lttng-modules-dkms 2.7.1-1 / usr / src / lttng-modules-2.7.1 / linux-patches / backport-tp-2.6.34-tracepoint-data.patch

commit 2c2a566b64b4254c530fb0c2222b30e8a739bac9
Author: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date:   Sat Sep 1 17:45:09 2012 -0700

    tracing: Let tracepoints have data passed to tracepoint callbacks (backport)
    
    Backport of commit 38516ab59fbc5b3bb278cf5e1fe2867c70cff32e for
    2.6.34.x. Keeping kABI compatibility.
    
    Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

---
 include/linux/tracepoint.h             |  149 +++++++++++++++++++++++++--------
 kernel/tracepoint.c                    |  144 ++++++++++++++++++++++---------
 samples/tracepoints/tp-samples-trace.h |    4 +-
 3 files changed, 220 insertions(+), 77 deletions(-)

Index: linux/include/linux/tracepoint.h
===================================================================
--- linux.orig/include/linux/tracepoint.h
+++ linux/include/linux/tracepoint.h
@@ -20,12 +20,20 @@
 struct module;
 struct tracepoint;
 
+#define HAVE_KABI_2635_TRACEPOINT
+
+struct tracepoint_func {
+	void *func;
+	void *data;
+	bool kabi_2635;
+};
+
 struct tracepoint {
 	const char *name;		/* Tracepoint name */
 	int state;			/* State. */
 	void (*regfunc)(void);
 	void (*unregfunc)(void);
-	void **funcs;
+	struct tracepoint_func *funcs;
 } __attribute__((aligned(32)));		/*
 					 * Aligned on 32 bytes because it is
 					 * globally visible and gcc happily
@@ -43,17 +51,33 @@ struct tracepoint {
 /*
  * it_func[0] is never NULL because there is at least one element in the array
  * when the array itself is non NULL.
- */
-#define __DO_TRACE(tp, proto, args)					\
-	do {								\
-		void **it_func;						\
+ *
+ * Note, the proto and args passed in includes "__data" as the first parameter.
+ * The reason for this is to handle the "void" prototype. If a tracepoint
+ * has a "void" prototype, then it is invalid to declare a function
+ * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
+ * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
+  */
+#define __DO_TRACE(tp, data_proto, data_args, proto, args)		\
+ 	do {								\
+		struct tracepoint_func *it_func_ptr;			\
+		void *it_func;						\
+ 									\
+ 		rcu_read_lock_sched_notrace();				\
+		it_func_ptr = rcu_dereference_sched((tp)->funcs);	\
+		if (it_func_ptr) {					\
+ 			do {						\
+				if (it_func_ptr->kabi_2635) {		\
+					void *__data;			\
 									\
-		rcu_read_lock_sched_notrace();				\
-		it_func = rcu_dereference_sched((tp)->funcs);		\
-		if (it_func) {						\
-			do {						\
-				((void(*)(proto))(*it_func))(args);	\
-			} while (*(++it_func));				\
+					it_func = (it_func_ptr)->func;	\
+					__data = (it_func_ptr)->data;	\
+					((void(*)(data_proto))(it_func))(data_args); \
+				} else {				\
+					it_func = (it_func_ptr)->func;	\
+					((void(*)(proto))(it_func))(args); \
+				}					\
+			} while ((++it_func_ptr)->func);		\
 		}							\
 		rcu_read_unlock_sched_notrace();			\
 	} while (0)
@@ -63,22 +87,39 @@ struct tracepoint {
  * not add unwanted padding between the beginning of the section and the
  * structure. Force alignment to the same alignment as the section start.
  */
-#define DECLARE_TRACE(name, proto, args)				\
+#define __DECLARE_TRACE(name, proto, args, data_proto, data_args)	\
 	extern struct tracepoint __tracepoint_##name;			\
 	static inline void trace_##name(proto)				\
 	{								\
 		if (unlikely(__tracepoint_##name.state))		\
 			__DO_TRACE(&__tracepoint_##name,		\
-				TP_PROTO(proto), TP_ARGS(args));	\
+				TP_PROTO(data_proto),			\
+				TP_ARGS(data_args),			\
+				TP_PROTO(proto),			\
+				TP_ARGS(args));				\
 	}								\
-	static inline int register_trace_##name(void (*probe)(proto))	\
-	{								\
+	static inline int						\
+	register_trace_##name(void (*probe)(proto))			\
+ 	{								\
 		return tracepoint_probe_register(#name, (void *)probe);	\
-	}								\
-	static inline int unregister_trace_##name(void (*probe)(proto))	\
-	{								\
-		return tracepoint_probe_unregister(#name, (void *)probe);\
-	}
+ 	}								\
+	static inline int						\
+	unregister_trace_##name(void (*probe)(proto))			\
+ 	{								\
+		return tracepoint_probe_unregister(#name, (void *)probe); \
+ 	}								\
+	static inline int						\
+	kabi_2635_register_trace_##name(void (*probe)(data_proto), void *data) \
+ 	{								\
+		return kabi_2635_tracepoint_probe_register(#name, (void *)probe,	\
+						 data);			\
+ 	}								\
+	static inline int						\
+	kabi_2635_unregister_trace_##name(void (*probe)(data_proto), void *data) \
+ 	{								\
+		return kabi_2635_tracepoint_probe_unregister(#name, (void *)probe, \
+						   data);		\
+ 	}
 
 
 #define DEFINE_TRACE_FN(name, reg, unreg)				\
@@ -100,19 +141,29 @@ extern void tracepoint_update_probe_rang
 	struct tracepoint *end);
 
 #else /* !CONFIG_TRACEPOINTS */
-#define DECLARE_TRACE(name, proto, args)				\
-	static inline void _do_trace_##name(struct tracepoint *tp, proto) \
-	{ }								\
-	static inline void trace_##name(proto)				\
-	{ }								\
-	static inline int register_trace_##name(void (*probe)(proto))	\
-	{								\
-		return -ENOSYS;						\
-	}								\
-	static inline int unregister_trace_##name(void (*probe)(proto))	\
-	{								\
-		return -ENOSYS;						\
-	}
+#define __DECLARE_TRACE(name, proto, args, data_proto, data_args)	\
+ 	static inline void trace_##name(proto)				\
+ 	{ }								\
+	static inline int						\
+	register_trace_##name(void (*probe)(proto))			\
+ 	{								\
+ 		return -ENOSYS;						\
+ 	}								\
+	static inline int						\
+	unregister_trace_##name(void (*probe)(proto))			\
+ 	{								\
+ 		return -ENOSYS;						\
+ 	}								\
+	static inline int						\
+	kabi_2635_register_trace_##name(void (*probe)(data_proto), void *data) \
+ 	{								\
+ 		return -ENOSYS;						\
+ 	}								\
+	static inline int						\
+	kabi_2635_unregister_trace_##name(void (*probe)(data_proto), void *data) \
+ 	{								\
+ 		return -ENOSYS;						\
+ 	}
 
 #define DEFINE_TRACE_FN(name, reg, unreg)
 #define DEFINE_TRACE(name)
@@ -123,6 +174,28 @@ static inline void tracepoint_update_pro
 	struct tracepoint *end)
 { }
 #endif /* CONFIG_TRACEPOINTS */
+
+/*
+ * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
+ * (void). "void" is a special value in a function prototype and can
+ * not be combined with other arguments. Since the DECLARE_TRACE()
+ * macro adds a data element at the beginning of the prototype,
+ * we need a way to differentiate "(void *data, proto)" from
+ * "(void *data, void)". The second prototype is invalid.
+ *
+ * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
+ * and "void *__data" as the callback prototype.
+ *
+ * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
+ * "void *__data, proto" as the callback prototype.
+ */
+#define DECLARE_TRACE_NOARGS(name)					\
+	__DECLARE_TRACE(name, void, , void *__data, __data)
+#define DECLARE_TRACE(name, proto, args)				\
+	__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),		\
+			PARAMS(void *__data, proto),			\
+			PARAMS(__data, args))
+
 #endif /* DECLARE_TRACE */
 
 /*
@@ -130,15 +203,23 @@ static inline void tracepoint_update_pro
  * Internal API, should not be used directly.
  */
 extern int tracepoint_probe_register(const char *name, void *probe);
+extern int kabi_2635_tracepoint_probe_register(const char *name, void *probe, void *data);
 
 /*
  * Disconnect a probe from a tracepoint.
  * Internal API, should not be used directly.
  */
-extern int tracepoint_probe_unregister(const char *name, void *probe);
+extern int
+tracepoint_probe_unregister(const char *name, void *probe);
+extern int
+kabi_2635_tracepoint_probe_unregister(const char *name, void *probe, void *data);
 
 extern int tracepoint_probe_register_noupdate(const char *name, void *probe);
+extern int kabi_2635_tracepoint_probe_register_noupdate(const char *name, void *probe,
+					      void *data);
 extern int tracepoint_probe_unregister_noupdate(const char *name, void *probe);
+extern int kabi_2635_tracepoint_probe_unregister_noupdate(const char *name, void *probe,
+						void *data);
 extern void tracepoint_probe_update_all(void);
 
 struct tracepoint_iter {
Index: linux/kernel/tracepoint.c
===================================================================
--- linux.orig/kernel/tracepoint.c
+++ linux/kernel/tracepoint.c
@@ -54,7 +54,7 @@ static struct hlist_head tracepoint_tabl
  */
 struct tracepoint_entry {
 	struct hlist_node hlist;
-	void **funcs;
+	struct tracepoint_func *funcs;
 	int refcount;	/* Number of times armed. 0 if disarmed. */
 	char name[0];
 };
@@ -64,12 +64,12 @@ struct tp_probes {
 		struct rcu_head rcu;
 		struct list_head list;
 	} u;
-	void *probes[0];
+	struct tracepoint_func probes[0];
 };
 
 static inline void *allocate_probes(int count)
 {
-	struct tp_probes *p  = kmalloc(count * sizeof(void *)
+	struct tp_probes *p  = kmalloc(count * sizeof(struct tracepoint_func)
 			+ sizeof(struct tp_probes), GFP_KERNEL);
 	return p == NULL ? NULL : p->probes;
 }
@@ -79,7 +79,7 @@ static void rcu_free_old_probes(struct r
 	kfree(container_of(head, struct tp_probes, u.rcu));
 }
 
-static inline void release_probes(void *old)
+static inline void release_probes(struct tracepoint_func *old)
 {
 	if (old) {
 		struct tp_probes *tp_probes = container_of(old,
@@ -95,15 +95,16 @@ static void debug_print_probes(struct tr
 	if (!tracepoint_debug || !entry->funcs)
 		return;
 
-	for (i = 0; entry->funcs[i]; i++)
-		printk(KERN_DEBUG "Probe %d : %p\n", i, entry->funcs[i]);
+	for (i = 0; entry->funcs[i].func; i++)
+		printk(KERN_DEBUG "Probe %d : %p\n", i, entry->funcs[i].func);
 }
 
-static void *
-tracepoint_entry_add_probe(struct tracepoint_entry *entry, void *probe)
+static struct tracepoint_func *
+tracepoint_entry_add_probe(struct tracepoint_entry *entry,
+			   void *probe, void *data, bool kabi_2635)
 {
 	int nr_probes = 0;
-	void **old, **new;
+	struct tracepoint_func *old, *new;
 
 	WARN_ON(!probe);
 
@@ -111,8 +112,9 @@ tracepoint_entry_add_probe(struct tracep
 	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)
+		for (nr_probes = 0; old[nr_probes].func; nr_probes++)
+			if (old[nr_probes].func == probe &&
+			    old[nr_probes].data == data)
 				return ERR_PTR(-EEXIST);
 	}
 	/* + 2 : one for new probe, one for NULL func */
@@ -120,9 +122,11 @@ tracepoint_entry_add_probe(struct tracep
 	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;
+		memcpy(new, old, nr_probes * sizeof(struct tracepoint_func));
+	new[nr_probes].func = probe;
+	new[nr_probes].data = data;
+	new[nr_probes].kabi_2635 = kabi_2635;
+	new[nr_probes + 1].func = NULL;
 	entry->refcount = nr_probes + 1;
 	entry->funcs = new;
 	debug_print_probes(entry);
@@ -130,10 +134,11 @@ tracepoint_entry_add_probe(struct tracep
 }
 
 static void *
-tracepoint_entry_remove_probe(struct tracepoint_entry *entry, void *probe)
+tracepoint_entry_remove_probe(struct tracepoint_entry *entry,
+			      void *probe, void *data)
 {
 	int nr_probes = 0, nr_del = 0, i;
-	void **old, **new;
+	struct tracepoint_func *old, *new;
 
 	old = entry->funcs;
 
@@ -142,8 +147,10 @@ tracepoint_entry_remove_probe(struct tra
 
 	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))
+	for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
+		if (!probe ||
+		    (old[nr_probes].func == probe &&
+		     old[nr_probes].data == data))
 			nr_del++;
 	}
 
@@ -160,10 +167,11 @@ tracepoint_entry_remove_probe(struct tra
 		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))
+		for (i = 0; old[i].func; i++)
+			if (probe &&
+			    (old[i].func != probe || old[i].data != data))
 				new[j++] = old[i];
-		new[nr_probes - nr_del] = NULL;
+		new[nr_probes - nr_del].func = NULL;
 		entry->refcount = nr_probes - nr_del;
 		entry->funcs = new;
 	}
@@ -315,18 +323,19 @@ static void tracepoint_update_probes(voi
 	module_update_tracepoints();
 }
 
-static void *tracepoint_add_probe(const char *name, void *probe)
+static struct tracepoint_func *
+tracepoint_add_probe(const char *name, void *probe, void *data, bool kabi_2635)
 {
 	struct tracepoint_entry *entry;
-	void *old;
+	struct tracepoint_func *old;
 
 	entry = get_tracepoint(name);
 	if (!entry) {
 		entry = add_tracepoint(name);
 		if (IS_ERR(entry))
-			return entry;
+			return (struct tracepoint_func *)entry;
 	}
-	old = tracepoint_entry_add_probe(entry, probe);
+	old = tracepoint_entry_add_probe(entry, probe, data, kabi_2635);
 	if (IS_ERR(old) && !entry->refcount)
 		remove_tracepoint(entry);
 	return old;
@@ -340,12 +349,14 @@ static void *tracepoint_add_probe(const
  * 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)
+static
+int ___tracepoint_probe_register(const char *name, void *probe, void *data,
+			bool kabi_2635)
 {
-	void *old;
+	struct tracepoint_func *old;
 
 	mutex_lock(&tracepoints_mutex);
-	old = tracepoint_add_probe(name, probe);
+	old = tracepoint_add_probe(name, probe, data, kabi_2635);
 	mutex_unlock(&tracepoints_mutex);
 	if (IS_ERR(old))
 		return PTR_ERR(old);
@@ -354,17 +365,30 @@ int tracepoint_probe_register(const char
 	release_probes(old);
 	return 0;
 }
+
+int kabi_2635_tracepoint_probe_register(const char *name, void *probe, void *data)
+{
+	return ___tracepoint_probe_register(name, probe, data, 1);
+}
+EXPORT_SYMBOL_GPL(kabi_2635_tracepoint_probe_register);
+
+
+int tracepoint_probe_register(const char *name, void *probe)
+{
+	return ___tracepoint_probe_register(name, probe, NULL, 0);
+}
 EXPORT_SYMBOL_GPL(tracepoint_probe_register);
 
-static void *tracepoint_remove_probe(const char *name, void *probe)
+static struct tracepoint_func *
+tracepoint_remove_probe(const char *name, void *probe, void *data)
 {
 	struct tracepoint_entry *entry;
-	void *old;
+	struct tracepoint_func *old;
 
 	entry = get_tracepoint(name);
 	if (!entry)
 		return ERR_PTR(-ENOENT);
-	old = tracepoint_entry_remove_probe(entry, probe);
+	old = tracepoint_entry_remove_probe(entry, probe, data);
 	if (IS_ERR(old))
 		return old;
 	if (!entry->refcount)
@@ -382,12 +406,13 @@ static void *tracepoint_remove_probe(con
  * itself uses stop_machine(), which insures that every preempt disabled section
  * have finished.
  */
-int tracepoint_probe_unregister(const char *name, void *probe)
+static
+int ___tracepoint_probe_unregister(const char *name, void *probe, void *data)
 {
-	void *old;
+	struct tracepoint_func *old;
 
 	mutex_lock(&tracepoints_mutex);
-	old = tracepoint_remove_probe(name, probe);
+	old = tracepoint_remove_probe(name, probe, data);
 	mutex_unlock(&tracepoints_mutex);
 	if (IS_ERR(old))
 		return PTR_ERR(old);
@@ -396,6 +421,17 @@ int tracepoint_probe_unregister(const ch
 	release_probes(old);
 	return 0;
 }
+
+int kabi_2635_tracepoint_probe_unregister(const char *name, void *probe, void *data)
+{
+	return ___tracepoint_probe_unregister(name, probe, data);
+}
+EXPORT_SYMBOL_GPL(kabi_2635_tracepoint_probe_unregister);
+
+int tracepoint_probe_unregister(const char *name, void *probe)
+{
+	return ___tracepoint_probe_unregister(name, probe, NULL);
+}
 EXPORT_SYMBOL_GPL(tracepoint_probe_unregister);
 
 static LIST_HEAD(old_probes);
@@ -418,12 +454,14 @@ static void tracepoint_add_old_probes(vo
  *
  * caller must call tracepoint_probe_update_all()
  */
-int tracepoint_probe_register_noupdate(const char *name, void *probe)
+static
+int ___tracepoint_probe_register_noupdate(const char *name, void *probe,
+				       void *data, bool kabi_2635)
 {
-	void *old;
+	struct tracepoint_func *old;
 
 	mutex_lock(&tracepoints_mutex);
-	old = tracepoint_add_probe(name, probe);
+	old = tracepoint_add_probe(name, probe, data, kabi_2635);
 	if (IS_ERR(old)) {
 		mutex_unlock(&tracepoints_mutex);
 		return PTR_ERR(old);
@@ -432,6 +470,18 @@ int tracepoint_probe_register_noupdate(c
 	mutex_unlock(&tracepoints_mutex);
 	return 0;
 }
+
+int kabi_2635_tracepoint_probe_register_noupdate(const char *name, void *probe,
+				       void *data)
+{
+	return ___tracepoint_probe_register_noupdate(name, probe, data, 1);
+}
+EXPORT_SYMBOL_GPL(kabi_2635_tracepoint_probe_register_noupdate);
+
+int tracepoint_probe_register_noupdate(const char *name, void *probe)
+{
+	return ___tracepoint_probe_register_noupdate(name, probe, NULL, 0);
+}
 EXPORT_SYMBOL_GPL(tracepoint_probe_register_noupdate);
 
 /**
@@ -441,12 +491,14 @@ EXPORT_SYMBOL_GPL(tracepoint_probe_regis
  *
  * caller must call tracepoint_probe_update_all()
  */
-int tracepoint_probe_unregister_noupdate(const char *name, void *probe)
+static
+int ___tracepoint_probe_unregister_noupdate(const char *name, void *probe,
+					 void *data)
 {
-	void *old;
+	struct tracepoint_func *old;
 
 	mutex_lock(&tracepoints_mutex);
-	old = tracepoint_remove_probe(name, probe);
+	old = tracepoint_remove_probe(name, probe, data);
 	if (IS_ERR(old)) {
 		mutex_unlock(&tracepoints_mutex);
 		return PTR_ERR(old);
@@ -455,6 +507,18 @@ int tracepoint_probe_unregister_noupdate
 	mutex_unlock(&tracepoints_mutex);
 	return 0;
 }
+
+int kabi_2635_tracepoint_probe_unregister_noupdate(const char *name, void *probe,
+					 void *data)
+{
+	return ___tracepoint_probe_unregister_noupdate(name, probe, data);
+}
+EXPORT_SYMBOL_GPL(kabi_2635_tracepoint_probe_unregister_noupdate);
+
+int tracepoint_probe_unregister_noupdate(const char *name, void *probe)
+{
+	return ___tracepoint_probe_unregister_noupdate(name, probe, NULL);
+}
 EXPORT_SYMBOL_GPL(tracepoint_probe_unregister_noupdate);
 
 /**
Index: linux/samples/tracepoints/tp-samples-trace.h
===================================================================
--- linux.orig/samples/tracepoints/tp-samples-trace.h
+++ linux/samples/tracepoints/tp-samples-trace.h
@@ -7,7 +7,5 @@
 DECLARE_TRACE(subsys_event,
 	TP_PROTO(struct inode *inode, struct file *file),
 	TP_ARGS(inode, file));
-DECLARE_TRACE(subsys_eventb,
-	TP_PROTO(void),
-	TP_ARGS());
+DECLARE_TRACE_NOARGS(subsys_eventb);
 #endif