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Commit 7e066fb8 authored by Mathieu Desnoyers's avatar Mathieu Desnoyers Committed by Ingo Molnar
Browse files

tracepoints: add DECLARE_TRACE() and DEFINE_TRACE() 



Impact: API *CHANGE*. Must update all tracepoint users.

Add DEFINE_TRACE() to tracepoints to let them declare the tracepoint
structure in a single spot for all the kernel. It helps reducing memory
consumption, especially when declaring a lot of tracepoints, e.g. for
kmalloc tracing.

*API CHANGE WARNING*: now, DECLARE_TRACE() must be used in headers for
tracepoint declarations rather than DEFINE_TRACE(). This is the sane way
to do it. The name previously used was misleading.

Updates scheduler instrumentation to follow this API change.

Signed-off-by: default avatarMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 32f85742

Documentation/tracepoints.txt

+6 −1
Original line number Diff line number Diff line
@@ -42,7 +42,7 @@ In include/trace/subsys.h : 


#include <linux/tracepoint.h>



DEFINE_TRACE(subsys_eventname,

DECLARE_TRACE(subsys_eventname,

	TPPTOTO(int firstarg, struct task_struct *p),

	TPARGS(firstarg, p));
@@ -50,6 +50,8 @@ In subsys/file.c (where the tracing statement must be added) : 


#include <trace/subsys.h>



DEFINE_TRACE(subsys_eventname);



void somefct(void)

{

	...
@@ -86,6 +88,9 @@ to limit collisions. Tracepoint names are global to the kernel: they are 
considered as being the same whether they are in the core kernel image or in

modules.



If the tracepoint has to be used in kernel modules, an

EXPORT_TRACEPOINT_SYMBOL_GPL() or EXPORT_TRACEPOINT_SYMBOL() can be used to

export the defined tracepoints.



* Probe / tracepoint example

include/asm-generic/vmlinux.lds.h

+1 −0
Original line number Diff line number Diff line
@@ -71,6 +71,7 @@ 
	VMLINUX_SYMBOL(__start___markers) = .;				\

	*(__markers)							\

	VMLINUX_SYMBOL(__stop___markers) = .;				\

	. = ALIGN(32);							\

	VMLINUX_SYMBOL(__start___tracepoints) = .;			\

	*(__tracepoints)						\

	VMLINUX_SYMBOL(__stop___tracepoints) = .;			\

include/linux/tracepoint.h

+25 −10
Original line number Diff line number Diff line
@@ -24,8 +24,12 @@ struct tracepoint { 
	const char *name;		/* Tracepoint name */

	int state;			/* State. */

	void **funcs;

} __attribute__((aligned(8)));



} __attribute__((aligned(32)));		/*

					 * Aligned on 32 bytes because it is

					 * globally visible and gcc happily

					 * align these on the structure size.

					 * Keep in sync with vmlinux.lds.h.

					 */



#define TPPROTO(args...)	args

#define TPARGS(args...)		args
@@ -55,15 +59,10 @@ 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 DEFINE_TRACE(name, proto, args)					\

#define DECLARE_TRACE(name, proto, args)				\

	extern struct tracepoint __tracepoint_##name;			\

	static inline void trace_##name(proto)				\

	{								\

		static const char __tpstrtab_##name[]			\

		__attribute__((section("__tracepoints_strings")))	\

		= #name;						\

		static struct tracepoint __tracepoint_##name		\

		__attribute__((section("__tracepoints"), aligned(8))) =	\

		{ __tpstrtab_##name, 0, NULL };				\

		if (unlikely(__tracepoint_##name.state))		\

			__DO_TRACE(&__tracepoint_##name,		\

				TPPROTO(proto), TPARGS(args));		\
@@ -77,11 +76,23 @@ struct tracepoint { 
		return tracepoint_probe_unregister(#name, (void *)probe);\

	}



#define DEFINE_TRACE(name)						\

	static const char __tpstrtab_##name[]				\

	__attribute__((section("__tracepoints_strings"))) = #name;	\

	struct tracepoint __tracepoint_##name				\

	__attribute__((section("__tracepoints"), aligned(32))) =	\

		{ __tpstrtab_##name, 0, NULL }



#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)				\

	EXPORT_SYMBOL_GPL(__tracepoint_##name)

#define EXPORT_TRACEPOINT_SYMBOL(name)					\

	EXPORT_SYMBOL(__tracepoint_##name)



extern void tracepoint_update_probe_range(struct tracepoint *begin,

	struct tracepoint *end);



#else /* !CONFIG_TRACEPOINTS */

#define DEFINE_TRACE(name, proto, args)			\

#define DECLARE_TRACE(name, proto, args)				\

	static inline void _do_trace_##name(struct tracepoint *tp, proto) \

	{ }								\

	static inline void trace_##name(proto)				\
@@ -95,6 +106,10 @@ extern void tracepoint_update_probe_range(struct tracepoint *begin, 
		return -ENOSYS;						\

	}



#define DEFINE_TRACE(name)

#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)

#define EXPORT_TRACEPOINT_SYMBOL(name)



static inline void tracepoint_update_probe_range(struct tracepoint *begin,

	struct tracepoint *end)

{ }

include/trace/sched.h

+12 −12
Original line number Diff line number Diff line
@@ -4,52 +4,52 @@ 
#include <linux/sched.h>

#include <linux/tracepoint.h>



DEFINE_TRACE(sched_kthread_stop,

DECLARE_TRACE(sched_kthread_stop,

	TPPROTO(struct task_struct *t),

		TPARGS(t));



DEFINE_TRACE(sched_kthread_stop_ret,

DECLARE_TRACE(sched_kthread_stop_ret,

	TPPROTO(int ret),

		TPARGS(ret));



DEFINE_TRACE(sched_wait_task,

DECLARE_TRACE(sched_wait_task,

	TPPROTO(struct rq *rq, struct task_struct *p),

		TPARGS(rq, p));



DEFINE_TRACE(sched_wakeup,

DECLARE_TRACE(sched_wakeup,

	TPPROTO(struct rq *rq, struct task_struct *p),

		TPARGS(rq, p));



DEFINE_TRACE(sched_wakeup_new,

DECLARE_TRACE(sched_wakeup_new,

	TPPROTO(struct rq *rq, struct task_struct *p),

		TPARGS(rq, p));



DEFINE_TRACE(sched_switch,

DECLARE_TRACE(sched_switch,

	TPPROTO(struct rq *rq, struct task_struct *prev,

		struct task_struct *next),

		TPARGS(rq, prev, next));



DEFINE_TRACE(sched_migrate_task,

DECLARE_TRACE(sched_migrate_task,

	TPPROTO(struct rq *rq, struct task_struct *p, int dest_cpu),

		TPARGS(rq, p, dest_cpu));



DEFINE_TRACE(sched_process_free,

DECLARE_TRACE(sched_process_free,

	TPPROTO(struct task_struct *p),

		TPARGS(p));



DEFINE_TRACE(sched_process_exit,

DECLARE_TRACE(sched_process_exit,

	TPPROTO(struct task_struct *p),

		TPARGS(p));



DEFINE_TRACE(sched_process_wait,

DECLARE_TRACE(sched_process_wait,

	TPPROTO(struct pid *pid),

		TPARGS(pid));



DEFINE_TRACE(sched_process_fork,

DECLARE_TRACE(sched_process_fork,

	TPPROTO(struct task_struct *parent, struct task_struct *child),

		TPARGS(parent, child));



DEFINE_TRACE(sched_signal_send,

DECLARE_TRACE(sched_signal_send,

	TPPROTO(int sig, struct task_struct *p),

		TPARGS(sig, p));

kernel/exit.c

+4 −0
Original line number Diff line number Diff line
@@ -54,6 +54,10 @@ 
#include <asm/pgtable.h>

#include <asm/mmu_context.h>



DEFINE_TRACE(sched_process_free);

DEFINE_TRACE(sched_process_exit);

DEFINE_TRACE(sched_process_wait);



static void exit_mm(struct task_struct * tsk);



static inline int task_detached(struct task_struct *p)