1 #include <linux/module.h> 2 #include <linux/kthread.h> 3 4 /* 5 * Any file that uses trace points, must include the header. 6 * But only one file, must include the header by defining 7 * CREATE_TRACE_POINTS first. This will make the C code that 8 * creates the handles for the trace points. 9 */ 10 #define CREATE_TRACE_POINTS 11 #include "trace-events-sample.h" 12 13 static const char *random_strings[] = { 14 "Mother Goose", 15 "Snoopy", 16 "Gandalf", 17 "Frodo", 18 "One ring to rule them all" 19 }; 20 21 static void simple_thread_func(int cnt) 22 { 23 int array[6]; 24 int len = cnt % 5; 25 int i; 26 27 set_current_state(TASK_INTERRUPTIBLE); 28 schedule_timeout(HZ); 29 30 for (i = 0; i < len; i++) 31 array[i] = i + 1; 32 array[i] = 0; 33 34 /* Silly tracepoints */ 35 trace_foo_bar("hello", cnt, array, random_strings[len], 36 ¤t->cpus_allowed); 37 38 trace_foo_with_template_simple("HELLO", cnt); 39 40 trace_foo_bar_with_cond("Some times print", cnt); 41 42 trace_foo_with_template_cond("prints other times", cnt); 43 44 trace_foo_with_template_print("I have to be different", cnt); 45 } 46 47 static int simple_thread(void *arg) 48 { 49 int cnt = 0; 50 51 while (!kthread_should_stop()) 52 simple_thread_func(cnt++); 53 54 return 0; 55 } 56 57 static struct task_struct *simple_tsk; 58 static struct task_struct *simple_tsk_fn; 59 60 static void simple_thread_func_fn(int cnt) 61 { 62 set_current_state(TASK_INTERRUPTIBLE); 63 schedule_timeout(HZ); 64 65 /* More silly tracepoints */ 66 trace_foo_bar_with_fn("Look at me", cnt); 67 trace_foo_with_template_fn("Look at me too", cnt); 68 } 69 70 static int simple_thread_fn(void *arg) 71 { 72 int cnt = 0; 73 74 while (!kthread_should_stop()) 75 simple_thread_func_fn(cnt++); 76 77 return 0; 78 } 79 80 static DEFINE_MUTEX(thread_mutex); 81 static int simple_thread_cnt; 82 83 int foo_bar_reg(void) 84 { 85 mutex_lock(&thread_mutex); 86 if (simple_thread_cnt++) 87 goto out; 88 89 pr_info("Starting thread for foo_bar_fn\n"); 90 /* 91 * We shouldn't be able to start a trace when the module is 92 * unloading (there's other locks to prevent that). But 93 * for consistency sake, we still take the thread_mutex. 94 */ 95 simple_tsk_fn = kthread_run(simple_thread_fn, NULL, "event-sample-fn"); 96 out: 97 mutex_unlock(&thread_mutex); 98 return 0; 99 } 100 101 void foo_bar_unreg(void) 102 { 103 mutex_lock(&thread_mutex); 104 if (--simple_thread_cnt) 105 goto out; 106 107 pr_info("Killing thread for foo_bar_fn\n"); 108 if (simple_tsk_fn) 109 kthread_stop(simple_tsk_fn); 110 simple_tsk_fn = NULL; 111 out: 112 mutex_unlock(&thread_mutex); 113 } 114 115 static int __init trace_event_init(void) 116 { 117 simple_tsk = kthread_run(simple_thread, NULL, "event-sample"); 118 if (IS_ERR(simple_tsk)) 119 return -1; 120 121 return 0; 122 } 123 124 static void __exit trace_event_exit(void) 125 { 126 kthread_stop(simple_tsk); 127 mutex_lock(&thread_mutex); 128 if (simple_tsk_fn) 129 kthread_stop(simple_tsk_fn); 130 simple_tsk_fn = NULL; 131 mutex_unlock(&thread_mutex); 132 } 133 134 module_init(trace_event_init); 135 module_exit(trace_event_exit); 136 137 MODULE_AUTHOR("Steven Rostedt"); 138 MODULE_DESCRIPTION("trace-events-sample"); 139 MODULE_LICENSE("GPL"); 140