Commit aad108aa authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Steven Rostedt

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: 's avatarSteven Rostedt <rostedt@goodmis.org>
parent e2ace001
......@@ -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
......
......@@ -2,4 +2,4 @@
obj-$(CONFIG_SAMPLES) += kobject/ kprobes/ trace_events/ livepatch/ \
hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/ \
configfs/ connector/ v4l/
configfs/ connector/ v4l/ trace_printk/
# builds a module that calls various trace_printk routines
# then to use one (as root): insmod <module_name.ko>
# This module can also be used to test the trace_printk code.
obj-$(CONFIG_SAMPLE_TRACE_PRINTK) += trace-printk.o
#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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