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