Commit aad108aa authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Steven Rostedt
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tracing: Add trace_printk sample code 



Add sample code to test trace_printk(). The trace_printk() functions should
never be used in production code. This makes testing it a bit more
difficult. Having a sample module that can test use cases of trace_printk()
can help out.

Currently it just tests trace_printk() where it will be converted into:

 trace_bputs()
 trace_puts()
 trace_bprintk()

as well as staying as the normal _trace_printk().

It also tests its use in interrupt context as that will test the auxilery
buffers.

Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent e2ace001

samples/Kconfig

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@@ -11,6 +11,13 @@ config SAMPLE_TRACE_EVENTS 
	help

	  This build trace event example modules.



config SAMPLE_TRACE_PRINTK

        tristate "Build trace_printk module - tests various trace_printk formats"

	depends on EVENT_TRACING && m

	help

	 This builds a module that calls trace_printk() and can be used to

	 test various trace_printk() calls from a module.



config SAMPLE_KOBJECT

	tristate "Build kobject examples -- loadable modules only"

	depends on m

samples/Makefile

+1 −1
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@@ -2,4 +2,4 @@ 


obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ trace_events/ livepatch/ \

			   hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/ \

			   configfs/ connector/ v4l/
 
			   configfs/ connector/ v4l/ trace_printk/

samples/trace_printk/Makefile

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# builds a module that calls various trace_printk routines

# then to use one (as root):  insmod <module_name.ko>



# This module can also be used to test the trace_printk code.



obj-$(CONFIG_SAMPLE_TRACE_PRINTK) += trace-printk.o

samples/trace_printk/trace-printk.c

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#include <linux/module.h>

#include <linux/kthread.h>

#include <linux/irq_work.h>



/* Must not be static to force gcc to consider these non constant */

char *trace_printk_test_global_str =

	"This is a dynamic string that will use trace_puts\n";



char *trace_printk_test_global_str_irq =

	"(irq) This is a dynamic string that will use trace_puts\n";



char *trace_printk_test_global_str_fmt =

	"%sThis is a %s that will use trace_printk\n";



static struct irq_work irqwork;



static void trace_printk_irq_work(struct irq_work *work)

{

	trace_printk("(irq) This is a static string that will use trace_bputs\n");

	trace_printk(trace_printk_test_global_str_irq);



	trace_printk("(irq) This is a %s that will use trace_bprintk()\n",

		     "static string");



	trace_printk(trace_printk_test_global_str_fmt,

		     "(irq) ", "dynamic string");

}



static int __init trace_printk_init(void)

{

	init_irq_work(&irqwork, trace_printk_irq_work);



	trace_printk("This is a static string that will use trace_bputs\n");

	trace_printk(trace_printk_test_global_str);



	/* Kick off printing in irq context */

	irq_work_queue(&irqwork);



	trace_printk("This is a %s that will use trace_bprintk()\n",

		     "static string");



	trace_printk(trace_printk_test_global_str_fmt, "", "dynamic string");



	return 0;

}



static void __exit trace_printk_exit(void)

{

}



module_init(trace_printk_init);

module_exit(trace_printk_exit);



MODULE_AUTHOR("Steven Rostedt");

MODULE_DESCRIPTION("trace-printk");

MODULE_LICENSE("GPL");

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