[lttng-modules.git] / ltt-debugfs-abi.c

/*
 * ltt-debugfs-abi.c
 *
 * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * LTTng debugfs ABI
 *
 * Mimic system calls for:
 * - session creation, returns a file descriptor or failure.
 *   - channel creation, returns a file descriptor or failure.
 *     - Operates on a session file descriptor
 *     - Takes all channel options as parameters.
 *   - stream get, returns a file descriptor or failure.
 *     - Operates on a channel file descriptor.
 *   - stream notifier get, returns a file descriptor or failure.
 *     - Operates on a channel file descriptor.
 *   - event creation, returns a file descriptor or failure.
 *     - Operates on a channel file descriptor
 *     - Takes an event name as parameter
 *     - Takes an instrumentation source as parameter
 *       - e.g. tracepoints, dynamic_probes...
 *     - Takes instrumentation source specific arguments.
 */

#include <linux/module.h>
#include <linux/debugfs.h>
#include <linux/anon_inodes.h>
#include <linux/file.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include "wrapper/vmalloc.h"	/* for wrapper_vmalloc_sync_all() */
#include "wrapper/ringbuffer/vfs.h"
#include "ltt-debugfs-abi.h"
#include "ltt-events.h"
#include "ltt-tracer.h"

/*
 * This is LTTng's own personal way to create a system call as an external
 * module. We use ioctl() on /sys/kernel/debug/lttng.
 */

static struct dentry *lttng_dentry;
static const struct file_operations lttng_fops;
static const struct file_operations lttng_session_fops;
static const struct file_operations lttng_channel_fops;
static const struct file_operations lttng_metadata_fops;
static const struct file_operations lttng_event_fops;

enum channel_type {
	PER_CPU_CHANNEL,
	METADATA_CHANNEL,
};

static
int lttng_abi_create_session(void)
{
	struct ltt_session *session;
	struct file *session_file;
	int session_fd, ret;

	session = ltt_session_create();
	if (!session)
		return -ENOMEM;
	session_fd = get_unused_fd();
	if (session_fd < 0) {
		ret = session_fd;
		goto fd_error;
	}
	session_file = anon_inode_getfile("[lttng_session]",
					  &lttng_session_fops,
					  session, O_RDWR);
	if (IS_ERR(session_file)) {
		ret = PTR_ERR(session_file);
		goto file_error;
	}
	session->file = session_file;
	fd_install(session_fd, session_file);
	return session_fd;

file_error:
	put_unused_fd(session_fd);
fd_error:
	ltt_session_destroy(session);
	return ret;
}

static
long lttng_abi_tracer_version(struct file *file, 
	struct lttng_kernel_tracer_version __user *uversion_param)
{
	struct lttng_kernel_tracer_version v;

	v.version = LTTNG_VERSION;
	v.patchlevel = LTTNG_PATCHLEVEL;
	v.sublevel = LTTNG_SUBLEVEL;

	if (copy_to_user(uversion_param, &v, sizeof(v)))
		return -EFAULT;
	return 0;
}

/**
 *	lttng_ioctl - lttng syscall through ioctl
 *
 *	@file: the file
 *	@cmd: the command
 *	@arg: command arg
 *
 *	This ioctl implements lttng commands:
 *	LTTNG_KERNEL_SESSION
 *		Returns a LTTng trace session file descriptor
 *
 * The returned session will be deleted when its file descriptor is closed.
 */
static
long lttng_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	switch (cmd) {
	case LTTNG_KERNEL_SESSION:
		return lttng_abi_create_session();
	case LTTNG_KERNEL_TRACER_VERSION:
		return lttng_abi_tracer_version(file,
				(struct lttng_kernel_tracer_version __user *) arg);
	default:
		return -ENOIOCTLCMD;
	}
}

static const struct file_operations lttng_fops = {
	.unlocked_ioctl = lttng_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl = lttng_ioctl,
#endif
};

/*
 * We tolerate no failure in this function (if one happens, we print a dmesg
 * error, but cannot return any error, because the channel information is
 * invariant.
 */
static
void lttng_metadata_create_events(struct file *channel_file)
{
	struct ltt_channel *channel = channel_file->private_data;
	char *event_name = "lttng_metadata";
	struct ltt_event *event;
	int ret;

	/*
	 * We tolerate no failure path after event creation. It will stay
	 * invariant for the rest of the session.
	 */
	event = ltt_event_create(channel, event_name, LTTNG_KERNEL_TRACEPOINTS,
				 NULL);
	if (!event) {
		goto create_error;
		ret = -EEXIST;
	}
	return;

create_error:
	WARN_ON(1);
	return;		/* not allowed to return error */
}

static
int lttng_abi_create_channel(struct file *session_file,
			     struct lttng_kernel_channel __user *uchan_param,
			     enum channel_type channel_type)
{
	struct ltt_session *session = session_file->private_data;
	const struct file_operations *fops;
	const char *transport_name;
	struct ltt_channel *chan;
	struct file *chan_file;
	struct lttng_kernel_channel chan_param;
	int chan_fd;
	int ret = 0;

	if (copy_from_user(&chan_param, uchan_param, sizeof(chan_param)))
		return -EFAULT;
	chan_fd = get_unused_fd();
	if (chan_fd < 0) {
		ret = chan_fd;
		goto fd_error;
	}
	chan_file = anon_inode_getfile("[lttng_channel]",
				       &lttng_channel_fops,
				       NULL, O_RDWR);
	if (IS_ERR(chan_file)) {
		ret = PTR_ERR(chan_file);
		goto file_error;
	}
	switch (channel_type) {
	case PER_CPU_CHANNEL:
		transport_name = chan_param.overwrite ?
			"relay-overwrite" : "relay-discard";
		fops = &lttng_channel_fops;
		break;
	case METADATA_CHANNEL:
		transport_name = "relay-metadata";
		fops = &lttng_metadata_fops;
		break;
	default:
		transport_name = "<unknown>";
		break;
	}
	/*
	 * We tolerate no failure path after channel creation. It will stay
	 * invariant for the rest of the session.
	 */
	chan = ltt_channel_create(session, transport_name, NULL,
				  chan_param.subbuf_size,
				  chan_param.num_subbuf,
				  chan_param.switch_timer_interval,
				  chan_param.read_timer_interval);
	if (!chan) {
		ret = -EINVAL;
		goto chan_error;
	}
	chan->file = chan_file;
	chan_file->private_data = chan;
	fd_install(chan_fd, chan_file);
	if (channel_type == METADATA_CHANNEL) {
		session->metadata = chan;
		lttng_metadata_create_events(chan_file);
	}

	/* The channel created holds a reference on the session */
	atomic_long_inc(&session_file->f_count);

	return chan_fd;

chan_error:
	fput(chan_file);
file_error:
	put_unused_fd(chan_fd);
fd_error:
	return ret;
}

/**
 *	lttng_session_ioctl - lttng session fd ioctl
 *
 *	@file: the file
 *	@cmd: the command
 *	@arg: command arg
 *
 *	This ioctl implements lttng commands:
 *	LTTNG_KERNEL_CHANNEL
 *		Returns a LTTng channel file descriptor
 *
 * The returned channel will be deleted when its file descriptor is closed.
 */
static
long lttng_session_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	struct ltt_session *session = file->private_data;

	switch (cmd) {
	case LTTNG_KERNEL_CHANNEL:
		return lttng_abi_create_channel(file,
				(struct lttng_kernel_channel __user *) arg,
				PER_CPU_CHANNEL);
	case LTTNG_KERNEL_SESSION_START:
		return ltt_session_start(session);
	case LTTNG_KERNEL_SESSION_STOP:
		return ltt_session_stop(session);
	case LTTNG_KERNEL_METADATA:
		return lttng_abi_create_channel(file,
				(struct lttng_kernel_channel __user *) arg,
				METADATA_CHANNEL);
	default:
		return -ENOIOCTLCMD;
	}
}

/*
 * Called when the last file reference is dropped.
 *
 * Big fat note: channels and events are invariant for the whole session after
 * their creation. So this session destruction also destroys all channel and
 * event structures specific to this session (they are not destroyed when their
 * individual file is released).
 */
static
int lttng_session_release(struct inode *inode, struct file *file)
{
	struct ltt_session *session = file->private_data;

	if (session)
		ltt_session_destroy(session);
	return 0;
}

static const struct file_operations lttng_session_fops = {
	.release = lttng_session_release,
	.unlocked_ioctl = lttng_session_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl = lttng_session_ioctl,
#endif
};

static
int lttng_abi_open_stream(struct file *channel_file)
{
	struct ltt_channel *channel = channel_file->private_data;
	struct lib_ring_buffer *buf;
	int stream_fd, ret;
	struct file *stream_file;

	buf = channel->ops->buffer_read_open(channel->chan);
	if (!buf)
		return -ENOENT;

	stream_fd = get_unused_fd();
	if (stream_fd < 0) {
		ret = stream_fd;
		goto fd_error;
	}
	stream_file = anon_inode_getfile("[lttng_stream]",
					 &lib_ring_buffer_file_operations,
					 buf, O_RDWR);
	if (IS_ERR(stream_file)) {
		ret = PTR_ERR(stream_file);
		goto file_error;
	}
	/*
	 * OPEN_FMODE, called within anon_inode_getfile/alloc_file, don't honor
	 * FMODE_LSEEK, FMODE_PREAD nor FMODE_PWRITE. We need to read from this
	 * file descriptor, so we set FMODE_PREAD here.
	 */
	stream_file->f_mode |= FMODE_PREAD;
	fd_install(stream_fd, stream_file);
	/*
	 * The stream holds a reference to the channel within the generic ring
	 * buffer library, so no need to hold a refcount on the channel and
	 * session files here.
	 */
	return stream_fd;

file_error:
	put_unused_fd(stream_fd);
fd_error:
	channel->ops->buffer_read_close(buf);
	return ret;
}

static
int lttng_abi_create_event(struct file *channel_file,
			   struct lttng_kernel_event __user *uevent_param)
{
	struct ltt_channel *channel = channel_file->private_data;
	struct ltt_event *event;
	char *event_name;
	struct lttng_kernel_event event_param;
	int event_fd, ret;
	struct file *event_file;

	if (copy_from_user(&event_param, uevent_param, sizeof(event_param)))
		return -EFAULT;
	event_name = kmalloc(PATH_MAX, GFP_KERNEL);
	if (!event_name)
		return -ENOMEM;
	if (strncpy_from_user(event_name, uevent_param->name, PATH_MAX) < 0) {
		ret = -EFAULT;
		goto name_error;
	}
	event_name[PATH_MAX - 1] = '\0';
	switch (event_param.instrumentation) {
	case LTTNG_KERNEL_KPROBES:
		event_param.u.kprobe.symbol_name[LTTNG_SYM_NAME_LEN - 1] = '\0';
		break;
	case LTTNG_KERNEL_FUNCTION_TRACER:
		event_param.u.ftrace.symbol_name[LTTNG_SYM_NAME_LEN - 1] = '\0';
		break;
	default:
		break;
	}
	event_fd = get_unused_fd();
	if (event_fd < 0) {
		ret = event_fd;
		goto fd_error;
	}
	event_file = anon_inode_getfile("[lttng_event]",
					&lttng_event_fops,
					NULL, O_RDWR);
	if (IS_ERR(event_file)) {
		ret = PTR_ERR(event_file);
		goto file_error;
	}
	/*
	 * We tolerate no failure path after event creation. It will stay
	 * invariant for the rest of the session.
	 */
	event = ltt_event_create(channel, event_name, &event_param, NULL);
	if (!event) {
		ret = -EEXIST;
		goto event_error;
	}
	event_file->private_data = event;
	fd_install(event_fd, event_file);
	/* The event holds a reference on the channel */
	atomic_long_inc(&channel_file->f_count);
	kfree(event_name);
	return event_fd;

event_error:
	fput(event_file);
file_error:
	put_unused_fd(event_fd);
fd_error:
name_error:
	kfree(event_name);
	return ret;
}

/**
 *	lttng_channel_ioctl - lttng syscall through ioctl
 *
 *	@file: the file
 *	@cmd: the command
 *	@arg: command arg
 *
 *	This ioctl implements lttng commands:
 *      LTTNG_KERNEL_STREAM
 *              Returns an event stream file descriptor or failure.
 *              (typically, one event stream records events from one CPU)
 *	LTTNG_KERNEL_EVENT
 *		Returns an event file descriptor or failure.
 *
 * Channel and event file descriptors also hold a reference on the session.
 */
static
long lttng_channel_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	switch (cmd) {
	case LTTNG_KERNEL_STREAM:
		return lttng_abi_open_stream(file);
	case LTTNG_KERNEL_EVENT:
		return lttng_abi_create_event(file, (struct lttng_kernel_event __user *) arg);
	default:
		return -ENOIOCTLCMD;
	}
}

/**
 *	lttng_metadata_ioctl - lttng syscall through ioctl
 *
 *	@file: the file
 *	@cmd: the command
 *	@arg: command arg
 *
 *	This ioctl implements lttng commands:
 *      LTTNG_KERNEL_STREAM
 *              Returns an event stream file descriptor or failure.
 *
 * Channel and event file descriptors also hold a reference on the session.
 */
static
long lttng_metadata_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	switch (cmd) {
	case LTTNG_KERNEL_STREAM:
		return lttng_abi_open_stream(file);
	default:
		return -ENOIOCTLCMD;
	}
}

/* TODO: poll */
#if 0
/**
 *	lttng_channel_poll - lttng stream addition/removal monitoring
 *
 *	@file: the file
 *	@wait: poll table
 */
unsigned int lttng_channel_poll(struct file *file, poll_table *wait)
{
	struct ltt_channel *channel = file->private_data;
	unsigned int mask = 0;

	if (file->f_mode & FMODE_READ) {
		poll_wait_set_exclusive(wait);
		poll_wait(file, &channel->notify_wait, wait);

		/* TODO: identify when the channel is being finalized. */
		if (finalized)
			return POLLHUP;
		else
			return POLLIN | POLLRDNORM;
	}
	return mask;

}
#endif //0

static
int lttng_channel_release(struct inode *inode, struct file *file)
{
	struct ltt_channel *channel = file->private_data;

	if (channel)
		fput(channel->session->file);
	return 0;
}

static const struct file_operations lttng_channel_fops = {
	.release = lttng_channel_release,
/* TODO */
#if 0
	.poll = lttng_channel_poll,
#endif //0
	.unlocked_ioctl = lttng_channel_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl = lttng_channel_ioctl,
#endif
};

static const struct file_operations lttng_metadata_fops = {
	.release = lttng_channel_release,
	.unlocked_ioctl = lttng_metadata_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl = lttng_metadata_ioctl,
#endif
};

static
int lttng_event_release(struct inode *inode, struct file *file)
{
	struct ltt_event *event = file->private_data;

	if (event) {
		ltt_event_unregister(event);
		fput(event->chan->file);
	}
	return 0;
}

/* TODO: filter control ioctl */
static const struct file_operations lttng_event_fops = {
	.release = lttng_event_release,
};

int __init ltt_debugfs_abi_init(void)
{
	int ret = 0;

	wrapper_vmalloc_sync_all();
	lttng_dentry = debugfs_create_file("lttng", S_IWUSR, NULL, NULL,
					   &lttng_fops);
	if (IS_ERR(lttng_dentry) || !lttng_dentry) {
		printk(KERN_ERR "Error creating LTTng control file\n");
		ret = -ENOMEM;
		goto error;
	}
error:
	return ret;
}

void __exit ltt_debugfs_abi_exit(void)
{
	debugfs_remove(lttng_dentry);
}
Commit	Line	Data
	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.
	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.
	23	*/
	24
	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"
	35	#include "ltt-tracer.h"
	36
	37	/*
	38	* This is LTTng's own personal way to create a system call as an external
	39	* module. We use ioctl() on /sys/kernel/debug/lttng.
	40	*/
	41
	42	static struct dentry *lttng_dentry;
	43	static const struct file_operations lttng_fops;
	44	static const struct file_operations lttng_session_fops;
	45	static const struct file_operations lttng_channel_fops;
	46	static const struct file_operations lttng_metadata_fops;
	47	static const struct file_operations lttng_event_fops;
	48
	49	enum channel_type {
	50	PER_CPU_CHANNEL,
	51	METADATA_CHANNEL,
	52	};
	53
	54	static
	55	int lttng_abi_create_session(void)
	56	{
	57	struct ltt_session *session;
	58	struct file *session_file;
	59	int session_fd, ret;
	60
	61	session = ltt_session_create();
	62	if (!session)
	63	return -ENOMEM;
	64	session_fd = get_unused_fd();
	65	if (session_fd < 0) {
	66	ret = session_fd;
	67	goto fd_error;
	68	}
	69	session_file = anon_inode_getfile("[lttng_session]",
	70	&lttng_session_fops,
	71	session, O_RDWR);
	72	if (IS_ERR(session_file)) {
	73	ret = PTR_ERR(session_file);
	74	goto file_error;
	75	}
	76	session->file = session_file;
	77	fd_install(session_fd, session_file);
	78	return session_fd;
	79
	80	file_error:
	81	put_unused_fd(session_fd);
	82	fd_error:
	83	ltt_session_destroy(session);
	84	return ret;
	85	}
	86
	87	static
	88	long lttng_abi_tracer_version(struct file *file,
	89	struct lttng_kernel_tracer_version __user *uversion_param)
	90	{
	91	struct lttng_kernel_tracer_version v;
	92
	93	v.version = LTTNG_VERSION;
	94	v.patchlevel = LTTNG_PATCHLEVEL;
	95	v.sublevel = LTTNG_SUBLEVEL;
	96
	97	if (copy_to_user(uversion_param, &v, sizeof(v)))
	98	return -EFAULT;
	99	return 0;
	100	}
	101
	102	/**
	103	* lttng_ioctl - lttng syscall through ioctl
	104	*
	105	* @file: the file
	106	* @cmd: the command
	107	* @arg: command arg
	108	*
	109	* This ioctl implements lttng commands:
	110	* LTTNG_KERNEL_SESSION
	111	* Returns a LTTng trace session file descriptor
	112	*
	113	* The returned session will be deleted when its file descriptor is closed.
	114	*/
	115	static
	116	long lttng_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
	117	{
	118	switch (cmd) {
	119	case LTTNG_KERNEL_SESSION:
	120	return lttng_abi_create_session();
	121	case LTTNG_KERNEL_TRACER_VERSION:
	122	return lttng_abi_tracer_version(file,
	123	(struct lttng_kernel_tracer_version __user *) arg);
	124	default:
	125	return -ENOIOCTLCMD;
	126	}
	127	}
	128
	129	static const struct file_operations lttng_fops = {
	130	.unlocked_ioctl = lttng_ioctl,
	131	#ifdef CONFIG_COMPAT
	132	.compat_ioctl = lttng_ioctl,
	133	#endif
	134	};
	135
	136	/*
	137	* We tolerate no failure in this function (if one happens, we print a dmesg
	138	* error, but cannot return any error, because the channel information is
	139	* invariant.
	140	*/
	141	static
	142	void lttng_metadata_create_events(struct file *channel_file)
	143	{
	144	struct ltt_channel *channel = channel_file->private_data;
	145	char *event_name = "lttng_metadata";
	146	struct ltt_event *event;
	147	int ret;
	148
	149	/*
	150	* We tolerate no failure path after event creation. It will stay
	151	* invariant for the rest of the session.
	152	*/
	153	event = ltt_event_create(channel, event_name, LTTNG_KERNEL_TRACEPOINTS,
	154	NULL);
	155	if (!event) {
	156	goto create_error;
	157	ret = -EEXIST;
	158	}
	159	return;
	160
	161	create_error:
	162	WARN_ON(1);
	163	return; /* not allowed to return error */
	164	}
	165
	166	static
	167	int lttng_abi_create_channel(struct file *session_file,
	168	struct lttng_kernel_channel __user *uchan_param,
	169	enum channel_type channel_type)
	170	{
	171	struct ltt_session *session = session_file->private_data;
	172	const struct file_operations *fops;
	173	const char *transport_name;
	174	struct ltt_channel *chan;
	175	struct file *chan_file;
	176	struct lttng_kernel_channel chan_param;
	177	int chan_fd;
	178	int ret = 0;
	179
	180	if (copy_from_user(&chan_param, uchan_param, sizeof(chan_param)))
	181	return -EFAULT;
	182	chan_fd = get_unused_fd();
	183	if (chan_fd < 0) {
	184	ret = chan_fd;
	185	goto fd_error;
	186	}
	187	chan_file = anon_inode_getfile("[lttng_channel]",
	188	&lttng_channel_fops,
	189	NULL, O_RDWR);
	190	if (IS_ERR(chan_file)) {
	191	ret = PTR_ERR(chan_file);
	192	goto file_error;
	193	}
	194	switch (channel_type) {
	195	case PER_CPU_CHANNEL:
	196	transport_name = chan_param.overwrite ?
	197	"relay-overwrite" : "relay-discard";
	198	fops = &lttng_channel_fops;
	199	break;
	200	case METADATA_CHANNEL:
	201	transport_name = "relay-metadata";
	202	fops = &lttng_metadata_fops;
	203	break;
	204	default:
	205	transport_name = "<unknown>";
	206	break;
	207	}
	208	/*
	209	* We tolerate no failure path after channel creation. It will stay
	210	* invariant for the rest of the session.
	211	*/
	212	chan = ltt_channel_create(session, transport_name, NULL,
	213	chan_param.subbuf_size,
	214	chan_param.num_subbuf,
	215	chan_param.switch_timer_interval,
	216	chan_param.read_timer_interval);
	217	if (!chan) {
	218	ret = -EINVAL;
	219	goto chan_error;
	220	}
	221	chan->file = chan_file;
	222	chan_file->private_data = chan;
	223	fd_install(chan_fd, chan_file);
	224	if (channel_type == METADATA_CHANNEL) {
	225	session->metadata = chan;
	226	lttng_metadata_create_events(chan_file);
	227	}
	228
	229	/* The channel created holds a reference on the session */
	230	atomic_long_inc(&session_file->f_count);
	231
	232	return chan_fd;
	233
	234	chan_error:
	235	fput(chan_file);
	236	file_error:
	237	put_unused_fd(chan_fd);
	238	fd_error:
	239	return ret;
	240	}
	241
	242	/**
	243	* lttng_session_ioctl - lttng session fd ioctl
	244	*
	245	* @file: the file
	246	* @cmd: the command
	247	* @arg: command arg
	248	*
	249	* This ioctl implements lttng commands:
	250	* LTTNG_KERNEL_CHANNEL
	251	* Returns a LTTng channel file descriptor
	252	*
	253	* The returned channel will be deleted when its file descriptor is closed.
	254	*/
	255	static
	256	long lttng_session_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
	257	{
	258	struct ltt_session *session = file->private_data;
	259
	260	switch (cmd) {
	261	case LTTNG_KERNEL_CHANNEL:
	262	return lttng_abi_create_channel(file,
	263	(struct lttng_kernel_channel __user *) arg,
	264	PER_CPU_CHANNEL);
	265	case LTTNG_KERNEL_SESSION_START:
	266	return ltt_session_start(session);
	267	case LTTNG_KERNEL_SESSION_STOP:
	268	return ltt_session_stop(session);
	269	case LTTNG_KERNEL_METADATA:
	270	return lttng_abi_create_channel(file,
	271	(struct lttng_kernel_channel __user *) arg,
	272	METADATA_CHANNEL);
	273	default:
	274	return -ENOIOCTLCMD;
	275	}
	276	}
	277
	278	/*
	279	* Called when the last file reference is dropped.
	280	*
	281	* Big fat note: channels and events are invariant for the whole session after
	282	* their creation. So this session destruction also destroys all channel and
	283	* event structures specific to this session (they are not destroyed when their
	284	* individual file is released).
	285	*/
	286	static
	287	int lttng_session_release(struct inode inode, struct file file)
	288	{
	289	struct ltt_session *session = file->private_data;
	290
	291	if (session)
	292	ltt_session_destroy(session);
	293	return 0;
	294	}
	295
	296	static const struct file_operations lttng_session_fops = {
	297	.release = lttng_session_release,
	298	.unlocked_ioctl = lttng_session_ioctl,
	299	#ifdef CONFIG_COMPAT
	300	.compat_ioctl = lttng_session_ioctl,
	301	#endif
	302	};
	303
	304	static
	305	int lttng_abi_open_stream(struct file *channel_file)
	306	{
	307	struct ltt_channel *channel = channel_file->private_data;
	308	struct lib_ring_buffer *buf;
	309	int stream_fd, ret;
	310	struct file *stream_file;
	311
	312	buf = channel->ops->buffer_read_open(channel->chan);
	313	if (!buf)
	314	return -ENOENT;
	315
	316	stream_fd = get_unused_fd();
	317	if (stream_fd < 0) {
	318	ret = stream_fd;
	319	goto fd_error;
	320	}
	321	stream_file = anon_inode_getfile("[lttng_stream]",
	322	&lib_ring_buffer_file_operations,
	323	buf, O_RDWR);
	324	if (IS_ERR(stream_file)) {
	325	ret = PTR_ERR(stream_file);
	326	goto file_error;
	327	}
	328	/*
	329	* OPEN_FMODE, called within anon_inode_getfile/alloc_file, don't honor
	330	* FMODE_LSEEK, FMODE_PREAD nor FMODE_PWRITE. We need to read from this
	331	* file descriptor, so we set FMODE_PREAD here.
	332	*/
	333	stream_file->f_mode \|= FMODE_PREAD;
	334	fd_install(stream_fd, stream_file);
	335	/*
	336	* The stream holds a reference to the channel within the generic ring
	337	* buffer library, so no need to hold a refcount on the channel and
	338	* session files here.
	339	*/
	340	return stream_fd;
	341
	342	file_error:
	343	put_unused_fd(stream_fd);
	344	fd_error:
	345	channel->ops->buffer_read_close(buf);
	346	return ret;
	347	}
	348
	349	static
	350	int lttng_abi_create_event(struct file *channel_file,
	351	struct lttng_kernel_event __user *uevent_param)
	352	{
	353	struct ltt_channel *channel = channel_file->private_data;
	354	struct ltt_event *event;
	355	char *event_name;
	356	struct lttng_kernel_event event_param;
	357	int event_fd, ret;
	358	struct file *event_file;
	359
	360	if (copy_from_user(&event_param, uevent_param, sizeof(event_param)))
	361	return -EFAULT;
	362	event_name = kmalloc(PATH_MAX, GFP_KERNEL);
	363	if (!event_name)
	364	return -ENOMEM;
	365	if (strncpy_from_user(event_name, uevent_param->name, PATH_MAX) < 0) {
	366	ret = -EFAULT;
	367	goto name_error;
	368	}
	369	event_name[PATH_MAX - 1] = '\0';
	370	switch (event_param.instrumentation) {
	371	case LTTNG_KERNEL_KPROBES:
	372	event_param.u.kprobe.symbol_name[LTTNG_SYM_NAME_LEN - 1] = '\0';
	373	break;
	374	case LTTNG_KERNEL_FUNCTION_TRACER:
	375	event_param.u.ftrace.symbol_name[LTTNG_SYM_NAME_LEN - 1] = '\0';
	376	break;
	377	default:
	378	break;
	379	}
	380	event_fd = get_unused_fd();
	381	if (event_fd < 0) {
	382	ret = event_fd;
	383	goto fd_error;
	384	}
	385	event_file = anon_inode_getfile("[lttng_event]",
	386	&lttng_event_fops,
	387	NULL, O_RDWR);
	388	if (IS_ERR(event_file)) {
	389	ret = PTR_ERR(event_file);
	390	goto file_error;
	391	}
	392	/*
	393	* We tolerate no failure path after event creation. It will stay
	394	* invariant for the rest of the session.
	395	*/
	396	event = ltt_event_create(channel, event_name, &event_param, NULL);
	397	if (!event) {
	398	ret = -EEXIST;
	399	goto event_error;
	400	}
	401	event_file->private_data = event;
	402	fd_install(event_fd, event_file);
	403	/* The event holds a reference on the channel */
	404	atomic_long_inc(&channel_file->f_count);
	405	kfree(event_name);
	406	return event_fd;
	407
	408	event_error:
	409	fput(event_file);
	410	file_error:
	411	put_unused_fd(event_fd);
	412	fd_error:
	413	name_error:
	414	kfree(event_name);
	415	return ret;
	416	}
	417
	418	/**
	419	* lttng_channel_ioctl - lttng syscall through ioctl
	420	*
	421	* @file: the file
	422	* @cmd: the command
	423	* @arg: command arg
	424	*
	425	* This ioctl implements lttng commands:
	426	* LTTNG_KERNEL_STREAM
	427	* Returns an event stream file descriptor or failure.
	428	* (typically, one event stream records events from one CPU)
	429	* LTTNG_KERNEL_EVENT
	430	* Returns an event file descriptor or failure.
	431	*
	432	* Channel and event file descriptors also hold a reference on the session.
	433	*/
	434	static
	435	long lttng_channel_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
	436	{
	437	switch (cmd) {
	438	case LTTNG_KERNEL_STREAM:
	439	return lttng_abi_open_stream(file);
	440	case LTTNG_KERNEL_EVENT:
	441	return lttng_abi_create_event(file, (struct lttng_kernel_event __user *) arg);
	442	default:
	443	return -ENOIOCTLCMD;
	444	}
	445	}
	446
	447	/**
	448	* lttng_metadata_ioctl - lttng syscall through ioctl
	449	*
	450	* @file: the file
	451	* @cmd: the command
	452	* @arg: command arg
	453	*
	454	* This ioctl implements lttng commands:
	455	* LTTNG_KERNEL_STREAM
	456	* Returns an event stream file descriptor or failure.
	457	*
	458	* Channel and event file descriptors also hold a reference on the session.
	459	*/
	460	static
	461	long lttng_metadata_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
	462	{
	463	switch (cmd) {
	464	case LTTNG_KERNEL_STREAM:
	465	return lttng_abi_open_stream(file);
	466	default:
	467	return -ENOIOCTLCMD;
	468	}
	469	}
	470
	471	/* TODO: poll */
	472	#if 0
	473	/**
	474	* lttng_channel_poll - lttng stream addition/removal monitoring
	475	*
	476	* @file: the file
	477	* @wait: poll table
	478	*/
	479	unsigned int lttng_channel_poll(struct file file, poll_table wait)
	480	{
	481	struct ltt_channel *channel = file->private_data;
	482	unsigned int mask = 0;
	483
	484	if (file->f_mode & FMODE_READ) {
	485	poll_wait_set_exclusive(wait);
	486	poll_wait(file, &channel->notify_wait, wait);
	487
	488	/* TODO: identify when the channel is being finalized. */
	489	if (finalized)
	490	return POLLHUP;
	491	else
	492	return POLLIN \| POLLRDNORM;
	493	}
	494	return mask;
	495
	496	}
	497	#endif //0
	498
	499	static
	500	int lttng_channel_release(struct inode inode, struct file file)
	501	{
	502	struct ltt_channel *channel = file->private_data;
	503
	504	if (channel)
	505	fput(channel->session->file);
	506	return 0;
	507	}
	508
	509	static const struct file_operations lttng_channel_fops = {
	510	.release = lttng_channel_release,
	511	/* TODO */
	512	#if 0
	513	.poll = lttng_channel_poll,
	514	#endif //0
	515	.unlocked_ioctl = lttng_channel_ioctl,
	516	#ifdef CONFIG_COMPAT
	517	.compat_ioctl = lttng_channel_ioctl,
	518	#endif
	519	};
	520
	521	static const struct file_operations lttng_metadata_fops = {
	522	.release = lttng_channel_release,
	523	.unlocked_ioctl = lttng_metadata_ioctl,
	524	#ifdef CONFIG_COMPAT
	525	.compat_ioctl = lttng_metadata_ioctl,
	526	#endif
	527	};
	528
	529	static
	530	int lttng_event_release(struct inode inode, struct file file)
	531	{
	532	struct ltt_event *event = file->private_data;
	533
	534	if (event) {
	535	ltt_event_unregister(event);
	536	fput(event->chan->file);
	537	}
	538	return 0;
	539	}
	540
	541	/* TODO: filter control ioctl */
	542	static const struct file_operations lttng_event_fops = {
	543	.release = lttng_event_release,
	544	};
	545
	546	int __init ltt_debugfs_abi_init(void)
	547	{
	548	int ret = 0;
	549
	550	wrapper_vmalloc_sync_all();
	551	lttng_dentry = debugfs_create_file("lttng", S_IWUSR, NULL, NULL,
	552	&lttng_fops);
	553	if (IS_ERR(lttng_dentry) \|\| !lttng_dentry) {
	554	printk(KERN_ERR "Error creating LTTng control file\n");
	555	ret = -ENOMEM;
	556	goto error;
	557	}
	558	error:
	559	return ret;
	560	}
	561
	562	void __exit ltt_debugfs_abi_exit(void)
	563	{
	564	debugfs_remove(lttng_dentry);
	565	}