src/lttng-ring-buffer-event-notifier-client.h

   1 /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
   2  *
   3  * lttng-ring-buffer-event-notifier-client.h
   4  *
   5  * LTTng lib ring buffer event notifier client template.
   6  *
   7  * Copyright (C) 2010-2020 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/types.h>
  12 #include <wrapper/vmalloc.h>    /* for wrapper_vmalloc_sync_mappings() */
  13 #include <lttng/events.h>
  14 #include <lttng/tracer.h>
  15
  16 static struct lttng_transport lttng_relay_transport;
  17
  18 struct event_notifier_packet_header {
  19         uint8_t  header_end[0];
  20 };
  21
  22 struct event_notifier_record_header {
  23         uint8_t header_end[0];          /* End of header */
  24 };
  25
  26 static const struct lib_ring_buffer_config client_config;
  27
  28 static inline
  29 u64 lib_ring_buffer_clock_read(struct channel *chan)
  30 {
  31         return 0;
  32 }
  33
  34 static inline
  35 size_t record_header_size(const struct lib_ring_buffer_config *config,
  36                                  struct channel *chan, size_t offset,
  37                                  size_t *pre_header_padding,
  38                                  struct lib_ring_buffer_ctx *ctx,
  39                                  void *client_ctx)
  40 {
  41         return 0;
  42 }
  43
  44 #include <ringbuffer/api.h>
  45
  46 static u64 client_ring_buffer_clock_read(struct channel *chan)
  47 {
  48         return 0;
  49 }
  50
  51 static
  52 size_t client_record_header_size(const struct lib_ring_buffer_config *config,
  53                                  struct channel *chan, size_t offset,
  54                                  size_t *pre_header_padding,
  55                                  struct lib_ring_buffer_ctx *ctx,
  56                                  void *client_ctx)
  57 {
  58         return 0;
  59 }
  60
  61 /**
  62  * client_packet_header_size - called on buffer-switch to a new sub-buffer
  63  *
  64  * Return header size without padding after the structure. Don't use packed
  65  * structure because gcc generates inefficient code on some architectures
  66  * (powerpc, mips..)
  67  */
  68 static size_t client_packet_header_size(void)
  69 {
  70         return offsetof(struct event_notifier_packet_header, header_end);
  71 }
  72
  73 static void client_buffer_begin(struct lib_ring_buffer *buf, u64 tsc,
  74                                 unsigned int subbuf_idx)
  75 {
  76 }
  77
  78 /*
  79  * offset is assumed to never be 0 here : never deliver a completely empty
  80  * subbuffer. data_size is between 1 and subbuf_size.
  81  */
  82 static void client_buffer_end(struct lib_ring_buffer *buf, u64 tsc,
  83                               unsigned int subbuf_idx, unsigned long data_size)
  84 {
  85 }
  86
  87 static int client_buffer_create(struct lib_ring_buffer *buf, void *priv,
  88                                 int cpu, const char *name)
  89 {
  90         return 0;
  91 }
  92
  93 static void client_buffer_finalize(struct lib_ring_buffer *buf, void *priv, int cpu)
  94 {
  95 }
  96
  97 static int client_timestamp_begin(const struct lib_ring_buffer_config *config,
  98                 struct lib_ring_buffer *buf, uint64_t *timestamp_begin)
  99 {
 100         return -ENOSYS;
 101 }
 102
 103 static int client_timestamp_end(const struct lib_ring_buffer_config *config,
 104                         struct lib_ring_buffer *bufb,
 105                         uint64_t *timestamp_end)
 106 {
 107         return -ENOSYS;
 108 }
 109
 110 static int client_events_discarded(const struct lib_ring_buffer_config *config,
 111                         struct lib_ring_buffer *bufb,
 112                         uint64_t *events_discarded)
 113 {
 114         return -ENOSYS;
 115 }
 116
 117 static int client_current_timestamp(const struct lib_ring_buffer_config *config,
 118                 struct lib_ring_buffer *bufb,
 119                 uint64_t *ts)
 120 {
 121         return -ENOSYS;
 122 }
 123
 124 static int client_content_size(const struct lib_ring_buffer_config *config,
 125                         struct lib_ring_buffer *bufb,
 126                         uint64_t *content_size)
 127 {
 128         return -ENOSYS;
 129 }
 130
 131 static int client_packet_size(const struct lib_ring_buffer_config *config,
 132                         struct lib_ring_buffer *bufb,
 133                         uint64_t *packet_size)
 134 {
 135         return -ENOSYS;
 136 }
 137
 138 static int client_stream_id(const struct lib_ring_buffer_config *config,
 139                         struct lib_ring_buffer *bufb,
 140                         uint64_t *stream_id)
 141 {
 142         return -ENOSYS;
 143 }
 144
 145 static int client_sequence_number(const struct lib_ring_buffer_config *config,
 146                         struct lib_ring_buffer *bufb,
 147                         uint64_t *seq)
 148 {
 149         return -ENOSYS;
 150 }
 151
 152 static
 153 int client_instance_id(const struct lib_ring_buffer_config *config,
 154                 struct lib_ring_buffer *bufb,
 155                 uint64_t *id)
 156 {
 157         return -ENOSYS;
 158 }
 159
 160 static void client_record_get(const struct lib_ring_buffer_config *config,
 161         struct channel *chan, struct lib_ring_buffer *buf,
 162         size_t offset, size_t *header_len,
 163         size_t *payload_len, u64 *timestamp)
 164 {
 165         struct event_notifier_record_header header;
 166         int ret;
 167
 168         ret = lib_ring_buffer_read(&buf->backend, offset, &header,
 169                         offsetof(struct event_notifier_record_header, header_end));
 170         CHAN_WARN_ON(chan, ret != offsetof(struct event_notifier_record_header, header_end));
 171         *header_len = offsetof(struct event_notifier_record_header, header_end);
 172         /*
 173          * Currently, only 64-bit event notifier ID.
 174          */
 175         *payload_len = sizeof(uint64_t);
 176         *timestamp = 0;
 177 }
 178
 179 static const struct lib_ring_buffer_config client_config = {
 180         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 181         .cb.record_header_size = client_record_header_size,
 182         .cb.subbuffer_header_size = client_packet_header_size,
 183         .cb.buffer_begin = client_buffer_begin,
 184         .cb.buffer_end = client_buffer_end,
 185         .cb.buffer_create = client_buffer_create,
 186         .cb.buffer_finalize = client_buffer_finalize,
 187         .cb.record_get = client_record_get,
 188
 189         .tsc_bits = 0,
 190         .alloc = RING_BUFFER_ALLOC_GLOBAL,
 191         .sync = RING_BUFFER_SYNC_GLOBAL,
 192         .mode = RING_BUFFER_MODE_TEMPLATE,
 193         .backend = RING_BUFFER_PAGE,
 194         .output = RING_BUFFER_OUTPUT_TEMPLATE,
 195         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 196         .ipi = RING_BUFFER_NO_IPI_BARRIER,
 197         .wakeup = RING_BUFFER_WAKEUP_BY_WRITER,
 198 };
 199
 200 static
 201 void release_priv_ops(void *priv_ops)
 202 {
 203         module_put(THIS_MODULE);
 204 }
 205
 206 static
 207 void lttng_channel_destroy(struct channel *chan)
 208 {
 209         channel_destroy(chan);
 210 }
 211
 212 static
 213 struct channel *_channel_create(const char *name,
 214                                 void *priv, void *buf_addr,
 215                                 size_t subbuf_size, size_t num_subbuf,
 216                                 unsigned int switch_timer_interval,
 217                                 unsigned int read_timer_interval)
 218 {
 219         struct lttng_event_notifier_group *event_notifier_group = priv;
 220         struct channel *chan;
 221
 222         chan = channel_create(&client_config, name,
 223                               event_notifier_group, buf_addr,
 224                               subbuf_size, num_subbuf, switch_timer_interval,
 225                               read_timer_interval);
 226         if (chan) {
 227                 /*
 228                  * Ensure this module is not unloaded before we finish
 229                  * using lttng_relay_transport.ops.
 230                  */
 231                 if (!try_module_get(THIS_MODULE)) {
 232                         printk(KERN_WARNING "LTTng: Can't lock event_notifier transport module.\n");
 233                         goto error;
 234                 }
 235                 chan->backend.priv_ops = &lttng_relay_transport.ops;
 236                 chan->backend.release_priv_ops = release_priv_ops;
 237         }
 238         return chan;
 239
 240 error:
 241         lttng_channel_destroy(chan);
 242         return NULL;
 243 }
 244
 245 static
 246 struct lib_ring_buffer *lttng_buffer_read_open(struct channel *chan)
 247 {
 248         struct lib_ring_buffer *buf;
 249
 250         buf = channel_get_ring_buffer(&client_config, chan, 0);
 251         if (!lib_ring_buffer_open_read(buf))
 252                 return buf;
 253         return NULL;
 254 }
 255
 256 static
 257 int lttng_buffer_has_read_closed_stream(struct channel *chan)
 258 {
 259         struct lib_ring_buffer *buf;
 260         int cpu;
 261
 262         for_each_channel_cpu(cpu, chan) {
 263                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 264                 if (!atomic_long_read(&buf->active_readers))
 265                         return 1;
 266         }
 267         return 0;
 268 }
 269
 270 static
 271 void lttng_buffer_read_close(struct lib_ring_buffer *buf)
 272 {
 273         lib_ring_buffer_release_read(buf);
 274 }
 275
 276 static
 277 int lttng_event_reserve(struct lib_ring_buffer_ctx *ctx, uint32_t event_id)
 278 {
 279         int ret;
 280
 281         ret = lib_ring_buffer_reserve(&client_config, ctx, NULL);
 282         if (ret)
 283                 return ret;
 284         lib_ring_buffer_backend_get_pages(&client_config, ctx,
 285                         &ctx->backend_pages);
 286         return 0;
 287 }
 288
 289 static
 290 void lttng_event_commit(struct lib_ring_buffer_ctx *ctx)
 291 {
 292         lib_ring_buffer_commit(&client_config, ctx);
 293 }
 294
 295 static
 296 void lttng_event_write(struct lib_ring_buffer_ctx *ctx, const void *src,
 297                      size_t len)
 298 {
 299         lib_ring_buffer_write(&client_config, ctx, src, len);
 300 }
 301
 302 static
 303 void lttng_event_write_from_user(struct lib_ring_buffer_ctx *ctx,
 304                                const void __user *src, size_t len)
 305 {
 306         lib_ring_buffer_copy_from_user_inatomic(&client_config, ctx, src, len);
 307 }
 308
 309 static
 310 void lttng_event_memset(struct lib_ring_buffer_ctx *ctx,
 311                 int c, size_t len)
 312 {
 313         lib_ring_buffer_memset(&client_config, ctx, c, len);
 314 }
 315
 316 static
 317 void lttng_event_strcpy(struct lib_ring_buffer_ctx *ctx, const char *src,
 318                 size_t len)
 319 {
 320         lib_ring_buffer_strcpy(&client_config, ctx, src, len, '#');
 321 }
 322
 323 static
 324 size_t lttng_packet_avail_size(struct channel *chan)
 325 {
 326         unsigned long o_begin;
 327         struct lib_ring_buffer *buf;
 328
 329         buf = chan->backend.buf;        /* Only for global buffer ! */
 330         o_begin = v_read(&client_config, &buf->offset);
 331         if (subbuf_offset(o_begin, chan) != 0) {
 332                 return chan->backend.subbuf_size - subbuf_offset(o_begin, chan);
 333         } else {
 334                 return chan->backend.subbuf_size - subbuf_offset(o_begin, chan)
 335                         - sizeof(struct event_notifier_packet_header);
 336         }
 337 }
 338
 339 static
 340 wait_queue_head_t *lttng_get_writer_buf_wait_queue(struct channel *chan, int cpu)
 341 {
 342         struct lib_ring_buffer *buf = channel_get_ring_buffer(&client_config,
 343                                         chan, cpu);
 344         return &buf->write_wait;
 345 }
 346
 347 static
 348 wait_queue_head_t *lttng_get_hp_wait_queue(struct channel *chan)
 349 {
 350         return &chan->hp_wait;
 351 }
 352
 353 static
 354 int lttng_is_finalized(struct channel *chan)
 355 {
 356         return lib_ring_buffer_channel_is_finalized(chan);
 357 }
 358
 359 static
 360 int lttng_is_disabled(struct channel *chan)
 361 {
 362         return lib_ring_buffer_channel_is_disabled(chan);
 363 }
 364
 365 static struct lttng_transport lttng_relay_transport = {
 366         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING,
 367         .owner = THIS_MODULE,
 368         .ops = {
 369                 .channel_create = _channel_create,
 370                 .channel_destroy = lttng_channel_destroy,
 371                 .buffer_read_open = lttng_buffer_read_open,
 372                 .buffer_has_read_closed_stream =
 373                         lttng_buffer_has_read_closed_stream,
 374                 .buffer_read_close = lttng_buffer_read_close,
 375                 .event_reserve = lttng_event_reserve,
 376                 .event_commit = lttng_event_commit,
 377                 .event_write_from_user = lttng_event_write_from_user,
 378                 .event_memset = lttng_event_memset,
 379                 .event_write = lttng_event_write,
 380                 .event_strcpy = lttng_event_strcpy,
 381                 .packet_avail_size = lttng_packet_avail_size,
 382                 .get_writer_buf_wait_queue = lttng_get_writer_buf_wait_queue,
 383                 .get_hp_wait_queue = lttng_get_hp_wait_queue,
 384                 .is_finalized = lttng_is_finalized,
 385                 .is_disabled = lttng_is_disabled,
 386                 .timestamp_begin = client_timestamp_begin,
 387                 .timestamp_end = client_timestamp_end,
 388                 .events_discarded = client_events_discarded,
 389                 .content_size = client_content_size,
 390                 .packet_size = client_packet_size,
 391                 .stream_id = client_stream_id,
 392                 .current_timestamp = client_current_timestamp,
 393                 .sequence_number = client_sequence_number,
 394                 .instance_id = client_instance_id,
 395         },
 396 };
 397
 398 static int __init lttng_ring_buffer_event_notifier_client_init(void)
 399 {
 400         /*
 401          * This vmalloc sync all also takes care of the lib ring buffer
 402          * vmalloc'd module pages when it is built as a module into LTTng.
 403          */
 404         wrapper_vmalloc_sync_mappings();
 405         lttng_transport_register(&lttng_relay_transport);
 406         return 0;
 407 }
 408
 409 module_init(lttng_ring_buffer_event_notifier_client_init);
 410
 411 static void __exit lttng_ring_buffer_event_notifier_client_exit(void)
 412 {
 413         lttng_transport_unregister(&lttng_relay_transport);
 414 }
 415
 416 module_exit(lttng_ring_buffer_event_notifier_client_exit);
 417
 418 MODULE_LICENSE("GPL and additional rights");
 419 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
 420 MODULE_DESCRIPTION("LTTng ring buffer " RING_BUFFER_MODE_TEMPLATE_STRING
 421                    " client");
 422 MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
 423         __stringify(LTTNG_MODULES_MINOR_VERSION) "."
 424         __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
 425         LTTNG_MODULES_EXTRAVERSION);