[PATCH 4/11] LTTng-core 0.5.108 : core

[Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>]

[-- Attachment #1: Type: text/plain, Size: 217 bytes --]

4 - Core tracer file
patch-2.6.17-lttng-core-0.5.108-core.diff

OpenPGP public key:              http://krystal.dyndns.org:8080/key/compudj.gpg
Key fingerprint:     8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68 

[-- Attachment #2: patch-2.6.17-lttng-core-0.5.108-core.diff --]
[-- Type: text/plain, Size: 33132 bytes --]

--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1740,6 +1740,13 @@ W:	http://lsm.immunix.org
 T:	git kernel.org:/pub/scm/linux/kernel/git/chrisw/lsm-2.6.git
 S:	Supported
 
+LINUX TRACE TOOLKIT NEXT GENERATION
+P:	Mathieu Desnoyers
+M:	mathieu.desnoyers@polymtl.ca
+L:	ltt-dev@listserv.shafik.org
+W:	http://ltt.polymtl.ca
+S:	Maintained
+
 LM83 HARDWARE MONITOR DRIVER
 P:	Jean Delvare
 M:	khali@linux-fr.org
--- /dev/null
+++ b/ltt/ltt-core.c
@@ -0,0 +1,895 @@
+/*
+ * ltt-core.c
+ *
+ * (C) Copyright	2005-2006 -
+ * 		Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca)
+ *
+ * Contains the kernel code for the Linux Trace Toolkit.
+ *
+ * Author:
+ *	Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca)
+ *
+ * Inspired from LTT :
+ *	Karim Yaghmour (karim@opersys.com)
+ *	Tom Zanussi (zanussi@us.ibm.com)
+ *	Bob Wisniewski (bob@watson.ibm.com)
+ * And from K42 :
+ *  Bob Wisniewski (bob@watson.ibm.com)
+ *
+ * Changelog:
+ *  19/10/05, Complete lockless mechanism. (Mathieu Desnoyers)
+ *	27/05/05, Modular redesign and rewrite. (Mathieu Desnoyers)
+
+ * Comments :
+ * num_active_traces protects the functors. Changing the pointer is an atomic
+ * operation, but the functions can only be called when in tracing. It is then
+ * safe to unload a module in which sits a functor when no tracing is active.
+ *
+ * filter_control functor is protected by incrementing its module refcount.
+ * 
+ */
+
+#include <linux/config.h>
+#include <linux/time.h>
+#include <linux/ltt-core.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/ltt-facilities.h>
+#include <linux/rcupdate.h>
+#include <linux/sched.h>
+#include <linux/bitops.h>
+#include <linux/fs.h>
+#include <asm/atomic.h>
+#include <linux/kref.h>
+
+/* Traces list writer locking */
+DECLARE_MUTEX(ltt_traces_sem);
+
+static struct timer_list ltt_async_wakeup_timer;
+
+/* Default callbacks for modules */
+int ltt_run_filter_default(void)
+{
+	return 1;
+}
+
+int ltt_filter_control_default
+	(enum ltt_filter_control_msg msg, struct ltt_trace_struct *trace)
+{
+	return 0;
+}
+
+int ltt_statedump_default(struct ltt_trace_struct *trace)
+{
+	return 0;
+}
+
+
+
+/* Callbacks for registered modules */
+
+int (*ltt_filter_control_functor)
+	(enum ltt_filter_control_msg msg, struct ltt_trace_struct *trace) =
+					ltt_filter_control_default;
+struct module *ltt_filter_control_owner = NULL;
+
+/* These function pointers are protected by trace activation check */
+
+int (*ltt_run_filter_functor)(void) = ltt_run_filter_default;
+struct module *ltt_run_filter_owner = NULL;
+
+// FIXME : integrate the filter in the logging chain.
+//
+int (*ltt_statedump_functor)(struct ltt_trace_struct *trace) = 
+					ltt_statedump_default;
+struct module *ltt_statedump_owner = NULL;
+					
+/* Module registration methods */
+
+int ltt_module_register(enum ltt_module_function name, void *function,
+		struct module *owner)
+{
+	int ret = 0;
+	
+	/* Protect these operations by disallowing them when tracing is
+	 * active */
+	if(ltt_traces.num_active_traces) {
+		ret = -EBUSY;
+		goto end;
+	}
+
+	switch(name) {
+		case LTT_FUNCTION_RUN_FILTER:
+			if(ltt_run_filter_owner != NULL) {
+				ret = -EEXIST;
+				goto end;
+			}
+			ltt_run_filter_functor = (int (*)(void))function;
+			ltt_run_filter_owner = owner;
+			break;
+		case LTT_FUNCTION_FILTER_CONTROL:
+			if(ltt_filter_control_owner != NULL) {
+				ret = -EEXIST;
+				goto end;
+			}
+			ltt_filter_control_functor = 
+				(int (*)(enum ltt_filter_control_msg,
+				struct ltt_trace_struct *))function;
+			break;
+		case LTT_FUNCTION_STATEDUMP:
+			if(ltt_statedump_owner != NULL) {
+				ret = -EEXIST;
+				goto end;
+			}
+			ltt_statedump_functor = 
+				(int (*)(struct ltt_trace_struct *))function;
+			ltt_statedump_owner = owner;
+			break;
+	}
+
+end:
+
+	return ret;
+}
+
+
+void ltt_module_unregister(enum ltt_module_function name)
+{
+	/* (BUG_ON) It should NEVER happen : modules has their reference count
+	 * incremented when tracing is active. */
+	BUG_ON(ltt_traces.num_active_traces);
+
+	switch(name) {
+		case LTT_FUNCTION_RUN_FILTER:
+			ltt_run_filter_functor = ltt_run_filter_default;
+			ltt_run_filter_owner = NULL;
+			break;
+		case LTT_FUNCTION_FILTER_CONTROL:
+			ltt_filter_control_functor = ltt_filter_control_default;
+			break;
+		case LTT_FUNCTION_STATEDUMP:
+			ltt_statedump_functor = ltt_statedump_default;
+			ltt_statedump_owner = NULL;
+			break;
+	}
+
+}
+
+EXPORT_SYMBOL_GPL(ltt_module_register);
+EXPORT_SYMBOL_GPL(ltt_module_unregister);
+
+static spinlock_t transport_list_lock = SPIN_LOCK_UNLOCKED;
+static LIST_HEAD(ltt_transport_list);
+
+void ltt_transport_register(struct ltt_transport *transport)
+{
+	spin_lock(&transport_list_lock);
+	list_add_tail(&transport->node, &ltt_transport_list);
+	spin_unlock(&transport_list_lock);
+}
+
+void ltt_transport_unregister(struct ltt_transport *transport)
+{
+	spin_lock(&transport_list_lock);
+	list_del(&transport->node);
+	spin_unlock(&transport_list_lock);
+}
+
+EXPORT_SYMBOL_GPL(ltt_transport_register);
+EXPORT_SYMBOL_GPL(ltt_transport_unregister);
+
+
+static inline int is_channel_overwrite(enum ltt_channels chan, enum trace_mode mode)
+{
+	switch(mode) {
+		case LTT_TRACE_NORMAL: return 0;
+		case LTT_TRACE_FLIGHT:
+			switch(chan) {
+				case LTT_CHANNEL_FACILITIES: return 0;
+				default: return 1;
+			}
+		case LTT_TRACE_HYBRID:
+			switch(chan) {
+				case LTT_CHANNEL_CPU: return 1;
+				default: return 0;
+			}
+		default: return 0;
+	}
+}
+
+
+void ltt_write_trace_header(struct ltt_trace_struct *trace,
+		struct ltt_trace_header *header)
+{
+	header->magic_number = LTT_TRACER_MAGIC_NUMBER;
+	header->major_version = LTT_TRACER_VERSION_MAJOR;
+	header->minor_version = LTT_TRACER_VERSION_MINOR;
+	header->float_word_order = 0;	 /* Kernel : no floating point */
+	header->arch_type = LTT_ARCH_TYPE;
+	header->arch_size = sizeof(void*);
+	header->arch_variant = LTT_ARCH_VARIANT;
+	switch(trace->mode) {
+		case LTT_TRACE_NORMAL:
+			header->flight_recorder = 0;
+			break;
+		case LTT_TRACE_FLIGHT:
+			header->flight_recorder = 1;
+			break;
+		case LTT_TRACE_HYBRID:
+			header->flight_recorder = 2;
+			break;
+		default:
+			header->flight_recorder = 0;
+	}
+	
+#ifdef CONFIG_LTT_HEARTBEAT_EVENT
+	header->has_heartbeat = 1;
+#else
+	header->has_heartbeat = 0;
+#endif //CONFIG_LTT_HEARTBEAT_EVENT
+
+#ifdef CONFIG_LTT_ALIGNMENT
+	header->has_alignment = sizeof(void*);
+#else
+	header->has_alignment = 0;
+#endif
+
+	header->freq_scale = trace->freq_scale;
+	header->start_freq = trace->start_freq;
+	header->start_tsc = trace->start_tsc;
+	header->start_monotonic = trace->start_monotonic;
+	header->start_time_sec = trace->start_time.tv_sec;
+	header->start_time_usec = trace->start_time.tv_usec;
+}
+EXPORT_SYMBOL_GPL(ltt_write_trace_header);
+
+static void trace_async_wakeup(struct ltt_trace_struct *trace)
+{
+	/* Must check each channel for pending read wakeup */
+	trace->ops->wakeup_channel(trace->channel.facilities);
+	trace->ops->wakeup_channel(trace->channel.interrupts);
+	trace->ops->wakeup_channel(trace->channel.processes);
+	trace->ops->wakeup_channel(trace->channel.modules);
+	trace->ops->wakeup_channel(trace->channel.cpu);
+	trace->ops->wakeup_channel(trace->channel.network);
+}
+
+/* Timer to send async wakeups to the readers */
+static void async_wakeup(unsigned long data)
+{
+	struct ltt_trace_struct *trace;
+	preempt_disable();
+	list_for_each_entry_rcu(trace, &ltt_traces.head, list) {
+		trace_async_wakeup(trace);
+	}
+	preempt_enable();
+
+	del_timer(&ltt_async_wakeup_timer);
+	ltt_async_wakeup_timer.expires = jiffies + 1;
+	add_timer(&ltt_async_wakeup_timer);
+}
+
+
+
+
+void ltt_wakeup_writers(void *private)
+{
+	struct ltt_channel_buf_struct *ltt_buf = private;
+	wake_up_interruptible(&ltt_buf->write_wait);
+}
+EXPORT_SYMBOL_GPL(ltt_wakeup_writers);
+
+
+/* _ltt_trace_find :
+ * find a trace by given name.
+ *
+ * Returns a pointer to the trace structure, NULL if not found. */
+static struct ltt_trace_struct *_ltt_trace_find(char *trace_name)
+{
+	int compare;
+	struct ltt_trace_struct *trace, *found=NULL;
+	
+	list_for_each_entry(trace, &ltt_traces.head, list) {
+		compare = strncmp(trace->trace_name, trace_name, NAME_MAX);
+
+		if(compare == 0) {
+			found = trace;
+			break;
+		}
+	}
+	
+	return found;
+}
+
+/* This function must be called with traces semaphore held. */
+static int _ltt_trace_create(char *trace_name,	enum trace_mode mode,
+				struct ltt_trace_struct *new_trace)
+{
+	int err = EPERM;
+
+	if(_ltt_trace_find(trace_name) != NULL) {
+		printk(KERN_ERR "LTT : Trace %s already exists\n", trace_name);
+		err = EEXIST;
+		goto traces_error;
+	}
+	list_add_rcu(&new_trace->list, &ltt_traces.head);
+	synchronize_sched();
+	/* Everything went fine, finish creation */
+	return 0;
+
+	/* Error handling */
+traces_error:
+	return err;
+}
+
+static void print_channel_errors(struct ltt_channel_struct *ltt_chan)
+{
+	struct ltt_trace_struct *trace = ltt_chan->trace;
+	unsigned int i;
+
+	for(i=0;i<NR_CPUS;i++) {
+		if(atomic_read(&ltt_chan->buf[i].events_lost))
+			printk(KERN_ALERT 
+				"LTT : %s : %d events lost "
+				"in %s channel (cpu %u).\n",
+				ltt_chan->channel_name,
+				atomic_read(&ltt_chan->buf[i].events_lost),
+				ltt_chan->channel_name, i);
+		if(atomic_read(&ltt_chan->buf[i].corrupted_subbuffers))
+			printk(KERN_ALERT 
+				"LTT : %s : %d corrupted subbuffers "
+				"in %s channel (cpu %u).\n",
+				ltt_chan->channel_name,
+				atomic_read(
+					&ltt_chan->buf[i].corrupted_subbuffers),
+				ltt_chan->channel_name, i);
+
+		trace->ops->print_errors(trace, ltt_chan, i);
+	}
+}
+
+static void ltt_release_trace(struct kref *kref)
+{
+	struct ltt_trace_struct *trace = container_of(kref,
+			struct ltt_trace_struct, kref);
+	kfree(trace);
+}
+
+void ltt_channel_destroy(void *object)
+{
+	struct ltt_channel_struct *ltt_chan =
+		(struct ltt_channel_struct *)object;
+	unsigned int i;
+
+	/* Note : we check that every channel has equal reserve/commit count.
+	 * It's ok if reserve and commit are surrounded by disable_preempt (see
+	 * synchronize_sched()), but it won't be the case for user space
+	 * tracing... be warned. FIXME */
+	print_channel_errors(ltt_chan);
+
+	for(i=0;i<NR_CPUS;i++) {
+		kfree(ltt_chan->buf[i].reserve_count);
+		kfree(ltt_chan->buf[i].commit_count);
+	}
+	kref_put(&ltt_chan->trace->kref, ltt_release_trace);
+	kfree(ltt_chan);
+}
+EXPORT_SYMBOL_GPL(ltt_channel_destroy);
+
+
+static void init_error_count(struct ltt_channel_struct *ltt_chan)
+{	
+	unsigned int i;
+	for(i=0;i<NR_CPUS;i++) {
+		atomic_set(&ltt_chan->buf[i].events_lost, 0);
+		atomic_set(&ltt_chan->buf[i].corrupted_subbuffers, 0);
+	}
+}
+
+static inline int prepare_chan_size_num(unsigned *subbuf_size, unsigned *n_subbufs,
+	unsigned default_size, unsigned default_n_subbufs)
+{
+	if(*subbuf_size == 0) *subbuf_size = default_size;
+	if(*n_subbufs == 0) *n_subbufs = default_n_subbufs;
+	*subbuf_size = (*subbuf_size + PAGE_SIZE-1)&PAGE_MASK;
+
+	/* Subbuf size and number must both be power of two */
+	if(hweight32(*subbuf_size) != 1) return EINVAL;
+	if(hweight32(*n_subbufs) != 1) return EINVAL;
+
+	return 0;
+}
+
+static int ltt_trace_create(char *trace_name, char *trace_type,
+		enum trace_mode mode,
+		unsigned subbuf_size_low, unsigned n_subbufs_low,
+		unsigned subbuf_size_med, unsigned n_subbufs_med,
+		unsigned subbuf_size_high, unsigned n_subbufs_high)
+{
+	int err = 0;
+	struct ltt_trace_struct *new_trace;
+	unsigned long flags;
+	struct ltt_transport *tran, *transport = NULL;
+	
+	if(prepare_chan_size_num(&subbuf_size_low, &n_subbufs_low,
+		LTT_DEFAULT_SUBBUF_SIZE_LOW, LTT_DEFAULT_N_SUBBUFS_LOW))
+		return EINVAL;
+
+	if(prepare_chan_size_num(&subbuf_size_med, &n_subbufs_med,
+		LTT_DEFAULT_SUBBUF_SIZE_MED, LTT_DEFAULT_N_SUBBUFS_MED))
+		return EINVAL;
+
+	if(prepare_chan_size_num(&subbuf_size_high, &n_subbufs_high,
+		LTT_DEFAULT_SUBBUF_SIZE_HIGH, LTT_DEFAULT_N_SUBBUFS_HIGH))
+		return EINVAL;
+
+	new_trace = kcalloc(1, sizeof(struct ltt_trace_struct), GFP_KERNEL);
+	if(!new_trace) {
+		printk(KERN_ERR
+			"LTT : Unable to allocate memory for trace %s\n",
+			trace_name);
+		err = ENOMEM;
+		goto traces_error;
+	}
+
+	kref_init(&new_trace->kref);
+	new_trace->active = 0;
+	strncpy(new_trace->trace_name, trace_name, NAME_MAX);
+	new_trace->paused = 0;
+	new_trace->mode = mode;
+	new_trace->freq_scale = ltt_freq_scale();
+
+	spin_lock(&transport_list_lock);
+	list_for_each_entry(tran, &ltt_transport_list, node) {
+		if (!strcmp(tran->name, trace_type)) {
+			transport = tran;
+			break;
+		}
+	}
+	spin_unlock(&transport_list_lock);
+
+	if (!transport) {
+		err = EINVAL;
+		printk(KERN_ERR	"LTT : Transport %s is not present.\n", trace_type);
+		goto trace_error;
+	}
+
+	if(!try_module_get(transport->owner)) {
+		err = ENODEV;
+		printk(KERN_ERR	"LTT : Can't lock transport module.\n");
+		goto trace_error;
+	}
+
+	new_trace->transport = transport;
+	new_trace->ops = &transport->ops;
+
+	err = -new_trace->ops->create_dirs(new_trace);
+	if (err)
+		goto dirs_error;
+
+	local_irq_save(flags);
+	new_trace->start_freq = ltt_frequency();
+	new_trace->start_tsc = ltt_get_timestamp64();
+	do_gettimeofday(&new_trace->start_time);
+	local_irq_restore(flags);
+	
+	/* Always put the facilities channel in non-overwrite mode :
+	 * This is a very low traffic channel and it can't afford to have its
+	 * data overwritten : this data (facilities info) is necessary to be
+	 * able to read the trace.
+	 *
+	 * WARNING : The heartbeat time _shouldn't_ write events in the
+	 * facilities channel as it would make the traffic too high. This is a
+	 * problematic case with flight recorder mode. FIXME
+	 */
+	err = new_trace->ops->create_channel(trace_name, new_trace,
+			new_trace->dentry.control_root, LTT_FACILITIES_CHANNEL,
+			&new_trace->channel.facilities, subbuf_size_low,
+			n_subbufs_low, is_channel_overwrite(LTT_CHANNEL_FACILITIES, mode));
+	if(err != 0) {
+		goto facilities_error;
+	}
+	err = new_trace->ops->create_channel(trace_name, new_trace,
+			new_trace->dentry.control_root, LTT_INTERRUPTS_CHANNEL,
+			&new_trace->channel.interrupts, subbuf_size_low,
+			n_subbufs_low, is_channel_overwrite(LTT_CHANNEL_INTERRUPTS, mode));
+	if(err != 0) {
+		goto interrupts_error;
+	}
+	err = new_trace->ops->create_channel(trace_name, new_trace,
+			new_trace->dentry.control_root, LTT_PROCESSES_CHANNEL,
+			&new_trace->channel.processes, subbuf_size_med,
+			n_subbufs_med, is_channel_overwrite(LTT_CHANNEL_PROCESSES, mode));
+	if(err != 0) {
+		goto processes_error;
+	}
+	err = new_trace->ops->create_channel(trace_name, new_trace,
+			new_trace->dentry.control_root, LTT_MODULES_CHANNEL,
+			&new_trace->channel.modules, subbuf_size_low,
+			n_subbufs_low, is_channel_overwrite(LTT_CHANNEL_MODULES, mode));
+	if(err != 0) {
+		goto modules_error;
+	}
+	err = new_trace->ops->create_channel(trace_name, new_trace,
+			new_trace->dentry.trace_root, LTT_CPU_CHANNEL,
+			&new_trace->channel.cpu, subbuf_size_high,
+			n_subbufs_high, is_channel_overwrite(LTT_CHANNEL_CPU, mode));
+	if(err != 0) {
+		goto cpu_error;
+	}
+	err = new_trace->ops->create_channel(trace_name, new_trace,
+			new_trace->dentry.control_root, LTT_NETWORK_CHANNEL,
+			&new_trace->channel.network, subbuf_size_low,
+			n_subbufs_low, is_channel_overwrite(LTT_CHANNEL_NETWORK, mode));
+	if(err != 0) {
+		goto network_error;
+	}
+	
+	init_error_count(new_trace->channel.facilities);
+	init_error_count(new_trace->channel.interrupts);
+	init_error_count(new_trace->channel.processes);
+	init_error_count(new_trace->channel.modules);
+	init_error_count(new_trace->channel.cpu);
+	init_error_count(new_trace->channel.network);
+
+	down(&ltt_traces_sem);
+
+	err = _ltt_trace_create(trace_name, mode, new_trace);
+
+	up(&ltt_traces_sem);
+	if(err != 0)
+		goto lock_create_error;
+	return err;
+
+lock_create_error:
+	new_trace->ops->remove_channel(new_trace->channel.network);
+network_error:
+	new_trace->ops->remove_channel(new_trace->channel.cpu);
+cpu_error:
+	new_trace->ops->remove_channel(new_trace->channel.modules);
+modules_error:
+	new_trace->ops->remove_channel(new_trace->channel.processes);
+processes_error:
+	new_trace->ops->remove_channel(new_trace->channel.interrupts);
+interrupts_error:
+	new_trace->ops->remove_channel(new_trace->channel.facilities);
+facilities_error:
+	new_trace->ops->remove_dirs(new_trace);
+dirs_error:
+	module_put(transport->owner);
+trace_error:
+	kref_put(&new_trace->kref, ltt_release_trace);
+traces_error:
+	return err;
+}
+
+/* Must be called while sure that trace is in the list. */
+static int _ltt_trace_destroy(struct ltt_trace_struct	*trace)
+{
+	int err = EPERM;
+	
+	if(trace == NULL) {
+		err = ENOENT;
+		goto traces_error;
+	}
+	if(trace->active) {
+		printk(KERN_ERR
+			"LTT : Can't destroy trace %s : tracer is active\n",
+			trace->trace_name);
+		err = EBUSY;
+		goto active_error;
+	}
+	/* Everything went fine */
+	list_del_rcu(&trace->list);
+	synchronize_sched();
+	/* If no more trace in the list, we can free the unused facilities */
+	if(list_empty(&ltt_traces.head))
+		ltt_facility_free_unused();
+	return 0;
+
+	/* error handling */
+active_error:
+traces_error:
+	return err;
+}
+
+/* Sleepable part of the destroy */
+static void __ltt_trace_destroy(struct ltt_trace_struct	*trace)
+{
+	trace->ops->finish_channel(trace->channel.facilities);
+	trace->ops->finish_channel(trace->channel.interrupts);
+	trace->ops->finish_channel(trace->channel.processes);
+	trace->ops->finish_channel(trace->channel.modules);
+	trace->ops->finish_channel(trace->channel.cpu);
+	trace->ops->finish_channel(trace->channel.network);
+
+	flush_scheduled_work();
+
+	if(ltt_traces.num_active_traces == 0) {
+		/* We stop the asynchronous delivery of reader wakeup, but
+		 * we must make one last check for reader wakeups pending. */
+		del_timer(&ltt_async_wakeup_timer);
+	}
+	/* The currently destroyed trace is not in the trace list anymore,
+	 * so it's safe to call the async wakeup ourself. It will deliver
+	 * the last subbuffers. */
+	trace_async_wakeup(trace);
+
+	trace->ops->remove_channel(trace->channel.facilities);
+	trace->ops->remove_channel(trace->channel.interrupts);
+	trace->ops->remove_channel(trace->channel.processes);
+	trace->ops->remove_channel(trace->channel.modules);
+	trace->ops->remove_channel(trace->channel.cpu);
+	trace->ops->remove_channel(trace->channel.network);
+
+	trace->ops->remove_dirs(trace);
+
+	module_put(trace->transport->owner);
+
+	kref_put(&trace->kref, ltt_release_trace);
+}
+
+static int ltt_trace_destroy(char *trace_name)
+{
+	int err = 0;
+	struct ltt_trace_struct* trace;
+
+	down(&ltt_traces_sem);
+	trace = _ltt_trace_find(trace_name);
+	err = _ltt_trace_destroy(trace);
+	if(err) goto error;
+	up(&ltt_traces_sem);
+	__ltt_trace_destroy(trace);
+	return err;
+
+	/* Error handling */
+error:
+	up(&ltt_traces_sem);
+	return err;
+}
+
+/* must be called from within a traces lock. */
+static int _ltt_trace_start(struct ltt_trace_struct* trace)
+{
+	int err = 0;
+
+	if(trace == NULL) {
+		err = ENOENT;
+		goto traces_error;
+	}
+	if(trace->active)
+		printk(KERN_INFO "LTT : Tracing already active for trace %s\n",
+				trace->trace_name);
+	if(ltt_traces.num_active_traces == 0) {
+		if(!try_module_get(ltt_run_filter_owner)) {
+			err = ENODEV;
+			printk(KERN_ERR "LTT : Can't lock filter module.\n");
+			goto get_ltt_run_filter_error;
+		}
+		if(!try_module_get(ltt_statedump_owner)) {
+			err = ENODEV;
+			printk(KERN_ERR
+				"LTT : Can't lock state dump module.\n");
+			goto get_ltt_statedump_error;
+		}
+#ifdef CONFIG_LTT_HEARTBEAT
+		if(ltt_heartbeat_trigger(LTT_HEARTBEAT_START)) {
+			err = ENODEV;
+			printk(KERN_ERR
+				"LTT : Heartbeat timer module no present.\n");
+			goto ltt_heartbeat_error;
+		}
+#endif //CONFIG_LTT_HEARTBEAT
+		init_timer(&ltt_async_wakeup_timer);
+		ltt_async_wakeup_timer.function = async_wakeup;
+		ltt_async_wakeup_timer.expires = jiffies + 1;
+		add_timer(&ltt_async_wakeup_timer);
+	}
+	trace->active = 1;
+	ltt_traces.num_active_traces++;	/* Read by trace points without
+					 * protection : be careful */
+	return err;
+
+	/* error handling */
+#ifdef CONFIG_LTT_HEARTBEAT
+ltt_heartbeat_error:
+	module_put(ltt_statedump_owner);
+#endif //CONFIG_LTT_HEARTBEAT
+get_ltt_statedump_error:
+	module_put(ltt_run_filter_owner);
+get_ltt_run_filter_error:
+traces_error:
+	return err;
+}
+
+static int ltt_trace_start(char *trace_name)
+{
+	int err = 0;
+	struct ltt_trace_struct* trace;
+
+	down(&ltt_traces_sem);
+
+	trace = _ltt_trace_find(trace_name);
+	if(trace == NULL) goto no_trace;
+	err = _ltt_trace_start(trace);
+
+	up(&ltt_traces_sem);
+	
+	/* Call the kernel state dump.
+	 * Events will be mixed with real kernel events, it's ok.
+	 * Notice that there is no protection on the trace : that's exactly
+	 * why we iterate on the list and check for trace equality instead of
+	 * directly using this trace handle inside the logging function. */
+	
+	/* State dump begin...
+	 * (must have send a tracing stop event if is the case...) */ //FIXME
+	ltt_facility_state_dump(trace);
+	ltt_statedump_functor(trace);
+
+	/* State dump finalize... tells state is coherent */ //FIXME
+	return err;
+
+	/* Error handling */
+no_trace:
+	up(&ltt_traces_sem);
+	return err;
+}
+
+
+/* must be called from within traces lock */
+static int _ltt_trace_stop(struct ltt_trace_struct* trace)
+{
+	int err = EPERM;
+
+	if(trace == NULL) {
+		err = ENOENT;
+		goto traces_error;
+	}
+	if(!trace->active)
+		printk(KERN_INFO "LTT : Tracing not active for trace %s\n",
+				trace->trace_name);
+	if(trace->active) {
+		trace->active = 0;
+		ltt_traces.num_active_traces--;
+		synchronize_sched(); /* Wait for each tracing to be finished */
+	}
+	if(ltt_traces.num_active_traces == 0) {
+#ifdef CONFIG_LTT_HEARTBEAT
+	/* stop the heartbeat if we are the last active trace */
+		ltt_heartbeat_trigger(LTT_HEARTBEAT_STOP);
+#endif //CONFIG_LTT_HEARTBEAT
+	/* Release the modules if we are the last active trace */
+		module_put(ltt_run_filter_owner);
+		module_put(ltt_statedump_owner);
+	}
+	/* Everything went fine */
+	return 0;
+
+	/* Error handling */
+traces_error:
+	return err;
+}
+
+static int ltt_trace_stop(char *trace_name)
+{
+	int err = 0;
+	struct ltt_trace_struct* trace;
+
+	down(&ltt_traces_sem);
+	trace = _ltt_trace_find(trace_name);
+	err = _ltt_trace_stop(trace);
+	up(&ltt_traces_sem);
+	return err;
+}
+
+
+/* Exported functions */
+
+int ltt_control(enum ltt_control_msg msg, char *trace_name, char *trace_type,
+		union ltt_control_args args)
+{
+	int err = EPERM;
+	
+	printk(KERN_ALERT "ltt_control : trace %s\n", trace_name);
+	switch(msg) {
+		case LTT_CONTROL_START:
+			printk(KERN_DEBUG "Start tracing %s\n", trace_name);
+			err = ltt_trace_start(trace_name);
+			break;
+		case LTT_CONTROL_STOP:
+			printk(KERN_DEBUG "Stop tracing %s\n", trace_name);
+			err = ltt_trace_stop(trace_name);
+			break;
+		case LTT_CONTROL_CREATE_TRACE:
+			printk(KERN_DEBUG "Creating trace %s\n", trace_name);
+			err = ltt_trace_create(trace_name, trace_type,
+				args.new_trace.mode,
+				args.new_trace.subbuf_size_low,
+				args.new_trace.n_subbufs_low,
+				args.new_trace.subbuf_size_med,
+				args.new_trace.n_subbufs_med,
+				args.new_trace.subbuf_size_high,
+				args.new_trace.n_subbufs_high);
+			break;
+		case LTT_CONTROL_DESTROY_TRACE:
+			printk(KERN_DEBUG "Destroying trace %s\n", trace_name);
+			err = ltt_trace_destroy(trace_name);
+			break;
+	}
+	return err;
+}
+EXPORT_SYMBOL_GPL(ltt_control);
+
+
+int ltt_filter_control(enum ltt_filter_control_msg msg, char *trace_name)
+{
+	int err;
+	struct ltt_trace_struct *trace;
+
+	printk(KERN_DEBUG "ltt_filter_control : trace %s\n", trace_name);
+	down(&ltt_traces_sem);
+	trace = _ltt_trace_find(trace_name);
+	if(trace == NULL) {
+		printk(KERN_ALERT
+			"Trace does not exist. Cannot proxy control request\n");
+		err = ENOENT;
+		goto trace_error;
+	}
+	if(!try_module_get(ltt_filter_control_owner)) {
+		err = ENODEV;
+		goto get_module_error;
+	}
+	switch(msg) {
+		case LTT_FILTER_DEFAULT_ACCEPT:
+			printk(KERN_DEBUG
+				"Proxy filter default accept %s\n", trace_name);
+			err = (*ltt_filter_control_functor)(msg, trace);
+			break;
+		case LTT_FILTER_DEFAULT_REJECT:
+			printk(KERN_DEBUG
+				"Proxy filter default reject %s\n", trace_name);
+			err = (*ltt_filter_control_functor)(msg, trace);
+			break;
+		default:
+			err = EPERM;
+	}
+	module_put(ltt_filter_control_owner);
+	
+get_module_error:
+trace_error:
+	up(&ltt_traces_sem);
+	return err;
+}
+EXPORT_SYMBOL_GPL(ltt_filter_control);
+
+static int __init ltt_core_init(void)
+{
+	printk(KERN_INFO "LTT : ltt-core init as module\n");
+
+	return 0;
+}
+
+static void __exit ltt_exit(void)
+{
+	struct ltt_trace_struct *trace;
+	
+	printk(KERN_INFO "LTT : ltt-core exit\n");
+	down(&ltt_traces_sem);
+	/* Stop each trace and destroy them */
+	list_for_each_entry_rcu(trace, &ltt_traces.head, list) {
+		_ltt_trace_stop(trace);
+		_ltt_trace_destroy(trace);/* it's doing a synchronize_sched() */
+		__ltt_trace_destroy(trace);
+	}
+	up(&ltt_traces_sem);
+}
+
+module_init(ltt_core_init)
+module_exit(ltt_exit)
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Linux Trace Toolkit Next Generation Tracer");
+
--- a/init/main.c
+++ b/init/main.c
@@ -47,6 +47,7 @@ #include <linux/unistd.h>
 #include <linux/rmap.h>
 #include <linux/mempolicy.h>
 #include <linux/key.h>
+#include <linux/ltt-core.h>
 
 #include <asm/io.h>
 #include <asm/bugs.h>
@@ -482,6 +483,9 @@ asmlinkage void __init start_kernel(void
 		   __stop___param - __start___param,
 		   &unknown_bootoption);
 	sort_main_extable();
+#ifdef CONFIG_LTT
+	ltt_init();
+#endif //CONFIG_LTT
 	trap_init();
 	rcu_init();
 	init_IRQ();
--- /dev/null
+++ b/kernel/ltt-base.c
@@ -0,0 +1,42 @@
+/*
+ * ltt-base.c
+ *
+ * (C) Copyright  2005 -
+ * 		Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca)
+ *
+ * Contains the kernel core code for Linux Trace Toolkit.
+ *
+ * This base ltt file is used when LTT is configured as a module. Otherwise,
+ * ltt-core defines the ltt_log_event directly. The cost of this modularisation
+ * is a pointer to dereference in the LTT tracing critical path.
+ *
+ * Author:
+ *	Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca)
+ *
+ */
+
+#include <linux/ltt-core.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <asm/atomic.h>
+
+/* Traces structures */
+struct ltt_traces ltt_traces = {
+	.head = LIST_HEAD_INIT(ltt_traces.head),
+	.num_active_traces = 0
+};
+
+EXPORT_SYMBOL(ltt_traces);
+
+volatile unsigned int ltt_nesting[NR_CPUS] = { [ 0 ... NR_CPUS-1 ] = 0 } ;
+
+EXPORT_SYMBOL(ltt_nesting);
+
+atomic_t lttng_logical_clock = ATOMIC_INIT(0);
+EXPORT_SYMBOL(lttng_logical_clock);
+
+void __init ltt_init(void)
+{
+	printk(KERN_INFO "LTT : ltt-base init\n");
+}
+
--- /dev/null
+++ b/kernel/ltt-heartbeat.c
@@ -0,0 +1,210 @@
+/*
+ * ltt-heartbeat.c
+ *
+ * (C) Copyright	2006 -
+ * 		Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca)
+ *
+ * notes : heartbeat timer cannot be used for early tracing in the boot process,
+ * as it depends on timer interrupts.
+ *
+ * The timer needs to be only on one CPU to support hotplug.
+ * We have the choice between schedule_delayed_work_on and an IPI to get each
+ * CPU to write the heartbeat. IPI have been chosen because it is considered
+ * faster than passing through the timer to get the work scheduled on all the
+ * CPUs.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/timer.h>
+#include <linux/ltt-core.h>
+#include <linux/workqueue.h>
+#include <linux/cpu.h>
+#include <linux/timex.h>
+#include <linux/ltt/ltt-facility-core.h>
+
+/* How often the LTT per-CPU timers fire */
+#define LTT_PERCPU_TIMER_FREQ  (HZ/10)
+
+static struct timer_list heartbeat_timer;
+static unsigned int precalc_heartbeat_expire = 0;
+
+#ifdef CONFIG_LTT_SYNTHETIC_TSC
+/* For architectures with 32 bits TSC */
+static struct synthetic_tsc_struct {
+	u32 tsc[2][2];	/* a pair of 2 32 bits. [0] is the MSB, [1] is LSB */
+	unsigned int index;	/* Index of the current synth. tsc. */
+} ____cacheline_aligned synthetic_tsc[NR_CPUS];
+
+/* Called from one CPU, before any tracing starts, to init each structure */
+static void ltt_heartbeat_init_synthetic_tsc(void)
+{
+	int cpu;
+	for(cpu=0;cpu<NR_CPUS;cpu++) {
+		synthetic_tsc[cpu].tsc[0][0] = 0;	
+		synthetic_tsc[cpu].tsc[0][1] = 0;	
+		synthetic_tsc[cpu].tsc[1][0] = 0;
+		synthetic_tsc[cpu].tsc[1][1] = 0;
+		synthetic_tsc[cpu].index = 0;
+	}
+}
+
+/* Called from heartbeat IPI : either in interrupt or process context */
+static void ltt_heartbeat_update_synthetic_tsc(void)
+{
+	struct synthetic_tsc_struct *cpu_synth;
+	u32 tsc;
+
+	preempt_disable();
+	cpu_synth = &synthetic_tsc[smp_processor_id()];
+	tsc = (u32)get_cycles();	/* We deal with a 32 LSB TSC */
+
+	if(tsc < cpu_synth->tsc[cpu_synth->index][1]) {
+		unsigned int new_index = cpu_synth->index ? 0 : 1; /* 0 <-> 1 */
+		/* Overflow */
+		/* Non atomic update of the non current synthetic TSC, followed
+		 * by an atomic index change. There is no write concurrency,
+		 * so the index read/write does not need to be atomic. */
+		cpu_synth->tsc[new_index][1] = tsc; /* LSB update */
+		cpu_synth->tsc[new_index][0] =
+			cpu_synth->tsc[cpu_synth->index][0]+1; /* MSB update */
+		cpu_synth->index = new_index;	/* atomic change of index */
+	} else {
+		/* No overflow : we can simply update the 32 LSB of the current
+		 * synthetic TSC as it's an atomic write. */
+		cpu_synth->tsc[cpu_synth->index][1] = tsc;
+	}
+	preempt_enable();
+}
+
+/* Called from buffer switch : in _any_ context (even NMI) */
+u64 ltt_heartbeat_read_synthetic_tsc(void)
+{
+	struct synthetic_tsc_struct *cpu_synth;
+	u64 ret;
+	unsigned int index;
+	u32 tsc;
+
+	preempt_disable();
+	cpu_synth = &synthetic_tsc[smp_processor_id()];
+	index = cpu_synth->index; /* atomic read */
+	tsc = (u32)get_cycles();	/* We deal with a 32 LSB TSC */
+
+	if(tsc < cpu_synth->tsc[index][1]) {
+		/* Overflow */
+		ret = ((u64)(cpu_synth->tsc[index][0]+1) << 32) | ((u64)tsc);
+	} else {
+		/* no overflow */
+		ret = ((u64)cpu_synth->tsc[index][0] << 32) | ((u64)tsc);
+	}
+	preempt_enable();
+	return ret;
+}
+EXPORT_SYMBOL_GPL(ltt_heartbeat_read_synthetic_tsc);
+#endif //CONFIG_LTT_SYNTHETIC_TSC
+
+
+static void heartbeat_ipi(void *info)
+{
+#ifdef CONFIG_LTT_SYNTHETIC_TSC
+	ltt_heartbeat_update_synthetic_tsc();
+#endif //CONFIG_LTT_SYNTHETIC_TSC
+
+#ifdef CONFIG_LTT_HEARTBEAT_EVENT
+	/* Log a heartbeat event for each trace, each tracefile */
+	trace_core_time_heartbeat(GET_CHANNEL_INDEX(facilities));
+	trace_core_time_heartbeat(GET_CHANNEL_INDEX(interrupts));
+	trace_core_time_heartbeat(GET_CHANNEL_INDEX(processes));
+	trace_core_time_heartbeat(GET_CHANNEL_INDEX(modules));
+	trace_core_time_heartbeat(GET_CHANNEL_INDEX(cpu));
+	trace_core_time_heartbeat(GET_CHANNEL_INDEX(network));
+#endif //CONFIG_LTT_HEARTBEAT_EVENT
+}
+
+/* We need to be in process context to do an IPI */
+static void heartbeat_work(void *dummy)
+{
+	on_each_cpu(heartbeat_ipi, NULL, 1, 0);
+}
+
+static DECLARE_WORK(hb_work, heartbeat_work, NULL);
+
+/**
+ * heartbeat_timer : - Timer function generating hearbeat.
+ * @data: unused
+ *
+ * Guarantees at least 1 execution of heartbeat before low word of TSC wraps.
+ */
+static void heartbeat_timer_fct(unsigned long data)
+{
+	PREPARE_WORK(&hb_work, heartbeat_work, NULL);
+	schedule_work(&hb_work);
+	
+	mod_timer(&heartbeat_timer, jiffies + precalc_heartbeat_expire);
+}
+
+
+/**
+ * init_heartbeat_timer: - Start timer generating hearbeat events.
+ */
+static void init_heartbeat_timer(void)
+{
+	if (loops_per_jiffy > 0) {
+		printk(KERN_DEBUG "LTT : ltt-heartbeat start\n");
+		precalc_heartbeat_expire = ( 0xffffffffUL/(loops_per_jiffy << 1)
+			- 1 - LTT_PERCPU_TIMER_FREQ) >> 1;
+
+		heartbeat_work(NULL);
+
+		init_timer(&heartbeat_timer);
+		heartbeat_timer.function = heartbeat_timer_fct;
+		heartbeat_timer.expires = jiffies + precalc_heartbeat_expire;
+		add_timer(&heartbeat_timer);
+	}
+	else
+		printk(KERN_WARNING
+			"LTT: No TSC for heartbeat timer "
+			"- continuing without one \n");
+}
+
+/**
+ * delete_heartbeat_timer: - Stop timer generating hearbeat events.
+ */
+static void delete_heartbeat_timer(void)
+{
+ 	if (loops_per_jiffy > 0) {
+		printk(KERN_DEBUG "LTT : ltt-heartbeat stop\n");
+		del_timer(&heartbeat_timer);
+	}
+}
+
+
+int ltt_heartbeat_trigger(enum ltt_heartbeat_functor_msg msg)
+{
+	printk(KERN_DEBUG "LTT : ltt-heartbeat trigger\n");
+	switch(msg) {
+		case LTT_HEARTBEAT_START:
+			init_heartbeat_timer();
+			break;
+		case LTT_HEARTBEAT_STOP:
+			delete_heartbeat_timer();
+			break;
+	}
+	return 0;
+}
+
+EXPORT_SYMBOL_GPL(ltt_heartbeat_trigger);
+
+static int __init ltt_heartbeat_init(void)
+{
+	printk(KERN_INFO "LTT : ltt-heartbeat init\n");
+#ifdef CONFIG_LTT_SYNTHETIC_TSC
+	ltt_heartbeat_init_synthetic_tsc();
+#endif //CONFIG_LTT_SYNTHETIC_TSC
+	return 0;
+}
+
+__initcall(ltt_heartbeat_init);
+
+