xref: /linux/samples/trace_printk/trace-printk.c (revision 48dea9a700c8728cc31a1dd44588b97578de86ee)
1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/module.h>
3 #include <linux/kthread.h>
4 #include <linux/irq_work.h>
5 
6 /* Must not be static to force gcc to consider these non constant */
7 char *trace_printk_test_global_str =
8 	"This is a dynamic string that will use trace_puts\n";
9 
10 char *trace_printk_test_global_str_irq =
11 	"(irq) This is a dynamic string that will use trace_puts\n";
12 
13 char *trace_printk_test_global_str_fmt =
14 	"%sThis is a %s that will use trace_printk\n";
15 
16 static struct irq_work irqwork;
17 
18 static void trace_printk_irq_work(struct irq_work *work)
19 {
20 	trace_printk("(irq) This is a static string that will use trace_bputs\n");
21 	trace_printk(trace_printk_test_global_str_irq);
22 
23 	trace_printk("(irq) This is a %s that will use trace_bprintk()\n",
24 		     "static string");
25 
26 	trace_printk(trace_printk_test_global_str_fmt,
27 		     "(irq) ", "dynamic string");
28 }
29 
30 static int __init trace_printk_init(void)
31 {
32 	init_irq_work(&irqwork, trace_printk_irq_work);
33 
34 	trace_printk("This is a static string that will use trace_bputs\n");
35 	trace_printk(trace_printk_test_global_str);
36 
37 	/* Kick off printing in irq context */
38 	irq_work_queue(&irqwork);
39 	irq_work_sync(&irqwork);
40 
41 	trace_printk("This is a %s that will use trace_bprintk()\n",
42 		     "static string");
43 
44 	trace_printk(trace_printk_test_global_str_fmt, "", "dynamic string");
45 
46 	return 0;
47 }
48 
49 static void __exit trace_printk_exit(void)
50 {
51 }
52 
53 module_init(trace_printk_init);
54 module_exit(trace_printk_exit);
55 
56 MODULE_AUTHOR("Steven Rostedt");
57 MODULE_DESCRIPTION("trace-printk");
58 MODULE_LICENSE("GPL");
59