Commit | Line | Data |
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4e3c1b9b MD |
1 | /* |
2 | * ltt-events.c | |
3 | * | |
4 | * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
5 | * | |
6 | * Holds LTTng per-session event registry. | |
7 | */ | |
8 | ||
9 | #include <linux/module.h> | |
c0e31d2e MD |
10 | #include <linux/list.h> |
11 | #include <linux/mutex.h> | |
12 | #include <linux/sched.h> | |
11b5a3c2 MD |
13 | #include <linux/slab.h> |
14 | #include <linux/vmalloc.h> /* For vmalloc_sync_all */ | |
4e3c1b9b MD |
15 | #include "ltt-events.h" |
16 | ||
17 | static LIST_HEAD(sessions); | |
c0e31d2e | 18 | static LIST_HEAD(ltt_transport_list); |
4e3c1b9b MD |
19 | static DEFINE_MUTEX(sessions_mutex); |
20 | static struct kmem_cache *event_cache; | |
21 | ||
abcca994 MD |
22 | static void synchronize_trace(void) |
23 | { | |
24 | synchronize_sched(); | |
25 | #ifdef CONFIG_PREEMPT_RT | |
26 | synchronize_rcu(); | |
27 | #endif | |
28 | } | |
29 | ||
baf20995 | 30 | struct ltt_session *ltt_session_create(void) |
4e3c1b9b MD |
31 | { |
32 | struct ltt_session *session; | |
33 | ||
34 | mutex_lock(&sessions_mutex); | |
f3d01b96 | 35 | session = kzalloc(sizeof(struct ltt_session), GFP_KERNEL); |
4e3c1b9b MD |
36 | if (!session) |
37 | return NULL; | |
4e3c1b9b | 38 | INIT_LIST_HEAD(&session->chan); |
f3d01b96 | 39 | INIT_LIST_HEAD(&session->events); |
4e3c1b9b MD |
40 | list_add(&session->list, &sessions); |
41 | mutex_unlock(&sessions_mutex); | |
42 | return session; | |
4e3c1b9b MD |
43 | } |
44 | ||
11b5a3c2 | 45 | void ltt_session_destroy(struct ltt_session *session) |
4e3c1b9b MD |
46 | { |
47 | struct ltt_channel *chan, *tmpchan; | |
48 | struct ltt_event *event, *tmpevent; | |
dda6a249 | 49 | int ret; |
4e3c1b9b MD |
50 | |
51 | mutex_lock(&sessions_mutex); | |
52fc2e1f | 52 | ACCESS_ONCE(session->active) = 0; |
dda6a249 MD |
53 | list_for_each_entry(event, &session->events, list) { |
54 | ret = _ltt_event_unregister(event); | |
55 | WARN_ON(ret); | |
56 | } | |
abcca994 | 57 | synchronize_trace(); /* Wait for in-flight events to complete */ |
4e3c1b9b MD |
58 | list_for_each_entry_safe(event, tmpevent, &session->events, list) |
59 | _ltt_event_destroy(event); | |
60 | list_for_each_entry_safe(chan, tmpchan, &session->chan, list) | |
61 | _ltt_channel_destroy(chan); | |
62 | list_del(&session->list); | |
63 | mutex_unlock(&sessions_mutex); | |
64 | kfree(session); | |
65 | } | |
66 | ||
c0e31d2e MD |
67 | int ltt_session_start(struct ltt_session *session) |
68 | { | |
69 | int ret = 0; | |
70 | ||
71 | mutex_lock(&sessions_mutex); | |
72 | if (session->active) { | |
73 | ret = -EBUSY; | |
74 | goto end; | |
75 | } | |
52fc2e1f | 76 | ACCESS_ONCE(session->active) = 1; |
c0e31d2e MD |
77 | synchronize_trace(); /* Wait for in-flight events to complete */ |
78 | end: | |
79 | mutex_unlock(&sessions_mutex); | |
11b5a3c2 | 80 | return ret; |
c0e31d2e MD |
81 | } |
82 | ||
83 | int ltt_session_stop(struct ltt_session *session) | |
84 | { | |
85 | int ret = 0; | |
86 | ||
87 | mutex_lock(&sessions_mutex); | |
88 | if (!session->active) { | |
89 | ret = -EBUSY; | |
90 | goto end; | |
91 | } | |
52fc2e1f | 92 | ACCESS_ONCE(session->active) = 0; |
c0e31d2e MD |
93 | synchronize_trace(); /* Wait for in-flight events to complete */ |
94 | end: | |
95 | mutex_unlock(&sessions_mutex); | |
11b5a3c2 | 96 | return ret; |
c0e31d2e MD |
97 | } |
98 | ||
c535175e | 99 | static struct ltt_transport *ltt_transport_find(const char *name) |
f3d01b96 MD |
100 | { |
101 | struct ltt_transport *transport; | |
102 | ||
103 | list_for_each_entry(transport, <t_transport_list, node) { | |
104 | if (!strcmp(transport->name, name)) | |
105 | return transport; | |
106 | } | |
107 | return NULL; | |
108 | } | |
109 | ||
baf20995 | 110 | struct ltt_channel *ltt_channel_create(struct ltt_session *session, |
5dbbdb43 MD |
111 | const char *transport_name, |
112 | void *buf_addr, | |
4e3c1b9b MD |
113 | size_t subbuf_size, size_t num_subbuf, |
114 | unsigned int switch_timer_interval, | |
115 | unsigned int read_timer_interval) | |
116 | { | |
117 | struct ltt_channel *chan; | |
f3d01b96 | 118 | struct ltt_transport *transport; |
4e3c1b9b MD |
119 | |
120 | mutex_lock(&sessions_mutex); | |
f3d01b96 MD |
121 | if (session->active) { |
122 | printk(KERN_WARNING "LTTng refusing to add channel to active session\n"); | |
e5382b6d | 123 | goto active; /* Refuse to add channel to active session */ |
c0e31d2e | 124 | } |
f3d01b96 MD |
125 | transport = ltt_transport_find(transport_name); |
126 | if (!transport) { | |
127 | printk(KERN_WARNING "LTTng transport %s not found\n", | |
128 | transport_name); | |
c0e31d2e | 129 | goto notransport; |
f3d01b96 | 130 | } |
f3d01b96 | 131 | chan = kzalloc(sizeof(struct ltt_channel), GFP_KERNEL); |
4e3c1b9b | 132 | if (!chan) |
c0e31d2e | 133 | goto nomem; |
4e3c1b9b | 134 | chan->session = session; |
653fe716 | 135 | init_waitqueue_head(&chan->notify_wait); |
11b5a3c2 MD |
136 | chan->chan = transport->ops.channel_create("[lttng]", session, buf_addr, |
137 | subbuf_size, num_subbuf, switch_timer_interval, | |
138 | read_timer_interval); | |
f3d01b96 MD |
139 | if (!chan->chan) |
140 | goto create_error; | |
11b5a3c2 | 141 | chan->ops = &transport->ops; |
4e3c1b9b MD |
142 | list_add(&chan->list, &session->chan); |
143 | mutex_unlock(&sessions_mutex); | |
144 | return chan; | |
145 | ||
f3d01b96 MD |
146 | create_error: |
147 | kfree(chan); | |
c0e31d2e MD |
148 | nomem: |
149 | notransport: | |
e5382b6d | 150 | active: |
4e3c1b9b MD |
151 | mutex_unlock(&sessions_mutex); |
152 | return NULL; | |
153 | } | |
154 | ||
155 | /* | |
156 | * Only used internally at session destruction. | |
157 | */ | |
11b5a3c2 | 158 | void _ltt_channel_destroy(struct ltt_channel *chan) |
4e3c1b9b | 159 | { |
11b5a3c2 | 160 | chan->ops->channel_destroy(chan->chan); |
4e3c1b9b MD |
161 | list_del(&chan->list); |
162 | kfree(chan); | |
163 | } | |
164 | ||
e5382b6d MD |
165 | /* |
166 | * Supports event creation while tracing session is active. | |
167 | */ | |
4e3c1b9b | 168 | struct ltt_event *ltt_event_create(struct ltt_channel *chan, char *name, |
baf20995 MD |
169 | enum instrum_type itype, |
170 | void *probe, void *filter) | |
4e3c1b9b MD |
171 | { |
172 | struct ltt_event *event; | |
3d084699 | 173 | int ret; |
4e3c1b9b MD |
174 | |
175 | mutex_lock(&sessions_mutex); | |
e5382b6d MD |
176 | if (chan->free_event_id == -1UL) |
177 | goto full; | |
4e3c1b9b | 178 | /* |
dda6a249 MD |
179 | * This is O(n^2) (for each event, the loop is called at event |
180 | * creation). Might require a hash if we have lots of events. | |
4e3c1b9b MD |
181 | */ |
182 | list_for_each_entry(event, &chan->session->events, list) | |
183 | if (!strcmp(event->name, name)) | |
184 | goto exist; | |
11b5a3c2 | 185 | event = kmem_cache_zalloc(event_cache, GFP_KERNEL); |
4e3c1b9b MD |
186 | if (!event) |
187 | goto cache_error; | |
188 | event->name = kmalloc(strlen(name) + 1, GFP_KERNEL); | |
189 | if (!event->name) | |
11b5a3c2 | 190 | goto name_error; |
4e3c1b9b MD |
191 | strcpy(event->name, name); |
192 | event->chan = chan; | |
baf20995 | 193 | event->probe = probe; |
4e3c1b9b | 194 | event->filter = filter; |
e5382b6d | 195 | event->id = chan->free_event_id++; |
baf20995 | 196 | event->itype = itype; |
e5382b6d MD |
197 | /* Populate ltt_event structure before tracepoint registration. */ |
198 | smp_wmb(); | |
baf20995 MD |
199 | switch (itype) { |
200 | case INSTRUM_TRACEPOINTS: | |
201 | ret = tracepoint_probe_register(name, probe, event); | |
11b5a3c2 MD |
202 | if (ret) |
203 | goto register_error; | |
baf20995 MD |
204 | break; |
205 | default: | |
206 | WARN_ON_ONCE(1); | |
207 | } | |
dda6a249 | 208 | list_add(&event->list, &chan->session->events); |
11b5a3c2 | 209 | mutex_unlock(&sessions_mutex); |
4e3c1b9b MD |
210 | return event; |
211 | ||
11b5a3c2 MD |
212 | register_error: |
213 | kfree(event->name); | |
214 | name_error: | |
215 | kmem_cache_free(event_cache, event); | |
4e3c1b9b MD |
216 | cache_error: |
217 | exist: | |
e5382b6d | 218 | full: |
4e3c1b9b MD |
219 | mutex_unlock(&sessions_mutex); |
220 | return NULL; | |
221 | } | |
222 | ||
223 | /* | |
224 | * Only used internally at session destruction. | |
225 | */ | |
dda6a249 | 226 | int _ltt_event_unregister(struct ltt_event *event) |
4e3c1b9b | 227 | { |
11b5a3c2 MD |
228 | int ret = -EINVAL; |
229 | ||
baf20995 MD |
230 | switch (event->itype) { |
231 | case INSTRUM_TRACEPOINTS: | |
11b5a3c2 MD |
232 | ret = tracepoint_probe_unregister(event->name, event->probe, |
233 | event); | |
234 | if (ret) | |
235 | return ret; | |
baf20995 MD |
236 | break; |
237 | default: | |
238 | WARN_ON_ONCE(1); | |
239 | } | |
dda6a249 MD |
240 | return ret; |
241 | } | |
242 | ||
243 | /* | |
244 | * Only used internally at session destruction. | |
245 | */ | |
246 | void _ltt_event_destroy(struct ltt_event *event) | |
247 | { | |
4e3c1b9b | 248 | kfree(event->name); |
dda6a249 | 249 | list_del(&event->list); |
11b5a3c2 | 250 | kmem_cache_free(event_cache, event); |
4e3c1b9b MD |
251 | } |
252 | ||
c0e31d2e MD |
253 | /** |
254 | * ltt_transport_register - LTT transport registration | |
255 | * @transport: transport structure | |
256 | * | |
257 | * Registers a transport which can be used as output to extract the data out of | |
258 | * LTTng. The module calling this registration function must ensure that no | |
259 | * trap-inducing code will be executed by the transport functions. E.g. | |
260 | * vmalloc_sync_all() must be called between a vmalloc and the moment the memory | |
261 | * is made visible to the transport function. This registration acts as a | |
262 | * vmalloc_sync_all. Therefore, only if the module allocates virtual memory | |
263 | * after its registration must it synchronize the TLBs. | |
264 | */ | |
265 | void ltt_transport_register(struct ltt_transport *transport) | |
266 | { | |
267 | /* | |
268 | * Make sure no page fault can be triggered by the module about to be | |
269 | * registered. We deal with this here so we don't have to call | |
270 | * vmalloc_sync_all() in each module's init. | |
271 | */ | |
272 | vmalloc_sync_all(); | |
273 | ||
274 | mutex_lock(&sessions_mutex); | |
275 | list_add_tail(&transport->node, <t_transport_list); | |
276 | mutex_unlock(&sessions_mutex); | |
277 | } | |
278 | EXPORT_SYMBOL_GPL(ltt_transport_register); | |
279 | ||
280 | /** | |
281 | * ltt_transport_unregister - LTT transport unregistration | |
282 | * @transport: transport structure | |
283 | */ | |
284 | void ltt_transport_unregister(struct ltt_transport *transport) | |
285 | { | |
286 | mutex_lock(&sessions_mutex); | |
287 | list_del(&transport->node); | |
288 | mutex_unlock(&sessions_mutex); | |
289 | } | |
290 | EXPORT_SYMBOL_GPL(ltt_transport_unregister); | |
291 | ||
292 | ||
4e3c1b9b MD |
293 | static int __init ltt_events_init(void) |
294 | { | |
1c25284c MD |
295 | int ret; |
296 | ||
11b5a3c2 MD |
297 | event_cache = KMEM_CACHE(ltt_event, 0); |
298 | if (!event_cache) | |
4e3c1b9b | 299 | return -ENOMEM; |
02119ee5 | 300 | ret = ltt_probes_init(); |
1c25284c MD |
301 | if (ret) |
302 | goto error; | |
02119ee5 MD |
303 | ret = ltt_debugfs_abi_init(); |
304 | if (ret) | |
305 | goto error_abi; | |
4e3c1b9b | 306 | return 0; |
02119ee5 MD |
307 | error_abi: |
308 | ltt_probes_exit(); | |
1c25284c MD |
309 | error: |
310 | kmem_cache_destroy(event_cache); | |
311 | return ret; | |
4e3c1b9b MD |
312 | } |
313 | ||
11b5a3c2 MD |
314 | module_init(ltt_events_init); |
315 | ||
4e3c1b9b MD |
316 | static void __exit ltt_events_exit(void) |
317 | { | |
92e94819 MD |
318 | struct ltt_session *session, *tmpsession; |
319 | ||
1c25284c | 320 | ltt_debugfs_abi_exit(); |
02119ee5 | 321 | ltt_probes_exit(); |
92e94819 MD |
322 | list_for_each_entry_safe(session, tmpsession, &sessions, list) |
323 | ltt_session_destroy(session); | |
11b5a3c2 | 324 | kmem_cache_destroy(event_cache); |
4e3c1b9b | 325 | } |
92e94819 | 326 | |
11b5a3c2 MD |
327 | module_exit(ltt_events_exit); |
328 | ||
92e94819 MD |
329 | MODULE_LICENSE("GPL and additional rights"); |
330 | MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>"); | |
331 | MODULE_DESCRIPTION("LTTng Events"); |