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); | |
11b5a3c2 | 35 | session = kmalloc(sizeof(struct ltt_session), GFP_KERNEL); |
4e3c1b9b MD |
36 | if (!session) |
37 | return NULL; | |
4e3c1b9b MD |
38 | INIT_LIST_HEAD(&session->chan); |
39 | list_add(&session->list, &sessions); | |
40 | mutex_unlock(&sessions_mutex); | |
41 | return session; | |
4e3c1b9b MD |
42 | } |
43 | ||
11b5a3c2 | 44 | void ltt_session_destroy(struct ltt_session *session) |
4e3c1b9b MD |
45 | { |
46 | struct ltt_channel *chan, *tmpchan; | |
47 | struct ltt_event *event, *tmpevent; | |
48 | ||
49 | mutex_lock(&sessions_mutex); | |
abcca994 MD |
50 | session->active = 0; |
51 | synchronize_trace(); /* Wait for in-flight events to complete */ | |
4e3c1b9b MD |
52 | list_for_each_entry_safe(event, tmpevent, &session->events, list) |
53 | _ltt_event_destroy(event); | |
54 | list_for_each_entry_safe(chan, tmpchan, &session->chan, list) | |
55 | _ltt_channel_destroy(chan); | |
56 | list_del(&session->list); | |
57 | mutex_unlock(&sessions_mutex); | |
58 | kfree(session); | |
59 | } | |
60 | ||
c0e31d2e MD |
61 | int ltt_session_start(struct ltt_session *session) |
62 | { | |
63 | int ret = 0; | |
64 | ||
65 | mutex_lock(&sessions_mutex); | |
66 | if (session->active) { | |
67 | ret = -EBUSY; | |
68 | goto end; | |
69 | } | |
70 | session->active = 1; | |
71 | synchronize_trace(); /* Wait for in-flight events to complete */ | |
72 | end: | |
73 | mutex_unlock(&sessions_mutex); | |
11b5a3c2 | 74 | return ret; |
c0e31d2e MD |
75 | } |
76 | ||
77 | int ltt_session_stop(struct ltt_session *session) | |
78 | { | |
79 | int ret = 0; | |
80 | ||
81 | mutex_lock(&sessions_mutex); | |
82 | if (!session->active) { | |
83 | ret = -EBUSY; | |
84 | goto end; | |
85 | } | |
86 | session->active = 0; | |
87 | synchronize_trace(); /* Wait for in-flight events to complete */ | |
88 | end: | |
89 | mutex_unlock(&sessions_mutex); | |
11b5a3c2 | 90 | return ret; |
c0e31d2e MD |
91 | } |
92 | ||
baf20995 | 93 | struct ltt_channel *ltt_channel_create(struct ltt_session *session, |
4e3c1b9b MD |
94 | int overwrite, void *buf_addr, |
95 | size_t subbuf_size, size_t num_subbuf, | |
96 | unsigned int switch_timer_interval, | |
97 | unsigned int read_timer_interval) | |
98 | { | |
99 | struct ltt_channel *chan; | |
c0e31d2e MD |
100 | struct ltt_transport *transport = NULL, *tran_iter; |
101 | char *transport_name; | |
4e3c1b9b MD |
102 | |
103 | mutex_lock(&sessions_mutex); | |
e5382b6d MD |
104 | if (session->active) |
105 | goto active; /* Refuse to add channel to active session */ | |
c0e31d2e MD |
106 | transport_name = overwrite ? "relay-overwrite" : "relay-discard"; |
107 | list_for_each_entry(tran_iter, <t_transport_list, node) { | |
108 | if (!strcmp(tran_iter->name, transport_name)) { | |
109 | transport = tran_iter; | |
110 | break; | |
111 | } | |
112 | } | |
113 | if (!transport) | |
114 | goto notransport; | |
baf20995 | 115 | chan = kmalloc(sizeof(struct ltt_channel), GFP_KERNEL); |
4e3c1b9b | 116 | if (!chan) |
c0e31d2e | 117 | goto nomem; |
4e3c1b9b | 118 | chan->session = session; |
653fe716 | 119 | init_waitqueue_head(&chan->notify_wait); |
11b5a3c2 MD |
120 | chan->chan = transport->ops.channel_create("[lttng]", session, buf_addr, |
121 | subbuf_size, num_subbuf, switch_timer_interval, | |
122 | read_timer_interval); | |
123 | chan->ops = &transport->ops; | |
4e3c1b9b MD |
124 | list_add(&chan->list, &session->chan); |
125 | mutex_unlock(&sessions_mutex); | |
126 | return chan; | |
127 | ||
c0e31d2e MD |
128 | nomem: |
129 | notransport: | |
e5382b6d | 130 | active: |
4e3c1b9b MD |
131 | mutex_unlock(&sessions_mutex); |
132 | return NULL; | |
133 | } | |
134 | ||
135 | /* | |
136 | * Only used internally at session destruction. | |
137 | */ | |
11b5a3c2 | 138 | void _ltt_channel_destroy(struct ltt_channel *chan) |
4e3c1b9b | 139 | { |
11b5a3c2 | 140 | chan->ops->channel_destroy(chan->chan); |
4e3c1b9b MD |
141 | list_del(&chan->list); |
142 | kfree(chan); | |
143 | } | |
144 | ||
e5382b6d MD |
145 | /* |
146 | * Supports event creation while tracing session is active. | |
147 | */ | |
4e3c1b9b | 148 | struct ltt_event *ltt_event_create(struct ltt_channel *chan, char *name, |
baf20995 MD |
149 | enum instrum_type itype, |
150 | void *probe, void *filter) | |
4e3c1b9b MD |
151 | { |
152 | struct ltt_event *event; | |
3d084699 | 153 | int ret; |
4e3c1b9b MD |
154 | |
155 | mutex_lock(&sessions_mutex); | |
e5382b6d MD |
156 | if (chan->free_event_id == -1UL) |
157 | goto full; | |
4e3c1b9b MD |
158 | /* |
159 | * This is O(n^2) (for each event loop called at event creation). | |
160 | * Might require a hash if we have lots of events. | |
161 | */ | |
162 | list_for_each_entry(event, &chan->session->events, list) | |
163 | if (!strcmp(event->name, name)) | |
164 | goto exist; | |
11b5a3c2 | 165 | event = kmem_cache_zalloc(event_cache, GFP_KERNEL); |
4e3c1b9b MD |
166 | if (!event) |
167 | goto cache_error; | |
168 | event->name = kmalloc(strlen(name) + 1, GFP_KERNEL); | |
169 | if (!event->name) | |
11b5a3c2 | 170 | goto name_error; |
4e3c1b9b MD |
171 | strcpy(event->name, name); |
172 | event->chan = chan; | |
baf20995 | 173 | event->probe = probe; |
4e3c1b9b | 174 | event->filter = filter; |
e5382b6d | 175 | event->id = chan->free_event_id++; |
baf20995 | 176 | event->itype = itype; |
e5382b6d MD |
177 | /* Populate ltt_event structure before tracepoint registration. */ |
178 | smp_wmb(); | |
baf20995 MD |
179 | switch (itype) { |
180 | case INSTRUM_TRACEPOINTS: | |
181 | ret = tracepoint_probe_register(name, probe, event); | |
11b5a3c2 MD |
182 | if (ret) |
183 | goto register_error; | |
baf20995 MD |
184 | break; |
185 | default: | |
186 | WARN_ON_ONCE(1); | |
187 | } | |
11b5a3c2 | 188 | mutex_unlock(&sessions_mutex); |
4e3c1b9b MD |
189 | return event; |
190 | ||
11b5a3c2 MD |
191 | register_error: |
192 | kfree(event->name); | |
193 | name_error: | |
194 | kmem_cache_free(event_cache, event); | |
4e3c1b9b MD |
195 | cache_error: |
196 | exist: | |
e5382b6d | 197 | full: |
4e3c1b9b MD |
198 | mutex_unlock(&sessions_mutex); |
199 | return NULL; | |
200 | } | |
201 | ||
202 | /* | |
203 | * Only used internally at session destruction. | |
204 | */ | |
205 | int _ltt_event_destroy(struct ltt_event *event) | |
206 | { | |
11b5a3c2 MD |
207 | int ret = -EINVAL; |
208 | ||
baf20995 MD |
209 | switch (event->itype) { |
210 | case INSTRUM_TRACEPOINTS: | |
11b5a3c2 MD |
211 | ret = tracepoint_probe_unregister(event->name, event->probe, |
212 | event); | |
213 | if (ret) | |
214 | return ret; | |
baf20995 MD |
215 | break; |
216 | default: | |
217 | WARN_ON_ONCE(1); | |
218 | } | |
4e3c1b9b | 219 | kfree(event->name); |
11b5a3c2 MD |
220 | kmem_cache_free(event_cache, event); |
221 | return ret; | |
4e3c1b9b MD |
222 | } |
223 | ||
c0e31d2e MD |
224 | /** |
225 | * ltt_transport_register - LTT transport registration | |
226 | * @transport: transport structure | |
227 | * | |
228 | * Registers a transport which can be used as output to extract the data out of | |
229 | * LTTng. The module calling this registration function must ensure that no | |
230 | * trap-inducing code will be executed by the transport functions. E.g. | |
231 | * vmalloc_sync_all() must be called between a vmalloc and the moment the memory | |
232 | * is made visible to the transport function. This registration acts as a | |
233 | * vmalloc_sync_all. Therefore, only if the module allocates virtual memory | |
234 | * after its registration must it synchronize the TLBs. | |
235 | */ | |
236 | void ltt_transport_register(struct ltt_transport *transport) | |
237 | { | |
238 | /* | |
239 | * Make sure no page fault can be triggered by the module about to be | |
240 | * registered. We deal with this here so we don't have to call | |
241 | * vmalloc_sync_all() in each module's init. | |
242 | */ | |
243 | vmalloc_sync_all(); | |
244 | ||
245 | mutex_lock(&sessions_mutex); | |
246 | list_add_tail(&transport->node, <t_transport_list); | |
247 | mutex_unlock(&sessions_mutex); | |
248 | } | |
249 | EXPORT_SYMBOL_GPL(ltt_transport_register); | |
250 | ||
251 | /** | |
252 | * ltt_transport_unregister - LTT transport unregistration | |
253 | * @transport: transport structure | |
254 | */ | |
255 | void ltt_transport_unregister(struct ltt_transport *transport) | |
256 | { | |
257 | mutex_lock(&sessions_mutex); | |
258 | list_del(&transport->node); | |
259 | mutex_unlock(&sessions_mutex); | |
260 | } | |
261 | EXPORT_SYMBOL_GPL(ltt_transport_unregister); | |
262 | ||
263 | ||
4e3c1b9b MD |
264 | static int __init ltt_events_init(void) |
265 | { | |
11b5a3c2 MD |
266 | event_cache = KMEM_CACHE(ltt_event, 0); |
267 | if (!event_cache) | |
4e3c1b9b MD |
268 | return -ENOMEM; |
269 | return 0; | |
270 | } | |
271 | ||
11b5a3c2 MD |
272 | module_init(ltt_events_init); |
273 | ||
4e3c1b9b MD |
274 | static void __exit ltt_events_exit(void) |
275 | { | |
92e94819 MD |
276 | struct ltt_session *session, *tmpsession; |
277 | ||
92e94819 MD |
278 | list_for_each_entry_safe(session, tmpsession, &sessions, list) |
279 | ltt_session_destroy(session); | |
11b5a3c2 | 280 | kmem_cache_destroy(event_cache); |
4e3c1b9b | 281 | } |
92e94819 | 282 | |
11b5a3c2 MD |
283 | module_exit(ltt_events_exit); |
284 | ||
92e94819 MD |
285 | MODULE_LICENSE("GPL and additional rights"); |
286 | MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>"); | |
287 | MODULE_DESCRIPTION("LTTng Events"); |