4 * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
8 * Mimic system calls for:
9 * - session creation, returns a file descriptor or failure.
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.
25 #include <linux/module.h>
26 #include <linux/debugfs.h>
27 #include <linux/anon_inodes.h>
28 #include <linux/file.h>
29 #include <linux/uaccess.h>
30 #include <linux/slab.h>
31 #include <linux/ringbuffer/vfs.h>
32 #include "ltt-debugfs-abi.h"
33 #include "ltt-events.h"
36 * This is LTTng's own personal way to create a system call as an external
37 * module. We use ioctl() on /sys/kernel/debug/lttng.
40 static struct dentry
*lttng_dentry
;
41 static const struct file_operations lttng_fops
;
42 static const struct file_operations lttng_session_fops
;
43 static const struct file_operations lttng_channel_fops
;
44 static const struct file_operations lttng_metadata_fops
;
45 static const struct file_operations lttng_event_fops
;
54 int lttng_abi_create_session(void)
56 struct ltt_session
*session
;
57 struct file
*session_file
;
60 session
= ltt_session_create();
63 session_fd
= get_unused_fd();
68 session_file
= anon_inode_getfile("[lttng_session]",
71 if (IS_ERR(session_file
)) {
72 ret
= PTR_ERR(session_file
);
75 session
->file
= session_file
;
76 fd_install(session_fd
, session_file
);
80 put_unused_fd(session_fd
);
82 ltt_session_destroy(session
);
87 * lttng_ioctl - lttng syscall through ioctl
93 * This ioctl implements lttng commands:
95 * Returns a LTTng trace session file descriptor
97 * The returned session will be deleted when its file descriptor is closed.
100 long lttng_ioctl(struct file
*file
, unsigned int cmd
, unsigned long arg
)
104 return lttng_abi_create_session();
110 static const struct file_operations lttng_fops
= {
111 .unlocked_ioctl
= lttng_ioctl
,
113 .compat_ioctl
= lttng_ioctl
,
118 * We tolerate no failure in this function (if one happens, we print a dmesg
119 * error, but cannot return any error, because the channel information is
123 void lttng_metadata_create_events(struct file
*channel_file
)
125 struct ltt_channel
*channel
= channel_file
->private_data
;
126 char *event_name
= "lttng-metadata";
127 struct ltt_event
*event
;
131 probe
= ltt_probe_get(event_name
);
137 * We tolerate no failure path after event creation. It will stay
138 * invariant for the rest of the session.
140 event
= ltt_event_create(channel
, event_name
, INSTRUM_TRACEPOINTS
,
149 ltt_probe_put(probe
);
152 return; /* not allowed to return error */
156 int lttng_abi_create_channel(struct file
*session_file
,
157 struct lttng_channel __user
*uchan_param
,
158 enum channel_type channel_type
)
160 struct ltt_session
*session
= session_file
->private_data
;
161 const struct file_operations
*fops
;
162 const char *transport_name
;
163 struct ltt_channel
*chan
;
164 struct file
*chan_file
;
165 struct lttng_channel chan_param
;
169 if (copy_from_user(&chan_param
, uchan_param
, sizeof(chan_param
)))
171 chan_fd
= get_unused_fd();
176 chan_file
= anon_inode_getfile("[lttng_channel]",
179 if (IS_ERR(chan_file
)) {
180 ret
= PTR_ERR(chan_file
);
183 switch (channel_type
) {
184 case PER_CPU_CHANNEL
:
185 transport_name
= chan_param
.overwrite
?
186 "relay-overwrite" : "relay-discard";
187 fops
= <tng_channel_fops
;
190 transport_name
= chan_param
.overwrite
?
191 "global-relay-overwrite" : "global-relay-discard";
192 fops
= <tng_channel_fops
;
194 case METADATA_CHANNEL
:
195 transport_name
= "global-relay-discard";
196 fops
= <tng_metadata_fops
;
199 transport_name
= "<unknown>";
203 * We tolerate no failure path after channel creation. It will stay
204 * invariant for the rest of the session.
206 chan
= ltt_channel_create(session
, transport_name
, NULL
,
207 chan_param
.subbuf_size
,
208 chan_param
.num_subbuf
,
209 chan_param
.switch_timer_interval
,
210 chan_param
.read_timer_interval
);
215 chan
->file
= chan_file
;
216 chan_file
->private_data
= chan
;
217 fd_install(chan_fd
, chan_file
);
218 if (channel_type
== METADATA_CHANNEL
)
219 lttng_metadata_create_events(chan_file
);
221 /* The channel created holds a reference on the session */
222 atomic_long_inc(&session_file
->f_count
);
229 put_unused_fd(chan_fd
);
235 * lttng_session_ioctl - lttng session fd ioctl
241 * This ioctl implements lttng commands:
243 * Returns a LTTng channel file descriptor
245 * The returned channel will be deleted when its file descriptor is closed.
248 long lttng_session_ioctl(struct file
*file
, unsigned int cmd
, unsigned long arg
)
250 struct ltt_session
*session
= file
->private_data
;
254 return lttng_abi_create_channel(file
,
255 (struct lttng_channel __user
*)arg
,
257 case LTTNG_SESSION_START
:
258 return ltt_session_start(session
);
259 case LTTNG_SESSION_STOP
:
260 return ltt_session_stop(session
);
262 return lttng_abi_create_channel(file
,
263 (struct lttng_channel __user
*)arg
,
271 * Called when the last file reference is dropped.
273 * Big fat note: channels and events are invariant for the whole session after
274 * their creation. So this session destruction also destroys all channel and
275 * event structures specific to this session (they are not destroyed when their
276 * individual file is released).
279 int lttng_session_release(struct inode
*inode
, struct file
*file
)
281 struct ltt_session
*session
= file
->private_data
;
284 ltt_session_destroy(session
);
288 static const struct file_operations lttng_session_fops
= {
289 .release
= lttng_session_release
,
290 .unlocked_ioctl
= lttng_session_ioctl
,
292 .compat_ioctl
= lttng_session_ioctl
,
297 int lttng_abi_open_stream(struct file
*channel_file
)
299 struct ltt_channel
*channel
= channel_file
->private_data
;
300 struct lib_ring_buffer
*buf
;
302 struct file
*stream_file
;
304 buf
= channel
->ops
->buffer_read_open(channel
->chan
);
308 stream_fd
= get_unused_fd();
313 stream_file
= anon_inode_getfile("[lttng_stream]",
314 &lib_ring_buffer_file_operations
,
316 if (IS_ERR(stream_file
)) {
317 ret
= PTR_ERR(stream_file
);
321 * OPEN_FMODE, called within anon_inode_getfile/alloc_file, don't honor
322 * FMODE_LSEEK, FMODE_PREAD nor FMODE_PWRITE. We need to read from this
323 * file descriptor, so we set FMODE_PREAD here.
325 stream_file
->f_mode
|= FMODE_PREAD
;
326 fd_install(stream_fd
, stream_file
);
328 * The stream holds a reference to the channel within the generic ring
329 * buffer library, so no need to hold a refcount on the channel and
330 * session files here.
335 put_unused_fd(stream_fd
);
337 channel
->ops
->buffer_read_close(buf
);
342 int lttng_abi_create_event(struct file
*channel_file
,
343 struct lttng_event __user
*uevent_param
)
345 struct ltt_channel
*channel
= channel_file
->private_data
;
346 struct ltt_event
*event
;
348 struct lttng_event event_param
;
350 struct file
*event_file
;
353 if (copy_from_user(&event_param
, uevent_param
, sizeof(event_param
)))
355 event_name
= kmalloc(PATH_MAX
, GFP_KERNEL
);
358 if (strncpy_from_user(event_name
, uevent_param
->name
, PATH_MAX
) < 0) {
362 event_name
[PATH_MAX
- 1] = '\0';
364 probe
= ltt_probe_get(event_name
);
369 event_fd
= get_unused_fd();
374 event_file
= anon_inode_getfile("[lttng_event]",
377 if (IS_ERR(event_file
)) {
378 ret
= PTR_ERR(event_file
);
382 * We tolerate no failure path after event creation. It will stay
383 * invariant for the rest of the session.
385 event
= ltt_event_create(channel
, event_name
, event_param
.itype
,
391 event_file
->private_data
= event
;
392 fd_install(event_fd
, event_file
);
393 /* The event holds a reference on the channel */
394 atomic_long_inc(&channel_file
->f_count
);
401 put_unused_fd(event_fd
);
403 ltt_probe_put(probe
);
411 * lttng_channel_ioctl - lttng syscall through ioctl
417 * This ioctl implements lttng commands:
419 * Returns an event stream file descriptor or failure.
420 * (typically, one event stream records events from one CPU)
422 * Returns an event file descriptor or failure.
424 * Channel and event file descriptors also hold a reference on the session.
427 long lttng_channel_ioctl(struct file
*file
, unsigned int cmd
, unsigned long arg
)
431 return lttng_abi_open_stream(file
);
433 return lttng_abi_create_event(file
, (struct lttng_event __user
*)arg
);
440 * lttng_metadata_ioctl - lttng syscall through ioctl
446 * This ioctl implements lttng commands:
448 * Returns an event stream file descriptor or failure.
450 * Channel and event file descriptors also hold a reference on the session.
453 long lttng_metadata_ioctl(struct file
*file
, unsigned int cmd
, unsigned long arg
)
457 return lttng_abi_open_stream(file
);
466 * lttng_channel_poll - lttng stream addition/removal monitoring
471 unsigned int lttng_channel_poll(struct file
*file
, poll_table
*wait
)
473 struct ltt_channel
*channel
= file
->private_data
;
474 unsigned int mask
= 0;
476 if (file
->f_mode
& FMODE_READ
) {
477 poll_wait_set_exclusive(wait
);
478 poll_wait(file
, &channel
->notify_wait
, wait
);
480 /* TODO: identify when the channel is being finalized. */
484 return POLLIN
| POLLRDNORM
;
492 int lttng_channel_release(struct inode
*inode
, struct file
*file
)
494 struct ltt_channel
*channel
= file
->private_data
;
497 fput(channel
->session
->file
);
501 static const struct file_operations lttng_channel_fops
= {
502 .release
= lttng_channel_release
,
505 .poll
= lttng_channel_poll
,
507 .unlocked_ioctl
= lttng_channel_ioctl
,
509 .compat_ioctl
= lttng_channel_ioctl
,
513 static const struct file_operations lttng_metadata_fops
= {
514 .release
= lttng_channel_release
,
515 .unlocked_ioctl
= lttng_metadata_ioctl
,
517 .compat_ioctl
= lttng_metadata_ioctl
,
522 int lttng_event_release(struct inode
*inode
, struct file
*file
)
524 struct ltt_event
*event
= file
->private_data
;
527 fput(event
->chan
->file
);
531 /* TODO: filter control ioctl */
532 static const struct file_operations lttng_event_fops
= {
533 .release
= lttng_event_release
,
536 int __init
ltt_debugfs_abi_init(void)
540 lttng_dentry
= debugfs_create_file("lttng", S_IWUSR
, NULL
, NULL
,
542 if (IS_ERR(lttng_dentry
) || !lttng_dentry
) {
543 printk(KERN_ERR
"Error creating LTTng control file\n");
551 void __exit
ltt_debugfs_abi_exit(void)
553 debugfs_remove(lttng_dentry
);