4 * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
6 * Holds LTTng per-session event registry.
9 #include <linux/module.h>
10 #include <linux/list.h>
11 #include <linux/mutex.h>
12 #include <linux/sched.h>
13 #include <linux/slab.h>
14 #include <linux/jiffies.h>
15 #include <linux/uuid.h>
16 #include "wrapper/vmalloc.h" /* for wrapper_vmalloc_sync_all() */
17 #include "ltt-events.h"
18 #include "ltt-tracer.h"
20 static LIST_HEAD(sessions
);
21 static LIST_HEAD(ltt_transport_list
);
22 static DEFINE_MUTEX(sessions_mutex
);
23 static struct kmem_cache
*event_cache
;
26 int _ltt_event_metadata_statedump(struct ltt_session
*session
,
27 struct ltt_channel
*chan
,
28 struct ltt_event
*event
);
30 int _ltt_session_metadata_statedump(struct ltt_session
*session
);
34 void synchronize_trace(void)
37 #ifdef CONFIG_PREEMPT_RT
42 struct ltt_session
*ltt_session_create(void)
44 struct ltt_session
*session
;
46 mutex_lock(&sessions_mutex
);
47 session
= kzalloc(sizeof(struct ltt_session
), GFP_KERNEL
);
50 INIT_LIST_HEAD(&session
->chan
);
51 INIT_LIST_HEAD(&session
->events
);
52 uuid_le_gen(&session
->uuid
);
53 list_add(&session
->list
, &sessions
);
54 mutex_unlock(&sessions_mutex
);
58 void ltt_session_destroy(struct ltt_session
*session
)
60 struct ltt_channel
*chan
, *tmpchan
;
61 struct ltt_event
*event
, *tmpevent
;
64 mutex_lock(&sessions_mutex
);
65 ACCESS_ONCE(session
->active
) = 0;
66 list_for_each_entry(event
, &session
->events
, list
) {
67 ret
= _ltt_event_unregister(event
);
70 synchronize_trace(); /* Wait for in-flight events to complete */
71 list_for_each_entry_safe(event
, tmpevent
, &session
->events
, list
)
72 _ltt_event_destroy(event
);
73 list_for_each_entry_safe(chan
, tmpchan
, &session
->chan
, list
)
74 _ltt_channel_destroy(chan
);
75 list_del(&session
->list
);
76 mutex_unlock(&sessions_mutex
);
80 int ltt_session_start(struct ltt_session
*session
)
83 struct ltt_channel
*chan
;
85 mutex_lock(&sessions_mutex
);
86 if (session
->active
) {
92 * Snapshot the number of events per channel to know the type of header
95 list_for_each_entry(chan
, &session
->chan
, list
) {
96 if (chan
->header_type
)
97 continue; /* don't change it if session stop/restart */
98 if (chan
->free_event_id
< 31)
99 chan
->header_type
= 1; /* compact */
101 chan
->header_type
= 2; /* large */
104 ACCESS_ONCE(session
->active
) = 1;
105 synchronize_trace(); /* Wait for in-flight events to complete */
106 ret
= _ltt_session_metadata_statedump(session
);
108 ACCESS_ONCE(session
->active
) = 0;
109 synchronize_trace(); /* Wait for in-flight events to complete */
112 mutex_unlock(&sessions_mutex
);
116 int ltt_session_stop(struct ltt_session
*session
)
120 mutex_lock(&sessions_mutex
);
121 if (!session
->active
) {
125 ACCESS_ONCE(session
->active
) = 0;
126 synchronize_trace(); /* Wait for in-flight events to complete */
128 mutex_unlock(&sessions_mutex
);
132 static struct ltt_transport
*ltt_transport_find(const char *name
)
134 struct ltt_transport
*transport
;
136 list_for_each_entry(transport
, <t_transport_list
, node
) {
137 if (!strcmp(transport
->name
, name
))
143 struct ltt_channel
*ltt_channel_create(struct ltt_session
*session
,
144 const char *transport_name
,
146 size_t subbuf_size
, size_t num_subbuf
,
147 unsigned int switch_timer_interval
,
148 unsigned int read_timer_interval
)
150 struct ltt_channel
*chan
;
151 struct ltt_transport
*transport
;
153 mutex_lock(&sessions_mutex
);
154 if (session
->active
) {
155 printk(KERN_WARNING
"LTTng refusing to add channel to active session\n");
156 goto active
; /* Refuse to add channel to active session */
158 transport
= ltt_transport_find(transport_name
);
160 printk(KERN_WARNING
"LTTng transport %s not found\n",
164 chan
= kzalloc(sizeof(struct ltt_channel
), GFP_KERNEL
);
167 chan
->session
= session
;
168 init_waitqueue_head(&chan
->notify_wait
);
169 chan
->chan
= transport
->ops
.channel_create("[lttng]", session
, buf_addr
,
170 subbuf_size
, num_subbuf
, switch_timer_interval
,
171 read_timer_interval
);
174 chan
->id
= session
->free_chan_id
++;
175 chan
->ops
= &transport
->ops
;
176 list_add(&chan
->list
, &session
->chan
);
177 mutex_unlock(&sessions_mutex
);
185 mutex_unlock(&sessions_mutex
);
190 * Only used internally at session destruction.
192 void _ltt_channel_destroy(struct ltt_channel
*chan
)
194 chan
->ops
->channel_destroy(chan
->chan
);
195 list_del(&chan
->list
);
200 * Supports event creation while tracing session is active.
202 struct ltt_event
*ltt_event_create(struct ltt_channel
*chan
, char *name
,
203 enum instrum_type itype
,
204 const struct lttng_event_desc
*event_desc
,
207 struct ltt_event
*event
;
210 mutex_lock(&sessions_mutex
);
211 if (chan
->free_event_id
== -1UL)
214 * This is O(n^2) (for each event, the loop is called at event
215 * creation). Might require a hash if we have lots of events.
217 list_for_each_entry(event
, &chan
->session
->events
, list
)
218 if (!strcmp(event
->desc
->name
, name
))
220 event
= kmem_cache_zalloc(event_cache
, GFP_KERNEL
);
224 event
->desc
= event_desc
;
225 event
->filter
= filter
;
226 event
->id
= chan
->free_event_id
++;
227 event
->itype
= itype
;
228 /* Populate ltt_event structure before tracepoint registration. */
231 case INSTRUM_TRACEPOINTS
:
232 ret
= tracepoint_probe_register(name
, event_desc
->probe_callback
,
240 ret
= _ltt_event_metadata_statedump(chan
->session
, chan
, event
);
242 goto statedump_error
;
243 list_add(&event
->list
, &chan
->session
->events
);
244 mutex_unlock(&sessions_mutex
);
248 WARN_ON_ONCE(tracepoint_probe_unregister(name
, event_desc
->probe_callback
,
251 kmem_cache_free(event_cache
, event
);
255 mutex_unlock(&sessions_mutex
);
260 * Only used internally at session destruction.
262 int _ltt_event_unregister(struct ltt_event
*event
)
266 switch (event
->itype
) {
267 case INSTRUM_TRACEPOINTS
:
268 ret
= tracepoint_probe_unregister(event
->desc
->name
,
269 event
->desc
->probe_callback
,
281 * Only used internally at session destruction.
283 void _ltt_event_destroy(struct ltt_event
*event
)
285 ltt_event_put(event
->desc
);
286 list_del(&event
->list
);
287 kmem_cache_free(event_cache
, event
);
291 * We have exclusive access to our metadata buffer (protected by the
292 * sessions_mutex), so we can do racy operations such as looking for
293 * remaining space left in packet and write, since mutual exclusion
294 * protects us from concurrent writes.
296 int lttng_metadata_printf(struct ltt_session
*session
,
297 const char *fmt
, ...)
299 struct lib_ring_buffer_ctx ctx
;
300 struct ltt_channel
*chan
= session
->metadata
;
302 int ret
= 0, waitret
;
303 size_t len
, reserve_len
, pos
;
306 WARN_ON_ONCE(!ACCESS_ONCE(session
->active
));
309 str
= kvasprintf(GFP_KERNEL
, fmt
, ap
);
317 for (pos
= 0; pos
< len
; pos
+= reserve_len
) {
318 reserve_len
= min_t(size_t,
319 chan
->ops
->packet_avail_size(chan
->chan
),
321 lib_ring_buffer_ctx_init(&ctx
, chan
->chan
, NULL
, reserve_len
,
324 * We don't care about metadata buffer's records lost
325 * count, because we always retry here. Report error if
326 * we need to bail out after timeout or being
329 waitret
= wait_event_interruptible_timeout(*chan
->ops
->get_reader_wait_queue(chan
),
331 ret
= chan
->ops
->event_reserve(&ctx
);
332 ret
!= -ENOBUFS
|| !ret
;
334 msecs_to_jiffies(LTTNG_METADATA_TIMEOUT_MSEC
));
335 if (!waitret
|| waitret
== -ERESTARTSYS
|| ret
) {
336 printk(KERN_WARNING
"LTTng: Failure to write metadata to buffers (%s)\n",
337 waitret
== -ERESTARTSYS
? "interrupted" :
338 (ret
== -ENOBUFS
? "timeout" : "I/O error"));
339 if (waitret
== -ERESTARTSYS
)
343 chan
->ops
->event_write(&ctx
, &str
[pos
], len
);
344 chan
->ops
->event_commit(&ctx
);
352 int _ltt_fields_metadata_statedump(struct ltt_session
*session
,
353 struct ltt_event
*event
)
355 const struct lttng_event_desc
*desc
= event
->desc
;
359 for (i
= 0; i
< desc
->nr_fields
; i
++) {
360 const struct lttng_event_field
*field
= &desc
->fields
[i
];
362 switch (field
->type
.atype
) {
364 ret
= lttng_metadata_printf(session
,
365 " integer { size = %u; align = %u; signed = %u;%s } %s;\n",
366 field
->type
.u
.basic
.integer
.size
,
367 field
->type
.u
.basic
.integer
.alignment
,
368 field
->type
.u
.basic
.integer
.signedness
,
370 field
->type
.u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
372 field
->type
.u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
377 ret
= lttng_metadata_printf(session
,
379 field
->type
.u
.basic
.enumeration
.name
,
384 const struct lttng_basic_type
*elem_type
;
386 elem_type
= &field
->type
.u
.array
.elem_type
;
387 ret
= lttng_metadata_printf(session
,
388 " integer { size = %u; align = %u; signed = %u;%s } %s[%u];\n",
389 elem_type
->u
.basic
.integer
.size
,
390 elem_type
->u
.basic
.integer
.alignment
,
391 elem_type
->u
.basic
.integer
.signedness
,
393 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
395 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
397 field
->name
, field
->type
.u
.array
.length
);
402 const struct lttng_basic_type
*elem_type
;
403 const struct lttng_basic_type
*length_type
;
405 elem_type
= &field
->type
.u
.sequence
.elem_type
;
406 length_type
= &field
->type
.u
.sequence
.length_type
;
407 ret
= lttng_metadata_printf(session
,
408 " integer { size = %u; align = %u; signed = %u;%s } %s[ integer { size = %u; align = %u; signed = %u;%s } ];\n",
409 elem_type
->u
.basic
.integer
.size
,
410 elem_type
->u
.basic
.integer
.alignment
,
411 elem_type
->u
.basic
.integer
.signedness
,
413 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
415 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
418 length_type
->u
.basic
.integer
.size
,
419 length_type
->u
.basic
.integer
.alignment
,
420 length_type
->u
.basic
.integer
.signedness
,
422 length_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
424 length_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : ""
431 ret
= lttng_metadata_printf(session
,
433 field
->type
.u
.basic
.string
.encoding
== lttng_encode_ASCII
?
434 " { encoding = ASCII; }" : "",
446 int _ltt_event_metadata_statedump(struct ltt_session
*session
,
447 struct ltt_channel
*chan
,
448 struct ltt_event
*event
)
452 if (event
->metadata_dumped
|| !ACCESS_ONCE(session
->active
))
454 if (chan
== session
->metadata
)
457 ret
= lttng_metadata_printf(session
,
462 " event.fields := struct {\n",
469 ret
= _ltt_fields_metadata_statedump(session
, event
);
474 * LTTng space reservation can only reserve multiples of the
477 ret
= lttng_metadata_printf(session
,
479 "};\n\n", ltt_get_header_alignment());
486 event
->metadata_dumped
= 1;
493 int _ltt_channel_metadata_statedump(struct ltt_session
*session
,
494 struct ltt_channel
*chan
)
498 if (chan
->metadata_dumped
|| !ACCESS_ONCE(session
->active
))
500 if (chan
== session
->metadata
)
503 WARN_ON_ONCE(!chan
->header_type
);
504 ret
= lttng_metadata_printf(session
,
507 " event.header := %s;\n",
510 chan
->header_type
== 1 ? "struct event_header_compact" :
511 "struct event_header_large");
515 chan
->metadata_dumped
= 1;
521 * Output metadata into this session's metadata buffers.
524 int _ltt_session_metadata_statedump(struct ltt_session
*session
)
527 struct ltt_channel
*chan
;
528 struct ltt_event
*event
;
531 if (!ACCESS_ONCE(session
->active
))
533 if (session
->metadata_dumped
)
535 if (!session
->metadata
) {
536 printk(KERN_WARNING
"LTTng: attempt to start tracing, but metadata channel is not found. Operation abort.\n");
540 snprintf(uuid_s
, sizeof(uuid_s
),
541 "%x%x%x%x-%x%x-%x%x-%x%x-%x%x%x%x%x%x",
542 uuid_s
[0], uuid_s
[1], uuid_s
[2], uuid_s
[3],
543 uuid_s
[4], uuid_s
[5], uuid_s
[6], uuid_s
[7],
544 uuid_s
[8], uuid_s
[9], uuid_s
[10], uuid_s
[11],
545 uuid_s
[12], uuid_s
[13], uuid_s
[14], uuid_s
[15]);
547 ret
= lttng_metadata_printf(session
,
548 "typealias integer {size = 8; align = %u; signed = false; } := uint8_t;\n"
549 "typealias integer {size = 32; align = %u; signed = false; } := uint32_t;\n"
550 "typealias integer {size = 64; align = %u; signed = false; } := uint64_t;\n"
556 " byte_order = %s;\n"
557 " packet.header := struct {\n"
559 " uint8_t uuid[16];\n"
560 " uint32_t stream_id;\n"
561 " uint64_t timestamp_begin;\n"
562 " uint64_t timestamp_end;\n"
563 " uint32_t content_size;\n"
564 " uint32_t packet_size;\n"
565 " uint32_t events_lost;\n"
568 ltt_alignof(uint8_t) * CHAR_BIT
,
569 ltt_alignof(uint32_t) * CHAR_BIT
,
570 ltt_alignof(uint64_t) * CHAR_BIT
,
584 list_for_each_entry(chan
, &session
->chan
, list
) {
585 ret
= _ltt_channel_metadata_statedump(session
, chan
);
590 list_for_each_entry(event
, &session
->events
, list
) {
591 ret
= _ltt_event_metadata_statedump(session
, chan
, event
);
595 session
->metadata_dumped
= 1;
601 * ltt_transport_register - LTT transport registration
602 * @transport: transport structure
604 * Registers a transport which can be used as output to extract the data out of
605 * LTTng. The module calling this registration function must ensure that no
606 * trap-inducing code will be executed by the transport functions. E.g.
607 * vmalloc_sync_all() must be called between a vmalloc and the moment the memory
608 * is made visible to the transport function. This registration acts as a
609 * vmalloc_sync_all. Therefore, only if the module allocates virtual memory
610 * after its registration must it synchronize the TLBs.
612 void ltt_transport_register(struct ltt_transport
*transport
)
615 * Make sure no page fault can be triggered by the module about to be
616 * registered. We deal with this here so we don't have to call
617 * vmalloc_sync_all() in each module's init.
619 wrapper_vmalloc_sync_all();
621 mutex_lock(&sessions_mutex
);
622 list_add_tail(&transport
->node
, <t_transport_list
);
623 mutex_unlock(&sessions_mutex
);
625 EXPORT_SYMBOL_GPL(ltt_transport_register
);
628 * ltt_transport_unregister - LTT transport unregistration
629 * @transport: transport structure
631 void ltt_transport_unregister(struct ltt_transport
*transport
)
633 mutex_lock(&sessions_mutex
);
634 list_del(&transport
->node
);
635 mutex_unlock(&sessions_mutex
);
637 EXPORT_SYMBOL_GPL(ltt_transport_unregister
);
639 static int __init
ltt_events_init(void)
643 event_cache
= KMEM_CACHE(ltt_event
, 0);
646 ret
= ltt_debugfs_abi_init();
651 kmem_cache_destroy(event_cache
);
655 module_init(ltt_events_init
);
657 static void __exit
ltt_events_exit(void)
659 struct ltt_session
*session
, *tmpsession
;
661 ltt_debugfs_abi_exit();
662 list_for_each_entry_safe(session
, tmpsession
, &sessions
, list
)
663 ltt_session_destroy(session
);
664 kmem_cache_destroy(event_cache
);
667 module_exit(ltt_events_exit
);
669 MODULE_LICENSE("GPL and additional rights");
670 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
671 MODULE_DESCRIPTION("LTTng Events");