Commit 769b0441 authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Ingo Molnar
Browse files

tracing/core: drop the old trace_printk() implementation in favour of trace_bprintk() 



Impact: faster and lighter tracing

Now that we have trace_bprintk() which is faster and consume lesser
memory than trace_printk() and has the same purpose, we can now drop
the old implementation in favour of the binary one from trace_bprintk(),
which means we move all the implementation of trace_bprintk() to
trace_printk(), so the Api doesn't change except that we must now use
trace_seq_bprintk() to print the TRACE_PRINT entries.

Some changes result of this:

- Previously, trace_bprintk depended of a single tracer and couldn't
  work without. This tracer has been dropped and the whole implementation
  of trace_printk() (like the module formats management) is now integrated
  in the tracing core (comes with CONFIG_TRACING), though we keep the file
  trace_printk (previously trace_bprintk.c) where we can find the module
  management. Thus we don't overflow trace.c

- changes some parts to use trace_seq_bprintk() to print TRACE_PRINT entries.

- change a bit trace_printk/trace_vprintk macros to support non-builtin formats
  constants, and fix 'const' qualifiers warnings. But this is all transparent for
  developers.

- etc...

V2:

- Rebase against last changes
- Fix mispell on the changelog

V3:

- Rebase against last changes (moving trace_printk() to kernel.h)

Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1236356510-8381-5-git-send-email-fweisbec@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 1ba28e02

include/linux/ftrace.h

+0 −25
Original line number Diff line number Diff line
@@ -223,31 +223,6 @@ extern int ftrace_make_nop(struct module *mod, 
 */

extern int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr);



#ifdef CONFIG_TRACE_BPRINTK

extern int trace_vbprintk(unsigned long ip, const char *fmt, va_list args);

extern int __trace_bprintk(unsigned long ip, const char *fmt, ...)

		__attribute__ ((format (printf, 2, 3)));



static inline void  ____trace_bprintk_check_format(const char *fmt, ...)

		__attribute__ ((format (printf, 1, 2)));

static inline void ____trace_bprintk_check_format(const char *fmt, ...) {}

#define __trace_bprintk_check_format(fmt, args...)			\

do {									\

	if (0)								\

		____trace_bprintk_check_format(fmt, ##args);		\

} while (0)



#define trace_bprintk(fmt, args...)					\

do {									\

	static char *__attribute__((section("__trace_bprintk_fmt")))	\

			trace_bprintk_fmt = fmt;			\

	__trace_bprintk_check_format(fmt, ##args);			\

	__trace_bprintk(_THIS_IP_, trace_bprintk_fmt, ##args);	\

} while (0)

#else

#define trace_bprintk trace_printk

#endif



/* May be defined in arch */

extern int ftrace_arch_read_dyn_info(char *buf, int size);

include/linux/kernel.h

+31 −3
Original line number Diff line number Diff line
@@ -423,6 +423,16 @@ extern void ftrace_off_permanent(void); 
extern void

ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3);



static inline void __attribute__ ((format (printf, 1, 2)))

____trace_printk_check_format(const char *fmt, ...)

{

}

#define __trace_printk_check_format(fmt, args...)			\

do {									\

	if (0)								\

		____trace_printk_check_format(fmt, ##args);		\

} while (0)



/**

 * trace_printk - printf formatting in the ftrace buffer

 * @fmt: the printf format for printing
@@ -439,13 +449,31 @@ ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3); 
 * Please refrain from leaving trace_printks scattered around in

 * your code.

 */

# define trace_printk(fmt...) __trace_printk(_THIS_IP_, fmt)



#define trace_printk(fmt, args...)					\

do {									\

	static const char *trace_printk_fmt				\

	__attribute__((section("__trace_printk_fmt")));			\

	trace_printk_fmt = fmt;					\

	__trace_printk_check_format(fmt, ##args);			\

	__trace_printk(_THIS_IP_, trace_printk_fmt, ##args);		\

} while (0)



extern int

__trace_printk(unsigned long ip, const char *fmt, ...)

	__attribute__ ((format (printf, 2, 3)));

# define ftrace_vprintk(fmt, ap) __trace_printk(_THIS_IP_, fmt, ap)



#define ftrace_vprintk(fmt, vargs)					\

do {									\

	static const char *trace_printk_fmt				\

	__attribute__((section("__trace_printk_fmt")));			\

	trace_printk_fmt = fmt;					\

	__ftrace_vprintk(_THIS_IP_, trace_printk_fmt, vargs);		\

} while (0)



extern int

__ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);



extern void ftrace_dump(void);

#else

static inline void
@@ -467,7 +495,7 @@ ftrace_vprintk(const char *fmt, va_list ap) 
	return 0;

}

static inline void ftrace_dump(void) { }

#endif

#endif /* CONFIG_TRACING */



/*

 *      Display an IP address in readable format.

include/linux/module.h

+1 −1
Original line number Diff line number Diff line
@@ -329,7 +329,7 @@ struct module 
	unsigned int num_tracepoints;

#endif



#ifdef CONFIG_TRACE_BPRINTK

#ifdef CONFIG_TRACING

	const char **trace_bprintk_fmt_start;

	unsigned int num_trace_bprintk_fmt;

#endif

kernel/trace/Kconfig

+1 −6
Original line number Diff line number Diff line
@@ -52,6 +52,7 @@ config TRACING 
	select STACKTRACE if STACKTRACE_SUPPORT

	select TRACEPOINTS

	select NOP_TRACER

	select BINARY_PRINTF



#

# Minimum requirements an architecture has to meet for us to
@@ -97,12 +98,6 @@ config FUNCTION_GRAPH_TRACER 
	  This is done by setting the current return address on the current

	  task structure into a stack of calls.



config TRACE_BPRINTK

	bool "Binary printk for tracing"

	default y

	depends on TRACING

	select BINARY_PRINTF



config IRQSOFF_TRACER

	bool "Interrupts-off Latency Tracer"

	default n

kernel/trace/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -22,7 +22,7 @@ obj-$(CONFIG_TRACING) += trace.o 
obj-$(CONFIG_TRACING) += trace_clock.o

obj-$(CONFIG_TRACING) += trace_output.o

obj-$(CONFIG_TRACING) += trace_stat.o

obj-$(CONFIG_TRACE_BPRINTK) += trace_bprintk.o

obj-$(CONFIG_TRACING) += trace_printk.o

obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o

obj-$(CONFIG_SYSPROF_TRACER) += trace_sysprof.o

obj-$(CONFIG_FUNCTION_TRACER) += trace_functions.o

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