Commit | Line | Data |
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baf20995 MD |
1 | /* |
2 | * ltt-debugfs-abi.c | |
3 | * | |
4 | * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
5 | * | |
6 | * LTTng debugfs ABI | |
7 | * | |
8 | * Mimic system calls for: | |
9 | * - session creation, returns a file descriptor or failure. | |
ad1c05e1 MD |
10 | * - channel creation, returns a file descriptor or failure. |
11 | * - Operates on a session file descriptor | |
12 | * - Takes all channel options as parameters. | |
13 | * - stream get, returns a file descriptor or failure. | |
14 | * - Operates on a channel file descriptor. | |
15 | * - stream notifier get, returns a file descriptor or failure. | |
16 | * - Operates on a channel file descriptor. | |
17 | * - event creation, returns a file descriptor or failure. | |
18 | * - Operates on a channel file descriptor | |
19 | * - Takes an event name as parameter | |
20 | * - Takes an instrumentation source as parameter | |
21 | * - e.g. tracepoints, dynamic_probes... | |
22 | * - Takes instrumentation source specific arguments. | |
baf20995 MD |
23 | */ |
24 | ||
25 | #include <linux/debugfs.h> | |
ad1c05e1 | 26 | #include "ltt-events.h" |
baf20995 MD |
27 | |
28 | /* | |
29 | * This is LTTng's own personal way to create a system call as an external | |
30 | * module. We use ioctl() on /sys/kernel/debug/lttng. | |
31 | */ | |
32 | ||
33 | static struct dentry *lttng_dentry; | |
ad1c05e1 MD |
34 | static const struct file_operations lttng_fops; |
35 | static const struct file_operations lttng_session_fops; | |
36 | static const struct file_operations lttng_channel_fops; | |
305d3e42 | 37 | static const struct file_operations lttng_event_fops; |
baf20995 MD |
38 | |
39 | /* | |
40 | * LTTng DebugFS ABI structures. | |
41 | */ | |
42 | ||
43 | struct lttng_channel { | |
baf20995 MD |
44 | int overwrite; /* 1: overwrite, 0: discard */ |
45 | u64 subbuf_size; | |
46 | u64 num_subbuf; | |
47 | unsigned int switch_timer_interval; | |
48 | unsigned int read_timer_interval; | |
49 | }; | |
50 | ||
51 | struct lttng_event { | |
baf20995 MD |
52 | enum instrum_type itype; |
53 | char name[]; | |
54 | }; | |
55 | ||
ad1c05e1 | 56 | static |
baf20995 MD |
57 | int lttng_abi_create_session(void) |
58 | { | |
59 | struct ltt_session *session; | |
03037b98 | 60 | struct file *session_filp; |
baf20995 MD |
61 | int session_fd; |
62 | ||
653fe716 | 63 | session = ltt_session_create(); |
baf20995 MD |
64 | if (!session) |
65 | return -ENOMEM; | |
66 | session_fd = get_unused_fd_flags(O_RDWR); | |
67 | if (session_fd < 0) { | |
68 | ret = session_fd; | |
69 | goto fd_error; | |
70 | } | |
03037b98 | 71 | session_filp = anon_inode_getfile("[lttng_session]", |
ad1c05e1 | 72 | <tng_session_fops, |
baf20995 | 73 | session, O_RDWR); |
03037b98 MD |
74 | if (IS_ERR(session_filp)) { |
75 | ret = PTR_ERR(session_filp); | |
baf20995 MD |
76 | goto file_error; |
77 | } | |
0a84a57f | 78 | session->file = session_filp; |
03037b98 | 79 | fd_install(session_fd, session_filp); |
baf20995 MD |
80 | return session_fd; |
81 | ||
82 | file_error: | |
83 | put_unused_fd(session_fd); | |
84 | fd_error: | |
85 | ltt_session_destroy(session); | |
86 | return ret; | |
87 | } | |
88 | ||
ad1c05e1 MD |
89 | /** |
90 | * lttng_ioctl - lttng syscall through ioctl | |
91 | * | |
92 | * @filp: the file | |
93 | * @cmd: the command | |
94 | * @arg: command arg | |
95 | * | |
96 | * This ioctl implements lttng commands: | |
97 | * LTTNG_SESSION | |
98 | * Returns a LTTng trace session file descriptor | |
99 | * | |
100 | * The returned session will be deleted when its file descriptor is closed. | |
101 | */ | |
102 | static | |
103 | long lttng_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) | |
104 | { | |
105 | switch (cmd) { | |
106 | case LTTNG_SESSION: | |
107 | return lttng_abi_create_session(); | |
108 | default: | |
109 | return -ENOIOCTLCMD; | |
110 | } | |
111 | } | |
112 | ||
ad1c05e1 MD |
113 | static const struct file_operations lttng_fops = { |
114 | .unlocked_ioctl = lttng_ioctl, | |
115 | #ifdef CONFIG_COMPAT | |
03037b98 | 116 | .compat_ioctl = lttng_ioctl, |
ad1c05e1 MD |
117 | #endif |
118 | } | |
119 | ||
120 | int lttng_abi_create_channel(struct file *session_filp, | |
121 | struct lttng_channel __user *uchan_param) | |
baf20995 | 122 | { |
ad1c05e1 | 123 | struct ltt_session *session = session_filp->private_data; |
baf20995 | 124 | struct ltt_channel *chan; |
ad1c05e1 | 125 | struct file *chan_filp; |
baf20995 MD |
126 | struct lttng_channel chan_param; |
127 | int chan_fd; | |
ad1c05e1 | 128 | int ret = 0; |
baf20995 | 129 | |
653fe716 | 130 | if (copy_from_user(&chan_param, uchan_param, sizeof(chan_param))) |
baf20995 | 131 | return -EFAULT; |
baf20995 MD |
132 | chan_fd = get_unused_fd_flags(O_RDWR); |
133 | if (chan_fd < 0) { | |
134 | ret = chan_fd; | |
135 | goto fd_error; | |
136 | } | |
ad1c05e1 MD |
137 | chan_filp = anon_inode_getfile("[lttng_channel]", |
138 | <tng_channel_fops, | |
03037b98 | 139 | NULL, O_RDWR); |
ad1c05e1 MD |
140 | if (IS_ERR(chan_filp)) { |
141 | ret = PTR_ERR(chan_filp); | |
baf20995 MD |
142 | goto file_error; |
143 | } | |
03037b98 MD |
144 | /* |
145 | * We tolerate no failure path after channel creation. It will stay | |
146 | * invariant for the rest of the session. | |
147 | */ | |
148 | chan = ltt_channel_create(session, chan_param->overwrite, NULL, | |
149 | chan_param->subbuf_size, | |
150 | chan_param->num_subbuf, | |
151 | chan_param->switch_timer_interval, | |
152 | chan_param->read_timer_interval); | |
153 | if (!chan) { | |
154 | ret = -ENOMEM; | |
155 | goto chan_error; | |
156 | } | |
0a84a57f | 157 | channel->file = chan_filp; |
03037b98 MD |
158 | chan_filp->private_data = chan; |
159 | fd_install(chan_fd, chan_filp); | |
ad1c05e1 MD |
160 | /* The channel created holds a reference on the session */ |
161 | atomic_inc(&session_filp->f_count); | |
162 | ||
baf20995 MD |
163 | return chan_fd; |
164 | ||
03037b98 MD |
165 | chan_error: |
166 | fput(chan_filp); | |
baf20995 MD |
167 | file_error: |
168 | put_unused_fd(chan_fd); | |
169 | fd_error: | |
baf20995 MD |
170 | return ret; |
171 | } | |
172 | ||
173 | /** | |
ad1c05e1 | 174 | * lttng_session_ioctl - lttng session fd ioctl |
baf20995 MD |
175 | * |
176 | * @filp: the file | |
177 | * @cmd: the command | |
178 | * @arg: command arg | |
179 | * | |
180 | * This ioctl implements lttng commands: | |
baf20995 MD |
181 | * LTTNG_CHANNEL |
182 | * Returns a LTTng channel file descriptor | |
ad1c05e1 MD |
183 | * |
184 | * The returned channel will be deleted when its file descriptor is closed. | |
185 | */ | |
186 | static | |
187 | long lttng_session_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) | |
188 | { | |
189 | switch (cmd) { | |
190 | case LTTNG_CHANNEL: | |
191 | return lttng_abi_create_channel(filp, (struct lttng_channel __user *)arg); | |
192 | default: | |
193 | return -ENOIOCTLCMD; | |
194 | } | |
195 | } | |
196 | ||
03037b98 MD |
197 | /* |
198 | * Called when the last file reference is dropped. | |
199 | * | |
200 | * Big fat note: channels and events are invariant for the whole session after | |
201 | * their creation. So this session destruction also destroys all channel and | |
202 | * event structures specific to this session (they are not destroyed when their | |
203 | * individual file is released). | |
204 | */ | |
ad1c05e1 | 205 | static |
03037b98 | 206 | int lttng_session_release(struct inode *inode, struct file *file) |
ad1c05e1 | 207 | { |
03037b98 MD |
208 | struct ltt_session *session = file->private_data; |
209 | return ltt_session_destroy(session); | |
ad1c05e1 | 210 | } |
ad1c05e1 MD |
211 | |
212 | static const struct file_operations lttng_session_fops = { | |
03037b98 | 213 | .release = lttng_session_release, |
ad1c05e1 MD |
214 | .unlocked_ioctl = lttng_session_ioctl, |
215 | #ifdef CONFIG_COMPAT | |
03037b98 | 216 | .compat_ioctl = lttng_session_ioctl, |
ad1c05e1 MD |
217 | #endif |
218 | } | |
219 | ||
220 | static | |
221 | int lttng_abi_open_stream(struct file *channel_filp) | |
222 | { | |
223 | struct ltt_channel *channel = channel_filp->private_data; | |
224 | struct lib_ring_buffer *buf; | |
225 | int stream_fd, ret; | |
226 | ||
227 | buf = ltt_buffer_read_open(channel->chan); | |
228 | if (!buf) | |
229 | return -ENOENT; | |
230 | ||
231 | stream_fd = get_unused_fd_flags(O_RDWR); | |
232 | if (stream_fd < 0) { | |
233 | ret = stream_fd; | |
234 | goto fd_error; | |
235 | } | |
236 | stream_filp = anon_inode_getfile("[lttng_stream]", | |
7f57c73c | 237 | &lib_ring_buffer_file_operations, |
ad1c05e1 MD |
238 | buf, O_RDWR); |
239 | if (IS_ERR(stream_filp)) { | |
240 | ret = PTR_ERR(stream_filp); | |
241 | goto file_error; | |
242 | } | |
03037b98 | 243 | fd_install(stream_fd, stream_filp); |
ad1c05e1 MD |
244 | /* The stream holds a reference on the channel */ |
245 | atomic_inc(&channel_filp->f_count); | |
246 | return stream_fd; | |
247 | ||
248 | file_error: | |
249 | put_unused_fd(stream_fd); | |
250 | fd_error: | |
251 | ltt_buffer_read_close(buf); | |
252 | return ret; | |
253 | } | |
254 | ||
653fe716 MD |
255 | static |
256 | int lttng_abi_create_event(struct file *channel_filp, | |
257 | struct lttng_event __user *uevent_param) | |
258 | { | |
259 | struct ltt_channel *channel = channel_filp->private_data; | |
260 | struct ltt_event *event; | |
261 | char *event_name; | |
262 | struct lttng_event event_param; | |
263 | int event_fd, ret; | |
264 | ||
265 | if (copy_from_user(&event_param, uevent_param, sizeof(event_param))) | |
266 | return -EFAULT; | |
267 | event_name = kmalloc(PATH_MAX, GFP_KERNEL); | |
268 | if (!event_name) | |
269 | return -ENOMEM; | |
270 | if (strncpy_from_user(event_name, &uevent_param->name, PATH_MAX)) { | |
271 | ret = -EFAULT; | |
272 | goto name_error; | |
273 | } | |
274 | event_name[PATH_MAX - 1] = '\0'; | |
653fe716 MD |
275 | event_fd = get_unused_fd_flags(O_RDWR); |
276 | if (event_fd < 0) { | |
277 | ret = event_fd; | |
278 | goto fd_error; | |
279 | } | |
280 | event_filp = anon_inode_getfile("[lttng_event]", | |
305d3e42 | 281 | <tng_event_fops, /* TODO: filter */ |
03037b98 | 282 | NULL, O_RDWR); |
653fe716 MD |
283 | if (IS_ERR(event_filp)) { |
284 | ret = PTR_ERR(event_filp); | |
285 | goto file_error; | |
286 | } | |
03037b98 MD |
287 | /* |
288 | * We tolerate no failure path after event creation. It will stay | |
289 | * invariant for the rest of the session. | |
290 | */ | |
291 | event = ltt_event_create(channel, event_param->itype, event_name, NULL); | |
292 | if (!event) { | |
293 | goto event_error; | |
294 | ret = -EEXIST; | |
295 | } | |
296 | event_filp->private_data = event; | |
297 | fd_install(event_fd, event_filp); | |
653fe716 MD |
298 | /* The event holds a reference on the channel */ |
299 | atomic_inc(&channel_filp->f_count); | |
03037b98 | 300 | kfree(event_name); |
653fe716 MD |
301 | return event_fd; |
302 | ||
03037b98 MD |
303 | event_error: |
304 | fput(event_filp); | |
653fe716 MD |
305 | file_error: |
306 | put_unused_fd(event_fd); | |
307 | fd_error: | |
653fe716 MD |
308 | name_error: |
309 | kfree(event_name); | |
310 | return ret; | |
311 | } | |
ad1c05e1 MD |
312 | |
313 | /** | |
314 | * lttng_channel_ioctl - lttng syscall through ioctl | |
315 | * | |
316 | * @filp: the file | |
317 | * @cmd: the command | |
318 | * @arg: command arg | |
319 | * | |
320 | * This ioctl implements lttng commands: | |
321 | * LTTNG_STREAM | |
322 | * Returns an event stream file descriptor or failure. | |
323 | * (typically, one event stream records events from one CPU) | |
baf20995 | 324 | * LTTNG_EVENT |
ad1c05e1 | 325 | * Returns an event file descriptor or failure. |
baf20995 MD |
326 | * |
327 | * The returned session will be deleted when its file descriptor is closed. | |
328 | * Channel and event file descriptors also hold a reference on the session. | |
329 | */ | |
ad1c05e1 MD |
330 | static |
331 | long lttng_channel_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) | |
baf20995 | 332 | { |
baf20995 | 333 | switch (cmd) { |
ad1c05e1 MD |
334 | case LTTNG_STREAM: |
335 | return lttng_abi_open_stream(filp); | |
baf20995 | 336 | case LTTNG_EVENT: |
ad1c05e1 | 337 | return lttng_abi_create_event(filp, (struct lttng_event __user *)arg); |
baf20995 MD |
338 | default: |
339 | return -ENOIOCTLCMD; | |
340 | } | |
341 | } | |
342 | ||
653fe716 MD |
343 | /** |
344 | * lttng_channel_poll - lttng stream addition/removal monitoring | |
345 | * | |
346 | * @filp: the file | |
347 | * @wait: poll table | |
348 | */ | |
349 | unsigned int lttng_channel_poll(struct file *filp, poll_table *wait) | |
350 | { | |
351 | struct ltt_channel *channel = filp->private_data; | |
352 | unsigned int mask = 0; | |
353 | ||
354 | if (filp->f_mode & FMODE_READ) { | |
355 | poll_wait_set_exclusive(wait); | |
356 | poll_wait(filp, &channel->notify_wait, wait); | |
357 | ||
358 | /* TODO: identify when the channel is being finalized. */ | |
359 | if (finalized) | |
360 | return POLLHUP; | |
361 | else | |
362 | return POLLIN | POLLRDNORM; | |
363 | } | |
364 | return mask; | |
365 | ||
366 | } | |
367 | ||
0a84a57f MD |
368 | static |
369 | int lttng_channel_release(struct inode *inode, struct file *file) | |
370 | { | |
371 | struct ltt_channel *channel = file->private_data; | |
372 | fput(channel->session->file); | |
373 | return 0; | |
374 | } | |
375 | ||
ad1c05e1 | 376 | static const struct file_operations lttng_channel_fops = { |
03037b98 | 377 | .release = lttng_channel_release, |
653fe716 | 378 | .poll = lttng_channel_poll, |
ad1c05e1 | 379 | .unlocked_ioctl = lttng_channel_ioctl, |
baf20995 | 380 | #ifdef CONFIG_COMPAT |
03037b98 | 381 | .compat_ioctl = lttng_channel_ioctl, |
baf20995 MD |
382 | #endif |
383 | } | |
384 | ||
0a84a57f MD |
385 | static |
386 | int lttng_event_release(struct inode *inode, struct file *file) | |
387 | { | |
388 | struct ltt_event *event = file->private_data; | |
389 | fput(event->chan->file); | |
390 | return 0; | |
391 | } | |
392 | ||
393 | static const struct file_operations lttng_event_fops = { | |
394 | .release = lttng_event_release, | |
395 | } | |
396 | ||
baf20995 MD |
397 | static int __init ltt_debugfs_abi_init(void) |
398 | { | |
399 | int ret = 0; | |
400 | ||
401 | lttng_dentry = debugfs_create_file("lttng", NULL); | |
402 | if (IS_ERR(lttng_dentry) || !lttng_dentry) | |
403 | printk(KERN_ERR "Error creating LTTng control file\n"); | |
404 | ret = -ENOMEM; | |
405 | goto error; | |
406 | } | |
407 | error: | |
408 | return ret; | |
409 | } | |
410 | ||
411 | static void __exit ltt_debugfs_abi_exit(void) | |
412 | { | |
413 | debugfs_remote(lttng_dentry); | |
414 | } |