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: Steven Rostedt <rostedt@goodmis.org>
diff --git a/samples/Kconfig b/samples/Kconfig
index 559a58b..27a2457 100644
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -11,6 +11,13 @@
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
diff --git a/samples/Makefile b/samples/Makefile
index 2e3b523..1a20169 100644
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -2,4 +2,4 @@
obj-$(CONFIG_SAMPLES) += kobject/ kprobes/ trace_events/ livepatch/ \
hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/ \
- configfs/ connector/ v4l/
+ configfs/ connector/ v4l/ trace_printk/
diff --git a/samples/trace_printk/Makefile b/samples/trace_printk/Makefile
new file mode 100644
index 0000000..19900ab
--- /dev/null
+++ b/samples/trace_printk/Makefile
@@ -0,0 +1,6 @@
+# builds a module that calls various trace_printk routines
+# then to use one (as root): insmod <module_name.ko>
+
+# This module can also be used to test the trace_printk code.
+
+obj-$(CONFIG_SAMPLE_TRACE_PRINTK) += trace-printk.o
diff --git a/samples/trace_printk/trace-printk.c b/samples/trace_printk/trace-printk.c
new file mode 100644
index 0000000..e9e0040f
--- /dev/null
+++ b/samples/trace_printk/trace-printk.c
@@ -0,0 +1,56 @@
+#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");