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_file
;
62 session
= ltt_session_create();
65 session_fd
= get_unused_fd_flags(O_RDWR
);
70 session_file
= anon_inode_getfile("[lttng_session]",
73 if (IS_ERR(session_file
)) {
74 ret
= PTR_ERR(session_file
);
77 fd_install(session_fd
, session_file
);
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();
113 long lttng_compat_ioctl(struct file
*filp
, unsigned int cmd
, unsigned long arg
)
117 return lttng_abi_create_session();
124 static const struct file_operations lttng_fops
= {
125 .unlocked_ioctl
= lttng_ioctl
,
127 .compat_ioctl
= lttng_compat_ioctl
,
131 int lttng_abi_create_channel(struct file
*session_filp
,
132 struct lttng_channel __user
*uchan_param
)
134 struct ltt_session
*session
= session_filp
->private_data
;
135 struct ltt_channel
*chan
;
136 struct file
*chan_filp
;
137 struct lttng_channel chan_param
;
141 if (copy_from_user(&chan_param
, uchan_param
, sizeof(chan_param
)))
143 chan
= ltt_channel_create(session
, chan_param
->overwrite
, NULL
,
144 chan_param
->subbuf_size
,
145 chan_param
->num_subbuf
,
146 chan_param
->switch_timer_interval
,
147 chan_param
->read_timer_interval
);
152 chan_fd
= get_unused_fd_flags(O_RDWR
);
157 chan_filp
= anon_inode_getfile("[lttng_channel]",
160 if (IS_ERR(chan_filp
)) {
161 ret
= PTR_ERR(chan_filp
);
165 /* The channel created holds a reference on the session */
166 atomic_inc(&session_filp
->f_count
);
171 put_unused_fd(chan_fd
);
173 ltt_channel_destroy(chan
);
179 * lttng_session_ioctl - lttng session fd ioctl
185 * This ioctl implements lttng commands:
187 * Returns a LTTng channel file descriptor
189 * The returned channel will be deleted when its file descriptor is closed.
192 long lttng_session_ioctl(struct file
*filp
, unsigned int cmd
, unsigned long arg
)
196 return lttng_abi_create_channel(filp
, (struct lttng_channel __user
*)arg
);
204 long lttng_session_compat_ioctl(struct file
*filp
, unsigned int cmd
, unsigned long arg
)
208 return lttng_abi_create_channel(filp
, (struct lttng_channel __user
*)arg
);
215 static const struct file_operations lttng_session_fops
= {
216 .unlocked_ioctl
= lttng_session_ioctl
,
218 .compat_ioctl
= lttng_session_compat_ioctl
,
223 int lttng_abi_open_stream(struct file
*channel_filp
)
225 struct ltt_channel
*channel
= channel_filp
->private_data
;
226 struct lib_ring_buffer
*buf
;
229 buf
= ltt_buffer_read_open(channel
->chan
);
233 stream_fd
= get_unused_fd_flags(O_RDWR
);
238 stream_filp
= anon_inode_getfile("[lttng_stream]",
241 if (IS_ERR(stream_filp
)) {
242 ret
= PTR_ERR(stream_filp
);
246 /* The stream holds a reference on the channel */
247 atomic_inc(&channel_filp
->f_count
);
251 put_unused_fd(stream_fd
);
253 ltt_buffer_read_close(buf
);
258 int lttng_abi_create_event(struct file
*channel_filp
,
259 struct lttng_event __user
*uevent_param
)
261 struct ltt_channel
*channel
= channel_filp
->private_data
;
262 struct ltt_event
*event
;
264 struct lttng_event event_param
;
267 if (copy_from_user(&event_param
, uevent_param
, sizeof(event_param
)))
269 event_name
= kmalloc(PATH_MAX
, GFP_KERNEL
);
272 if (strncpy_from_user(event_name
, &uevent_param
->name
, PATH_MAX
)) {
276 event_name
[PATH_MAX
- 1] = '\0';
277 event
= ltt_event_create(channel
, event_param
->itype
, event_name
, NULL
);
281 event_fd
= get_unused_fd_flags(O_RDWR
);
286 event_filp
= anon_inode_getfile("[lttng_event]",
289 if (IS_ERR(event_filp
)) {
290 ret
= PTR_ERR(event_filp
);
294 /* The event holds a reference on the channel */
295 atomic_inc(&channel_filp
->f_count
);
299 put_unused_fd(event_fd
);
301 ltt_event_destroy(event
);
308 * lttng_channel_ioctl - lttng syscall through ioctl
314 * This ioctl implements lttng commands:
316 * Returns an event stream file descriptor or failure.
317 * (typically, one event stream records events from one CPU)
319 * Returns an event file descriptor or failure.
321 * The returned session will be deleted when its file descriptor is closed.
322 * Channel and event file descriptors also hold a reference on the session.
325 long lttng_channel_ioctl(struct file
*filp
, unsigned int cmd
, unsigned long arg
)
329 return lttng_abi_open_stream(filp
);
331 return lttng_abi_create_event(filp
, (struct lttng_event __user
*)arg
);
339 long lttng_channel_compat_ioctl(struct file
*filp
, unsigned int cmd
, unsigned long arg
)
343 return lttng_abi_open_stream(filp
);
345 return lttng_abi_create_event(filp
, (struct lttng_event __user
*)arg
);
353 * lttng_channel_poll - lttng stream addition/removal monitoring
358 unsigned int lttng_channel_poll(struct file
*filp
, poll_table
*wait
)
360 struct ltt_channel
*channel
= filp
->private_data
;
361 unsigned int mask
= 0;
363 if (filp
->f_mode
& FMODE_READ
) {
364 poll_wait_set_exclusive(wait
);
365 poll_wait(filp
, &channel
->notify_wait
, wait
);
367 /* TODO: identify when the channel is being finalized. */
371 return POLLIN
| POLLRDNORM
;
377 static const struct file_operations lttng_channel_fops
= {
378 .poll
= lttng_channel_poll
,
379 .unlocked_ioctl
= lttng_channel_ioctl
,
381 .compat_ioctl
= lttng_channel_compat_ioctl
,
385 static int __init
ltt_debugfs_abi_init(void)
389 lttng_dentry
= debugfs_create_file("lttng", NULL
);
390 if (IS_ERR(lttng_dentry
) || !lttng_dentry
)
391 printk(KERN_ERR
"Error creating LTTng control file\n");
399 static void __exit
ltt_debugfs_abi_exit(void)
401 debugfs_remote(lttng_dentry
);