| 1 | /* |
| 2 | * ltt/ltt-channels.c |
| 3 | * |
| 4 | * (C) Copyright 2008 - Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca) |
| 5 | * |
| 6 | * LTTng channel management. |
| 7 | * |
| 8 | * Author: |
| 9 | * Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca) |
| 10 | * |
| 11 | * This library is free software; you can redistribute it and/or |
| 12 | * modify it under the terms of the GNU Lesser General Public |
| 13 | * License as published by the Free Software Foundation; either |
| 14 | * version 2.1 of the License, or (at your option) any later version. |
| 15 | * |
| 16 | * This library is distributed in the hope that it will be useful, |
| 17 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 18 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 19 | * Lesser General Public License for more details. |
| 20 | * |
| 21 | * You should have received a copy of the GNU Lesser General Public |
| 22 | * License along with this library; if not, write to the Free Software |
| 23 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 24 | */ |
| 25 | |
| 26 | #include <stdlib.h> |
| 27 | #include <ust/marker.h> |
| 28 | #include "channels.h" |
| 29 | #include "usterr.h" |
| 30 | |
| 31 | /* |
| 32 | * ltt_channel_mutex may be nested inside the LTT trace mutex. |
| 33 | * ltt_channel_mutex mutex may be nested inside markers mutex. |
| 34 | */ |
| 35 | static DEFINE_MUTEX(ltt_channel_mutex); |
| 36 | static LIST_HEAD(ltt_channels); |
| 37 | /* |
| 38 | * Index of next channel in array. Makes sure that as long as a trace channel is |
| 39 | * allocated, no array index will be re-used when a channel is freed and then |
| 40 | * another channel is allocated. This index is cleared and the array indexeds |
| 41 | * get reassigned when the index_kref goes back to 0, which indicates that no |
| 42 | * more trace channels are allocated. |
| 43 | */ |
| 44 | static unsigned int free_index; |
| 45 | static struct kref index_kref; /* Keeps track of allocated trace channels */ |
| 46 | |
| 47 | int ust_channels_overwrite_by_default = 0; |
| 48 | int ust_channels_request_collection_by_default = 1; |
| 49 | |
| 50 | static struct ltt_channel_setting *lookup_channel(const char *name) |
| 51 | { |
| 52 | struct ltt_channel_setting *iter; |
| 53 | |
| 54 | list_for_each_entry(iter, <t_channels, list) |
| 55 | if (strcmp(name, iter->name) == 0) |
| 56 | return iter; |
| 57 | return NULL; |
| 58 | } |
| 59 | |
| 60 | /* |
| 61 | * Must be called when channel refcount falls to 0 _and_ also when the last |
| 62 | * trace is freed. This function is responsible for compacting the channel and |
| 63 | * event IDs when no users are active. |
| 64 | * |
| 65 | * Called with lock_markers() and channels mutex held. |
| 66 | */ |
| 67 | static void release_channel_setting(struct kref *kref) |
| 68 | { |
| 69 | struct ltt_channel_setting *setting = container_of(kref, |
| 70 | struct ltt_channel_setting, kref); |
| 71 | struct ltt_channel_setting *iter; |
| 72 | |
| 73 | if (uatomic_read(&index_kref.refcount) == 0 |
| 74 | && uatomic_read(&setting->kref.refcount) == 0) { |
| 75 | list_del(&setting->list); |
| 76 | free(setting); |
| 77 | |
| 78 | free_index = 0; |
| 79 | list_for_each_entry(iter, <t_channels, list) { |
| 80 | iter->index = free_index++; |
| 81 | iter->free_event_id = 0; |
| 82 | } |
| 83 | /* FIXME: why not run this? */ |
| 84 | //ust// markers_compact_event_ids(); |
| 85 | } |
| 86 | } |
| 87 | |
| 88 | /* |
| 89 | * Perform channel index compaction when the last trace channel is freed. |
| 90 | * |
| 91 | * Called with lock_markers() and channels mutex held. |
| 92 | */ |
| 93 | static void release_trace_channel(struct kref *kref) |
| 94 | { |
| 95 | struct ltt_channel_setting *iter, *n; |
| 96 | |
| 97 | list_for_each_entry_safe(iter, n, <t_channels, list) |
| 98 | release_channel_setting(&iter->kref); |
| 99 | } |
| 100 | |
| 101 | /** |
| 102 | * ltt_channels_register - Register a trace channel. |
| 103 | * @name: channel name |
| 104 | * |
| 105 | * Uses refcounting. |
| 106 | */ |
| 107 | int ltt_channels_register(const char *name) |
| 108 | { |
| 109 | struct ltt_channel_setting *setting; |
| 110 | int ret = 0; |
| 111 | |
| 112 | mutex_lock(<t_channel_mutex); |
| 113 | setting = lookup_channel(name); |
| 114 | if (setting) { |
| 115 | if (uatomic_read(&setting->kref.refcount) == 0) |
| 116 | goto init_kref; |
| 117 | else { |
| 118 | kref_get(&setting->kref); |
| 119 | goto end; |
| 120 | } |
| 121 | } |
| 122 | setting = zmalloc(sizeof(*setting)); |
| 123 | if (!setting) { |
| 124 | ret = -ENOMEM; |
| 125 | goto end; |
| 126 | } |
| 127 | list_add(&setting->list, <t_channels); |
| 128 | strncpy(setting->name, name, PATH_MAX-1); |
| 129 | setting->index = free_index++; |
| 130 | init_kref: |
| 131 | kref_init(&setting->kref); |
| 132 | end: |
| 133 | mutex_unlock(<t_channel_mutex); |
| 134 | return ret; |
| 135 | } |
| 136 | //ust// EXPORT_SYMBOL_GPL(ltt_channels_register); |
| 137 | |
| 138 | /** |
| 139 | * ltt_channels_unregister - Unregister a trace channel. |
| 140 | * @name: channel name |
| 141 | * |
| 142 | * Must be called with markers mutex held. |
| 143 | */ |
| 144 | int ltt_channels_unregister(const char *name) |
| 145 | { |
| 146 | struct ltt_channel_setting *setting; |
| 147 | int ret = 0; |
| 148 | |
| 149 | mutex_lock(<t_channel_mutex); |
| 150 | setting = lookup_channel(name); |
| 151 | if (!setting || uatomic_read(&setting->kref.refcount) == 0) { |
| 152 | ret = -ENOENT; |
| 153 | goto end; |
| 154 | } |
| 155 | kref_put(&setting->kref, release_channel_setting); |
| 156 | end: |
| 157 | mutex_unlock(<t_channel_mutex); |
| 158 | return ret; |
| 159 | } |
| 160 | //ust// EXPORT_SYMBOL_GPL(ltt_channels_unregister); |
| 161 | |
| 162 | /** |
| 163 | * ltt_channels_set_default - Set channel default behavior. |
| 164 | * @name: default channel name |
| 165 | * @subbuf_size: size of the subbuffers |
| 166 | * @subbuf_cnt: number of subbuffers |
| 167 | */ |
| 168 | int ltt_channels_set_default(const char *name, |
| 169 | unsigned int subbuf_size, |
| 170 | unsigned int subbuf_cnt) |
| 171 | { |
| 172 | struct ltt_channel_setting *setting; |
| 173 | int ret = 0; |
| 174 | |
| 175 | mutex_lock(<t_channel_mutex); |
| 176 | setting = lookup_channel(name); |
| 177 | if (!setting || uatomic_read(&setting->kref.refcount) == 0) { |
| 178 | ret = -ENOENT; |
| 179 | goto end; |
| 180 | } |
| 181 | setting->subbuf_size = subbuf_size; |
| 182 | setting->subbuf_cnt = subbuf_cnt; |
| 183 | end: |
| 184 | mutex_unlock(<t_channel_mutex); |
| 185 | return ret; |
| 186 | } |
| 187 | //ust// EXPORT_SYMBOL_GPL(ltt_channels_set_default); |
| 188 | |
| 189 | /** |
| 190 | * ltt_channels_get_name_from_index - get channel name from channel index |
| 191 | * @index: channel index |
| 192 | * |
| 193 | * Allows to lookup the channel name given its index. Done to keep the name |
| 194 | * information outside of each trace channel instance. |
| 195 | */ |
| 196 | const char *ltt_channels_get_name_from_index(unsigned int index) |
| 197 | { |
| 198 | struct ltt_channel_setting *iter; |
| 199 | |
| 200 | list_for_each_entry(iter, <t_channels, list) |
| 201 | if (iter->index == index && uatomic_read(&iter->kref.refcount)) |
| 202 | return iter->name; |
| 203 | return NULL; |
| 204 | } |
| 205 | //ust// EXPORT_SYMBOL_GPL(ltt_channels_get_name_from_index); |
| 206 | |
| 207 | static struct ltt_channel_setting * |
| 208 | ltt_channels_get_setting_from_name(const char *name) |
| 209 | { |
| 210 | struct ltt_channel_setting *iter; |
| 211 | |
| 212 | list_for_each_entry(iter, <t_channels, list) |
| 213 | if (!strcmp(iter->name, name) |
| 214 | && uatomic_read(&iter->kref.refcount)) |
| 215 | return iter; |
| 216 | return NULL; |
| 217 | } |
| 218 | |
| 219 | /** |
| 220 | * ltt_channels_get_index_from_name - get channel index from channel name |
| 221 | * @name: channel name |
| 222 | * |
| 223 | * Allows to lookup the channel index given its name. Done to keep the name |
| 224 | * information outside of each trace channel instance. |
| 225 | * Returns -1 if not found. |
| 226 | */ |
| 227 | int ltt_channels_get_index_from_name(const char *name) |
| 228 | { |
| 229 | struct ltt_channel_setting *setting; |
| 230 | |
| 231 | setting = ltt_channels_get_setting_from_name(name); |
| 232 | if (setting) |
| 233 | return setting->index; |
| 234 | else |
| 235 | return -1; |
| 236 | } |
| 237 | //ust// EXPORT_SYMBOL_GPL(ltt_channels_get_index_from_name); |
| 238 | |
| 239 | /** |
| 240 | * ltt_channels_trace_alloc - Allocate channel structures for a trace |
| 241 | * @subbuf_size: subbuffer size. 0 uses default. |
| 242 | * @subbuf_cnt: number of subbuffers per per-cpu buffers. 0 uses default. |
| 243 | * @flags: Default channel flags |
| 244 | * |
| 245 | * Use the current channel list to allocate the channels for a trace. |
| 246 | * Called with trace lock held. Does not perform the trace buffer allocation, |
| 247 | * because we must let the user overwrite specific channel sizes. |
| 248 | */ |
| 249 | struct ust_channel *ltt_channels_trace_alloc(unsigned int *nr_channels, |
| 250 | int overwrite, |
| 251 | int request_collection, |
| 252 | int active) |
| 253 | { |
| 254 | struct ust_channel *channel = NULL; |
| 255 | struct ltt_channel_setting *iter; |
| 256 | |
| 257 | mutex_lock(<t_channel_mutex); |
| 258 | if (!free_index) { |
| 259 | WARN("ltt_channels_trace_alloc: no free_index; are there any probes connected?"); |
| 260 | goto end; |
| 261 | } |
| 262 | if (!uatomic_read(&index_kref.refcount)) |
| 263 | kref_init(&index_kref); |
| 264 | else |
| 265 | kref_get(&index_kref); |
| 266 | *nr_channels = free_index; |
| 267 | channel = zmalloc(sizeof(struct ust_channel) * free_index); |
| 268 | if (!channel) { |
| 269 | WARN("ltt_channel_struct: channel null after alloc"); |
| 270 | goto end; |
| 271 | } |
| 272 | list_for_each_entry(iter, <t_channels, list) { |
| 273 | if (!uatomic_read(&iter->kref.refcount)) |
| 274 | continue; |
| 275 | channel[iter->index].subbuf_size = iter->subbuf_size; |
| 276 | channel[iter->index].subbuf_cnt = iter->subbuf_cnt; |
| 277 | channel[iter->index].overwrite = overwrite; |
| 278 | channel[iter->index].request_collection = request_collection; |
| 279 | channel[iter->index].active = active; |
| 280 | channel[iter->index].channel_name = iter->name; |
| 281 | } |
| 282 | end: |
| 283 | mutex_unlock(<t_channel_mutex); |
| 284 | return channel; |
| 285 | } |
| 286 | //ust// EXPORT_SYMBOL_GPL(ltt_channels_trace_alloc); |
| 287 | |
| 288 | /** |
| 289 | * ltt_channels_trace_free - Free one trace's channels |
| 290 | * @channels: channels to free |
| 291 | * |
| 292 | * Called with trace lock held. The actual channel buffers must be freed before |
| 293 | * this function is called. |
| 294 | */ |
| 295 | void ltt_channels_trace_free(struct ust_channel *channels) |
| 296 | { |
| 297 | lock_markers(); |
| 298 | mutex_lock(<t_channel_mutex); |
| 299 | free(channels); |
| 300 | kref_put(&index_kref, release_trace_channel); |
| 301 | mutex_unlock(<t_channel_mutex); |
| 302 | unlock_markers(); |
| 303 | } |
| 304 | //ust// EXPORT_SYMBOL_GPL(ltt_channels_trace_free); |
| 305 | |
| 306 | /** |
| 307 | * _ltt_channels_get_event_id - get next event ID for a marker |
| 308 | * @channel: channel name |
| 309 | * @name: event name |
| 310 | * |
| 311 | * Returns a unique event ID (for this channel) or < 0 on error. |
| 312 | * Must be called with channels mutex held. |
| 313 | */ |
| 314 | int _ltt_channels_get_event_id(const char *channel, const char *name) |
| 315 | { |
| 316 | struct ltt_channel_setting *setting; |
| 317 | int ret; |
| 318 | |
| 319 | setting = ltt_channels_get_setting_from_name(channel); |
| 320 | if (!setting) { |
| 321 | ret = -ENOENT; |
| 322 | goto end; |
| 323 | } |
| 324 | if (strcmp(channel, "metadata") == 0) { |
| 325 | if (strcmp(name, "core_marker_id") == 0) |
| 326 | ret = 0; |
| 327 | else if (strcmp(name, "core_marker_format") == 0) |
| 328 | ret = 1; |
| 329 | else if (strcmp(name, "testev") == 0) |
| 330 | ret = 2; |
| 331 | else |
| 332 | ret = -ENOENT; |
| 333 | goto end; |
| 334 | } |
| 335 | if (setting->free_event_id == EVENTS_PER_CHANNEL - 1) { |
| 336 | ret = -ENOSPC; |
| 337 | goto end; |
| 338 | } |
| 339 | ret = setting->free_event_id++; |
| 340 | end: |
| 341 | return ret; |
| 342 | } |
| 343 | |
| 344 | /** |
| 345 | * ltt_channels_get_event_id - get next event ID for a marker |
| 346 | * @channel: channel name |
| 347 | * @name: event name |
| 348 | * |
| 349 | * Returns a unique event ID (for this channel) or < 0 on error. |
| 350 | */ |
| 351 | int ltt_channels_get_event_id(const char *channel, const char *name) |
| 352 | { |
| 353 | int ret; |
| 354 | |
| 355 | mutex_lock(<t_channel_mutex); |
| 356 | ret = _ltt_channels_get_event_id(channel, name); |
| 357 | mutex_unlock(<t_channel_mutex); |
| 358 | return ret; |
| 359 | } |
| 360 | |
| 361 | //ust// MODULE_LICENSE("GPL"); |
| 362 | //ust// MODULE_AUTHOR("Mathieu Desnoyers"); |
| 363 | //ust// MODULE_DESCRIPTION("Linux Trace Toolkit Next Generation Channel Management"); |