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/debugfs.h>
26 #include "ltt-events.h"
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.
33 static struct dentry
*lttng_dentry
;
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
;
39 * LTTng DebugFS ABI structures.
42 struct lttng_channel
{
43 int overwrite
; /* 1: overwrite, 0: discard */
46 unsigned int switch_timer_interval
;
47 unsigned int read_timer_interval
;
51 enum instrum_type itype
;
56 int lttng_abi_create_session(void)
58 struct ltt_session
*session
;
59 struct file
*session_filp
;
62 session
= ltt_session_create();
65 session_fd
= get_unused_fd_flags(O_RDWR
);
70 session_filp
= anon_inode_getfile("[lttng_session]",
73 if (IS_ERR(session_filp
)) {
74 ret
= PTR_ERR(session_filp
);
77 fd_install(session_fd
, session_filp
);
81 put_unused_fd(session_fd
);
83 ltt_session_destroy(session
);
88 * lttng_ioctl - lttng syscall through ioctl
94 * This ioctl implements lttng commands:
96 * Returns a LTTng trace session file descriptor
98 * The returned session will be deleted when its file descriptor is closed.
101 long lttng_ioctl(struct file
*filp
, unsigned int cmd
, unsigned long arg
)
105 return lttng_abi_create_session();
111 static const struct file_operations lttng_fops
= {
112 .unlocked_ioctl
= lttng_ioctl
,
114 .compat_ioctl
= lttng_ioctl
,
118 int lttng_abi_create_channel(struct file
*session_filp
,
119 struct lttng_channel __user
*uchan_param
)
121 struct ltt_session
*session
= session_filp
->private_data
;
122 struct ltt_channel
*chan
;
123 struct file
*chan_filp
;
124 struct lttng_channel chan_param
;
128 if (copy_from_user(&chan_param
, uchan_param
, sizeof(chan_param
)))
130 chan_fd
= get_unused_fd_flags(O_RDWR
);
135 chan_filp
= anon_inode_getfile("[lttng_channel]",
138 if (IS_ERR(chan_filp
)) {
139 ret
= PTR_ERR(chan_filp
);
143 * We tolerate no failure path after channel creation. It will stay
144 * invariant for the rest of the session.
146 chan
= ltt_channel_create(session
, chan_param
->overwrite
, NULL
,
147 chan_param
->subbuf_size
,
148 chan_param
->num_subbuf
,
149 chan_param
->switch_timer_interval
,
150 chan_param
->read_timer_interval
);
155 chan_filp
->private_data
= chan
;
156 fd_install(chan_fd
, chan_filp
);
157 /* The channel created holds a reference on the session */
158 atomic_inc(&session_filp
->f_count
);
165 put_unused_fd(chan_fd
);
171 * lttng_session_ioctl - lttng session fd ioctl
177 * This ioctl implements lttng commands:
179 * Returns a LTTng channel file descriptor
181 * The returned channel will be deleted when its file descriptor is closed.
184 long lttng_session_ioctl(struct file
*filp
, unsigned int cmd
, unsigned long arg
)
188 return lttng_abi_create_channel(filp
, (struct lttng_channel __user
*)arg
);
195 * Called when the last file reference is dropped.
197 * Big fat note: channels and events are invariant for the whole session after
198 * their creation. So this session destruction also destroys all channel and
199 * event structures specific to this session (they are not destroyed when their
200 * individual file is released).
203 int lttng_session_release(struct inode
*inode
, struct file
*file
)
205 struct ltt_session
*session
= file
->private_data
;
206 return ltt_session_destroy(session
);
209 static const struct file_operations lttng_session_fops
= {
210 .release
= lttng_session_release
,
211 .unlocked_ioctl
= lttng_session_ioctl
,
213 .compat_ioctl
= lttng_session_ioctl
,
218 int lttng_abi_open_stream(struct file
*channel_filp
)
220 struct ltt_channel
*channel
= channel_filp
->private_data
;
221 struct lib_ring_buffer
*buf
;
224 buf
= ltt_buffer_read_open(channel
->chan
);
228 stream_fd
= get_unused_fd_flags(O_RDWR
);
233 stream_filp
= anon_inode_getfile("[lttng_stream]",
234 &lib_ring_buffer_file_operations
,
236 if (IS_ERR(stream_filp
)) {
237 ret
= PTR_ERR(stream_filp
);
240 fd_install(stream_fd
, stream_filp
);
241 /* The stream holds a reference on the channel */
242 atomic_inc(&channel_filp
->f_count
);
246 put_unused_fd(stream_fd
);
248 ltt_buffer_read_close(buf
);
253 int lttng_abi_create_event(struct file
*channel_filp
,
254 struct lttng_event __user
*uevent_param
)
256 struct ltt_channel
*channel
= channel_filp
->private_data
;
257 struct ltt_event
*event
;
259 struct lttng_event event_param
;
262 if (copy_from_user(&event_param
, uevent_param
, sizeof(event_param
)))
264 event_name
= kmalloc(PATH_MAX
, GFP_KERNEL
);
267 if (strncpy_from_user(event_name
, &uevent_param
->name
, PATH_MAX
)) {
271 event_name
[PATH_MAX
- 1] = '\0';
272 event_fd
= get_unused_fd_flags(O_RDWR
);
277 event_filp
= anon_inode_getfile("[lttng_event]",
280 if (IS_ERR(event_filp
)) {
281 ret
= PTR_ERR(event_filp
);
285 * We tolerate no failure path after event creation. It will stay
286 * invariant for the rest of the session.
288 event
= ltt_event_create(channel
, event_param
->itype
, event_name
, NULL
);
293 event_filp
->private_data
= event
;
294 fd_install(event_fd
, event_filp
);
295 /* The event holds a reference on the channel */
296 atomic_inc(&channel_filp
->f_count
);
303 put_unused_fd(event_fd
);
311 * lttng_channel_ioctl - lttng syscall through ioctl
317 * This ioctl implements lttng commands:
319 * Returns an event stream file descriptor or failure.
320 * (typically, one event stream records events from one CPU)
322 * Returns an event file descriptor or failure.
324 * The returned session will be deleted when its file descriptor is closed.
325 * Channel and event file descriptors also hold a reference on the session.
328 long lttng_channel_ioctl(struct file
*filp
, unsigned int cmd
, unsigned long arg
)
332 return lttng_abi_open_stream(filp
);
334 return lttng_abi_create_event(filp
, (struct lttng_event __user
*)arg
);
341 * lttng_channel_poll - lttng stream addition/removal monitoring
346 unsigned int lttng_channel_poll(struct file
*filp
, poll_table
*wait
)
348 struct ltt_channel
*channel
= filp
->private_data
;
349 unsigned int mask
= 0;
351 if (filp
->f_mode
& FMODE_READ
) {
352 poll_wait_set_exclusive(wait
);
353 poll_wait(filp
, &channel
->notify_wait
, wait
);
355 /* TODO: identify when the channel is being finalized. */
359 return POLLIN
| POLLRDNORM
;
365 static const struct file_operations lttng_channel_fops
= {
366 .release
= lttng_channel_release
,
367 .poll
= lttng_channel_poll
,
368 .unlocked_ioctl
= lttng_channel_ioctl
,
370 .compat_ioctl
= lttng_channel_ioctl
,
374 static int __init
ltt_debugfs_abi_init(void)
378 lttng_dentry
= debugfs_create_file("lttng", NULL
);
379 if (IS_ERR(lttng_dentry
) || !lttng_dentry
)
380 printk(KERN_ERR
"Error creating LTTng control file\n");
388 static void __exit
ltt_debugfs_abi_exit(void)
390 debugfs_remote(lttng_dentry
);