| 1 | /* |
| 2 | * ltt-probes.c |
| 3 | * |
| 4 | * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 5 | * |
| 6 | * Holds LTTng probes registry. |
| 7 | */ |
| 8 | |
| 9 | #include <linux/module.h> |
| 10 | #include <linux/list.h> |
| 11 | #include <linux/mutex.h> |
| 12 | |
| 13 | #include "ltt-events.h" |
| 14 | |
| 15 | static LIST_HEAD(probe_list); |
| 16 | static DEFINE_MUTEX(probe_mutex); |
| 17 | |
| 18 | static |
| 19 | const struct lttng_event_desc *find_event(const char *name) |
| 20 | { |
| 21 | struct lttng_probe_desc *probe_desc; |
| 22 | int i; |
| 23 | |
| 24 | list_for_each_entry(probe_desc, &probe_list, head) { |
| 25 | for (i = 0; i < probe_desc->nr_events; i++) { |
| 26 | if (!strcmp(probe_desc->event_desc[i].name, name)) |
| 27 | return &probe_desc->event_desc[i]; |
| 28 | } |
| 29 | } |
| 30 | return NULL; |
| 31 | } |
| 32 | |
| 33 | /* |
| 34 | * TODO: registration of probe descriptions in dynamically allocated memory (not |
| 35 | * directly in a module memory) will require some care for refcounting: it's |
| 36 | * currently done by just refcounting the module in event_get/put. |
| 37 | */ |
| 38 | int ltt_probe_register(struct lttng_probe_desc *desc) |
| 39 | { |
| 40 | int ret = 0; |
| 41 | int i; |
| 42 | |
| 43 | mutex_lock(&probe_mutex); |
| 44 | /* |
| 45 | * TODO: This is O(N^2). Turn into a hash table when probe registration |
| 46 | * overhead becomes an issue. |
| 47 | */ |
| 48 | for (i = 0; i < desc->nr_events; i++) { |
| 49 | if (find_event(desc->event_desc[i].name)) { |
| 50 | ret = -EEXIST; |
| 51 | goto end; |
| 52 | } |
| 53 | } |
| 54 | list_add(&desc->head, &probe_list); |
| 55 | end: |
| 56 | mutex_unlock(&probe_mutex); |
| 57 | return ret; |
| 58 | } |
| 59 | EXPORT_SYMBOL_GPL(ltt_probe_register); |
| 60 | |
| 61 | void ltt_probe_unregister(struct lttng_probe_desc *desc) |
| 62 | { |
| 63 | mutex_lock(&probe_mutex); |
| 64 | list_del(&desc->head); |
| 65 | mutex_unlock(&probe_mutex); |
| 66 | } |
| 67 | EXPORT_SYMBOL_GPL(ltt_probe_unregister); |
| 68 | |
| 69 | const struct lttng_event_desc *ltt_event_get(const char *name) |
| 70 | { |
| 71 | const struct lttng_event_desc *event; |
| 72 | int ret; |
| 73 | |
| 74 | mutex_lock(&probe_mutex); |
| 75 | event = find_event(name); |
| 76 | mutex_unlock(&probe_mutex); |
| 77 | if (!event) |
| 78 | return NULL; |
| 79 | ret = try_module_get(__module_text_address((unsigned long) event)); |
| 80 | WARN_ON_ONCE(!ret); |
| 81 | return event; |
| 82 | } |
| 83 | EXPORT_SYMBOL_GPL(ltt_event_get); |
| 84 | |
| 85 | void ltt_event_put(const struct lttng_event_desc *event) |
| 86 | { |
| 87 | module_put(__module_text_address((unsigned long) event)); |
| 88 | } |
| 89 | EXPORT_SYMBOL_GPL(ltt_event_put); |