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