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 "wrapper/vmalloc.h" /* for wrapper_vmalloc_sync_all() */
16 #include "ltt-events.h"
17 #include "ltt-tracer.h"
19 static LIST_HEAD(sessions
);
20 static LIST_HEAD(ltt_transport_list
);
21 static DEFINE_MUTEX(sessions_mutex
);
22 static struct kmem_cache
*event_cache
;
25 int _ltt_event_metadata_statedump(struct ltt_session
*session
,
26 struct ltt_channel
*chan
,
27 struct ltt_event
*event
);
29 int _ltt_session_metadata_statedump(struct ltt_session
*session
);
33 void synchronize_trace(void)
36 #ifdef CONFIG_PREEMPT_RT
41 struct ltt_session
*ltt_session_create(void)
43 struct ltt_session
*session
;
45 mutex_lock(&sessions_mutex
);
46 session
= kzalloc(sizeof(struct ltt_session
), GFP_KERNEL
);
49 INIT_LIST_HEAD(&session
->chan
);
50 INIT_LIST_HEAD(&session
->events
);
51 list_add(&session
->list
, &sessions
);
52 mutex_unlock(&sessions_mutex
);
56 void ltt_session_destroy(struct ltt_session
*session
)
58 struct ltt_channel
*chan
, *tmpchan
;
59 struct ltt_event
*event
, *tmpevent
;
62 mutex_lock(&sessions_mutex
);
63 ACCESS_ONCE(session
->active
) = 0;
64 list_for_each_entry(event
, &session
->events
, list
) {
65 ret
= _ltt_event_unregister(event
);
68 synchronize_trace(); /* Wait for in-flight events to complete */
69 list_for_each_entry_safe(event
, tmpevent
, &session
->events
, list
)
70 _ltt_event_destroy(event
);
71 list_for_each_entry_safe(chan
, tmpchan
, &session
->chan
, list
)
72 _ltt_channel_destroy(chan
);
73 list_del(&session
->list
);
74 mutex_unlock(&sessions_mutex
);
78 int ltt_session_start(struct ltt_session
*session
)
81 struct ltt_channel
*chan
;
83 mutex_lock(&sessions_mutex
);
84 if (session
->active
) {
90 * Snapshot the number of events per channel to know the type of header
93 list_for_each_entry(chan
, &session
->chan
, list
) {
94 if (chan
->header_type
)
95 continue; /* don't change it if session stop/restart */
96 if (chan
->free_event_id
< 31)
97 chan
->header_type
= 1; /* compact */
99 chan
->header_type
= 2; /* large */
102 ACCESS_ONCE(session
->active
) = 1;
103 synchronize_trace(); /* Wait for in-flight events to complete */
104 ret
= _ltt_session_metadata_statedump(session
);
106 ACCESS_ONCE(session
->active
) = 0;
107 synchronize_trace(); /* Wait for in-flight events to complete */
110 mutex_unlock(&sessions_mutex
);
114 int ltt_session_stop(struct ltt_session
*session
)
118 mutex_lock(&sessions_mutex
);
119 if (!session
->active
) {
123 ACCESS_ONCE(session
->active
) = 0;
124 synchronize_trace(); /* Wait for in-flight events to complete */
126 mutex_unlock(&sessions_mutex
);
130 static struct ltt_transport
*ltt_transport_find(const char *name
)
132 struct ltt_transport
*transport
;
134 list_for_each_entry(transport
, <t_transport_list
, node
) {
135 if (!strcmp(transport
->name
, name
))
141 struct ltt_channel
*ltt_channel_create(struct ltt_session
*session
,
142 const char *transport_name
,
144 size_t subbuf_size
, size_t num_subbuf
,
145 unsigned int switch_timer_interval
,
146 unsigned int read_timer_interval
)
148 struct ltt_channel
*chan
;
149 struct ltt_transport
*transport
;
151 mutex_lock(&sessions_mutex
);
152 if (session
->active
) {
153 printk(KERN_WARNING
"LTTng refusing to add channel to active session\n");
154 goto active
; /* Refuse to add channel to active session */
156 transport
= ltt_transport_find(transport_name
);
158 printk(KERN_WARNING
"LTTng transport %s not found\n",
162 chan
= kzalloc(sizeof(struct ltt_channel
), GFP_KERNEL
);
165 chan
->session
= session
;
166 init_waitqueue_head(&chan
->notify_wait
);
167 chan
->chan
= transport
->ops
.channel_create("[lttng]", session
, buf_addr
,
168 subbuf_size
, num_subbuf
, switch_timer_interval
,
169 read_timer_interval
);
172 chan
->id
= session
->free_chan_id
++;
173 chan
->ops
= &transport
->ops
;
174 list_add(&chan
->list
, &session
->chan
);
175 mutex_unlock(&sessions_mutex
);
183 mutex_unlock(&sessions_mutex
);
188 * Only used internally at session destruction.
190 void _ltt_channel_destroy(struct ltt_channel
*chan
)
192 chan
->ops
->channel_destroy(chan
->chan
);
193 list_del(&chan
->list
);
198 * Supports event creation while tracing session is active.
200 struct ltt_event
*ltt_event_create(struct ltt_channel
*chan
, char *name
,
201 enum instrum_type itype
,
202 const struct lttng_event_desc
*event_desc
,
205 struct ltt_event
*event
;
208 mutex_lock(&sessions_mutex
);
209 if (chan
->free_event_id
== -1UL)
212 * This is O(n^2) (for each event, the loop is called at event
213 * creation). Might require a hash if we have lots of events.
215 list_for_each_entry(event
, &chan
->session
->events
, list
)
216 if (!strcmp(event
->desc
->name
, name
))
218 event
= kmem_cache_zalloc(event_cache
, GFP_KERNEL
);
222 event
->desc
= event_desc
;
223 event
->filter
= filter
;
224 event
->id
= chan
->free_event_id
++;
225 event
->itype
= itype
;
226 /* Populate ltt_event structure before tracepoint registration. */
229 case INSTRUM_TRACEPOINTS
:
230 ret
= tracepoint_probe_register(name
, event_desc
->probe_callback
,
238 ret
= _ltt_event_metadata_statedump(chan
->session
, chan
, event
);
240 goto statedump_error
;
241 list_add(&event
->list
, &chan
->session
->events
);
242 mutex_unlock(&sessions_mutex
);
246 WARN_ON_ONCE(tracepoint_probe_unregister(name
, event_desc
->probe_callback
,
249 kmem_cache_free(event_cache
, event
);
253 mutex_unlock(&sessions_mutex
);
258 * Only used internally at session destruction.
260 int _ltt_event_unregister(struct ltt_event
*event
)
264 switch (event
->itype
) {
265 case INSTRUM_TRACEPOINTS
:
266 ret
= tracepoint_probe_unregister(event
->desc
->name
,
267 event
->desc
->probe_callback
,
279 * Only used internally at session destruction.
281 void _ltt_event_destroy(struct ltt_event
*event
)
283 ltt_event_put(event
->desc
);
284 list_del(&event
->list
);
285 kmem_cache_free(event_cache
, event
);
288 int lttng_metadata_printf(struct ltt_session
*session
,
289 const char *fmt
, ...)
291 struct lib_ring_buffer_ctx ctx
;
292 struct ltt_channel
*chan
= session
->metadata
;
294 int ret
= 0, waitret
;
298 WARN_ON_ONCE(!ACCESS_ONCE(session
->active
));
301 str
= kvasprintf(GFP_KERNEL
, fmt
, ap
);
306 len
= strlen(str
) + 1;
307 lib_ring_buffer_ctx_init(&ctx
, chan
->chan
, NULL
, len
, sizeof(char), -1);
309 * We don't care about metadata buffer's records lost count, because we
310 * always retry here. Report error if we need to bail out after timeout
311 * or being interrupted.
313 waitret
= wait_event_interruptible_timeout(*chan
->ops
->get_reader_wait_queue(chan
),
315 ret
= chan
->ops
->event_reserve(&ctx
);
316 ret
!= -ENOBUFS
|| !ret
;
318 msecs_to_jiffies(LTTNG_METADATA_TIMEOUT_MSEC
));
319 if (waitret
|| ret
) {
320 printk(KERN_WARNING
"LTTng: Failure to write metadata to buffers (%s)\n",
321 waitret
== -ERESTARTSYS
? "interrupted" :
322 (ret
== -ENOBUFS
? "timeout" : "I/O error"));
323 if (waitret
== -ERESTARTSYS
)
327 chan
->ops
->event_write(&ctx
, str
, len
);
328 chan
->ops
->event_commit(&ctx
);
335 int _ltt_fields_metadata_statedump(struct ltt_session
*session
,
336 struct ltt_event
*event
)
338 const struct lttng_event_desc
*desc
= event
->desc
;
342 for (i
= 0; i
< desc
->nr_fields
; i
++) {
343 const struct lttng_event_field
*field
= &desc
->fields
[i
];
345 switch (field
->type
.atype
) {
347 ret
= lttng_metadata_printf(session
,
348 " integer { size = %u; align = %u; signed = %u;%s } %s;\n",
349 field
->type
.u
.basic
.integer
.size
,
350 field
->type
.u
.basic
.integer
.alignment
,
351 field
->type
.u
.basic
.integer
.signedness
,
353 field
->type
.u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
355 field
->type
.u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
360 ret
= lttng_metadata_printf(session
,
362 field
->type
.u
.basic
.enumeration
.name
,
367 const struct lttng_basic_type
*elem_type
;
369 elem_type
= &field
->type
.u
.array
.elem_type
;
370 ret
= lttng_metadata_printf(session
,
371 " integer { size = %u; align = %u; signed = %u;%s } %s[%u];\n",
372 elem_type
->u
.basic
.integer
.size
,
373 elem_type
->u
.basic
.integer
.alignment
,
374 elem_type
->u
.basic
.integer
.signedness
,
376 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
378 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
380 field
->name
, field
->type
.u
.array
.length
);
385 const struct lttng_basic_type
*elem_type
;
386 const struct lttng_basic_type
*length_type
;
388 elem_type
= &field
->type
.u
.sequence
.elem_type
;
389 length_type
= &field
->type
.u
.sequence
.length_type
;
390 ret
= lttng_metadata_printf(session
,
391 " integer { size = %u; align = %u; signed = %u;%s } %s[ integer { size = %u; align = %u; signed = %u;%s } ];\n",
392 elem_type
->u
.basic
.integer
.size
,
393 elem_type
->u
.basic
.integer
.alignment
,
394 elem_type
->u
.basic
.integer
.signedness
,
396 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
398 elem_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : "",
401 length_type
->u
.basic
.integer
.size
,
402 length_type
->u
.basic
.integer
.alignment
,
403 length_type
->u
.basic
.integer
.signedness
,
405 length_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = le;" : "",
407 length_type
->u
.basic
.integer
.reverse_byte_order
? " byte_order = be;" : ""
414 ret
= lttng_metadata_printf(session
,
416 field
->type
.u
.basic
.string
.encoding
== lttng_encode_ASCII
?
417 " { encoding = ASCII; }" : "",
429 int _ltt_event_metadata_statedump(struct ltt_session
*session
,
430 struct ltt_channel
*chan
,
431 struct ltt_event
*event
)
435 if (event
->metadata_dumped
|| !ACCESS_ONCE(session
->active
))
437 if (chan
== session
->metadata
)
440 ret
= lttng_metadata_printf(session
,
445 " event.fields := struct {\n",
452 ret
= _ltt_fields_metadata_statedump(session
, event
);
457 * LTTng space reservation can only reserve multiples of the
460 ret
= lttng_metadata_printf(session
,
462 "};\n", ltt_get_header_alignment());
469 event
->metadata_dumped
= 1;
476 int _ltt_channel_metadata_statedump(struct ltt_session
*session
,
477 struct ltt_channel
*chan
)
481 if (chan
->metadata_dumped
|| !ACCESS_ONCE(session
->active
))
483 if (chan
== session
->metadata
)
486 WARN_ON_ONCE(!chan
->header_type
);
487 ret
= lttng_metadata_printf(session
,
490 " event.header := %s;\n",
493 chan
->header_type
== 1 ? "struct event_header_compact" :
494 "struct event_header_large");
498 chan
->metadata_dumped
= 1;
504 * Output metadata into this session's metadata buffers.
507 int _ltt_session_metadata_statedump(struct ltt_session
*session
)
509 struct ltt_channel
*chan
;
510 struct ltt_event
*event
;
513 if (!ACCESS_ONCE(session
->active
))
515 if (session
->metadata_dumped
)
517 if (!session
->metadata
) {
518 printk(KERN_WARNING
"LTTng: attempt to start tracing, but metadata channel is not found. Operation abort.\n");
523 list_for_each_entry(chan
, &session
->chan
, list
) {
524 ret
= _ltt_channel_metadata_statedump(session
, chan
);
529 list_for_each_entry(event
, &session
->events
, list
) {
530 ret
= _ltt_event_metadata_statedump(session
, chan
, event
);
534 session
->metadata_dumped
= 1;
540 * ltt_transport_register - LTT transport registration
541 * @transport: transport structure
543 * Registers a transport which can be used as output to extract the data out of
544 * LTTng. The module calling this registration function must ensure that no
545 * trap-inducing code will be executed by the transport functions. E.g.
546 * vmalloc_sync_all() must be called between a vmalloc and the moment the memory
547 * is made visible to the transport function. This registration acts as a
548 * vmalloc_sync_all. Therefore, only if the module allocates virtual memory
549 * after its registration must it synchronize the TLBs.
551 void ltt_transport_register(struct ltt_transport
*transport
)
554 * Make sure no page fault can be triggered by the module about to be
555 * registered. We deal with this here so we don't have to call
556 * vmalloc_sync_all() in each module's init.
558 wrapper_vmalloc_sync_all();
560 mutex_lock(&sessions_mutex
);
561 list_add_tail(&transport
->node
, <t_transport_list
);
562 mutex_unlock(&sessions_mutex
);
564 EXPORT_SYMBOL_GPL(ltt_transport_register
);
567 * ltt_transport_unregister - LTT transport unregistration
568 * @transport: transport structure
570 void ltt_transport_unregister(struct ltt_transport
*transport
)
572 mutex_lock(&sessions_mutex
);
573 list_del(&transport
->node
);
574 mutex_unlock(&sessions_mutex
);
576 EXPORT_SYMBOL_GPL(ltt_transport_unregister
);
578 static int __init
ltt_events_init(void)
582 event_cache
= KMEM_CACHE(ltt_event
, 0);
585 ret
= ltt_debugfs_abi_init();
590 kmem_cache_destroy(event_cache
);
594 module_init(ltt_events_init
);
596 static void __exit
ltt_events_exit(void)
598 struct ltt_session
*session
, *tmpsession
;
600 ltt_debugfs_abi_exit();
601 list_for_each_entry_safe(session
, tmpsession
, &sessions
, list
)
602 ltt_session_destroy(session
);
603 kmem_cache_destroy(event_cache
);
606 module_exit(ltt_events_exit
);
608 MODULE_LICENSE("GPL and additional rights");
609 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
610 MODULE_DESCRIPTION("LTTng Events");