepoint
*))
855 new_tracepoint_cb
= cb
;
858 static void new_tracepoints(struct lttng_ust_tracepoint
* const *start
,
859 struct lttng_ust_tracepoint
* const *end
)
861 if (new_tracepoint_cb
) {
862 struct lttng_ust_tracepoint
* const *t
;
864 for (t
= start
; t
< end
; t
++) {
866 new_tracepoint_cb(*t
);
871 int tracepoint_register_lib(struct lttng_ust_tracepoint
* const *tracepoints_start
,
872 int tracepoints_count
)
874 struct tracepoint_lib
*pl
, *iter
;
878 pl
= (struct tracepoint_lib
*) zmalloc(sizeof(struct tracepoint_lib
));
880 PERROR("Unable to register tracepoint lib");
883 pl
->tracepoints_start
= tracepoints_start
;
884 pl
->tracepoints_count
= tracepoints_count
;
885 CDS_INIT_LIST_HEAD(&pl
->callsites
);
887 pthread_mutex_lock(&tracepoint_mutex
);
889 * We sort the libs by struct lib pointer address.
891 cds_list_for_each_entry_reverse(iter
, &libs
, list
) {
892 BUG_ON(iter
== pl
); /* Should never be in the list twice */
894 /* We belong to the location right after iter. */
895 cds_list_add(&pl
->list
, &iter
->list
);
899 /* We should be added at the head of the list */
900 cds_list_add(&pl
->list
, &libs
);
902 new_tracepoints(tracepoints_start
, tracepoints_start
+ tracepoints_count
);
903 lib_register_callsites(pl
);
904 lib_update_tracepoints(pl
);
905 pthread_mutex_unlock(&tracepoint_mutex
);
907 DBG("just registered a tracepoints section from %p and having %d tracepoints",
908 tracepoints_start
, tracepoints_count
);
912 for (i
= 0; i
< tracepoints_count
; i
++) {
913 DBG("registered tracepoint: %s", tracepoints_start
[i
]->name
);
920 int tracepoint_unregister_lib(struct lttng_ust_tracepoint
* const *tracepoints_start
)
922 struct tracepoint_lib
*lib
;
924 pthread_mutex_lock(&tracepoint_mutex
);
925 cds_list_for_each_entry(lib
, &libs
, list
) {
926 if (lib
->tracepoints_start
!= tracepoints_start
)
929 cds_list_del(&lib
->list
);
931 * Unregistering a callsite also decreases the
932 * callsite reference count of the corresponding
933 * tracepoint, and disables the tracepoint if
934 * the reference count drops to zero.
936 lib_unregister_callsites(lib
);
937 DBG("just unregistered a tracepoints section from %p",
938 lib
->tracepoints_start
);
942 pthread_mutex_unlock(&tracepoint_mutex
);
947 * Report in debug message whether the compiler correctly supports weak
948 * hidden symbols. This test checks that the address associated with two
949 * weak symbols with hidden visibility is the same when declared within
950 * two compile units part of the same module.
952 static void check_weak_hidden(void)
954 DBG("Your compiler treats weak symbols with hidden visibility for integer objects as %s between compile units part of the same module.",
955 &__tracepoint_test_symbol1
== lttng_ust_tp_check_weak_hidden1() ?
957 "DIFFERENT addresses");
958 DBG("Your compiler treats weak symbols with hidden visibility for pointer objects as %s between compile units part of the same module.",
959 &__tracepoint_test_symbol2
== lttng_ust_tp_check_weak_hidden2() ?
961 "DIFFERENT addresses");
962 DBG("Your compiler treats weak symbols with hidden visibility for 24-byte structure objects as %s between compile units part of the same module.",
963 &__tracepoint_test_symbol3
== lttng_ust_tp_check_weak_hidden3() ?
965 "DIFFERENT addresses");
968 void init_tracepoint(void)
970 if (uatomic_xchg(&initialized
, 1) == 1)
976 void exit_tracepoint(void)
982 * Create the wrapper symbols.
984 #undef tp_rcu_read_lock_bp
985 #undef tp_rcu_read_unlock_bp
986 #undef tp_rcu_dereference_bp
988 void tp_rcu_read_lock_bp(void)
993 void tp_rcu_read_unlock_bp(void)
995 urcu_bp_read_unlock();
998 void *tp_rcu_dereference_sym_bp(void *p
)
1000 return urcu_bp_dereference(p
);
1004 * Programs that have threads that survive after they exit, and therefore call
1005 * library destructors, should disable the tracepoint destructors by calling
1006 * tp_disable_destructors(). This will leak the tracepoint
1007 * instrumentation library shared object, leaving its teardown to the operating
1008 * system process teardown.
1010 * To access and/or modify this value, users need to use a combination of
1011 * dlopen(3) and dlsym(3) to get an handle on the
1012 * tp_disable_destructors and tp_get_destructors_state symbols below.
1014 void tp_disable_destructors(void)
1016 uatomic_set(&tracepoint_destructors_state
, 0);
1020 * Returns 1 if the destructors are enabled and should be executed.
1021 * Returns 0 if the destructors are disabled.
1023 int tp_get_destructors_state(void)
1025 return uatomic_read(&tracepoint_destructors_state
);