| 1 | /* |
| 2 | * buffers.h |
| 3 | * LTTng userspace tracer buffering system |
| 4 | * |
| 5 | * Copyright (C) 2009 - Pierre-Marc Fournier (pierre-marc dot fournier at polymtl dot ca) |
| 6 | * Copyright (C) 2008 - Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca) |
| 7 | * |
| 8 | * This library is free software; you can redistribute it and/or |
| 9 | * modify it under the terms of the GNU Lesser General Public |
| 10 | * License as published by the Free Software Foundation; either |
| 11 | * version 2.1 of the License, or (at your option) any later version. |
| 12 | * |
| 13 | * This library is distributed in the hope that it will be useful, |
| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 16 | * Lesser General Public License for more details. |
| 17 | * |
| 18 | * You should have received a copy of the GNU Lesser General Public |
| 19 | * License along with this library; if not, write to the Free Software |
| 20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 21 | */ |
| 22 | |
| 23 | #ifndef _UST_BUFFERS_H |
| 24 | #define _UST_BUFFERS_H |
| 25 | |
| 26 | #include <assert.h> |
| 27 | #include <ust/kernelcompat.h> |
| 28 | #include "usterr.h" |
| 29 | #include "channels.h" |
| 30 | #include "tracerconst.h" |
| 31 | #include "tracercore.h" |
| 32 | #include "header-inline.h" |
| 33 | |
| 34 | /***** FIXME: SHOULD BE REMOVED ***** */ |
| 35 | |
| 36 | /* |
| 37 | * BUFFER_TRUNC zeroes the subbuffer offset and the subbuffer number parts of |
| 38 | * the offset, which leaves only the buffer number. |
| 39 | */ |
| 40 | #define BUFFER_TRUNC(offset, chan) \ |
| 41 | ((offset) & (~((chan)->alloc_size-1))) |
| 42 | #define BUFFER_OFFSET(offset, chan) ((offset) & ((chan)->alloc_size - 1)) |
| 43 | #define SUBBUF_OFFSET(offset, chan) ((offset) & ((chan)->subbuf_size - 1)) |
| 44 | #define SUBBUF_ALIGN(offset, chan) \ |
| 45 | (((offset) + (chan)->subbuf_size) & (~((chan)->subbuf_size - 1))) |
| 46 | #define SUBBUF_TRUNC(offset, chan) \ |
| 47 | ((offset) & (~((chan)->subbuf_size - 1))) |
| 48 | #define SUBBUF_INDEX(offset, chan) \ |
| 49 | (BUFFER_OFFSET((offset), chan) >> (chan)->subbuf_size_order) |
| 50 | |
| 51 | /* |
| 52 | * Tracks changes to rchan/rchan_buf structs |
| 53 | */ |
| 54 | #define UST_CHANNEL_VERSION 8 |
| 55 | |
| 56 | /**************************************/ |
| 57 | |
| 58 | struct commit_counters { |
| 59 | long cc; /* ATOMIC */ |
| 60 | long cc_sb; /* ATOMIC - Incremented _once_ at sb switch */ |
| 61 | }; |
| 62 | |
| 63 | struct ust_buffer { |
| 64 | /* First 32 bytes cache-hot cacheline */ |
| 65 | long offset; /* Current offset in the buffer *atomic* */ |
| 66 | struct commit_counters *commit_count; /* Commit count per sub-buffer */ |
| 67 | long consumed; /* Current offset in the buffer *atomic* access (shared) */ |
| 68 | unsigned long last_tsc; /* |
| 69 | * Last timestamp written in the buffer. |
| 70 | */ |
| 71 | /* End of first 32 bytes cacheline */ |
| 72 | long active_readers; /* ATOMIC - Active readers count standard atomic access (shared) */ |
| 73 | long events_lost; /* ATOMIC */ |
| 74 | long corrupted_subbuffers; /* *ATOMIC* */ |
| 75 | /* one byte is written to this pipe when data is available, in order |
| 76 | to wake the consumer */ |
| 77 | /* portability: Single byte writes must be as quick as possible. The kernel-side |
| 78 | buffer must be large enough so the writer doesn't block. From the pipe(7) |
| 79 | man page: Since linux 2.6.11, the pipe capacity is 65536 bytes. */ |
| 80 | int data_ready_fd_write; |
| 81 | /* the reading end of the pipe */ |
| 82 | int data_ready_fd_read; |
| 83 | |
| 84 | unsigned int finalized; |
| 85 | //ust// struct timer_list switch_timer; /* timer for periodical switch */ |
| 86 | unsigned long switch_timer_interval; /* 0 = unset */ |
| 87 | |
| 88 | struct ust_channel *chan; |
| 89 | |
| 90 | struct kref kref; |
| 91 | void *buf_data; |
| 92 | size_t buf_size; |
| 93 | int shmid; |
| 94 | unsigned int cpu; |
| 95 | |
| 96 | /* commit count per subbuffer; must be at end of struct */ |
| 97 | long commit_seq[0] ____cacheline_aligned; /* ATOMIC */ |
| 98 | } ____cacheline_aligned; |
| 99 | |
| 100 | /* |
| 101 | * A switch is done during tracing or as a final flush after tracing (so it |
| 102 | * won't write in the new sub-buffer). |
| 103 | * FIXME: make this message clearer |
| 104 | */ |
| 105 | enum force_switch_mode { FORCE_ACTIVE, FORCE_FLUSH }; |
| 106 | |
| 107 | extern int ltt_reserve_slot_lockless_slow(struct ust_trace *trace, |
| 108 | struct ust_channel *ltt_channel, void **transport_data, |
| 109 | size_t data_size, size_t *slot_size, long *buf_offset, u64 *tsc, |
| 110 | unsigned int *rflags, int largest_align, int cpu); |
| 111 | |
| 112 | extern void ltt_force_switch_lockless_slow(struct ust_buffer *buf, |
| 113 | enum force_switch_mode mode); |
| 114 | |
| 115 | |
| 116 | static __inline__ void ust_buffers_do_copy(void *dest, const void *src, size_t len) |
| 117 | { |
| 118 | union { |
| 119 | const void *src; |
| 120 | const u8 *src8; |
| 121 | const u16 *src16; |
| 122 | const u32 *src32; |
| 123 | const u64 *src64; |
| 124 | } u = { .src = src }; |
| 125 | |
| 126 | switch (len) { |
| 127 | case 0: break; |
| 128 | case 1: *(u8 *)dest = *u.src8; |
| 129 | break; |
| 130 | case 2: *(u16 *)dest = *u.src16; |
| 131 | break; |
| 132 | case 4: *(u32 *)dest = *u.src32; |
| 133 | break; |
| 134 | case 8: *(u64 *)dest = *u.src64; |
| 135 | break; |
| 136 | default: |
| 137 | memcpy(dest, src, len); |
| 138 | } |
| 139 | } |
| 140 | |
| 141 | static __inline__ void *ust_buffers_offset_address(struct ust_buffer *buf, size_t offset) |
| 142 | { |
| 143 | return ((char *)buf->buf_data)+offset; |
| 144 | } |
| 145 | |
| 146 | /* |
| 147 | * Last TSC comparison functions. Check if the current TSC overflows |
| 148 | * LTT_TSC_BITS bits from the last TSC read. Reads and writes last_tsc |
| 149 | * atomically. |
| 150 | */ |
| 151 | |
| 152 | /* FIXME: does this test work properly? */ |
| 153 | #if (BITS_PER_LONG == 32) |
| 154 | static __inline__ void save_last_tsc(struct ust_buffer *ltt_buf, |
| 155 | u64 tsc) |
| 156 | { |
| 157 | ltt_buf->last_tsc = (unsigned long)(tsc >> LTT_TSC_BITS); |
| 158 | } |
| 159 | |
| 160 | static __inline__ int last_tsc_overflow(struct ust_buffer *ltt_buf, |
| 161 | u64 tsc) |
| 162 | { |
| 163 | unsigned long tsc_shifted = (unsigned long)(tsc >> LTT_TSC_BITS); |
| 164 | |
| 165 | if (unlikely((tsc_shifted - ltt_buf->last_tsc))) |
| 166 | return 1; |
| 167 | else |
| 168 | return 0; |
| 169 | } |
| 170 | #else |
| 171 | static __inline__ void save_last_tsc(struct ust_buffer *ltt_buf, |
| 172 | u64 tsc) |
| 173 | { |
| 174 | ltt_buf->last_tsc = (unsigned long)tsc; |
| 175 | } |
| 176 | |
| 177 | static __inline__ int last_tsc_overflow(struct ust_buffer *ltt_buf, |
| 178 | u64 tsc) |
| 179 | { |
| 180 | if (unlikely((tsc - ltt_buf->last_tsc) >> LTT_TSC_BITS)) |
| 181 | return 1; |
| 182 | else |
| 183 | return 0; |
| 184 | } |
| 185 | #endif |
| 186 | |
| 187 | static __inline__ void ltt_reserve_push_reader( |
| 188 | struct ust_channel *rchan, |
| 189 | struct ust_buffer *buf, |
| 190 | long offset) |
| 191 | { |
| 192 | long consumed_old, consumed_new; |
| 193 | |
| 194 | do { |
| 195 | consumed_old = uatomic_read(&buf->consumed); |
| 196 | /* |
| 197 | * If buffer is in overwrite mode, push the reader consumed |
| 198 | * count if the write position has reached it and we are not |
| 199 | * at the first iteration (don't push the reader farther than |
| 200 | * the writer). This operation can be done concurrently by many |
| 201 | * writers in the same buffer, the writer being at the farthest |
| 202 | * write position sub-buffer index in the buffer being the one |
| 203 | * which will win this loop. |
| 204 | * If the buffer is not in overwrite mode, pushing the reader |
| 205 | * only happens if a sub-buffer is corrupted. |
| 206 | */ |
| 207 | if (unlikely((SUBBUF_TRUNC(offset, buf->chan) |
| 208 | - SUBBUF_TRUNC(consumed_old, buf->chan)) |
| 209 | >= rchan->alloc_size)) |
| 210 | consumed_new = SUBBUF_ALIGN(consumed_old, buf->chan); |
| 211 | else |
| 212 | return; |
| 213 | } while (unlikely(uatomic_cmpxchg(&buf->consumed, consumed_old, |
| 214 | consumed_new) != consumed_old)); |
| 215 | } |
| 216 | |
| 217 | static __inline__ void ltt_vmcore_check_deliver( |
| 218 | struct ust_buffer *buf, |
| 219 | long commit_count, long idx) |
| 220 | { |
| 221 | uatomic_set(&buf->commit_seq[idx], commit_count); |
| 222 | } |
| 223 | |
| 224 | static __inline__ void ltt_check_deliver(struct ust_channel *chan, |
| 225 | struct ust_buffer *buf, |
| 226 | long offset, long commit_count, long idx) |
| 227 | { |
| 228 | long old_commit_count = commit_count - chan->subbuf_size; |
| 229 | |
| 230 | /* Check if all commits have been done */ |
| 231 | if (unlikely((BUFFER_TRUNC(offset, chan) |
| 232 | >> chan->n_subbufs_order) |
| 233 | - (old_commit_count |
| 234 | & chan->commit_count_mask) == 0)) { |
| 235 | /* |
| 236 | * If we succeeded in updating the cc_sb, we are delivering |
| 237 | * the subbuffer. Deals with concurrent updates of the "cc" |
| 238 | * value without adding a add_return atomic operation to the |
| 239 | * fast path. |
| 240 | */ |
| 241 | if (likely(uatomic_cmpxchg(&buf->commit_count[idx].cc_sb, |
| 242 | old_commit_count, commit_count) |
| 243 | == old_commit_count)) { |
| 244 | int result; |
| 245 | |
| 246 | /* |
| 247 | * Set noref flag for this subbuffer. |
| 248 | */ |
| 249 | //ust// ltt_set_noref_flag(rchan, buf, idx); |
| 250 | ltt_vmcore_check_deliver(buf, commit_count, idx); |
| 251 | |
| 252 | /* wakeup consumer */ |
| 253 | result = write(buf->data_ready_fd_write, "1", 1); |
| 254 | if(result == -1) { |
| 255 | PERROR("write (in ltt_relay_buffer_flush)"); |
| 256 | ERR("this should never happen!"); |
| 257 | } |
| 258 | } |
| 259 | } |
| 260 | } |
| 261 | |
| 262 | static __inline__ int ltt_poll_deliver(struct ust_channel *chan, struct ust_buffer *buf) |
| 263 | { |
| 264 | long consumed_old, consumed_idx, commit_count, write_offset; |
| 265 | |
| 266 | consumed_old = uatomic_read(&buf->consumed); |
| 267 | consumed_idx = SUBBUF_INDEX(consumed_old, buf->chan); |
| 268 | commit_count = uatomic_read(&buf->commit_count[consumed_idx].cc_sb); |
| 269 | /* |
| 270 | * No memory barrier here, since we are only interested |
| 271 | * in a statistically correct polling result. The next poll will |
| 272 | * get the data is we are racing. The mb() that ensures correct |
| 273 | * memory order is in get_subbuf. |
| 274 | */ |
| 275 | write_offset = uatomic_read(&buf->offset); |
| 276 | |
| 277 | /* |
| 278 | * Check that the subbuffer we are trying to consume has been |
| 279 | * already fully committed. |
| 280 | */ |
| 281 | |
| 282 | if (((commit_count - chan->subbuf_size) |
| 283 | & chan->commit_count_mask) |
| 284 | - (BUFFER_TRUNC(consumed_old, buf->chan) |
| 285 | >> chan->n_subbufs_order) |
| 286 | != 0) |
| 287 | return 0; |
| 288 | |
| 289 | /* |
| 290 | * Check that we are not about to read the same subbuffer in |
| 291 | * which the writer head is. |
| 292 | */ |
| 293 | if ((SUBBUF_TRUNC(write_offset, buf->chan) |
| 294 | - SUBBUF_TRUNC(consumed_old, buf->chan)) |
| 295 | == 0) |
| 296 | return 0; |
| 297 | |
| 298 | return 1; |
| 299 | |
| 300 | } |
| 301 | |
| 302 | /* |
| 303 | * returns 0 if reserve ok, or 1 if the slow path must be taken. |
| 304 | */ |
| 305 | static __inline__ int ltt_relay_try_reserve( |
| 306 | struct ust_channel *chan, |
| 307 | struct ust_buffer *buf, |
| 308 | size_t data_size, |
| 309 | u64 *tsc, unsigned int *rflags, int largest_align, |
| 310 | long *o_begin, long *o_end, long *o_old, |
| 311 | size_t *before_hdr_pad, size_t *size) |
| 312 | { |
| 313 | *o_begin = uatomic_read(&buf->offset); |
| 314 | *o_old = *o_begin; |
| 315 | |
| 316 | *tsc = trace_clock_read64(); |
| 317 | |
| 318 | //ust// #ifdef CONFIG_LTT_VMCORE |
| 319 | //ust// prefetch(&buf->commit_count[SUBBUF_INDEX(*o_begin, rchan)]); |
| 320 | //ust// prefetch(&buf->commit_seq[SUBBUF_INDEX(*o_begin, rchan)]); |
| 321 | //ust// #else |
| 322 | //ust// prefetchw(&buf->commit_count[SUBBUF_INDEX(*o_begin, rchan)]); |
| 323 | //ust// #endif |
| 324 | if (last_tsc_overflow(buf, *tsc)) |
| 325 | *rflags = LTT_RFLAG_ID_SIZE_TSC; |
| 326 | |
| 327 | if (unlikely(SUBBUF_OFFSET(*o_begin, buf->chan) == 0)) |
| 328 | return 1; |
| 329 | |
| 330 | *size = ust_get_header_size(chan, |
| 331 | *o_begin, data_size, |
| 332 | before_hdr_pad, *rflags); |
| 333 | *size += ltt_align(*o_begin + *size, largest_align) + data_size; |
| 334 | if (unlikely((SUBBUF_OFFSET(*o_begin, buf->chan) + *size) |
| 335 | > buf->chan->subbuf_size)) |
| 336 | return 1; |
| 337 | |
| 338 | /* |
| 339 | * Event fits in the current buffer and we are not on a switch |
| 340 | * boundary. It's safe to write. |
| 341 | */ |
| 342 | *o_end = *o_begin + *size; |
| 343 | |
| 344 | if (unlikely((SUBBUF_OFFSET(*o_end, buf->chan)) == 0)) |
| 345 | /* |
| 346 | * The offset_end will fall at the very beginning of the next |
| 347 | * subbuffer. |
| 348 | */ |
| 349 | return 1; |
| 350 | |
| 351 | return 0; |
| 352 | } |
| 353 | |
| 354 | static __inline__ int ltt_reserve_slot(struct ust_trace *trace, |
| 355 | struct ust_channel *chan, void **transport_data, |
| 356 | size_t data_size, size_t *slot_size, long *buf_offset, u64 *tsc, |
| 357 | unsigned int *rflags, int largest_align, int cpu) |
| 358 | { |
| 359 | struct ust_buffer *buf = chan->buf[cpu]; |
| 360 | long o_begin, o_end, o_old; |
| 361 | size_t before_hdr_pad; |
| 362 | |
| 363 | /* |
| 364 | * Perform retryable operations. |
| 365 | */ |
| 366 | /* FIXME: make this rellay per cpu? */ |
| 367 | if (unlikely(LOAD_SHARED(ltt_nesting) > 4)) { |
| 368 | DBG("Dropping event because nesting is too deep."); |
| 369 | uatomic_inc(&buf->events_lost); |
| 370 | return -EPERM; |
| 371 | } |
| 372 | |
| 373 | if (unlikely(ltt_relay_try_reserve(chan, buf, |
| 374 | data_size, tsc, rflags, |
| 375 | largest_align, &o_begin, &o_end, &o_old, |
| 376 | &before_hdr_pad, slot_size))) |
| 377 | goto slow_path; |
| 378 | |
| 379 | if (unlikely(uatomic_cmpxchg(&buf->offset, o_old, o_end) != o_old)) |
| 380 | goto slow_path; |
| 381 | |
| 382 | /* |
| 383 | * Atomically update last_tsc. This update races against concurrent |
| 384 | * atomic updates, but the race will always cause supplementary full TSC |
| 385 | * events, never the opposite (missing a full TSC event when it would be |
| 386 | * needed). |
| 387 | */ |
| 388 | save_last_tsc(buf, *tsc); |
| 389 | |
| 390 | /* |
| 391 | * Push the reader if necessary |
| 392 | */ |
| 393 | ltt_reserve_push_reader(chan, buf, o_end - 1); |
| 394 | |
| 395 | /* |
| 396 | * Clear noref flag for this subbuffer. |
| 397 | */ |
| 398 | //ust// ltt_clear_noref_flag(chan, buf, SUBBUF_INDEX(o_end - 1, chan)); |
| 399 | |
| 400 | *buf_offset = o_begin + before_hdr_pad; |
| 401 | return 0; |
| 402 | slow_path: |
| 403 | return ltt_reserve_slot_lockless_slow(trace, chan, |
| 404 | transport_data, data_size, slot_size, buf_offset, tsc, |
| 405 | rflags, largest_align, cpu); |
| 406 | } |
| 407 | |
| 408 | /* |
| 409 | * Force a sub-buffer switch for a per-cpu buffer. This operation is |
| 410 | * completely reentrant : can be called while tracing is active with |
| 411 | * absolutely no lock held. |
| 412 | */ |
| 413 | static __inline__ void ltt_force_switch(struct ust_buffer *buf, |
| 414 | enum force_switch_mode mode) |
| 415 | { |
| 416 | return ltt_force_switch_lockless_slow(buf, mode); |
| 417 | } |
| 418 | |
| 419 | /* |
| 420 | * for flight recording. must be called after relay_commit. |
| 421 | * This function increments the subbuffers's commit_seq counter each time the |
| 422 | * commit count reaches back the reserve offset (module subbuffer size). It is |
| 423 | * useful for crash dump. |
| 424 | */ |
| 425 | //ust// #ifdef CONFIG_LTT_VMCORE |
| 426 | static __inline__ void ltt_write_commit_counter(struct ust_channel *chan, |
| 427 | struct ust_buffer *buf, long idx, long buf_offset, |
| 428 | long commit_count, size_t data_size) |
| 429 | { |
| 430 | long offset; |
| 431 | long commit_seq_old; |
| 432 | |
| 433 | offset = buf_offset + data_size; |
| 434 | |
| 435 | /* |
| 436 | * SUBBUF_OFFSET includes commit_count_mask. We can simply |
| 437 | * compare the offsets within the subbuffer without caring about |
| 438 | * buffer full/empty mismatch because offset is never zero here |
| 439 | * (subbuffer header and event headers have non-zero length). |
| 440 | */ |
| 441 | if (unlikely(SUBBUF_OFFSET(offset - commit_count, buf->chan))) |
| 442 | return; |
| 443 | |
| 444 | commit_seq_old = uatomic_read(&buf->commit_seq[idx]); |
| 445 | while (commit_seq_old < commit_count) |
| 446 | commit_seq_old = uatomic_cmpxchg(&buf->commit_seq[idx], |
| 447 | commit_seq_old, commit_count); |
| 448 | |
| 449 | DBG("commit_seq for channel %s_%d, subbuf %ld is now %ld", buf->chan->channel_name, buf->cpu, idx, commit_count); |
| 450 | } |
| 451 | //ust// #else |
| 452 | //ust// static __inline__ void ltt_write_commit_counter(struct ust_buffer *buf, |
| 453 | //ust// long idx, long buf_offset, long commit_count, size_t data_size) |
| 454 | //ust// { |
| 455 | //ust// } |
| 456 | //ust// #endif |
| 457 | |
| 458 | /* |
| 459 | * Atomic unordered slot commit. Increments the commit count in the |
| 460 | * specified sub-buffer, and delivers it if necessary. |
| 461 | * |
| 462 | * Parameters: |
| 463 | * |
| 464 | * @ltt_channel : channel structure |
| 465 | * @transport_data: transport-specific data |
| 466 | * @buf_offset : offset following the event header. |
| 467 | * @data_size : size of the event data. |
| 468 | * @slot_size : size of the reserved slot. |
| 469 | */ |
| 470 | static __inline__ void ltt_commit_slot( |
| 471 | struct ust_channel *chan, |
| 472 | struct ust_buffer *buf, long buf_offset, |
| 473 | size_t data_size, size_t slot_size) |
| 474 | { |
| 475 | long offset_end = buf_offset; |
| 476 | long endidx = SUBBUF_INDEX(offset_end - 1, chan); |
| 477 | long commit_count; |
| 478 | |
| 479 | #ifdef LTT_NO_IPI_BARRIER |
| 480 | smp_wmb(); |
| 481 | #else |
| 482 | /* |
| 483 | * Must write slot data before incrementing commit count. |
| 484 | * This compiler barrier is upgraded into a smp_mb() by the IPI |
| 485 | * sent by get_subbuf(). |
| 486 | */ |
| 487 | barrier(); |
| 488 | #endif |
| 489 | uatomic_add(&buf->commit_count[endidx].cc, slot_size); |
| 490 | /* |
| 491 | * commit count read can race with concurrent OOO commit count updates. |
| 492 | * This is only needed for ltt_check_deliver (for non-polling delivery |
| 493 | * only) and for ltt_write_commit_counter. The race can only cause the |
| 494 | * counter to be read with the same value more than once, which could |
| 495 | * cause : |
| 496 | * - Multiple delivery for the same sub-buffer (which is handled |
| 497 | * gracefully by the reader code) if the value is for a full |
| 498 | * sub-buffer. It's important that we can never miss a sub-buffer |
| 499 | * delivery. Re-reading the value after the uatomic_add ensures this. |
| 500 | * - Reading a commit_count with a higher value that what was actually |
| 501 | * added to it for the ltt_write_commit_counter call (again caused by |
| 502 | * a concurrent committer). It does not matter, because this function |
| 503 | * is interested in the fact that the commit count reaches back the |
| 504 | * reserve offset for a specific sub-buffer, which is completely |
| 505 | * independent of the order. |
| 506 | */ |
| 507 | commit_count = uatomic_read(&buf->commit_count[endidx].cc); |
| 508 | |
| 509 | ltt_check_deliver(chan, buf, offset_end - 1, commit_count, endidx); |
| 510 | /* |
| 511 | * Update data_size for each commit. It's needed only for extracting |
| 512 | * ltt buffers from vmcore, after crash. |
| 513 | */ |
| 514 | ltt_write_commit_counter(chan, buf, endidx, buf_offset, commit_count, data_size); |
| 515 | } |
| 516 | |
| 517 | void _ust_buffers_write(struct ust_buffer *buf, size_t offset, |
| 518 | const void *src, size_t len, ssize_t cpy); |
| 519 | |
| 520 | static __inline__ int ust_buffers_write(struct ust_buffer *buf, size_t offset, |
| 521 | const void *src, size_t len) |
| 522 | { |
| 523 | size_t cpy; |
| 524 | size_t buf_offset = BUFFER_OFFSET(offset, buf->chan); |
| 525 | |
| 526 | assert(buf_offset < buf->chan->subbuf_size*buf->chan->subbuf_cnt); |
| 527 | |
| 528 | cpy = min_t(size_t, len, buf->buf_size - buf_offset); |
| 529 | ust_buffers_do_copy(buf->buf_data + buf_offset, src, cpy); |
| 530 | |
| 531 | if (unlikely(len != cpy)) |
| 532 | _ust_buffers_write(buf, buf_offset, src, len, cpy); |
| 533 | return len; |
| 534 | } |
| 535 | |
| 536 | extern int ust_buffers_get_subbuf(struct ust_buffer *buf, long *consumed); |
| 537 | extern int ust_buffers_put_subbuf(struct ust_buffer *buf, unsigned long uconsumed_old); |
| 538 | |
| 539 | extern void init_ustrelay_transport(void); |
| 540 | |
| 541 | #endif /* _UST_BUFFERS_H */ |