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.
13 #include <urcu/list.h>
14 #include <urcu/hlist.h>
17 #include <urcu/compiler.h>
18 #include <urcu/uatomic.h>
19 #include <uuid/uuid.h>
20 #include <ust/tracepoint.h>
24 #include <ust/lttng-events.h>
25 #include <ust/usterr-signal-safe.h>
27 #include "ltt-tracer.h"
28 #include "ltt-tracer-core.h"
30 #include "../libringbuffer/shm.h"
33 #include <ust/kcompat/jhash.h>
36 * The sessions mutex is the centralized mutex across UST tracing
37 * control and probe registration. All operations within this file are
38 * called by the communication thread, under ust_lock protection.
40 static DEFINE_MUTEX(sessions_mutex
);
44 pthread_mutex_lock(&sessions_mutex
);
49 pthread_mutex_unlock(&sessions_mutex
);
52 static CDS_LIST_HEAD(sessions
);
53 static CDS_LIST_HEAD(ltt_transport_list
);
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
,
148 ret
|= _ltt_event_metadata_statedump(chan
->session
, chan
,
154 void synchronize_trace(void)
159 struct ltt_session
*ltt_session_create(void)
161 struct ltt_session
*session
;
163 session
= zmalloc(sizeof(struct ltt_session
));
166 CDS_INIT_LIST_HEAD(&session
->chan
);
167 CDS_INIT_LIST_HEAD(&session
->events
);
168 uuid_generate(session
->uuid
);
169 cds_list_add(&session
->list
, &sessions
);
173 void ltt_session_destroy(struct ltt_session
*session
)
175 struct ltt_channel
*chan
, *tmpchan
;
176 struct ltt_event
*event
, *tmpevent
;
179 CMM_ACCESS_ONCE(session
->active
) = 0;
180 cds_list_for_each_entry(event
, &session
->events
, list
) {
181 ret
= _ltt_event_unregister(event
);
184 synchronize_trace(); /* Wait for in-flight events to complete */
185 cds_list_for_each_entry_safe(event
, tmpevent
, &session
->events
, list
)
186 _ltt_event_destroy(event
);
187 cds_list_for_each_entry_safe(chan
, tmpchan
, &session
->chan
, list
)
188 _ltt_channel_destroy(chan
);
189 cds_list_del(&session
->list
);
193 int ltt_session_enable(struct ltt_session
*session
)
196 struct ltt_channel
*chan
;
198 if (session
->active
) {
204 * Snapshot the number of events per channel to know the type of header
207 cds_list_for_each_entry(chan
, &session
->chan
, list
) {
208 if (chan
->header_type
)
209 continue; /* don't change it if session stop/restart */
210 if (chan
->free_event_id
< 31)
211 chan
->header_type
= 1; /* compact */
213 chan
->header_type
= 2; /* large */
216 CMM_ACCESS_ONCE(session
->active
) = 1;
217 CMM_ACCESS_ONCE(session
->been_active
) = 1;
218 ret
= _ltt_session_metadata_statedump(session
);
220 CMM_ACCESS_ONCE(session
->active
) = 0;
225 int ltt_session_disable(struct ltt_session
*session
)
229 if (!session
->active
) {
233 CMM_ACCESS_ONCE(session
->active
) = 0;
238 int ltt_channel_enable(struct ltt_channel
*channel
)
242 if (channel
== channel
->session
->metadata
)
244 old
= uatomic_xchg(&channel
->enabled
, 1);
250 int ltt_channel_disable(struct ltt_channel
*channel
)
254 if (channel
== channel
->session
->metadata
)
256 old
= uatomic_xchg(&channel
->enabled
, 0);
262 int ltt_event_enable(struct ltt_event
*event
)
266 if (event
->chan
== event
->chan
->session
->metadata
)
268 old
= uatomic_xchg(&event
->enabled
, 1);
274 int ltt_event_disable(struct ltt_event
*event
)
278 if (event
->chan
== event
->chan
->session
->metadata
)
280 old
= uatomic_xchg(&event
->enabled
, 0);
286 static struct ltt_transport
*ltt_transport_find(const char *name
)
288 struct ltt_transport
*transport
;
290 cds_list_for_each_entry(transport
, <t_transport_list
, node
) {
291 if (!strcmp(transport
->name
, name
))
297 struct ltt_channel
*ltt_channel_create(struct ltt_session
*session
,
298 const char *transport_name
,
300 size_t subbuf_size
, size_t num_subbuf
,
301 unsigned int switch_timer_interval
,
302 unsigned int read_timer_interval
,
303 int *shm_fd
, int *wait_fd
,
304 uint64_t *memory_map_size
)
306 struct ltt_channel
*chan
;
307 struct ltt_transport
*transport
;
309 if (session
->been_active
)
310 goto active
; /* Refuse to add channel to active session */
311 transport
= ltt_transport_find(transport_name
);
313 DBG("LTTng transport %s not found\n",
317 chan
= zmalloc(sizeof(struct ltt_channel
));
320 chan
->session
= session
;
321 chan
->id
= session
->free_chan_id
++;
323 * Note: the channel creation op already writes into the packet
324 * headers. Therefore the "chan" information used as input
325 * should be already accessible.
327 transport
->ops
.channel_create("[lttng]", chan
, buf_addr
,
328 subbuf_size
, num_subbuf
, switch_timer_interval
,
329 read_timer_interval
, shm_fd
, wait_fd
,
334 chan
->ops
= &transport
->ops
;
335 cds_list_add(&chan
->list
, &session
->chan
);
347 * Only used internally at session destruction.
350 void _ltt_channel_destroy(struct ltt_channel
*chan
)
352 chan
->ops
->channel_destroy(chan
);
353 cds_list_del(&chan
->list
);
354 lttng_destroy_context(chan
->ctx
);
359 * Supports event creation while tracing session is active.
361 struct ltt_event
*ltt_event_create(struct ltt_channel
*chan
,
362 struct lttng_ust_event
*event_param
,
365 struct ltt_event
*event
;
368 if (chan
->used_event_id
== -1UL)
371 * This is O(n^2) (for each event, the loop is called at event
372 * creation). Might require a hash if we have lots of events.
374 cds_list_for_each_entry(event
, &chan
->session
->events
, list
)
375 if (event
->desc
&& !strcmp(event
->desc
->name
, event_param
->name
))
377 event
= zmalloc(sizeof(struct ltt_event
));
381 event
->filter
= filter
;
383 * used_event_id counts the maximum number of event IDs that can
384 * register if all probes register.
386 chan
->used_event_id
++;
388 event
->instrumentation
= event_param
->instrumentation
;
389 /* Populate ltt_event structure before tracepoint registration. */
391 switch (event_param
->instrumentation
) {
392 case LTTNG_UST_TRACEPOINT
:
393 event
->desc
= ltt_event_get(event_param
->name
);
395 ret
= __tracepoint_probe_register(event_param
->name
,
396 event
->desc
->probe_callback
,
400 event
->id
= chan
->free_event_id
++;
403 * If the probe is not present, event->desc stays NULL,
404 * waiting for the probe to register, and the event->id
407 ret
= add_pending_probe(event
, event_param
->name
);
409 goto add_pending_error
;
416 ret
= _ltt_event_metadata_statedump(chan
->session
, chan
, event
);
418 goto statedump_error
;
420 cds_list_add(&event
->list
, &chan
->session
->events
);
425 WARN_ON_ONCE(__tracepoint_probe_unregister(event_param
->name
,
426 event
->desc
->probe_callback
,
428 ltt_event_put(event
->desc
);
440 * Only used internally at session destruction.
442 int _ltt_event_unregister(struct ltt_event
*event
)
446 switch (event
->instrumentation
) {
447 case LTTNG_UST_TRACEPOINT
:
449 ret
= __tracepoint_probe_unregister(event
->desc
->name
,
450 event
->desc
->probe_callback
,
455 remove_pending_probe(event
->pending_probe
);
466 * Only used internally at session destruction.
469 void _ltt_event_destroy(struct ltt_event
*event
)
471 switch (event
->instrumentation
) {
472 case LTTNG_UST_TRACEPOINT
:
474 ltt_event_put(event
->desc
);
480 cds_list_del(&event
->list
);
481 lttng_destroy_context(event
->ctx
);
486 * We have exclusive access to our metadata buffer (protected by the
487 * ust_lock), so we can do racy operations such as looking for
488 * remaining space left in packet and write, since mutual exclusion
489 * protects us from concurrent writes.
491 int lttng_metadata_printf(struct ltt_session
*session
,
492 const char *fmt
, ...)
494 struct lib_ring_buffer_ctx ctx
;
495 struct ltt_channel
*chan
= session
->metadata
;
497 int ret
= 0, waitret
;
498 size_t len
, reserve_len
, pos
;
501 WARN_ON_ONCE(!CMM_ACCESS_ONCE(session
->active
));
504 ret
= vasprintf(&str
, fmt
, ap
);
512 for (pos
= 0; pos
< len
; pos
+= reserve_len
) {
513 reserve_len
= min_t(size_t,
514 chan
->ops
->packet_avail_size(chan
->chan
, chan
->handle
),
516 lib_ring_buffer_ctx_init(&ctx
, chan
->chan
, NULL
, reserve_len
,
517 sizeof(char), -1, chan
->handle
);
519 * We don't care about metadata buffer's records lost
520 * count, because we always retry here. Report error if
521 * we need to bail out after timeout or being
524 waitret
= wait_cond_interruptible_timeout(
526 ret
= chan
->ops
->event_reserve(&ctx
, 0);
527 ret
!= -ENOBUFS
|| !ret
;
529 LTTNG_METADATA_TIMEOUT_MSEC
);
530 if (waitret
== -ETIMEDOUT
|| waitret
== -EINTR
|| ret
) {
531 DBG("LTTng: Failure to write metadata to buffers (%s)\n",
532 waitret
== -EINTR
? "interrupted" :
533 (ret
== -ENOBUFS
? "timeout" : "I/O error"));
534 if (waitret
== -EINTR
)
538 chan
->ops
->event_write(&ctx
, &str
[pos
], reserve_len
);
539 chan
->ops
->event_commit(&ctx
);
547 int _ltt_field_statedump(struct ltt_session
*session
,
548 const struct lttng_event_field
*field
)
552 switch (field
->type
.atype
) {
554 ret
= lttng_metadata_printf(session
,
555 " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s;\n",
556 field
->type
.u
.basic
.integer
.size
,
557 field
->type
.u
.basic
.integer
.alignment
,
558 field
->type
.u
.basic
.integer
.signedness
,
559 (field
->type
.u
.basic
.integer
.encoding
== lttng_encode_none
)
561 : (field
->type
.u
.basic
.integer
.encoding
== lttng_encode_UTF8
)
564 field
->type
.u
.basic
.integer
.base
,
566 field
->type
.u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
568 field
->type
.u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
573 ret
= lttng_metadata_printf(session
,
574 " floating_point { exp_dig = %u; mant_dig = %u; align = %u; } _%s;\n",
575 field
->type
.u
.basic
._float
.exp_dig
,
576 field
->type
.u
.basic
._float
.mant_dig
,
577 field
->type
.u
.basic
._float
.alignment
,
579 field
->type
.u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
581 field
->type
.u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
586 ret
= lttng_metadata_printf(session
,
588 field
->type
.u
.basic
.enumeration
.name
,
593 const struct lttng_basic_type
*elem_type
;
595 elem_type
= &field
->type
.u
.array
.elem_type
;
596 ret
= lttng_metadata_printf(session
,
597 " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[%u];\n",
598 elem_type
->u
.basic
.integer
.size
,
599 elem_type
->u
.basic
.integer
.alignment
,
600 elem_type
->u
.basic
.integer
.signedness
,
601 (elem_type
->u
.basic
.integer
.encoding
== lttng_encode_none
)
603 : (elem_type
->u
.basic
.integer
.encoding
== lttng_encode_UTF8
)
606 elem_type
->u
.basic
.integer
.base
,
608 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
610 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
612 field
->name
, field
->type
.u
.array
.length
);
617 const struct lttng_basic_type
*elem_type
;
618 const struct lttng_basic_type
*length_type
;
620 elem_type
= &field
->type
.u
.sequence
.elem_type
;
621 length_type
= &field
->type
.u
.sequence
.length_type
;
622 ret
= lttng_metadata_printf(session
,
623 " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } __%s_length;\n",
624 length_type
->u
.basic
.integer
.size
,
625 (unsigned int) length_type
->u
.basic
.integer
.alignment
,
626 length_type
->u
.basic
.integer
.signedness
,
627 (length_type
->u
.basic
.integer
.encoding
== lttng_encode_none
)
629 : ((length_type
->u
.basic
.integer
.encoding
== lttng_encode_UTF8
)
632 length_type
->u
.basic
.integer
.base
,
634 length_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
636 length_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
642 ret
= lttng_metadata_printf(session
,
643 " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[ __%s_length ];\n",
644 elem_type
->u
.basic
.integer
.size
,
645 (unsigned int) elem_type
->u
.basic
.integer
.alignment
,
646 elem_type
->u
.basic
.integer
.signedness
,
647 (elem_type
->u
.basic
.integer
.encoding
== lttng_encode_none
)
649 : ((elem_type
->u
.basic
.integer
.encoding
== lttng_encode_UTF8
)
652 elem_type
->u
.basic
.integer
.base
,
654 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
656 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
664 /* Default encoding is UTF8 */
665 ret
= lttng_metadata_printf(session
,
667 field
->type
.u
.basic
.string
.encoding
== lttng_encode_ASCII
?
668 " { encoding = ASCII; }" : "",
679 int _ltt_context_metadata_statedump(struct ltt_session
*session
,
680 struct lttng_ctx
*ctx
)
687 for (i
= 0; i
< ctx
->nr_fields
; i
++) {
688 const struct lttng_ctx_field
*field
= &ctx
->fields
[i
];
690 ret
= _ltt_field_statedump(session
, &field
->event_field
);
698 int _ltt_fields_metadata_statedump(struct ltt_session
*session
,
699 struct ltt_event
*event
)
701 const struct lttng_event_desc
*desc
= event
->desc
;
705 for (i
= 0; i
< desc
->nr_fields
; i
++) {
706 const struct lttng_event_field
*field
= &desc
->fields
[i
];
708 ret
= _ltt_field_statedump(session
, field
);
716 int _ltt_event_metadata_statedump(struct ltt_session
*session
,
717 struct ltt_channel
*chan
,
718 struct ltt_event
*event
)
722 if (event
->metadata_dumped
|| !CMM_ACCESS_ONCE(session
->active
))
724 if (chan
== session
->metadata
)
727 * Don't print events for which probe load is pending.
732 ret
= lttng_metadata_printf(session
,
736 " stream_id = %u;\n",
744 ret
= lttng_metadata_printf(session
,
745 " context := struct {\n");
749 ret
= _ltt_context_metadata_statedump(session
, event
->ctx
);
753 ret
= lttng_metadata_printf(session
,
759 ret
= lttng_metadata_printf(session
,
760 " fields := struct {\n"
765 ret
= _ltt_fields_metadata_statedump(session
, event
);
770 * LTTng space reservation can only reserve multiples of the
773 ret
= lttng_metadata_printf(session
,
779 event
->metadata_dumped
= 1;
786 int _ltt_channel_metadata_statedump(struct ltt_session
*session
,
787 struct ltt_channel
*chan
)
791 if (chan
->metadata_dumped
|| !CMM_ACCESS_ONCE(session
->active
))
793 if (chan
== session
->metadata
)
796 WARN_ON_ONCE(!chan
->header_type
);
797 ret
= lttng_metadata_printf(session
,
800 " event.header := %s;\n"
801 " packet.context := struct packet_context;\n",
803 chan
->header_type
== 1 ? "struct event_header_compact" :
804 "struct event_header_large");
809 ret
= lttng_metadata_printf(session
,
810 " event.context := struct {\n");
814 ret
= _ltt_context_metadata_statedump(session
, chan
->ctx
);
818 ret
= lttng_metadata_printf(session
,
824 ret
= lttng_metadata_printf(session
,
827 chan
->metadata_dumped
= 1;
833 int _ltt_stream_packet_context_declare(struct ltt_session
*session
)
835 return lttng_metadata_printf(session
,
836 "struct packet_context {\n"
837 " uint64_t timestamp_begin;\n"
838 " uint64_t timestamp_end;\n"
839 " uint32_t events_discarded;\n"
840 " uint32_t content_size;\n"
841 " uint32_t packet_size;\n"
842 " uint32_t cpu_id;\n"
850 * id 31 is reserved to indicate an extended header.
853 * id: range: 0 - 65534.
854 * id 65535 is reserved to indicate an extended header.
857 int _ltt_event_header_declare(struct ltt_session
*session
)
859 return lttng_metadata_printf(session
,
860 "struct event_header_compact {\n"
861 " enum : uint5_t { compact = 0 ... 30, extended = 31 } id;\n"
864 " uint27_t timestamp;\n"
868 " uint64_t timestamp;\n"
873 "struct event_header_large {\n"
874 " enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;\n"
877 " uint32_t timestamp;\n"
881 " uint64_t timestamp;\n"
885 lttng_alignof(uint32_t) * CHAR_BIT
,
886 lttng_alignof(uint16_t) * CHAR_BIT
891 * Output metadata into this session's metadata buffers.
894 int _ltt_session_metadata_statedump(struct ltt_session
*session
)
896 unsigned char *uuid_c
= session
->uuid
;
898 struct ltt_channel
*chan
;
899 struct ltt_event
*event
;
902 if (!CMM_ACCESS_ONCE(session
->active
))
904 if (session
->metadata_dumped
)
906 if (!session
->metadata
) {
907 DBG("LTTng: attempt to start tracing, but metadata channel is not found. Operation abort.\n");
911 snprintf(uuid_s
, sizeof(uuid_s
),
912 "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
913 uuid_c
[0], uuid_c
[1], uuid_c
[2], uuid_c
[3],
914 uuid_c
[4], uuid_c
[5], uuid_c
[6], uuid_c
[7],
915 uuid_c
[8], uuid_c
[9], uuid_c
[10], uuid_c
[11],
916 uuid_c
[12], uuid_c
[13], uuid_c
[14], uuid_c
[15]);
918 ret
= lttng_metadata_printf(session
,
919 "typealias integer { size = 8; align = %u; signed = false; } := uint8_t;\n"
920 "typealias integer { size = 16; align = %u; signed = false; } := uint16_t;\n"
921 "typealias integer { size = 32; align = %u; signed = false; } := uint32_t;\n"
922 "typealias integer { size = 64; align = %u; signed = false; } := uint64_t;\n"
923 "typealias integer { size = 5; align = 1; signed = false; } := uint5_t;\n"
924 "typealias integer { size = 27; align = 1; signed = false; } := uint27_t;\n"
930 " byte_order = %s;\n"
931 " packet.header := struct {\n"
933 " uint8_t uuid[16];\n"
934 " uint32_t stream_id;\n"
937 lttng_alignof(uint8_t) * CHAR_BIT
,
938 lttng_alignof(uint16_t) * CHAR_BIT
,
939 lttng_alignof(uint32_t) * CHAR_BIT
,
940 lttng_alignof(uint64_t) * CHAR_BIT
,
953 ret
= _ltt_stream_packet_context_declare(session
);
957 ret
= _ltt_event_header_declare(session
);
962 cds_list_for_each_entry(chan
, &session
->chan
, list
) {
963 ret
= _ltt_channel_metadata_statedump(session
, chan
);
968 cds_list_for_each_entry(event
, &session
->events
, list
) {
969 ret
= _ltt_event_metadata_statedump(session
, event
->chan
, event
);
973 session
->metadata_dumped
= 1;
979 * ltt_transport_register - LTT transport registration
980 * @transport: transport structure
982 * Registers a transport which can be used as output to extract the data out of
983 * LTTng. Called with ust_lock held.
985 void ltt_transport_register(struct ltt_transport
*transport
)
987 cds_list_add_tail(&transport
->node
, <t_transport_list
);
991 * ltt_transport_unregister - LTT transport unregistration
992 * @transport: transport structure
993 * Called with ust_lock held.
995 void ltt_transport_unregister(struct ltt_transport
*transport
)
997 cds_list_del(&transport
->node
);
1000 void ltt_events_exit(void)
1002 struct ltt_session
*session
, *tmpsession
;
1004 cds_list_for_each_entry_safe(session
, tmpsession
, &sessions
, list
)
1005 ltt_session_destroy(session
);