4 * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
6 * Holds LTTng per-session event registry.
8 * Dual LGPL v2.1/GPL v2 license.
14 #include <urcu/list.h>
15 #include <urcu/hlist.h>
18 #include <urcu/compiler.h>
19 #include <urcu/uatomic.h>
20 #include <uuid/uuid.h>
21 #include <lttng/tracepoint.h>
25 #include <lttng/ust-events.h>
26 #include <lttng/usterr-signal-safe.h>
27 #include "lttng/core.h"
28 #include "ltt-tracer.h"
29 #include "ltt-tracer-core.h"
30 #include "lttng/wait.h"
31 #include "../libringbuffer/shm.h"
34 #include <lttng/kcompat/jhash.h>
37 * The sessions mutex is the centralized mutex across UST tracing
38 * control and probe registration. All operations within this file are
39 * called by the communication thread, under ust_lock protection.
41 static DEFINE_MUTEX(sessions_mutex
);
45 pthread_mutex_lock(&sessions_mutex
);
50 pthread_mutex_unlock(&sessions_mutex
);
53 static CDS_LIST_HEAD(sessions
);
56 * Pending probes hash table, containing the registered ltt events for
57 * which tracepoint probes are still missing. Protected by the sessions
60 #define PENDING_PROBE_HASH_BITS 6
61 #define PENDING_PROBE_HASH_SIZE (1 << PENDING_PROBE_HASH_BITS)
62 static struct cds_hlist_head pending_probe_table
[PENDING_PROBE_HASH_SIZE
];
64 struct ust_pending_probe
{
65 struct ltt_event
*event
;
66 struct cds_hlist_node node
;
70 static void _ltt_event_destroy(struct ltt_event
*event
);
71 static void _ltt_channel_destroy(struct ltt_channel
*chan
);
72 static int _ltt_event_unregister(struct ltt_event
*event
);
74 int _ltt_event_metadata_statedump(struct ltt_session
*session
,
75 struct ltt_channel
*chan
,
76 struct ltt_event
*event
);
78 int _ltt_session_metadata_statedump(struct ltt_session
*session
);
81 * called at event creation if probe is missing.
82 * called with session mutex held.
85 int add_pending_probe(struct ltt_event
*event
, const char *name
)
87 struct cds_hlist_head
*head
;
88 struct ust_pending_probe
*e
;
89 size_t name_len
= strlen(name
) + 1;
90 u32 hash
= jhash(name
, name_len
- 1, 0);
92 head
= &pending_probe_table
[hash
& (PENDING_PROBE_HASH_SIZE
- 1)];
93 e
= zmalloc(sizeof(struct ust_pending_probe
) + name_len
);
96 memcpy(&e
->name
[0], name
, name_len
);
97 cds_hlist_add_head(&e
->node
, head
);
99 event
->pending_probe
= e
;
104 * remove a pending probe. called when at event teardown and when an
105 * event is fixed (probe is loaded).
106 * called with session mutex held.
109 void remove_pending_probe(struct ust_pending_probe
*e
)
113 cds_hlist_del(&e
->node
);
118 * Called at library load: connect the probe on the events pending on
120 * called with session mutex held.
122 int pending_probe_fix_events(const struct lttng_event_desc
*desc
)
124 struct cds_hlist_head
*head
;
125 struct cds_hlist_node
*node
, *p
;
126 struct ust_pending_probe
*e
;
127 const char *name
= desc
->name
;
128 size_t name_len
= strlen(name
) + 1;
129 u32 hash
= jhash(name
, name_len
- 1, 0);
132 head
= &pending_probe_table
[hash
& (PENDING_PROBE_HASH_SIZE
- 1)];
133 cds_hlist_for_each_entry_safe(e
, node
, p
, head
, node
) {
134 struct ltt_event
*event
;
135 struct ltt_channel
*chan
;
137 if (strcmp(name
, e
->name
))
141 assert(!event
->desc
);
143 event
->pending_probe
= NULL
;
144 remove_pending_probe(e
);
145 ret
|= __tracepoint_probe_register(name
,
146 event
->desc
->probe_callback
,
150 event
->id
= chan
->free_event_id
++;
151 ret
|= _ltt_event_metadata_statedump(chan
->session
, chan
,
157 void synchronize_trace(void)
162 struct ltt_session
*ltt_session_create(void)
164 struct ltt_session
*session
;
166 session
= zmalloc(sizeof(struct ltt_session
));
169 CDS_INIT_LIST_HEAD(&session
->chan
);
170 CDS_INIT_LIST_HEAD(&session
->events
);
171 uuid_generate(session
->uuid
);
172 cds_list_add(&session
->list
, &sessions
);
176 void ltt_session_destroy(struct ltt_session
*session
)
178 struct ltt_channel
*chan
, *tmpchan
;
179 struct ltt_event
*event
, *tmpevent
;
182 CMM_ACCESS_ONCE(session
->active
) = 0;
183 cds_list_for_each_entry(event
, &session
->events
, list
) {
184 ret
= _ltt_event_unregister(event
);
187 synchronize_trace(); /* Wait for in-flight events to complete */
188 cds_list_for_each_entry_safe(event
, tmpevent
, &session
->events
, list
)
189 _ltt_event_destroy(event
);
190 cds_list_for_each_entry_safe(chan
, tmpchan
, &session
->chan
, list
)
191 _ltt_channel_destroy(chan
);
192 cds_list_del(&session
->list
);
196 int ltt_session_enable(struct ltt_session
*session
)
199 struct ltt_channel
*chan
;
201 if (session
->active
) {
207 * Snapshot the number of events per channel to know the type of header
210 cds_list_for_each_entry(chan
, &session
->chan
, list
) {
211 if (chan
->header_type
)
212 continue; /* don't change it if session stop/restart */
213 if (chan
->free_event_id
< 31)
214 chan
->header_type
= 1; /* compact */
216 chan
->header_type
= 2; /* large */
219 CMM_ACCESS_ONCE(session
->active
) = 1;
220 CMM_ACCESS_ONCE(session
->been_active
) = 1;
221 ret
= _ltt_session_metadata_statedump(session
);
223 CMM_ACCESS_ONCE(session
->active
) = 0;
228 int ltt_session_disable(struct ltt_session
*session
)
232 if (!session
->active
) {
236 CMM_ACCESS_ONCE(session
->active
) = 0;
241 int ltt_channel_enable(struct ltt_channel
*channel
)
245 if (channel
== channel
->session
->metadata
)
247 old
= uatomic_xchg(&channel
->enabled
, 1);
253 int ltt_channel_disable(struct ltt_channel
*channel
)
257 if (channel
== channel
->session
->metadata
)
259 old
= uatomic_xchg(&channel
->enabled
, 0);
265 int ltt_event_enable(struct ltt_event
*event
)
269 if (event
->chan
== event
->chan
->session
->metadata
)
271 old
= uatomic_xchg(&event
->enabled
, 1);
277 int ltt_event_disable(struct ltt_event
*event
)
281 if (event
->chan
== event
->chan
->session
->metadata
)
283 old
= uatomic_xchg(&event
->enabled
, 0);
289 struct ltt_channel
*ltt_channel_create(struct ltt_session
*session
,
290 const char *transport_name
,
292 size_t subbuf_size
, size_t num_subbuf
,
293 unsigned int switch_timer_interval
,
294 unsigned int read_timer_interval
,
295 int *shm_fd
, int *wait_fd
,
296 uint64_t *memory_map_size
)
298 struct ltt_channel
*chan
= NULL
;
299 struct ltt_transport
*transport
;
301 if (session
->been_active
)
302 goto active
; /* Refuse to add channel to active session */
303 transport
= ltt_transport_find(transport_name
);
305 DBG("LTTng transport %s not found\n",
310 * Note: the channel creation op already writes into the packet
311 * headers. Therefore the "chan" information used as input
312 * should be already accessible.
314 chan
= transport
->ops
.channel_create("[lttng]", buf_addr
,
315 subbuf_size
, num_subbuf
, switch_timer_interval
,
316 read_timer_interval
, shm_fd
, wait_fd
,
320 chan
->session
= session
;
321 chan
->id
= session
->free_chan_id
++;
323 chan
->ops
= &transport
->ops
;
324 cds_list_add(&chan
->list
, &session
->chan
);
334 * Only used internally at session destruction.
337 void _ltt_channel_destroy(struct ltt_channel
*chan
)
339 cds_list_del(&chan
->list
);
340 lttng_destroy_context(chan
->ctx
);
341 chan
->ops
->channel_destroy(chan
);
345 * Supports event creation while tracing session is active.
347 struct ltt_event
*ltt_event_create(struct ltt_channel
*chan
,
348 struct lttng_ust_event
*event_param
,
351 struct ltt_event
*event
;
354 if (chan
->used_event_id
== -1UL)
357 * This is O(n^2) (for each event, the loop is called at event
358 * creation). Might require a hash if we have lots of events.
360 cds_list_for_each_entry(event
, &chan
->session
->events
, list
)
361 if (event
->desc
&& !strcmp(event
->desc
->name
, event_param
->name
))
363 event
= zmalloc(sizeof(struct ltt_event
));
367 event
->filter
= filter
;
369 * used_event_id counts the maximum number of event IDs that can
370 * register if all probes register.
372 chan
->used_event_id
++;
374 event
->instrumentation
= event_param
->instrumentation
;
375 /* Populate ltt_event structure before tracepoint registration. */
377 switch (event_param
->instrumentation
) {
378 case LTTNG_UST_TRACEPOINT
:
379 event
->desc
= ltt_event_get(event_param
->name
);
381 ret
= __tracepoint_probe_register(event_param
->name
,
382 event
->desc
->probe_callback
,
386 event
->id
= chan
->free_event_id
++;
389 * If the probe is not present, event->desc stays NULL,
390 * waiting for the probe to register, and the event->id
393 ret
= add_pending_probe(event
, event_param
->name
);
395 goto add_pending_error
;
402 ret
= _ltt_event_metadata_statedump(chan
->session
, chan
, event
);
404 goto statedump_error
;
406 cds_list_add(&event
->list
, &chan
->session
->events
);
411 WARN_ON_ONCE(__tracepoint_probe_unregister(event_param
->name
,
412 event
->desc
->probe_callback
,
414 ltt_event_put(event
->desc
);
426 * Only used internally at session destruction.
428 int _ltt_event_unregister(struct ltt_event
*event
)
432 switch (event
->instrumentation
) {
433 case LTTNG_UST_TRACEPOINT
:
435 ret
= __tracepoint_probe_unregister(event
->desc
->name
,
436 event
->desc
->probe_callback
,
441 remove_pending_probe(event
->pending_probe
);
452 * Only used internally at session destruction.
455 void _ltt_event_destroy(struct ltt_event
*event
)
457 switch (event
->instrumentation
) {
458 case LTTNG_UST_TRACEPOINT
:
460 ltt_event_put(event
->desc
);
466 cds_list_del(&event
->list
);
467 lttng_destroy_context(event
->ctx
);
472 * We have exclusive access to our metadata buffer (protected by the
473 * ust_lock), so we can do racy operations such as looking for
474 * remaining space left in packet and write, since mutual exclusion
475 * protects us from concurrent writes.
477 int lttng_metadata_printf(struct ltt_session
*session
,
478 const char *fmt
, ...)
480 struct lttng_ust_lib_ring_buffer_ctx ctx
;
481 struct ltt_channel
*chan
= session
->metadata
;
483 int ret
= 0, waitret
;
484 size_t len
, reserve_len
, pos
;
487 WARN_ON_ONCE(!CMM_ACCESS_ONCE(session
->active
));
490 ret
= vasprintf(&str
, fmt
, ap
);
498 for (pos
= 0; pos
< len
; pos
+= reserve_len
) {
499 reserve_len
= min_t(size_t,
500 chan
->ops
->packet_avail_size(chan
->chan
, chan
->handle
),
502 lib_ring_buffer_ctx_init(&ctx
, chan
->chan
, NULL
, reserve_len
,
503 sizeof(char), -1, chan
->handle
);
505 * We don't care about metadata buffer's records lost
506 * count, because we always retry here. Report error if
507 * we need to bail out after timeout or being
510 waitret
= wait_cond_interruptible_timeout(
512 ret
= chan
->ops
->event_reserve(&ctx
, 0);
513 ret
!= -ENOBUFS
|| !ret
;
515 LTTNG_METADATA_TIMEOUT_MSEC
);
516 if (waitret
== -ETIMEDOUT
|| waitret
== -EINTR
|| ret
) {
517 DBG("LTTng: Failure to write metadata to buffers (%s)\n",
518 waitret
== -EINTR
? "interrupted" :
519 (ret
== -ENOBUFS
? "timeout" : "I/O error"));
520 if (waitret
== -EINTR
)
524 chan
->ops
->event_write(&ctx
, &str
[pos
], reserve_len
);
525 chan
->ops
->event_commit(&ctx
);
533 int _ltt_field_statedump(struct ltt_session
*session
,
534 const struct lttng_event_field
*field
)
538 switch (field
->type
.atype
) {
540 ret
= lttng_metadata_printf(session
,
541 " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s;\n",
542 field
->type
.u
.basic
.integer
.size
,
543 field
->type
.u
.basic
.integer
.alignment
,
544 field
->type
.u
.basic
.integer
.signedness
,
545 (field
->type
.u
.basic
.integer
.encoding
== lttng_encode_none
)
547 : (field
->type
.u
.basic
.integer
.encoding
== lttng_encode_UTF8
)
550 field
->type
.u
.basic
.integer
.base
,
551 #if (BYTE_ORDER == BIG_ENDIAN)
552 field
->type
.u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
554 field
->type
.u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
559 ret
= lttng_metadata_printf(session
,
560 " floating_point { exp_dig = %u; mant_dig = %u; align = %u;%s } _%s;\n",
561 field
->type
.u
.basic
._float
.exp_dig
,
562 field
->type
.u
.basic
._float
.mant_dig
,
563 field
->type
.u
.basic
._float
.alignment
,
564 #if (BYTE_ORDER == BIG_ENDIAN)
565 field
->type
.u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
567 field
->type
.u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
572 ret
= lttng_metadata_printf(session
,
574 field
->type
.u
.basic
.enumeration
.name
,
579 const struct lttng_basic_type
*elem_type
;
581 elem_type
= &field
->type
.u
.array
.elem_type
;
582 ret
= lttng_metadata_printf(session
,
583 " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[%u];\n",
584 elem_type
->u
.basic
.integer
.size
,
585 elem_type
->u
.basic
.integer
.alignment
,
586 elem_type
->u
.basic
.integer
.signedness
,
587 (elem_type
->u
.basic
.integer
.encoding
== lttng_encode_none
)
589 : (elem_type
->u
.basic
.integer
.encoding
== lttng_encode_UTF8
)
592 elem_type
->u
.basic
.integer
.base
,
593 #if (BYTE_ORDER == BIG_ENDIAN)
594 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
596 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
598 field
->name
, field
->type
.u
.array
.length
);
603 const struct lttng_basic_type
*elem_type
;
604 const struct lttng_basic_type
*length_type
;
606 elem_type
= &field
->type
.u
.sequence
.elem_type
;
607 length_type
= &field
->type
.u
.sequence
.length_type
;
608 ret
= lttng_metadata_printf(session
,
609 " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } __%s_length;\n",
610 length_type
->u
.basic
.integer
.size
,
611 (unsigned int) length_type
->u
.basic
.integer
.alignment
,
612 length_type
->u
.basic
.integer
.signedness
,
613 (length_type
->u
.basic
.integer
.encoding
== lttng_encode_none
)
615 : ((length_type
->u
.basic
.integer
.encoding
== lttng_encode_UTF8
)
618 length_type
->u
.basic
.integer
.base
,
619 #if (BYTE_ORDER == BIG_ENDIAN)
620 length_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
622 length_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
628 ret
= lttng_metadata_printf(session
,
629 " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[ __%s_length ];\n",
630 elem_type
->u
.basic
.integer
.size
,
631 (unsigned int) elem_type
->u
.basic
.integer
.alignment
,
632 elem_type
->u
.basic
.integer
.signedness
,
633 (elem_type
->u
.basic
.integer
.encoding
== lttng_encode_none
)
635 : ((elem_type
->u
.basic
.integer
.encoding
== lttng_encode_UTF8
)
638 elem_type
->u
.basic
.integer
.base
,
639 #if (BYTE_ORDER == BIG_ENDIAN)
640 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
642 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
650 /* Default encoding is UTF8 */
651 ret
= lttng_metadata_printf(session
,
653 field
->type
.u
.basic
.string
.encoding
== lttng_encode_ASCII
?
654 " { encoding = ASCII; }" : "",
665 int _ltt_context_metadata_statedump(struct ltt_session
*session
,
666 struct lttng_ctx
*ctx
)
673 for (i
= 0; i
< ctx
->nr_fields
; i
++) {
674 const struct lttng_ctx_field
*field
= &ctx
->fields
[i
];
676 ret
= _ltt_field_statedump(session
, &field
->event_field
);
684 int _ltt_fields_metadata_statedump(struct ltt_session
*session
,
685 struct ltt_event
*event
)
687 const struct lttng_event_desc
*desc
= event
->desc
;
691 for (i
= 0; i
< desc
->nr_fields
; i
++) {
692 const struct lttng_event_field
*field
= &desc
->fields
[i
];
694 ret
= _ltt_field_statedump(session
, field
);
702 int _ltt_event_metadata_statedump(struct ltt_session
*session
,
703 struct ltt_channel
*chan
,
704 struct ltt_event
*event
)
708 if (event
->metadata_dumped
|| !CMM_ACCESS_ONCE(session
->active
))
710 if (chan
== session
->metadata
)
713 * Don't print events for which probe load is pending.
718 ret
= lttng_metadata_printf(session
,
722 " stream_id = %u;\n",
730 ret
= lttng_metadata_printf(session
,
731 " context := struct {\n");
735 ret
= _ltt_context_metadata_statedump(session
, event
->ctx
);
739 ret
= lttng_metadata_printf(session
,
745 ret
= lttng_metadata_printf(session
,
746 " fields := struct {\n"
751 ret
= _ltt_fields_metadata_statedump(session
, event
);
756 * LTTng space reservation can only reserve multiples of the
759 ret
= lttng_metadata_printf(session
,
765 event
->metadata_dumped
= 1;
772 int _ltt_channel_metadata_statedump(struct ltt_session
*session
,
773 struct ltt_channel
*chan
)
777 if (chan
->metadata_dumped
|| !CMM_ACCESS_ONCE(session
->active
))
779 if (chan
== session
->metadata
)
782 WARN_ON_ONCE(!chan
->header_type
);
783 ret
= lttng_metadata_printf(session
,
786 " event.header := %s;\n"
787 " packet.context := struct packet_context;\n",
789 chan
->header_type
== 1 ? "struct event_header_compact" :
790 "struct event_header_large");
795 ret
= lttng_metadata_printf(session
,
796 " event.context := struct {\n");
800 ret
= _ltt_context_metadata_statedump(session
, chan
->ctx
);
804 ret
= lttng_metadata_printf(session
,
810 ret
= lttng_metadata_printf(session
,
813 chan
->metadata_dumped
= 1;
819 int _ltt_stream_packet_context_declare(struct ltt_session
*session
)
821 return lttng_metadata_printf(session
,
822 "struct packet_context {\n"
823 " uint64_t timestamp_begin;\n"
824 " uint64_t timestamp_end;\n"
825 " uint32_t events_discarded;\n"
826 " uint32_t content_size;\n"
827 " uint32_t packet_size;\n"
828 " uint32_t cpu_id;\n"
836 * id 31 is reserved to indicate an extended header.
839 * id: range: 0 - 65534.
840 * id 65535 is reserved to indicate an extended header.
843 int _ltt_event_header_declare(struct ltt_session
*session
)
845 return lttng_metadata_printf(session
,
846 "struct event_header_compact {\n"
847 " enum : uint5_t { compact = 0 ... 30, extended = 31 } id;\n"
850 " uint27_t timestamp;\n"
854 " uint64_t timestamp;\n"
859 "struct event_header_large {\n"
860 " enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;\n"
863 " uint32_t timestamp;\n"
867 " uint64_t timestamp;\n"
871 lttng_alignof(uint32_t) * CHAR_BIT
,
872 lttng_alignof(uint16_t) * CHAR_BIT
877 * Output metadata into this session's metadata buffers.
880 int _ltt_session_metadata_statedump(struct ltt_session
*session
)
882 unsigned char *uuid_c
= session
->uuid
;
884 struct ltt_channel
*chan
;
885 struct ltt_event
*event
;
888 if (!CMM_ACCESS_ONCE(session
->active
))
890 if (session
->metadata_dumped
)
892 if (!session
->metadata
) {
893 DBG("LTTng: attempt to start tracing, but metadata channel is not found. Operation abort.\n");
897 snprintf(uuid_s
, sizeof(uuid_s
),
898 "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
899 uuid_c
[0], uuid_c
[1], uuid_c
[2], uuid_c
[3],
900 uuid_c
[4], uuid_c
[5], uuid_c
[6], uuid_c
[7],
901 uuid_c
[8], uuid_c
[9], uuid_c
[10], uuid_c
[11],
902 uuid_c
[12], uuid_c
[13], uuid_c
[14], uuid_c
[15]);
904 ret
= lttng_metadata_printf(session
,
905 "typealias integer { size = 8; align = %u; signed = false; } := uint8_t;\n"
906 "typealias integer { size = 16; align = %u; signed = false; } := uint16_t;\n"
907 "typealias integer { size = 32; align = %u; signed = false; } := uint32_t;\n"
908 "typealias integer { size = 64; align = %u; signed = false; } := uint64_t;\n"
909 "typealias integer { size = 5; align = 1; signed = false; } := uint5_t;\n"
910 "typealias integer { size = 27; align = 1; signed = false; } := uint27_t;\n"
916 " byte_order = %s;\n"
917 " packet.header := struct {\n"
919 " uint8_t uuid[16];\n"
920 " uint32_t stream_id;\n"
923 lttng_alignof(uint8_t) * CHAR_BIT
,
924 lttng_alignof(uint16_t) * CHAR_BIT
,
925 lttng_alignof(uint32_t) * CHAR_BIT
,
926 lttng_alignof(uint64_t) * CHAR_BIT
,
930 #if (BYTE_ORDER == BIG_ENDIAN)
939 ret
= _ltt_stream_packet_context_declare(session
);
943 ret
= _ltt_event_header_declare(session
);
948 cds_list_for_each_entry(chan
, &session
->chan
, list
) {
949 ret
= _ltt_channel_metadata_statedump(session
, chan
);
954 cds_list_for_each_entry(event
, &session
->events
, list
) {
955 ret
= _ltt_event_metadata_statedump(session
, event
->chan
, event
);
959 session
->metadata_dumped
= 1;
964 void lttng_ust_events_exit(void)
966 struct ltt_session
*session
, *tmpsession
;
968 cds_list_for_each_entry_safe(session
, tmpsession
, &sessions
, list
)
969 ltt_session_destroy(session
);