| 1 | /* probe-example.c |
| 2 | * |
| 3 | * Connects a two functions to marker call sites. |
| 4 | * |
| 5 | * (C) Copyright 2007 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> |
| 6 | * |
| 7 | * This file is released under the GPLv2. |
| 8 | * See the file COPYING for more details. |
| 9 | */ |
| 10 | |
| 11 | #include <linux/sched.h> |
| 12 | #include <linux/kernel.h> |
| 13 | #include <linux/module.h> |
| 14 | #include <linux/marker.h> |
| 15 | #include <asm/atomic.h> |
| 16 | |
| 17 | #define NUM_PROBES (sizeof(probe_array) / sizeof(struct probe_data)) |
| 18 | |
| 19 | struct probe_data { |
| 20 | const char *name; |
| 21 | const char *format; |
| 22 | marker_probe_func *probe_func; |
| 23 | }; |
| 24 | |
| 25 | void probe_subsystem_event(const struct __mark_marker_c *mdata, |
| 26 | const char *format, ...) |
| 27 | { |
| 28 | va_list ap; |
| 29 | /* Declare args */ |
| 30 | unsigned int value; |
| 31 | const char *mystr; |
| 32 | |
| 33 | /* Assign args */ |
| 34 | va_start(ap, format); |
| 35 | value = va_arg(ap, typeof(value)); |
| 36 | mystr = va_arg(ap, typeof(mystr)); |
| 37 | |
| 38 | /* Call printk */ |
| 39 | printk("Value %u, string %s\n", value, mystr); |
| 40 | |
| 41 | /* or count, check rights, serialize data in a buffer */ |
| 42 | |
| 43 | va_end(ap); |
| 44 | } |
| 45 | |
| 46 | atomic_t eventb_count = ATOMIC_INIT(0); |
| 47 | |
| 48 | void probe_subsystem_eventb(const struct __mark_marker_c *mdata, |
| 49 | const char *format, ...) |
| 50 | { |
| 51 | /* Increment counter */ |
| 52 | atomic_inc(&eventb_count); |
| 53 | } |
| 54 | |
| 55 | static struct probe_data probe_array[] = |
| 56 | { |
| 57 | { .name = "subsystem_event", |
| 58 | .format = "%d %s", |
| 59 | .probe_func = probe_subsystem_event }, |
| 60 | { .name = "subsystem_eventb", |
| 61 | .format = MARK_NOARGS, |
| 62 | .probe_func = probe_subsystem_eventb }, |
| 63 | }; |
| 64 | |
| 65 | static int __init probe_init(void) |
| 66 | { |
| 67 | int result; |
| 68 | uint8_t eID; |
| 69 | |
| 70 | for (eID = 0; eID < NUM_PROBES; eID++) { |
| 71 | result = marker_set_probe(probe_array[eID].name, |
| 72 | probe_array[eID].format, |
| 73 | probe_array[eID].probe_func, &probe_array[eID]); |
| 74 | if (!result) |
| 75 | printk(KERN_INFO "Unable to register probe %s\n", |
| 76 | probe_array[eID].name); |
| 77 | } |
| 78 | return 0; |
| 79 | } |
| 80 | |
| 81 | static void __exit probe_fini(void) |
| 82 | { |
| 83 | uint8_t eID; |
| 84 | |
| 85 | for (eID = 0; eID < NUM_PROBES; eID++) { |
| 86 | marker_remove_probe(probe_array[eID].name); |
| 87 | } |
| 88 | synchronize_sched(); /* Wait for probes to finish */ |
| 89 | printk("Number of event b : %u\n", atomic_read(&eventb_count)); |
| 90 | } |
| 91 | |
| 92 | module_init(probe_init); |
| 93 | module_exit(probe_fini); |
| 94 | |
| 95 | MODULE_LICENSE("GPL"); |
| 96 | MODULE_AUTHOR("Mathieu Desnoyers"); |
| 97 | MODULE_DESCRIPTION("SUBSYSTEM Probe"); |