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 "wrapper/vmalloc.h" /* for wrapper_vmalloc_sync_all() */
32 #include "wrapper/ringbuffer/vfs.h"
33 #include "ltt-debugfs-abi.h"
34 #include "ltt-events.h"
37 * This is LTTng's own personal way to create a system call as an external
38 * module. We use ioctl() on /sys/kernel/debug/lttng.
41 static struct dentry
*lttng_dentry
;
42 static const struct file_operations lttng_fops
;
43 static const struct file_operations lttng_session_fops
;
44 static const struct file_operations lttng_channel_fops
;
45 static const struct file_operations lttng_metadata_fops
;
46 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:
94 * LTTNG_KERNEL_SESSION
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
)
103 case LTTNG_KERNEL_SESSION
:
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 const struct lttng_event_desc
*event_desc
;
128 struct ltt_event
*event
;
131 event_desc
= ltt_event_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
, LTTNG_KERNEL_TRACEPOINTS
,
149 ltt_event_put(event_desc
);
152 return; /* not allowed to return error */
156 int lttng_abi_create_channel(struct file
*session_file
,
157 struct lttng_kernel_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_kernel_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
;
189 case METADATA_CHANNEL
:
190 transport_name
= "relay-metadata";
191 fops
= <tng_metadata_fops
;
194 transport_name
= "<unknown>";
198 * We tolerate no failure path after channel creation. It will stay
199 * invariant for the rest of the session.
201 chan
= ltt_channel_create(session
, transport_name
, NULL
,
202 chan_param
.subbuf_size
,
203 chan_param
.num_subbuf
,
204 chan_param
.switch_timer_interval
,
205 chan_param
.read_timer_interval
);
210 chan
->file
= chan_file
;
211 chan_file
->private_data
= chan
;
212 fd_install(chan_fd
, chan_file
);
213 if (channel_type
== METADATA_CHANNEL
) {
214 lttng_metadata_create_events(chan_file
);
215 session
->metadata
= chan
;
218 /* The channel created holds a reference on the session */
219 atomic_long_inc(&session_file
->f_count
);
226 put_unused_fd(chan_fd
);
232 * lttng_session_ioctl - lttng session fd ioctl
238 * This ioctl implements lttng commands:
239 * LTTNG_KERNEL_CHANNEL
240 * Returns a LTTng channel file descriptor
242 * The returned channel will be deleted when its file descriptor is closed.
245 long lttng_session_ioctl(struct file
*file
, unsigned int cmd
, unsigned long arg
)
247 struct ltt_session
*session
= file
->private_data
;
250 case LTTNG_KERNEL_CHANNEL
:
251 return lttng_abi_create_channel(file
,
252 (struct lttng_kernel_channel __user
*) arg
,
254 case LTTNG_KERNEL_SESSION_START
:
255 return ltt_session_start(session
);
256 case LTTNG_KERNEL_SESSION_STOP
:
257 return ltt_session_stop(session
);
258 case LTTNG_KERNEL_METADATA
:
259 return lttng_abi_create_channel(file
,
260 (struct lttng_kernel_channel __user
*) arg
,
268 * Called when the last file reference is dropped.
270 * Big fat note: channels and events are invariant for the whole session after
271 * their creation. So this session destruction also destroys all channel and
272 * event structures specific to this session (they are not destroyed when their
273 * individual file is released).
276 int lttng_session_release(struct inode
*inode
, struct file
*file
)
278 struct ltt_session
*session
= file
->private_data
;
281 ltt_session_destroy(session
);
285 static const struct file_operations lttng_session_fops
= {
286 .release
= lttng_session_release
,
287 .unlocked_ioctl
= lttng_session_ioctl
,
289 .compat_ioctl
= lttng_session_ioctl
,
294 int lttng_abi_open_stream(struct file
*channel_file
)
296 struct ltt_channel
*channel
= channel_file
->private_data
;
297 struct lib_ring_buffer
*buf
;
299 struct file
*stream_file
;
301 buf
= channel
->ops
->buffer_read_open(channel
->chan
);
305 stream_fd
= get_unused_fd();
310 stream_file
= anon_inode_getfile("[lttng_stream]",
311 &lib_ring_buffer_file_operations
,
313 if (IS_ERR(stream_file
)) {
314 ret
= PTR_ERR(stream_file
);
318 * OPEN_FMODE, called within anon_inode_getfile/alloc_file, don't honor
319 * FMODE_LSEEK, FMODE_PREAD nor FMODE_PWRITE. We need to read from this
320 * file descriptor, so we set FMODE_PREAD here.
322 stream_file
->f_mode
|= FMODE_PREAD
;
323 fd_install(stream_fd
, stream_file
);
325 * The stream holds a reference to the channel within the generic ring
326 * buffer library, so no need to hold a refcount on the channel and
327 * session files here.
332 put_unused_fd(stream_fd
);
334 channel
->ops
->buffer_read_close(buf
);
339 int lttng_abi_create_event(struct file
*channel_file
,
340 struct lttng_kernel_event __user
*uevent_param
)
342 struct ltt_channel
*channel
= channel_file
->private_data
;
343 const struct lttng_event_desc
*event_desc
;
344 struct ltt_event
*event
;
346 struct lttng_kernel_event event_param
;
348 struct file
*event_file
;
350 if (copy_from_user(&event_param
, uevent_param
, sizeof(event_param
)))
352 event_name
= kmalloc(PATH_MAX
, GFP_KERNEL
);
355 if (strncpy_from_user(event_name
, uevent_param
->name
, PATH_MAX
) < 0) {
359 event_name
[PATH_MAX
- 1] = '\0';
361 event_desc
= ltt_event_get(event_name
);
366 event_fd
= get_unused_fd();
371 event_file
= anon_inode_getfile("[lttng_event]",
374 if (IS_ERR(event_file
)) {
375 ret
= PTR_ERR(event_file
);
379 * We tolerate no failure path after event creation. It will stay
380 * invariant for the rest of the session.
382 event
= ltt_event_create(channel
, event_name
, event_param
.instrumentation
,
388 event_file
->private_data
= event
;
389 fd_install(event_fd
, event_file
);
390 /* The event holds a reference on the channel */
391 atomic_long_inc(&channel_file
->f_count
);
398 put_unused_fd(event_fd
);
400 ltt_event_put(event_desc
);
408 * lttng_channel_ioctl - lttng syscall through ioctl
414 * This ioctl implements lttng commands:
415 * LTTNG_KERNEL_STREAM
416 * Returns an event stream file descriptor or failure.
417 * (typically, one event stream records events from one CPU)
419 * Returns an event file descriptor or failure.
421 * Channel and event file descriptors also hold a reference on the session.
424 long lttng_channel_ioctl(struct file
*file
, unsigned int cmd
, unsigned long arg
)
427 case LTTNG_KERNEL_STREAM
:
428 return lttng_abi_open_stream(file
);
429 case LTTNG_KERNEL_EVENT
:
430 return lttng_abi_create_event(file
, (struct lttng_kernel_event __user
*) arg
);
437 * lttng_metadata_ioctl - lttng syscall through ioctl
443 * This ioctl implements lttng commands:
444 * LTTNG_KERNEL_STREAM
445 * Returns an event stream file descriptor or failure.
447 * Channel and event file descriptors also hold a reference on the session.
450 long lttng_metadata_ioctl(struct file
*file
, unsigned int cmd
, unsigned long arg
)
453 case LTTNG_KERNEL_STREAM
:
454 return lttng_abi_open_stream(file
);
463 * lttng_channel_poll - lttng stream addition/removal monitoring
468 unsigned int lttng_channel_poll(struct file
*file
, poll_table
*wait
)
470 struct ltt_channel
*channel
= file
->private_data
;
471 unsigned int mask
= 0;
473 if (file
->f_mode
& FMODE_READ
) {
474 poll_wait_set_exclusive(wait
);
475 poll_wait(file
, &channel
->notify_wait
, wait
);
477 /* TODO: identify when the channel is being finalized. */
481 return POLLIN
| POLLRDNORM
;
489 int lttng_channel_release(struct inode
*inode
, struct file
*file
)
491 struct ltt_channel
*channel
= file
->private_data
;
494 fput(channel
->session
->file
);
498 static const struct file_operations lttng_channel_fops
= {
499 .release
= lttng_channel_release
,
502 .poll
= lttng_channel_poll
,
504 .unlocked_ioctl
= lttng_channel_ioctl
,
506 .compat_ioctl
= lttng_channel_ioctl
,
510 static const struct file_operations lttng_metadata_fops
= {
511 .release
= lttng_channel_release
,
512 .unlocked_ioctl
= lttng_metadata_ioctl
,
514 .compat_ioctl
= lttng_metadata_ioctl
,
519 int lttng_event_release(struct inode
*inode
, struct file
*file
)
521 struct ltt_event
*event
= file
->private_data
;
524 ltt_event_unregister(event
);
525 fput(event
->chan
->file
);
530 /* TODO: filter control ioctl */
531 static const struct file_operations lttng_event_fops
= {
532 .release
= lttng_event_release
,
535 int __init
ltt_debugfs_abi_init(void)
539 wrapper_vmalloc_sync_all();
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
);