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