| 1 | /* |
| 2 | * LTT core in-kernel infrastructure. |
| 3 | * |
| 4 | * Copyright 2006 - Mathieu Desnoyers mathieu.desnoyers@polymtl.ca |
| 5 | * |
| 6 | * Dual LGPL v2.1/GPL v2 license. |
| 7 | */ |
| 8 | |
| 9 | #include <linux/percpu.h> |
| 10 | #include <linux/module.h> |
| 11 | #include <linux/debugfs.h> |
| 12 | #include <linux/kref.h> |
| 13 | #include <linux/cpu.h> |
| 14 | |
| 15 | #include "ltt-tracer-core.h" |
| 16 | |
| 17 | /* Traces structures */ |
| 18 | struct ltt_traces ltt_traces = { |
| 19 | .setup_head = LIST_HEAD_INIT(ltt_traces.setup_head), |
| 20 | .head = LIST_HEAD_INIT(ltt_traces.head), |
| 21 | }; |
| 22 | EXPORT_SYMBOL(ltt_traces); |
| 23 | |
| 24 | /* Traces list writer locking */ |
| 25 | static DEFINE_MUTEX(ltt_traces_mutex); |
| 26 | |
| 27 | /* root dentry mutex */ |
| 28 | static DEFINE_MUTEX(ltt_root_mutex); |
| 29 | /* dentry of ltt's root dir */ |
| 30 | static struct dentry *ltt_root_dentry; |
| 31 | static struct kref ltt_root_kref = { |
| 32 | .refcount = ATOMIC_INIT(0), |
| 33 | }; |
| 34 | |
| 35 | static void ltt_root_release(struct kref *ref) |
| 36 | { |
| 37 | debugfs_remove(ltt_root_dentry); |
| 38 | ltt_root_dentry = NULL; |
| 39 | } |
| 40 | |
| 41 | void put_ltt_root(void) |
| 42 | { |
| 43 | mutex_lock(<t_root_mutex); |
| 44 | if (ltt_root_dentry) |
| 45 | kref_put(<t_root_kref, ltt_root_release); |
| 46 | mutex_unlock(<t_root_mutex); |
| 47 | } |
| 48 | EXPORT_SYMBOL_GPL(put_ltt_root); |
| 49 | |
| 50 | struct dentry *get_ltt_root(void) |
| 51 | { |
| 52 | mutex_lock(<t_root_mutex); |
| 53 | if (!ltt_root_dentry) { |
| 54 | ltt_root_dentry = debugfs_create_dir(LTT_ROOT, NULL); |
| 55 | if (!ltt_root_dentry) { |
| 56 | printk(KERN_ERR "LTT : create ltt root dir failed\n"); |
| 57 | goto out; |
| 58 | } |
| 59 | kref_init(<t_root_kref); |
| 60 | goto out; |
| 61 | } |
| 62 | kref_get(<t_root_kref); |
| 63 | out: |
| 64 | mutex_unlock(<t_root_mutex); |
| 65 | return ltt_root_dentry; |
| 66 | } |
| 67 | EXPORT_SYMBOL_GPL(get_ltt_root); |
| 68 | |
| 69 | /* |
| 70 | * ltt_lock_traces/ltt_unlock_traces also disables cpu hotplug. |
| 71 | */ |
| 72 | void ltt_lock_traces(void) |
| 73 | { |
| 74 | mutex_lock(<t_traces_mutex); |
| 75 | get_online_cpus(); |
| 76 | } |
| 77 | EXPORT_SYMBOL_GPL(ltt_lock_traces); |
| 78 | |
| 79 | void ltt_unlock_traces(void) |
| 80 | { |
| 81 | put_online_cpus(); |
| 82 | mutex_unlock(<t_traces_mutex); |
| 83 | } |
| 84 | EXPORT_SYMBOL_GPL(ltt_unlock_traces); |
| 85 | |
| 86 | DEFINE_PER_CPU(unsigned int, ltt_nesting); |
| 87 | EXPORT_PER_CPU_SYMBOL(ltt_nesting); |
| 88 | |
| 89 | int ltt_run_filter_default(void *trace, uint16_t eID) |
| 90 | { |
| 91 | return 1; |
| 92 | } |
| 93 | |
| 94 | /* This function pointer is protected by a trace activation check */ |
| 95 | ltt_run_filter_functor ltt_run_filter = ltt_run_filter_default; |
| 96 | EXPORT_SYMBOL_GPL(ltt_run_filter); |
| 97 | |
| 98 | void ltt_filter_register(ltt_run_filter_functor func) |
| 99 | { |
| 100 | ltt_run_filter = func; |
| 101 | } |
| 102 | EXPORT_SYMBOL_GPL(ltt_filter_register); |
| 103 | |
| 104 | void ltt_filter_unregister(void) |
| 105 | { |
| 106 | ltt_run_filter = ltt_run_filter_default; |
| 107 | } |
| 108 | EXPORT_SYMBOL_GPL(ltt_filter_unregister); |
| 109 | |
| 110 | MODULE_LICENSE("GPL and additional rights"); |
| 111 | MODULE_AUTHOR("Mathieu Desnoyers"); |
| 112 | MODULE_DESCRIPTION("Linux Trace Toolkit Next Generation Tracer Core"); |