| 1 | /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only) |
| 2 | * |
| 3 | * lttng-clock.c |
| 4 | * |
| 5 | * Copyright (C) 2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 6 | */ |
| 7 | |
| 8 | #include <linux/module.h> |
| 9 | #include <linux/kmod.h> |
| 10 | #include <linux/mutex.h> |
| 11 | |
| 12 | #include <wrapper/trace-clock.h> |
| 13 | #include <lttng/events.h> |
| 14 | #include <lttng/tracer.h> |
| 15 | #include <lttng/events-internal.h> |
| 16 | |
| 17 | struct lttng_trace_clock *lttng_trace_clock; |
| 18 | EXPORT_SYMBOL_GPL(lttng_trace_clock); |
| 19 | |
| 20 | static DEFINE_MUTEX(clock_mutex); |
| 21 | static struct module *lttng_trace_clock_mod; /* plugin */ |
| 22 | static int clock_used; /* refcount */ |
| 23 | |
| 24 | int lttng_clock_register_plugin(struct lttng_trace_clock *ltc, |
| 25 | struct module *mod) |
| 26 | { |
| 27 | int ret = 0; |
| 28 | |
| 29 | mutex_lock(&clock_mutex); |
| 30 | if (clock_used) { |
| 31 | ret = -EBUSY; |
| 32 | goto end; |
| 33 | } |
| 34 | if (lttng_trace_clock_mod) { |
| 35 | ret = -EEXIST; |
| 36 | goto end; |
| 37 | } |
| 38 | /* set clock */ |
| 39 | WRITE_ONCE(lttng_trace_clock, ltc); |
| 40 | lttng_trace_clock_mod = mod; |
| 41 | end: |
| 42 | mutex_unlock(&clock_mutex); |
| 43 | return ret; |
| 44 | } |
| 45 | EXPORT_SYMBOL_GPL(lttng_clock_register_plugin); |
| 46 | |
| 47 | void lttng_clock_unregister_plugin(struct lttng_trace_clock *ltc, |
| 48 | struct module *mod) |
| 49 | { |
| 50 | mutex_lock(&clock_mutex); |
| 51 | WARN_ON_ONCE(clock_used); |
| 52 | if (!lttng_trace_clock_mod) { |
| 53 | goto end; |
| 54 | } |
| 55 | WARN_ON_ONCE(lttng_trace_clock_mod != mod); |
| 56 | |
| 57 | WRITE_ONCE(lttng_trace_clock, NULL); |
| 58 | lttng_trace_clock_mod = NULL; |
| 59 | end: |
| 60 | mutex_unlock(&clock_mutex); |
| 61 | } |
| 62 | EXPORT_SYMBOL_GPL(lttng_clock_unregister_plugin); |
| 63 | |
| 64 | void lttng_clock_ref(void) |
| 65 | { |
| 66 | mutex_lock(&clock_mutex); |
| 67 | clock_used++; |
| 68 | if (lttng_trace_clock_mod) { |
| 69 | int ret; |
| 70 | |
| 71 | ret = try_module_get(lttng_trace_clock_mod); |
| 72 | if (!ret) { |
| 73 | printk(KERN_ERR "LTTng: LTTng-clock cannot get clock plugin module\n"); |
| 74 | WRITE_ONCE(lttng_trace_clock, NULL); |
| 75 | lttng_trace_clock_mod = NULL; |
| 76 | } |
| 77 | } |
| 78 | mutex_unlock(&clock_mutex); |
| 79 | } |
| 80 | EXPORT_SYMBOL_GPL(lttng_clock_ref); |
| 81 | |
| 82 | void lttng_clock_unref(void) |
| 83 | { |
| 84 | mutex_lock(&clock_mutex); |
| 85 | clock_used--; |
| 86 | if (lttng_trace_clock_mod) |
| 87 | module_put(lttng_trace_clock_mod); |
| 88 | mutex_unlock(&clock_mutex); |
| 89 | } |
| 90 | EXPORT_SYMBOL_GPL(lttng_clock_unref); |
| 91 | |
| 92 | MODULE_LICENSE("GPL and additional rights"); |
| 93 | MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>"); |
| 94 | MODULE_DESCRIPTION("LTTng Clock"); |
| 95 | MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "." |
| 96 | __stringify(LTTNG_MODULES_MINOR_VERSION) "." |
| 97 | __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION) |
| 98 | LTTNG_MODULES_EXTRAVERSION); |