| 1 | /* |
| 2 | * ltt-events.c |
| 3 | * |
| 4 | * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 5 | * |
| 6 | * Holds LTTng per-session event registry. |
| 7 | */ |
| 8 | |
| 9 | #include <linux/module.h> |
| 10 | #include "ltt-events.h" |
| 11 | |
| 12 | static LIST_HEAD(sessions); |
| 13 | static DEFINE_MUTEX(sessions_mutex); |
| 14 | static struct kmem_cache *event_cache; |
| 15 | |
| 16 | static void synchronize_trace(void) |
| 17 | { |
| 18 | synchronize_sched(); |
| 19 | #ifdef CONFIG_PREEMPT_RT |
| 20 | synchronize_rcu(); |
| 21 | #endif |
| 22 | } |
| 23 | |
| 24 | struct ltt_session *ltt_session_create(char *name) |
| 25 | { |
| 26 | struct ltt_session *session; |
| 27 | |
| 28 | mutex_lock(&sessions_mutex); |
| 29 | list_for_each_entry(session, &sessions, list) |
| 30 | if (!strcmp(session->name, name)) |
| 31 | goto exist; |
| 32 | session = kmalloc(sizeof(struct ltt_session) + strlen(name) + 1); |
| 33 | if (!session) |
| 34 | return NULL; |
| 35 | strcpy(session->name, name); |
| 36 | INIT_LIST_HEAD(&session->chan); |
| 37 | list_add(&session->list, &sessions); |
| 38 | mutex_unlock(&sessions_mutex); |
| 39 | return session; |
| 40 | |
| 41 | exist: |
| 42 | mutex_unlock(&sessions_mutex); |
| 43 | return NULL; |
| 44 | } |
| 45 | |
| 46 | int ltt_session_destroy(struct ltt_session *session) |
| 47 | { |
| 48 | struct ltt_channel *chan, *tmpchan; |
| 49 | struct ltt_event *event, *tmpevent; |
| 50 | |
| 51 | mutex_lock(&sessions_mutex); |
| 52 | session->active = 0; |
| 53 | synchronize_trace(); /* Wait for in-flight events to complete */ |
| 54 | list_for_each_entry_safe(event, tmpevent, &session->events, list) |
| 55 | _ltt_event_destroy(event); |
| 56 | list_for_each_entry_safe(chan, tmpchan, &session->chan, list) |
| 57 | _ltt_channel_destroy(chan); |
| 58 | list_del(&session->list); |
| 59 | mutex_unlock(&sessions_mutex); |
| 60 | kfree(session); |
| 61 | } |
| 62 | |
| 63 | struct ltt_channel *ltt_channel_create(struct ltt_session *session, char *name, |
| 64 | int overwrite, void *buf_addr, |
| 65 | size_t subbuf_size, size_t num_subbuf, |
| 66 | unsigned int switch_timer_interval, |
| 67 | unsigned int read_timer_interval) |
| 68 | { |
| 69 | struct ltt_channel *chan; |
| 70 | |
| 71 | mutex_lock(&sessions_mutex); |
| 72 | if (session->active) |
| 73 | goto active; /* Refuse to add channel to active session */ |
| 74 | list_for_each_entry(chan, &session->chan, list) |
| 75 | if (!strcmp(chan->name, name)) |
| 76 | goto exist; |
| 77 | chan = kmalloc(sizeof(struct ltt_channel) + strlen(name) + 1, GFP_KERNEL); |
| 78 | if (!chan) |
| 79 | return NULL; |
| 80 | strcpy(chan->name, name); |
| 81 | chan->session = session; |
| 82 | |
| 83 | /* TODO: create rb channel */ |
| 84 | list_add(&chan->list, &session->chan); |
| 85 | mutex_unlock(&sessions_mutex); |
| 86 | return chan; |
| 87 | |
| 88 | exist: |
| 89 | active: |
| 90 | mutex_unlock(&sessions_mutex); |
| 91 | return NULL; |
| 92 | } |
| 93 | |
| 94 | /* |
| 95 | * Only used internally at session destruction. |
| 96 | */ |
| 97 | int _ltt_channel_destroy(struct ltt_channel *chan) |
| 98 | { |
| 99 | /* TODO: destroy rb channel */ |
| 100 | list_del(&chan->list); |
| 101 | kfree(chan); |
| 102 | } |
| 103 | |
| 104 | /* |
| 105 | * Supports event creation while tracing session is active. |
| 106 | */ |
| 107 | struct ltt_event *ltt_event_create(struct ltt_channel *chan, char *name, |
| 108 | void *filter) |
| 109 | { |
| 110 | struct ltt_event *event; |
| 111 | int ret; |
| 112 | |
| 113 | mutex_lock(&sessions_mutex); |
| 114 | if (chan->free_event_id == -1UL) |
| 115 | goto full; |
| 116 | /* |
| 117 | * This is O(n^2) (for each event loop called at event creation). |
| 118 | * Might require a hash if we have lots of events. |
| 119 | */ |
| 120 | list_for_each_entry(event, &chan->session->events, list) |
| 121 | if (!strcmp(event->name, name)) |
| 122 | goto exist; |
| 123 | event = kmem_cache_zalloc(events_cache, GFP_KERNEL); |
| 124 | if (!event) |
| 125 | goto cache_error; |
| 126 | event->name = kmalloc(strlen(name) + 1, GFP_KERNEL); |
| 127 | if (!event->name) |
| 128 | goto error; |
| 129 | strcpy(event->name, name); |
| 130 | event->chan = chan; |
| 131 | event->filter = filter; |
| 132 | event->id = chan->free_event_id++; |
| 133 | mutex_unlock(&sessions_mutex); |
| 134 | /* Populate ltt_event structure before tracepoint registration. */ |
| 135 | smp_wmb(); |
| 136 | return event; |
| 137 | |
| 138 | error: |
| 139 | kmem_cache_free(event); |
| 140 | cache_error: |
| 141 | exist: |
| 142 | full: |
| 143 | mutex_unlock(&sessions_mutex); |
| 144 | return NULL; |
| 145 | } |
| 146 | |
| 147 | /* |
| 148 | * Only used internally at session destruction. |
| 149 | */ |
| 150 | int _ltt_event_destroy(struct ltt_event *event) |
| 151 | { |
| 152 | /* TODO unregister from tracepoint */ |
| 153 | kfree(event->name); |
| 154 | kmem_cache_free(event); |
| 155 | } |
| 156 | |
| 157 | static int __init ltt_events_init(void) |
| 158 | { |
| 159 | int ret; |
| 160 | |
| 161 | events_cache = KMEM_CACHE(ltt_event, 0); |
| 162 | if (!events_cache) |
| 163 | return -ENOMEM; |
| 164 | |
| 165 | /* TODO: show ABI to userspace */ |
| 166 | |
| 167 | return 0; |
| 168 | } |
| 169 | |
| 170 | static void __exit ltt_events_exit(void) |
| 171 | { |
| 172 | struct ltt_session *session, *tmpsession; |
| 173 | |
| 174 | /* TODO: hide ABI from userspace, wait for callers to release refs. */ |
| 175 | |
| 176 | list_for_each_entry_safe(session, tmpsession, &sessions, list) |
| 177 | ltt_session_destroy(session); |
| 178 | kmem_cache_destroy(events_cache); |
| 179 | } |
| 180 | |
| 181 | MODULE_LICENSE("GPL and additional rights"); |
| 182 | MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>"); |
| 183 | MODULE_DESCRIPTION("LTTng Events"); |