kernel/tracepoint.c - LeafOS-Devices/android_kernel_samsung_gta4xl - Gitiles

 /*
  * Copyright (C) 2008 Mathieu Desnoyers
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  */
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/types.h>
 #include <linux/jhash.h>
 #include <linux/list.h>
 #include <linux/rcupdate.h>
 #include <linux/tracepoint.h>
 #include <linux/err.h>
 #include <linux/slab.h>

 extern struct tracepoint __start___tracepoints[];
 extern struct tracepoint __stop___tracepoints[];

 /* Set to 1 to enable tracepoint debug output */
 static const int tracepoint_debug;

 /*
  * tracepoints_mutex nests inside module_mutex. Tracepoints mutex protects the
  * builtin and module tracepoints and the hash table.
  */
 static DEFINE_MUTEX(tracepoints_mutex);

 /*
  * Tracepoint hash table, containing the active tracepoints.
  * Protected by tracepoints_mutex.
  */
 #define TRACEPOINT_HASH_BITS 6
 #define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS)
 static struct hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE];

 /*
  * Note about RCU :
  * It is used to to delay the free of multiple probes array until a quiescent
  * state is reached.
  * Tracepoint entries modifications are protected by the tracepoints_mutex.
  */
 struct tracepoint_entry {
 	struct hlist_node hlist;
 	void **funcs;
 	int refcount;	/* Number of times armed. 0 if disarmed. */
 	char name[0];
 };

 struct tp_probes {
 	union {
 		struct rcu_head rcu;
 		struct list_head list;
 	} u;
 	void *probes[0];
 };

 static inline void *allocate_probes(int count)
 {
 	struct tp_probes *p  = kmalloc(count * sizeof(void *)
 			+ sizeof(struct tp_probes), GFP_KERNEL);
 	return p == NULL ? NULL : p->probes;
 }

 static void rcu_free_old_probes(struct rcu_head *head)
 {
 	kfree(container_of(head, struct tp_probes, u.rcu));
 }

 static inline void release_probes(void *old)
 {
 	if (old) {
 		struct tp_probes *tp_probes = container_of(old,
 			struct tp_probes, probes[0]);
 		call_rcu_sched(&tp_probes->u.rcu, rcu_free_old_probes);
 	}
 }

 static void debug_print_probes(struct tracepoint_entry *entry)
 {
 	int i;

 	if (!tracepoint_debug || !entry->funcs)
 		return;

 	for (i = 0; entry->funcs[i]; i++)
 		printk(KERN_DEBUG "Probe %d : %p\n", i, entry->funcs[i]);
 }

 static void *
 tracepoint_entry_add_probe(struct tracepoint_entry *entry, void *probe)
 {
 	int nr_probes = 0;
 	void **old, **new;

 	WARN_ON(!probe);

 	debug_print_probes(entry);
 	old = entry->funcs;
 	if (old) {
 		/* (N -> N+1), (N != 0, 1) probes */
 		for (nr_probes = 0; old[nr_probes]; nr_probes++)
 			if (old[nr_probes] == probe)
 				return ERR_PTR(-EEXIST);
 	}
 	/* + 2 : one for new probe, one for NULL func */
 	new = allocate_probes(nr_probes + 2);
 	if (new == NULL)
 		return ERR_PTR(-ENOMEM);
 	if (old)
 		memcpy(new, old, nr_probes * sizeof(void *));
 	new[nr_probes] = probe;
 	new[nr_probes + 1] = NULL;
 	entry->refcount = nr_probes + 1;
 	entry->funcs = new;
 	debug_print_probes(entry);
 	return old;
 }

 static void *
 tracepoint_entry_remove_probe(struct tracepoint_entry *entry, void *probe)
 {
 	int nr_probes = 0, nr_del = 0, i;
 	void **old, **new;

 	old = entry->funcs;

 	if (!old)
 		return ERR_PTR(-ENOENT);

 	debug_print_probes(entry);
 	/* (N -> M), (N > 1, M >= 0) probes */
 	for (nr_probes = 0; old[nr_probes]; nr_probes++) {
 		if ((!probe || old[nr_probes] == probe))
 			nr_del++;
 	}

 	if (nr_probes - nr_del == 0) {
 		/* N -> 0, (N > 1) */
 		entry->funcs = NULL;
 		entry->refcount = 0;
 		debug_print_probes(entry);
 		return old;
 	} else {
 		int j = 0;
 		/* N -> M, (N > 1, M > 0) */
 		/* + 1 for NULL */
 		new = allocate_probes(nr_probes - nr_del + 1);
 		if (new == NULL)
 			return ERR_PTR(-ENOMEM);
 		for (i = 0; old[i]; i++)
 			if ((probe && old[i] != probe))
 				new[j++] = old[i];
 		new[nr_probes - nr_del] = NULL;
 		entry->refcount = nr_probes - nr_del;
 		entry->funcs = new;
 	}
 	debug_print_probes(entry);
 	return old;
 }

 /*
  * Get tracepoint if the tracepoint is present in the tracepoint hash table.
  * Must be called with tracepoints_mutex held.
  * Returns NULL if not present.
  */
 static struct tracepoint_entry *get_tracepoint(const char *name)
 {
 	struct hlist_head *head;
 	struct hlist_node *node;
 	struct tracepoint_entry *e;
 	u32 hash = jhash(name, strlen(name), 0);

 	head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
 	hlist_for_each_entry(e, node, head, hlist) {
 		if (!strcmp(name, e->name))
 			return e;
 	}
 	return NULL;
 }

 /*
  * Add the tracepoint to the tracepoint hash table. Must be called with
  * tracepoints_mutex held.
  */
 static struct tracepoint_entry *add_tracepoint(const char *name)
 {
 	struct hlist_head *head;
 	struct hlist_node *node;
 	struct tracepoint_entry *e;
 	size_t name_len = strlen(name) + 1;
 	u32 hash = jhash(name, name_len-1, 0);

 	head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
 	hlist_for_each_entry(e, node, head, hlist) {
 		if (!strcmp(name, e->name)) {
 			printk(KERN_NOTICE
 				"tracepoint %s busy\n", name);
 			return ERR_PTR(-EEXIST);	/* Already there */
 		}
 	}
 	/*
 	 * Using kmalloc here to allocate a variable length element. Could
 	 * cause some memory fragmentation if overused.
 	 */
 	e = kmalloc(sizeof(struct tracepoint_entry) + name_len, GFP_KERNEL);
 	if (!e)
 		return ERR_PTR(-ENOMEM);
 	memcpy(&e->name[0], name, name_len);
 	e->funcs = NULL;
 	e->refcount = 0;
 	hlist_add_head(&e->hlist, head);
 	return e;
 }

 /*
  * Remove the tracepoint from the tracepoint hash table. Must be called with
  * mutex_lock held.
  */
 static inline void remove_tracepoint(struct tracepoint_entry *e)
 {
 	hlist_del(&e->hlist);
 	kfree(e);
 }

 /*
  * Sets the probe callback corresponding to one tracepoint.
  */
 static void set_tracepoint(struct tracepoint_entry **entry,
 	struct tracepoint *elem, int active)
 {
 	WARN_ON(strcmp((*entry)->name, elem->name) != 0);

 	/*
 	 * rcu_assign_pointer has a smp_wmb() which makes sure that the new
 	 * probe callbacks array is consistent before setting a pointer to it.
 	 * This array is referenced by __DO_TRACE from
 	 * include/linux/tracepoints.h. A matching smp_read_barrier_depends()
 	 * is used.
 	 */
 	rcu_assign_pointer(elem->funcs, (*entry)->funcs);
 	elem->state = active;
 }

 /*
  * Disable a tracepoint and its probe callback.
  * Note: only waiting an RCU period after setting elem->call to the empty
  * function insures that the original callback is not used anymore. This insured
  * by preempt_disable around the call site.
  */
 static void disable_tracepoint(struct tracepoint *elem)
 {
 	elem->state = 0;
 	rcu_assign_pointer(elem->funcs, NULL);
 }

 /**
  * tracepoint_update_probe_range - Update a probe range
  * @begin: beginning of the range
  * @end: end of the range
  *
  * Updates the probe callback corresponding to a range of tracepoints.
  */
 void tracepoint_update_probe_range(struct tracepoint *begin,
 	struct tracepoint *end)
 {
 	struct tracepoint *iter;
 	struct tracepoint_entry *mark_entry;

 	mutex_lock(&tracepoints_mutex);
 	for (iter = begin; iter < end; iter++) {
 		mark_entry = get_tracepoint(iter->name);
 		if (mark_entry) {
 			set_tracepoint(&mark_entry, iter,
 					!!mark_entry->refcount);
 		} else {
 			disable_tracepoint(iter);
 		}
 	}
 	mutex_unlock(&tracepoints_mutex);
 }

 /*
  * Update probes, removing the faulty probes.
  */
 static void tracepoint_update_probes(void)
 {
 	/* Core kernel tracepoints */
 	tracepoint_update_probe_range(__start___tracepoints,
 		__stop___tracepoints);
 	/* tracepoints in modules. */
 	module_update_tracepoints();
 }

 static void *tracepoint_add_probe(const char *name, void *probe)
 {
 	struct tracepoint_entry *entry;
 	void *old;

 	entry = get_tracepoint(name);
 	if (!entry) {
 		entry = add_tracepoint(name);
 		if (IS_ERR(entry))
 			return entry;
 	}
 	old = tracepoint_entry_add_probe(entry, probe);
 	if (IS_ERR(old) && !entry->refcount)
 		remove_tracepoint(entry);
 	return old;
 }

 /**
  * tracepoint_probe_register -  Connect a probe to a tracepoint
  * @name: tracepoint name
  * @probe: probe handler
  *
  * Returns 0 if ok, error value on error.
  * The probe address must at least be aligned on the architecture pointer size.
  */
 int tracepoint_probe_register(const char *name, void *probe)
 {
 	void *old;

 	mutex_lock(&tracepoints_mutex);
 	old = tracepoint_add_probe(name, probe);
 	mutex_unlock(&tracepoints_mutex);
 	if (IS_ERR(old))
 		return PTR_ERR(old);

 	tracepoint_update_probes();		/* may update entry */
 	release_probes(old);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(tracepoint_probe_register);

 static void *tracepoint_remove_probe(const char *name, void *probe)
 {
 	struct tracepoint_entry *entry;
 	void *old;

 	entry = get_tracepoint(name);
 	if (!entry)
 		return ERR_PTR(-ENOENT);
 	old = tracepoint_entry_remove_probe(entry, probe);
 	if (IS_ERR(old))
 		return old;
 	if (!entry->refcount)
 		remove_tracepoint(entry);
 	return old;
 }

 /**
  * tracepoint_probe_unregister -  Disconnect a probe from a tracepoint
  * @name: tracepoint name
  * @probe: probe function pointer
  *
  * We do not need to call a synchronize_sched to make sure the probes have
  * finished running before doing a module unload, because the module unload
  * itself uses stop_machine(), which insures that every preempt disabled section
  * have finished.
  */
 int tracepoint_probe_unregister(const char *name, void *probe)
 {
 	void *old;

 	mutex_lock(&tracepoints_mutex);
 	old = tracepoint_remove_probe(name, probe);
 	mutex_unlock(&tracepoints_mutex);
 	if (IS_ERR(old))
 		return PTR_ERR(old);

 	tracepoint_update_probes();		/* may update entry */
 	release_probes(old);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(tracepoint_probe_unregister);

 static LIST_HEAD(old_probes);
 static int need_update;

 static void tracepoint_add_old_probes(void *old)
 {
 	need_update = 1;
 	if (old) {
 		struct tp_probes *tp_probes = container_of(old,
 			struct tp_probes, probes[0]);
 		list_add(&tp_probes->u.list, &old_probes);
 	}
 }

 /**
  * tracepoint_probe_register_noupdate -  register a probe but not connect
  * @name: tracepoint name
  * @probe: probe handler
  *
  * caller must call tracepoint_probe_update_all()
  */
 int tracepoint_probe_register_noupdate(const char *name, void *probe)
 {
 	void *old;

 	mutex_lock(&tracepoints_mutex);
 	old = tracepoint_add_probe(name, probe);
 	if (IS_ERR(old)) {
 		mutex_unlock(&tracepoints_mutex);
 		return PTR_ERR(old);
 	}
 	tracepoint_add_old_probes(old);
 	mutex_unlock(&tracepoints_mutex);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(tracepoint_probe_register_noupdate);

 /**
  * tracepoint_probe_unregister_noupdate -  remove a probe but not disconnect
  * @name: tracepoint name
  * @probe: probe function pointer
  *
  * caller must call tracepoint_probe_update_all()
  */
 int tracepoint_probe_unregister_noupdate(const char *name, void *probe)
 {
 	void *old;

 	mutex_lock(&tracepoints_mutex);
 	old = tracepoint_remove_probe(name, probe);
 	if (IS_ERR(old)) {
 		mutex_unlock(&tracepoints_mutex);
 		return PTR_ERR(old);
 	}
 	tracepoint_add_old_probes(old);
 	mutex_unlock(&tracepoints_mutex);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(tracepoint_probe_unregister_noupdate);

 /**
  * tracepoint_probe_update_all -  update tracepoints
  */
 void tracepoint_probe_update_all(void)
 {
 	LIST_HEAD(release_probes);
 	struct tp_probes *pos, *next;

 	mutex_lock(&tracepoints_mutex);
 	if (!need_update) {
 		mutex_unlock(&tracepoints_mutex);
 		return;
 	}
 	if (!list_empty(&old_probes))
 		list_replace_init(&old_probes, &release_probes);
 	need_update = 0;
 	mutex_unlock(&tracepoints_mutex);

 	tracepoint_update_probes();
 	list_for_each_entry_safe(pos, next, &release_probes, u.list) {
 		list_del(&pos->u.list);
 		call_rcu_sched(&pos->u.rcu, rcu_free_old_probes);
 	}
 }
 EXPORT_SYMBOL_GPL(tracepoint_probe_update_all);

 /**
  * tracepoint_get_iter_range - Get a next tracepoint iterator given a range.
  * @tracepoint: current tracepoints (in), next tracepoint (out)
  * @begin: beginning of the range
  * @end: end of the range
  *
  * Returns whether a next tracepoint has been found (1) or not (0).
  * Will return the first tracepoint in the range if the input tracepoint is
  * NULL.
  */
 int tracepoint_get_iter_range(struct tracepoint **tracepoint,
 	struct tracepoint *begin, struct tracepoint *end)
 {
 	if (!*tracepoint && begin != end) {
 		*tracepoint = begin;
 		return 1;
 	}
 	if (*tracepoint >= begin && *tracepoint < end)
 		return 1;
 	return 0;
 }
 EXPORT_SYMBOL_GPL(tracepoint_get_iter_range);

 static void tracepoint_get_iter(struct tracepoint_iter *iter)
 {
 	int found = 0;

 	/* Core kernel tracepoints */
 	if (!iter->module) {
 		found = tracepoint_get_iter_range(&iter->tracepoint,
 				__start___tracepoints, __stop___tracepoints);
 		if (found)
 			goto end;
 	}
 	/* tracepoints in modules. */
 	found = module_get_iter_tracepoints(iter);
 end:
 	if (!found)
 		tracepoint_iter_reset(iter);
 }

 void tracepoint_iter_start(struct tracepoint_iter *iter)
 {
 	tracepoint_get_iter(iter);
 }
 EXPORT_SYMBOL_GPL(tracepoint_iter_start);

 void tracepoint_iter_next(struct tracepoint_iter *iter)
 {
 	iter->tracepoint++;
 	/*
 	 * iter->tracepoint may be invalid because we blindly incremented it.
 	 * Make sure it is valid by marshalling on the tracepoints, getting the
 	 * tracepoints from following modules if necessary.
 	 */
 	tracepoint_get_iter(iter);
 }
 EXPORT_SYMBOL_GPL(tracepoint_iter_next);

 void tracepoint_iter_stop(struct tracepoint_iter *iter)
 {
 }
 EXPORT_SYMBOL_GPL(tracepoint_iter_stop);

 void tracepoint_iter_reset(struct tracepoint_iter *iter)
 {
 	iter->module = NULL;
 	iter->tracepoint = NULL;
 }
 EXPORT_SYMBOL_GPL(tracepoint_iter_reset);

 int tracepoint_module_notify(struct notifier_block *self,
 			     unsigned long val, void *data)
 {
 	struct module *mod = data;

 	switch (val) {
 	case MODULE_STATE_COMING:
 		tracepoint_update_probe_range(mod->tracepoints,
 			mod->tracepoints + mod->num_tracepoints);
 		break;
 	case MODULE_STATE_GOING:
 		tracepoint_update_probe_range(mod->tracepoints,
 			mod->tracepoints + mod->num_tracepoints);
 		break;
 	}
 	return 0;
 }

 struct notifier_block tracepoint_module_nb = {
 	.notifier_call = tracepoint_module_notify,
 	.priority = 0,
 };

 static int init_tracepoints(void)
 {
 	return register_module_notifier(&tracepoint_module_nb);
 }
 __initcall(init_tracepoints);
	/*
	* Copyright (C) 2008 Mathieu Desnoyers
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	*/
	#include <linux/module.h>
	#include <linux/mutex.h>
	#include <linux/types.h>
	#include <linux/jhash.h>
	#include <linux/list.h>
	#include <linux/rcupdate.h>
	#include <linux/tracepoint.h>
	#include <linux/err.h>
	#include <linux/slab.h>

	extern struct tracepoint __start___tracepoints[];
	extern struct tracepoint __stop___tracepoints[];

	/* Set to 1 to enable tracepoint debug output */
	static const int tracepoint_debug;

	/*
	* tracepoints_mutex nests inside module_mutex. Tracepoints mutex protects the
	* builtin and module tracepoints and the hash table.
	*/
	static DEFINE_MUTEX(tracepoints_mutex);

	/*
	* Tracepoint hash table, containing the active tracepoints.
	* Protected by tracepoints_mutex.
	*/
	#define TRACEPOINT_HASH_BITS 6
	#define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS)
	static struct hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE];

	/*
	* Note about RCU :
	* It is used to to delay the free of multiple probes array until a quiescent
	* state is reached.
	* Tracepoint entries modifications are protected by the tracepoints_mutex.
	*/
	struct tracepoint_entry {
	struct hlist_node hlist;
	void **funcs;
	int refcount; /* Number of times armed. 0 if disarmed. */
	char name[0];
	};

	struct tp_probes {
	union {
	struct rcu_head rcu;
	struct list_head list;
	} u;
	void *probes[0];
	};

	static inline void *allocate_probes(int count)
	{
	struct tp_probes p = kmalloc(count sizeof(void *)
	+ sizeof(struct tp_probes), GFP_KERNEL);
	return p == NULL ? NULL : p->probes;
	}

	static void rcu_free_old_probes(struct rcu_head *head)
	{
	kfree(container_of(head, struct tp_probes, u.rcu));
	}

	static inline void release_probes(void *old)
	{
	if (old) {
	struct tp_probes *tp_probes = container_of(old,
	struct tp_probes, probes[0]);
	call_rcu_sched(&tp_probes->u.rcu, rcu_free_old_probes);
	}
	}

	static void debug_print_probes(struct tracepoint_entry *entry)
	{
	int i;

	if (!tracepoint_debug \|\| !entry->funcs)
	return;

	for (i = 0; entry->funcs[i]; i++)
	printk(KERN_DEBUG "Probe %d : %p\n", i, entry->funcs[i]);
	}

	static void *
	tracepoint_entry_add_probe(struct tracepoint_entry entry, void probe)
	{
	int nr_probes = 0;
	void old, new;

	WARN_ON(!probe);

	debug_print_probes(entry);
	old = entry->funcs;
	if (old) {
	/* (N -> N+1), (N != 0, 1) probes */
	for (nr_probes = 0; old[nr_probes]; nr_probes++)
	if (old[nr_probes] == probe)
	return ERR_PTR(-EEXIST);
	}
	/* + 2 : one for new probe, one for NULL func */
	new = allocate_probes(nr_probes + 2);
	if (new == NULL)
	return ERR_PTR(-ENOMEM);
	if (old)
	memcpy(new, old, nr_probes * sizeof(void *));
	new[nr_probes] = probe;
	new[nr_probes + 1] = NULL;
	entry->refcount = nr_probes + 1;
	entry->funcs = new;
	debug_print_probes(entry);
	return old;
	}

	static void *
	tracepoint_entry_remove_probe(struct tracepoint_entry entry, void probe)
	{
	int nr_probes = 0, nr_del = 0, i;
	void old, new;

	old = entry->funcs;

	if (!old)
	return ERR_PTR(-ENOENT);

	debug_print_probes(entry);
	/* (N -> M), (N > 1, M >= 0) probes */
	for (nr_probes = 0; old[nr_probes]; nr_probes++) {
	if ((!probe \|\| old[nr_probes] == probe))
	nr_del++;
	}

	if (nr_probes - nr_del == 0) {
	/* N -> 0, (N > 1) */
	entry->funcs = NULL;
	entry->refcount = 0;
	debug_print_probes(entry);
	return old;
	} else {
	int j = 0;
	/* N -> M, (N > 1, M > 0) */
	/* + 1 for NULL */
	new = allocate_probes(nr_probes - nr_del + 1);
	if (new == NULL)
	return ERR_PTR(-ENOMEM);
	for (i = 0; old[i]; i++)
	if ((probe && old[i] != probe))
	new[j++] = old[i];
	new[nr_probes - nr_del] = NULL;
	entry->refcount = nr_probes - nr_del;
	entry->funcs = new;
	}
	debug_print_probes(entry);
	return old;
	}

	/*
	* Get tracepoint if the tracepoint is present in the tracepoint hash table.
	* Must be called with tracepoints_mutex held.
	* Returns NULL if not present.
	*/
	static struct tracepoint_entry get_tracepoint(const char name)
	{
	struct hlist_head *head;
	struct hlist_node *node;
	struct tracepoint_entry *e;
	u32 hash = jhash(name, strlen(name), 0);

	head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
	hlist_for_each_entry(e, node, head, hlist) {
	if (!strcmp(name, e->name))
	return e;
	}
	return NULL;
	}

	/*
	* Add the tracepoint to the tracepoint hash table. Must be called with
	* tracepoints_mutex held.
	*/
	static struct tracepoint_entry add_tracepoint(const char name)
	{
	struct hlist_head *head;
	struct hlist_node *node;
	struct tracepoint_entry *e;
	size_t name_len = strlen(name) + 1;
	u32 hash = jhash(name, name_len-1, 0);

	head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
	hlist_for_each_entry(e, node, head, hlist) {
	if (!strcmp(name, e->name)) {
	printk(KERN_NOTICE
	"tracepoint %s busy\n", name);
	return ERR_PTR(-EEXIST); /* Already there */
	}
	}
	/*
	* Using kmalloc here to allocate a variable length element. Could
	* cause some memory fragmentation if overused.
	*/
	e = kmalloc(sizeof(struct tracepoint_entry) + name_len, GFP_KERNEL);
	if (!e)
	return ERR_PTR(-ENOMEM);
	memcpy(&e->name[0], name, name_len);
	e->funcs = NULL;
	e->refcount = 0;
	hlist_add_head(&e->hlist, head);
	return e;
	}

	/*
	* Remove the tracepoint from the tracepoint hash table. Must be called with
	* mutex_lock held.
	*/
	static inline void remove_tracepoint(struct tracepoint_entry *e)
	{
	hlist_del(&e->hlist);
	kfree(e);
	}

	/*
	* Sets the probe callback corresponding to one tracepoint.
	*/
	static void set_tracepoint(struct tracepoint_entry **entry,
	struct tracepoint *elem, int active)
	{
	WARN_ON(strcmp((*entry)->name, elem->name) != 0);

	/*
	* rcu_assign_pointer has a smp_wmb() which makes sure that the new
	* probe callbacks array is consistent before setting a pointer to it.
	* This array is referenced by __DO_TRACE from
	* include/linux/tracepoints.h. A matching smp_read_barrier_depends()
	* is used.
	*/
	rcu_assign_pointer(elem->funcs, (*entry)->funcs);
	elem->state = active;
	}

	/*
	* Disable a tracepoint and its probe callback.
	* Note: only waiting an RCU period after setting elem->call to the empty
	* function insures that the original callback is not used anymore. This insured
	* by preempt_disable around the call site.
	*/
	static void disable_tracepoint(struct tracepoint *elem)
	{
	elem->state = 0;
	rcu_assign_pointer(elem->funcs, NULL);
	}

	/**
	* tracepoint_update_probe_range - Update a probe range
	* @begin: beginning of the range
	* @end: end of the range
	*
	* Updates the probe callback corresponding to a range of tracepoints.
	*/
	void tracepoint_update_probe_range(struct tracepoint *begin,
	struct tracepoint *end)
	{
	struct tracepoint *iter;
	struct tracepoint_entry *mark_entry;

	mutex_lock(&tracepoints_mutex);
	for (iter = begin; iter < end; iter++) {
	mark_entry = get_tracepoint(iter->name);
	if (mark_entry) {
	set_tracepoint(&mark_entry, iter,
	!!mark_entry->refcount);
	} else {
	disable_tracepoint(iter);
	}
	}
	mutex_unlock(&tracepoints_mutex);
	}

	/*
	* Update probes, removing the faulty probes.
	*/
	static void tracepoint_update_probes(void)
	{
	/* Core kernel tracepoints */
	tracepoint_update_probe_range(__start___tracepoints,
	__stop___tracepoints);
	/* tracepoints in modules. */
	module_update_tracepoints();
	}

	static void tracepoint_add_probe(const char name, void *probe)
	{
	struct tracepoint_entry *entry;
	void *old;

	entry = get_tracepoint(name);
	if (!entry) {
	entry = add_tracepoint(name);
	if (IS_ERR(entry))
	return entry;
	}
	old = tracepoint_entry_add_probe(entry, probe);
	if (IS_ERR(old) && !entry->refcount)
	remove_tracepoint(entry);
	return old;
	}

	/**
	* tracepoint_probe_register - Connect a probe to a tracepoint
	* @name: tracepoint name
	* @probe: probe handler
	*
	* Returns 0 if ok, error value on error.
	* The probe address must at least be aligned on the architecture pointer size.
	*/
	int tracepoint_probe_register(const char name, void probe)
	{
	void *old;

	mutex_lock(&tracepoints_mutex);
	old = tracepoint_add_probe(name, probe);
	mutex_unlock(&tracepoints_mutex);
	if (IS_ERR(old))
	return PTR_ERR(old);

	tracepoint_update_probes(); /* may update entry */
	release_probes(old);
	return 0;
	}
	EXPORT_SYMBOL_GPL(tracepoint_probe_register);

	static void tracepoint_remove_probe(const char name, void *probe)
	{
	struct tracepoint_entry *entry;
	void *old;

	entry = get_tracepoint(name);
	if (!entry)
	return ERR_PTR(-ENOENT);
	old = tracepoint_entry_remove_probe(entry, probe);
	if (IS_ERR(old))
	return old;
	if (!entry->refcount)
	remove_tracepoint(entry);
	return old;
	}

	/**
	* tracepoint_probe_unregister - Disconnect a probe from a tracepoint
	* @name: tracepoint name
	* @probe: probe function pointer
	*
	* We do not need to call a synchronize_sched to make sure the probes have
	* finished running before doing a module unload, because the module unload
	* itself uses stop_machine(), which insures that every preempt disabled section
	* have finished.
	*/
	int tracepoint_probe_unregister(const char name, void probe)
	{
	void *old;

	mutex_lock(&tracepoints_mutex);
	old = tracepoint_remove_probe(name, probe);
	mutex_unlock(&tracepoints_mutex);
	if (IS_ERR(old))
	return PTR_ERR(old);

	tracepoint_update_probes(); /* may update entry */
	release_probes(old);
	return 0;
	}
	EXPORT_SYMBOL_GPL(tracepoint_probe_unregister);

	static LIST_HEAD(old_probes);
	static int need_update;

	static void tracepoint_add_old_probes(void *old)
	{
	need_update = 1;
	if (old) {
	struct tp_probes *tp_probes = container_of(old,
	struct tp_probes, probes[0]);
	list_add(&tp_probes->u.list, &old_probes);
	}
	}

	/**
	* tracepoint_probe_register_noupdate - register a probe but not connect
	* @name: tracepoint name
	* @probe: probe handler
	*
	* caller must call tracepoint_probe_update_all()
	*/
	int tracepoint_probe_register_noupdate(const char name, void probe)
	{
	void *old;

	mutex_lock(&tracepoints_mutex);
	old = tracepoint_add_probe(name, probe);
	if (IS_ERR(old)) {
	mutex_unlock(&tracepoints_mutex);
	return PTR_ERR(old);
	}
	tracepoint_add_old_probes(old);
	mutex_unlock(&tracepoints_mutex);
	return 0;
	}
	EXPORT_SYMBOL_GPL(tracepoint_probe_register_noupdate);

	/**
	* tracepoint_probe_unregister_noupdate - remove a probe but not disconnect
	* @name: tracepoint name
	* @probe: probe function pointer
	*
	* caller must call tracepoint_probe_update_all()
	*/
	int tracepoint_probe_unregister_noupdate(const char name, void probe)
	{
	void *old;

	mutex_lock(&tracepoints_mutex);
	old = tracepoint_remove_probe(name, probe);
	if (IS_ERR(old)) {
	mutex_unlock(&tracepoints_mutex);
	return PTR_ERR(old);
	}
	tracepoint_add_old_probes(old);
	mutex_unlock(&tracepoints_mutex);
	return 0;
	}
	EXPORT_SYMBOL_GPL(tracepoint_probe_unregister_noupdate);

	/**
	* tracepoint_probe_update_all - update tracepoints
	*/
	void tracepoint_probe_update_all(void)
	{
	LIST_HEAD(release_probes);
	struct tp_probes pos, next;

	mutex_lock(&tracepoints_mutex);
	if (!need_update) {
	mutex_unlock(&tracepoints_mutex);
	return;
	}
	if (!list_empty(&old_probes))
	list_replace_init(&old_probes, &release_probes);
	need_update = 0;
	mutex_unlock(&tracepoints_mutex);

	tracepoint_update_probes();
	list_for_each_entry_safe(pos, next, &release_probes, u.list) {
	list_del(&pos->u.list);
	call_rcu_sched(&pos->u.rcu, rcu_free_old_probes);
	}
	}
	EXPORT_SYMBOL_GPL(tracepoint_probe_update_all);

	/**
	* tracepoint_get_iter_range - Get a next tracepoint iterator given a range.
	* @tracepoint: current tracepoints (in), next tracepoint (out)
	* @begin: beginning of the range
	* @end: end of the range
	*
	* Returns whether a next tracepoint has been found (1) or not (0).
	* Will return the first tracepoint in the range if the input tracepoint is
	* NULL.
	*/
	int tracepoint_get_iter_range(struct tracepoint **tracepoint,
	struct tracepoint begin, struct tracepoint end)
	{
	if (!*tracepoint && begin != end) {
	*tracepoint = begin;
	return 1;
	}
	if (tracepoint >= begin && tracepoint < end)
	return 1;
	return 0;
	}
	EXPORT_SYMBOL_GPL(tracepoint_get_iter_range);

	static void tracepoint_get_iter(struct tracepoint_iter *iter)
	{
	int found = 0;

	/* Core kernel tracepoints */
	if (!iter->module) {
	found = tracepoint_get_iter_range(&iter->tracepoint,
	__start___tracepoints, __stop___tracepoints);
	if (found)
	goto end;
	}
	/* tracepoints in modules. */
	found = module_get_iter_tracepoints(iter);
	end:
	if (!found)
	tracepoint_iter_reset(iter);
	}

	void tracepoint_iter_start(struct tracepoint_iter *iter)
	{
	tracepoint_get_iter(iter);
	}
	EXPORT_SYMBOL_GPL(tracepoint_iter_start);

	void tracepoint_iter_next(struct tracepoint_iter *iter)
	{
	iter->tracepoint++;
	/*
	* iter->tracepoint may be invalid because we blindly incremented it.
	* Make sure it is valid by marshalling on the tracepoints, getting the
	* tracepoints from following modules if necessary.
	*/
	tracepoint_get_iter(iter);
	}
	EXPORT_SYMBOL_GPL(tracepoint_iter_next);

	void tracepoint_iter_stop(struct tracepoint_iter *iter)
	{
	}
	EXPORT_SYMBOL_GPL(tracepoint_iter_stop);

	void tracepoint_iter_reset(struct tracepoint_iter *iter)
	{
	iter->module = NULL;
	iter->tracepoint = NULL;
	}
	EXPORT_SYMBOL_GPL(tracepoint_iter_reset);

	int tracepoint_module_notify(struct notifier_block *self,
	unsigned long val, void *data)
	{
	struct module *mod = data;

	switch (val) {
	case MODULE_STATE_COMING:
	tracepoint_update_probe_range(mod->tracepoints,
	mod->tracepoints + mod->num_tracepoints);
	break;
	case MODULE_STATE_GOING:
	tracepoint_update_probe_range(mod->tracepoints,
	mod->tracepoints + mod->num_tracepoints);
	break;
	}
	return 0;
	}

	struct notifier_block tracepoint_module_nb = {
	.notifier_call = tracepoint_module_notify,
	.priority = 0,
	};

	static int init_tracepoints(void)
	{
	return register_module_notifier(&tracepoint_module_nb);
	}
	__initcall(init_tracepoints);