add debug message when events are lost in a subbuffer, on buffer_end
[ust.git] / libust / buffers.c
CommitLineData
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1/*
2 * buffers.c
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
204141ee 23#include <unistd.h>
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24#include <sys/mman.h>
25#include <sys/ipc.h>
26#include <sys/shm.h>
27#include <fcntl.h>
28#include <ust/kernelcompat.h>
29#include <kcompat/kref.h>
30#include "buffers.h"
31#include "channels.h"
32#include "tracer.h"
33#include "tracercore.h"
34#include "usterr.h"
35
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36struct ltt_reserve_switch_offsets {
37 long begin, end, old;
38 long begin_switch, end_switch_current, end_switch_old;
39 size_t before_hdr_pad, size;
40};
41
42
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43static DEFINE_MUTEX(ust_buffers_channels_mutex);
44static LIST_HEAD(ust_buffers_channels);
45
204141ee
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46static int get_n_cpus(void)
47{
48 int result;
49 static int n_cpus = 0;
50
51 if(n_cpus) {
52 return n_cpus;
53 }
54
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55 /* On Linux, when some processors are offline
56 * _SC_NPROCESSORS_CONF counts the offline
57 * processors, whereas _SC_NPROCESSORS_ONLN
58 * does not. If we used _SC_NPROCESSORS_ONLN,
59 * getcpu() could return a value greater than
60 * this sysconf, in which case the arrays
61 * indexed by processor would overflow.
62 */
63 result = sysconf(_SC_NPROCESSORS_CONF);
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64 if(result == -1) {
65 return -1;
66 }
67
68 n_cpus = result;
69
70 return result;
71}
72
b73a4c47
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73/* _ust_buffers_write()
74 *
75 * @buf: destination buffer
76 * @offset: offset in destination
77 * @src: source buffer
78 * @len: length of source
79 * @cpy: already copied
80 */
81
82void _ust_buffers_write(struct ust_buffer *buf, size_t offset,
83 const void *src, size_t len, ssize_t cpy)
84{
85 do {
86 len -= cpy;
87 src += cpy;
88 offset += cpy;
89
90 WARN_ON(offset >= buf->buf_size);
91
92 cpy = min_t(size_t, len, buf->buf_size - offset);
93 ust_buffers_do_copy(buf->buf_data + offset, src, cpy);
94 } while (unlikely(len != cpy));
95}
96
97static int ust_buffers_init_buffer(struct ust_trace *trace,
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98 struct ust_channel *ltt_chan,
99 struct ust_buffer *buf,
100 unsigned int n_subbufs);
101
102static int ust_buffers_alloc_buf(struct ust_buffer *buf, size_t *size)
103{
104 void *ptr;
105 int result;
106
107 *size = PAGE_ALIGN(*size);
108
109 result = buf->shmid = shmget(getpid(), *size, IPC_CREAT | IPC_EXCL | 0700);
110 if(result == -1 && errno == EINVAL) {
111 ERR("shmget() returned EINVAL; maybe /proc/sys/kernel/shmmax should be increased.");
112 return -1;
113 }
114 else if(result == -1) {
115 PERROR("shmget");
116 return -1;
117 }
118
204141ee 119 /* FIXME: should have matching call to shmdt */
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120 ptr = shmat(buf->shmid, NULL, 0);
121 if(ptr == (void *) -1) {
122 perror("shmat");
123 goto destroy_shmem;
124 }
125
126 /* Already mark the shared memory for destruction. This will occur only
127 * when all users have detached.
128 */
129 result = shmctl(buf->shmid, IPC_RMID, NULL);
130 if(result == -1) {
131 perror("shmctl");
132 return -1;
133 }
134
135 buf->buf_data = ptr;
136 buf->buf_size = *size;
137
138 return 0;
139
140 destroy_shmem:
141 result = shmctl(buf->shmid, IPC_RMID, NULL);
142 if(result == -1) {
143 perror("shmctl");
144 }
145
146 return -1;
147}
148
204141ee 149int ust_buffers_create_buf(struct ust_channel *channel, int cpu)
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150{
151 int result;
204141ee 152 struct ust_buffer *buf = channel->buf[cpu];
b5b073e2 153
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154 buf->cpu = cpu;
155 result = ust_buffers_alloc_buf(buf, &channel->alloc_size);
b5b073e2 156 if(result)
204141ee 157 return -1;
b5b073e2 158
204141ee 159 buf->chan = channel;
b5b073e2 160 kref_get(&channel->kref);
204141ee 161 return 0;
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162}
163
164static void ust_buffers_destroy_channel(struct kref *kref)
165{
166 struct ust_channel *chan = container_of(kref, struct ust_channel, kref);
167 free(chan);
168}
169
170static void ust_buffers_destroy_buf(struct ust_buffer *buf)
171{
172 struct ust_channel *chan = buf->chan;
173 int result;
174
175 result = munmap(buf->buf_data, buf->buf_size);
176 if(result == -1) {
177 PERROR("munmap");
178 }
179
204141ee 180//ust// chan->buf[buf->cpu] = NULL;
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181 free(buf);
182 kref_put(&chan->kref, ust_buffers_destroy_channel);
183}
184
185/* called from kref_put */
186static void ust_buffers_remove_buf(struct kref *kref)
187{
188 struct ust_buffer *buf = container_of(kref, struct ust_buffer, kref);
189 ust_buffers_destroy_buf(buf);
190}
191
204141ee 192int ust_buffers_open_buf(struct ust_channel *chan, int cpu)
b5b073e2 193{
204141ee 194 int result;
b5b073e2 195
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196 result = ust_buffers_create_buf(chan, cpu);
197 if (result == -1)
198 return -1;
b5b073e2 199
204141ee 200 kref_init(&chan->buf[cpu]->kref);
b5b073e2 201
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202 result = ust_buffers_init_buffer(chan->trace, chan, chan->buf[cpu], chan->subbuf_cnt);
203 if(result == -1)
204 return -1;
b5b073e2 205
204141ee 206 return 0;
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207
208 /* FIXME: decrementally destroy on error? */
209}
210
211/**
212 * ust_buffers_close_buf - close a channel buffer
213 * @buf: buffer
214 */
215static void ust_buffers_close_buf(struct ust_buffer *buf)
216{
217 kref_put(&buf->kref, ust_buffers_remove_buf);
218}
219
220int ust_buffers_channel_open(struct ust_channel *chan, size_t subbuf_size, size_t subbuf_cnt)
221{
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222 int i;
223 int result;
224
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225 if(subbuf_size == 0 || subbuf_cnt == 0)
226 return -1;
227
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228 /* Check that the subbuffer size is larger than a page. */
229 WARN_ON_ONCE(subbuf_size < PAGE_SIZE);
230
231 /*
232 * Make sure the number of subbuffers and subbuffer size are power of 2.
233 */
234 WARN_ON_ONCE(hweight32(subbuf_size) != 1);
235 WARN_ON(hweight32(subbuf_cnt) != 1);
236
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237 chan->version = UST_CHANNEL_VERSION;
238 chan->subbuf_cnt = subbuf_cnt;
239 chan->subbuf_size = subbuf_size;
240 chan->subbuf_size_order = get_count_order(subbuf_size);
b73a4c47 241 chan->alloc_size = subbuf_size * subbuf_cnt;
204141ee 242
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243 kref_init(&chan->kref);
244
245 mutex_lock(&ust_buffers_channels_mutex);
204141ee
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246 for(i=0; i<chan->n_cpus; i++) {
247 result = ust_buffers_open_buf(chan, i);
248 if (result == -1)
249 goto error;
250 }
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251 list_add(&chan->list, &ust_buffers_channels);
252 mutex_unlock(&ust_buffers_channels_mutex);
253
254 return 0;
255
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256 /* Jump directly inside the loop to close the buffers that were already
257 * opened. */
258 for(; i>=0; i--) {
259 ust_buffers_close_buf(chan->buf[i]);
260error:
120b0ec3 261 do {} while(0);
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262 }
263
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264 kref_put(&chan->kref, ust_buffers_destroy_channel);
265 mutex_unlock(&ust_buffers_channels_mutex);
266 return -1;
267}
268
269void ust_buffers_channel_close(struct ust_channel *chan)
270{
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271 int i;
272 if(!chan)
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273 return;
274
275 mutex_lock(&ust_buffers_channels_mutex);
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276 for(i=0; i<chan->n_cpus; i++) {
277 /* FIXME: if we make it here, then all buffers were necessarily allocated. Moreover, we don't
278 * initialize to NULL so we cannot use this check. Should we? */
279//ust// if (chan->buf[i])
280 ust_buffers_close_buf(chan->buf[i]);
281 }
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282
283 list_del(&chan->list);
284 kref_put(&chan->kref, ust_buffers_destroy_channel);
285 mutex_unlock(&ust_buffers_channels_mutex);
286}
287
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288/*
289 * -------
290 */
291
204141ee 292static void ust_buffers_destroy_buffer(struct ust_channel *ltt_chan, int cpu);
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293
294static void ltt_force_switch(struct ust_buffer *buf,
295 enum force_switch_mode mode);
296
297/*
298 * Trace callbacks
299 */
b73a4c47 300static void ltt_buffer_begin(struct ust_buffer *buf,
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301 u64 tsc, unsigned int subbuf_idx)
302{
303 struct ust_channel *channel = buf->chan;
304 struct ltt_subbuffer_header *header =
305 (struct ltt_subbuffer_header *)
b73a4c47 306 ust_buffers_offset_address(buf,
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307 subbuf_idx * buf->chan->subbuf_size);
308
309 header->cycle_count_begin = tsc;
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310 header->data_size = 0xFFFFFFFF; /* for recognizing crashed buffers */
311 header->sb_size = 0xFFFFFFFF; /* for recognizing crashed buffers */
312 /* FIXME: add memory barrier? */
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313 ltt_write_trace_header(channel->trace, header);
314}
315
316/*
317 * offset is assumed to never be 0 here : never deliver a completely empty
318 * subbuffer. The lost size is between 0 and subbuf_size-1.
319 */
b73a4c47 320static notrace void ltt_buffer_end(struct ust_buffer *buf,
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321 u64 tsc, unsigned int offset, unsigned int subbuf_idx)
322{
323 struct ltt_subbuffer_header *header =
324 (struct ltt_subbuffer_header *)
b73a4c47 325 ust_buffers_offset_address(buf,
b5b073e2 326 subbuf_idx * buf->chan->subbuf_size);
8c36d1ee 327 u32 data_size = SUBBUF_OFFSET(offset - 1, buf->chan) + 1;
b5b073e2 328
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329 header->data_size = data_size;
330 header->sb_size = PAGE_ALIGN(data_size);
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331 header->cycle_count_end = tsc;
332 header->events_lost = local_read(&buf->events_lost);
333 header->subbuf_corrupt = local_read(&buf->corrupted_subbuffers);
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334 if(unlikely(header->events_lost > 0)) {
335 DBG("Some events (%d) were lost in %s_%d", header->events_lost, buf->chan->channel_name, buf->cpu);
336 }
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337}
338
339/*
340 * This function should not be called from NMI interrupt context
341 */
342static notrace void ltt_buf_unfull(struct ust_buffer *buf,
343 unsigned int subbuf_idx,
344 long offset)
345{
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346}
347
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348/*
349 * Promote compiler barrier to a smp_mb().
350 * For the specific LTTng case, this IPI call should be removed if the
351 * architecture does not reorder writes. This should eventually be provided by
352 * a separate architecture-specific infrastructure.
353 */
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354//ust// static void remote_mb(void *info)
355//ust// {
356//ust// smp_mb();
357//ust// }
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358
359int ust_buffers_get_subbuf(struct ust_buffer *buf, long *consumed)
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360{
361 struct ust_channel *channel = buf->chan;
362 long consumed_old, consumed_idx, commit_count, write_offset;
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363//ust// int retval;
364
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365 consumed_old = atomic_long_read(&buf->consumed);
366 consumed_idx = SUBBUF_INDEX(consumed_old, buf->chan);
b73a4c47 367 commit_count = local_read(&buf->commit_count[consumed_idx].cc_sb);
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368 /*
369 * Make sure we read the commit count before reading the buffer
370 * data and the write offset. Correct consumed offset ordering
371 * wrt commit count is insured by the use of cmpxchg to update
372 * the consumed offset.
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373 * smp_call_function_single can fail if the remote CPU is offline,
374 * this is OK because then there is no wmb to execute there.
375 * If our thread is executing on the same CPU as the on the buffers
376 * belongs to, we don't have to synchronize it at all. If we are
377 * migrated, the scheduler will take care of the memory barriers.
378 * Normally, smp_call_function_single() should ensure program order when
379 * executing the remote function, which implies that it surrounds the
380 * function execution with :
381 * smp_mb()
382 * send IPI
383 * csd_lock_wait
384 * recv IPI
385 * smp_mb()
386 * exec. function
387 * smp_mb()
388 * csd unlock
389 * smp_mb()
390 *
391 * However, smp_call_function_single() does not seem to clearly execute
392 * such barriers. It depends on spinlock semantic to provide the barrier
393 * before executing the IPI and, when busy-looping, csd_lock_wait only
394 * executes smp_mb() when it has to wait for the other CPU.
395 *
396 * I don't trust this code. Therefore, let's add the smp_mb() sequence
397 * required ourself, even if duplicated. It has no performance impact
398 * anyway.
399 *
400 * smp_mb() is needed because smp_rmb() and smp_wmb() only order read vs
401 * read and write vs write. They do not ensure core synchronization. We
402 * really have to ensure total order between the 3 barriers running on
403 * the 2 CPUs.
404 */
405//ust// #ifdef LTT_NO_IPI_BARRIER
406 /*
407 * Local rmb to match the remote wmb to read the commit count before the
408 * buffer data and the write offset.
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409 */
410 smp_rmb();
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411//ust// #else
412//ust// if (raw_smp_processor_id() != buf->cpu) {
413//ust// smp_mb(); /* Total order with IPI handler smp_mb() */
414//ust// smp_call_function_single(buf->cpu, remote_mb, NULL, 1);
415//ust// smp_mb(); /* Total order with IPI handler smp_mb() */
416//ust// }
417//ust// #endif
418
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419 write_offset = local_read(&buf->offset);
420 /*
421 * Check that the subbuffer we are trying to consume has been
422 * already fully committed.
423 */
424 if (((commit_count - buf->chan->subbuf_size)
425 & channel->commit_count_mask)
426 - (BUFFER_TRUNC(consumed_old, buf->chan)
427 >> channel->n_subbufs_order)
428 != 0) {
429 return -EAGAIN;
430 }
431 /*
432 * Check that we are not about to read the same subbuffer in
433 * which the writer head is.
434 */
435 if ((SUBBUF_TRUNC(write_offset, buf->chan)
436 - SUBBUF_TRUNC(consumed_old, buf->chan))
437 == 0) {
438 return -EAGAIN;
439 }
440
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441 /* FIXME: is this ok to disable the reading feature? */
442//ust// retval = update_read_sb_index(buf, consumed_idx);
443//ust// if (retval)
444//ust// return retval;
445
446 *consumed = consumed_old;
447
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448 return 0;
449}
450
b73a4c47 451int ust_buffers_put_subbuf(struct ust_buffer *buf, unsigned long uconsumed_old)
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452{
453 long consumed_new, consumed_old;
454
455 consumed_old = atomic_long_read(&buf->consumed);
456 consumed_old = consumed_old & (~0xFFFFFFFFL);
457 consumed_old = consumed_old | uconsumed_old;
458 consumed_new = SUBBUF_ALIGN(consumed_old, buf->chan);
459
460//ust// spin_lock(&ltt_buf->full_lock);
461 if (atomic_long_cmpxchg(&buf->consumed, consumed_old,
462 consumed_new)
463 != consumed_old) {
464 /* We have been pushed by the writer : the last
465 * buffer read _is_ corrupted! It can also
466 * happen if this is a buffer we never got. */
467//ust// spin_unlock(&ltt_buf->full_lock);
468 return -EIO;
469 } else {
470 /* tell the client that buffer is now unfull */
471 int index;
472 long data;
473 index = SUBBUF_INDEX(consumed_old, buf->chan);
474 data = BUFFER_OFFSET(consumed_old, buf->chan);
475 ltt_buf_unfull(buf, index, data);
476//ust// spin_unlock(&ltt_buf->full_lock);
477 }
478 return 0;
479}
480
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481//ust// static void switch_buffer(unsigned long data)
482//ust// {
483//ust// struct ltt_channel_buf_struct *ltt_buf =
484//ust// (struct ltt_channel_buf_struct *)data;
485//ust// struct rchan_buf *buf = ltt_buf->rbuf;
486//ust//
487//ust// if (buf)
488//ust// ltt_force_switch(buf, FORCE_ACTIVE);
489//ust//
490//ust// ltt_buf->switch_timer.expires += ltt_buf->switch_timer_interval;
491//ust// add_timer_on(&ltt_buf->switch_timer, smp_processor_id());
492//ust// }
493//ust//
494//ust// static void start_switch_timer(struct ltt_channel_struct *ltt_channel)
495//ust// {
496//ust// struct rchan *rchan = ltt_channel->trans_channel_data;
497//ust// int cpu;
498//ust//
499//ust// if (!ltt_channel->switch_timer_interval)
500//ust// return;
501//ust//
502//ust// // TODO : hotplug
503//ust// for_each_online_cpu(cpu) {
504//ust// struct ltt_channel_buf_struct *ltt_buf;
505//ust// struct rchan_buf *buf;
506//ust//
507//ust// buf = rchan->buf[cpu];
508//ust// ltt_buf = buf->chan_private;
509//ust// buf->random_access = 1;
510//ust// ltt_buf->switch_timer_interval =
511//ust// ltt_channel->switch_timer_interval;
512//ust// init_timer(&ltt_buf->switch_timer);
513//ust// ltt_buf->switch_timer.function = switch_buffer;
514//ust// ltt_buf->switch_timer.expires = jiffies +
515//ust// ltt_buf->switch_timer_interval;
516//ust// ltt_buf->switch_timer.data = (unsigned long)ltt_buf;
517//ust// add_timer_on(&ltt_buf->switch_timer, cpu);
518//ust// }
519//ust// }
520//ust//
521//ust// /*
522//ust// * Cannot use del_timer_sync with add_timer_on, so use an IPI to locally
523//ust// * delete the timer.
524//ust// */
525//ust// static void stop_switch_timer_ipi(void *info)
526//ust// {
527//ust// struct ltt_channel_buf_struct *ltt_buf =
528//ust// (struct ltt_channel_buf_struct *)info;
529//ust//
530//ust// del_timer(&ltt_buf->switch_timer);
531//ust// }
532//ust//
533//ust// static void stop_switch_timer(struct ltt_channel_struct *ltt_channel)
534//ust// {
535//ust// struct rchan *rchan = ltt_channel->trans_channel_data;
536//ust// int cpu;
537//ust//
538//ust// if (!ltt_channel->switch_timer_interval)
539//ust// return;
540//ust//
541//ust// // TODO : hotplug
542//ust// for_each_online_cpu(cpu) {
543//ust// struct ltt_channel_buf_struct *ltt_buf;
544//ust// struct rchan_buf *buf;
545//ust//
546//ust// buf = rchan->buf[cpu];
547//ust// ltt_buf = buf->chan_private;
548//ust// smp_call_function(stop_switch_timer_ipi, ltt_buf, 1);
549//ust// buf->random_access = 0;
550//ust// }
551//ust// }
552
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553//ust// static void ust_buffers_print_written(struct ust_channel *chan,
554//ust// long cons_off, unsigned int cpu)
555//ust// {
556//ust// struct ust_buffer *buf = chan->buf[cpu];
557//ust// long cons_idx, events_count;
558//ust//
559//ust// cons_idx = SUBBUF_INDEX(cons_off, chan);
560//ust// events_count = local_read(&buf->commit_count[cons_idx].events);
561//ust//
562//ust// if (events_count)
563//ust// printk(KERN_INFO
564//ust// "channel %s: %lu events written (cpu %u, index %lu)\n",
565//ust// chan->channel_name, events_count, cpu, cons_idx);
566//ust// }
b73a4c47 567
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568static void ltt_relay_print_subbuffer_errors(
569 struct ust_channel *channel,
204141ee 570 long cons_off, int cpu)
b5b073e2 571{
204141ee 572 struct ust_buffer *ltt_buf = channel->buf[cpu];
b73a4c47 573 long cons_idx, commit_count, commit_count_sb, write_offset;
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574
575 cons_idx = SUBBUF_INDEX(cons_off, channel);
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576 commit_count = local_read(&ltt_buf->commit_count[cons_idx].cc);
577 commit_count_sb = local_read(&ltt_buf->commit_count[cons_idx].cc_sb);
578
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579 /*
580 * No need to order commit_count and write_offset reads because we
581 * execute after trace is stopped when there are no readers left.
582 */
583 write_offset = local_read(&ltt_buf->offset);
584 WARN( "LTT : unread channel %s offset is %ld "
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585 "and cons_off : %ld (cpu %d)\n",
586 channel->channel_name, write_offset, cons_off, cpu);
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587 /* Check each sub-buffer for non filled commit count */
588 if (((commit_count - channel->subbuf_size) & channel->commit_count_mask)
589 - (BUFFER_TRUNC(cons_off, channel) >> channel->n_subbufs_order) != 0) {
590 ERR("LTT : %s : subbuffer %lu has non filled "
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591 "commit count [cc, cc_sb] [%lu,%lu].\n",
592 channel->channel_name, cons_idx, commit_count, commit_count_sb);
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593 }
594 ERR("LTT : %s : commit count : %lu, subbuf size %zd\n",
595 channel->channel_name, commit_count,
596 channel->subbuf_size);
597}
598
b73a4c47 599static void ltt_relay_print_errors(struct ust_trace *trace,
204141ee 600 struct ust_channel *channel, int cpu)
b5b073e2 601{
204141ee 602 struct ust_buffer *ltt_buf = channel->buf[cpu];
b5b073e2
PMF
603 long cons_off;
604
4292ed8a
PMF
605 /*
606 * Can be called in the error path of allocation when
607 * trans_channel_data is not yet set.
608 */
609 if (!channel)
610 return;
611
e17571a5
PMF
612//ust// for (cons_off = 0; cons_off < rchan->alloc_size;
613//ust// cons_off = SUBBUF_ALIGN(cons_off, rchan))
614//ust// ust_buffers_print_written(ltt_chan, cons_off, cpu);
b5b073e2
PMF
615 for (cons_off = atomic_long_read(&ltt_buf->consumed);
616 (SUBBUF_TRUNC(local_read(&ltt_buf->offset),
617 channel)
618 - cons_off) > 0;
619 cons_off = SUBBUF_ALIGN(cons_off, channel))
204141ee 620 ltt_relay_print_subbuffer_errors(channel, cons_off, cpu);
b5b073e2
PMF
621}
622
204141ee 623static void ltt_relay_print_buffer_errors(struct ust_channel *channel, int cpu)
b5b073e2 624{
b73a4c47 625 struct ust_trace *trace = channel->trace;
204141ee 626 struct ust_buffer *ltt_buf = channel->buf[cpu];
b5b073e2
PMF
627
628 if (local_read(&ltt_buf->events_lost))
b73a4c47 629 ERR("channel %s: %ld events lost (cpu %d)",
b5b073e2 630 channel->channel_name,
b73a4c47 631 local_read(&ltt_buf->events_lost), cpu);
b5b073e2 632 if (local_read(&ltt_buf->corrupted_subbuffers))
b73a4c47 633 ERR("channel %s : %ld corrupted subbuffers (cpu %d)",
b5b073e2 634 channel->channel_name,
b73a4c47 635 local_read(&ltt_buf->corrupted_subbuffers), cpu);
b5b073e2 636
204141ee 637 ltt_relay_print_errors(trace, channel, cpu);
b5b073e2
PMF
638}
639
640static void ltt_relay_release_channel(struct kref *kref)
641{
642 struct ust_channel *ltt_chan = container_of(kref,
643 struct ust_channel, kref);
644 free(ltt_chan->buf);
645}
646
647/*
648 * Create ltt buffer.
649 */
b73a4c47 650//ust// static int ltt_relay_create_buffer(struct ust_trace *trace,
b5b073e2
PMF
651//ust// struct ltt_channel_struct *ltt_chan, struct rchan_buf *buf,
652//ust// unsigned int cpu, unsigned int n_subbufs)
653//ust// {
654//ust// struct ltt_channel_buf_struct *ltt_buf =
655//ust// percpu_ptr(ltt_chan->buf, cpu);
656//ust// unsigned int j;
b73a4c47 657//ust//
b5b073e2
PMF
658//ust// ltt_buf->commit_count =
659//ust// kzalloc_node(sizeof(ltt_buf->commit_count) * n_subbufs,
660//ust// GFP_KERNEL, cpu_to_node(cpu));
661//ust// if (!ltt_buf->commit_count)
662//ust// return -ENOMEM;
663//ust// kref_get(&trace->kref);
664//ust// kref_get(&trace->ltt_transport_kref);
665//ust// kref_get(&ltt_chan->kref);
666//ust// local_set(&ltt_buf->offset, ltt_subbuffer_header_size());
667//ust// atomic_long_set(&ltt_buf->consumed, 0);
668//ust// atomic_long_set(&ltt_buf->active_readers, 0);
669//ust// for (j = 0; j < n_subbufs; j++)
670//ust// local_set(&ltt_buf->commit_count[j], 0);
671//ust// init_waitqueue_head(&ltt_buf->write_wait);
672//ust// atomic_set(&ltt_buf->wakeup_readers, 0);
673//ust// spin_lock_init(&ltt_buf->full_lock);
b73a4c47 674//ust//
b5b073e2
PMF
675//ust// ltt_buffer_begin_callback(buf, trace->start_tsc, 0);
676//ust// /* atomic_add made on local variable on data that belongs to
677//ust// * various CPUs : ok because tracing not started (for this cpu). */
678//ust// local_add(ltt_subbuffer_header_size(), &ltt_buf->commit_count[0]);
b73a4c47 679//ust//
b5b073e2
PMF
680//ust// local_set(&ltt_buf->events_lost, 0);
681//ust// local_set(&ltt_buf->corrupted_subbuffers, 0);
b73a4c47 682//ust//
b5b073e2
PMF
683//ust// return 0;
684//ust// }
685
b73a4c47 686static int ust_buffers_init_buffer(struct ust_trace *trace,
b5b073e2
PMF
687 struct ust_channel *ltt_chan, struct ust_buffer *buf,
688 unsigned int n_subbufs)
689{
690 unsigned int j;
691 int fds[2];
692 int result;
693
694 buf->commit_count =
b73a4c47 695 zmalloc(sizeof(*buf->commit_count) * n_subbufs);
b5b073e2
PMF
696 if (!buf->commit_count)
697 return -ENOMEM;
698 kref_get(&trace->kref);
699 kref_get(&trace->ltt_transport_kref);
700 kref_get(&ltt_chan->kref);
701 local_set(&buf->offset, ltt_subbuffer_header_size());
702 atomic_long_set(&buf->consumed, 0);
703 atomic_long_set(&buf->active_readers, 0);
b73a4c47
PMF
704 for (j = 0; j < n_subbufs; j++) {
705 local_set(&buf->commit_count[j].cc, 0);
706 local_set(&buf->commit_count[j].cc_sb, 0);
707 }
b5b073e2
PMF
708//ust// init_waitqueue_head(&buf->write_wait);
709//ust// atomic_set(&buf->wakeup_readers, 0);
710//ust// spin_lock_init(&buf->full_lock);
711
b73a4c47 712 ltt_buffer_begin(buf, trace->start_tsc, 0);
b5b073e2 713
b73a4c47 714 local_add(ltt_subbuffer_header_size(), &buf->commit_count[0].cc);
b5b073e2
PMF
715
716 local_set(&buf->events_lost, 0);
717 local_set(&buf->corrupted_subbuffers, 0);
718
719 result = pipe(fds);
720 if(result == -1) {
721 PERROR("pipe");
722 return -1;
723 }
724 buf->data_ready_fd_read = fds[0];
725 buf->data_ready_fd_write = fds[1];
726
727 /* FIXME: do we actually need this? */
728 result = fcntl(fds[0], F_SETFL, O_NONBLOCK);
729 if(result == -1) {
730 PERROR("fcntl");
731 }
732
733//ust// buf->commit_seq = malloc(sizeof(buf->commit_seq) * n_subbufs);
734//ust// if(!ltt_buf->commit_seq) {
735//ust// return -1;
736//ust// }
37315729 737 memset(buf->commit_seq, 0, sizeof(buf->commit_seq[0]) * n_subbufs);
b5b073e2
PMF
738
739 /* FIXME: decrementally destroy on error */
740
741 return 0;
742}
743
744/* FIXME: use this function */
204141ee 745static void ust_buffers_destroy_buffer(struct ust_channel *ltt_chan, int cpu)
b5b073e2 746{
b73a4c47 747 struct ust_trace *trace = ltt_chan->trace;
204141ee 748 struct ust_buffer *ltt_buf = ltt_chan->buf[cpu];
b5b073e2
PMF
749
750 kref_put(&ltt_chan->trace->ltt_transport_kref,
751 ltt_release_transport);
204141ee 752 ltt_relay_print_buffer_errors(ltt_chan, cpu);
b5b073e2
PMF
753//ust// free(ltt_buf->commit_seq);
754 kfree(ltt_buf->commit_count);
755 ltt_buf->commit_count = NULL;
756 kref_put(&ltt_chan->kref, ltt_relay_release_channel);
757 kref_put(&trace->kref, ltt_release_trace);
758//ust// wake_up_interruptible(&trace->kref_wq);
759}
760
204141ee 761static int ust_buffers_alloc_channel_buf_structs(struct ust_channel *chan)
b5b073e2
PMF
762{
763 void *ptr;
764 int result;
204141ee
PMF
765 size_t size;
766 int i;
b5b073e2 767
204141ee 768 size = PAGE_ALIGN(1);
b5b073e2 769
204141ee 770 for(i=0; i<chan->n_cpus; i++) {
b5b073e2 771
204141ee
PMF
772 result = chan->buf_struct_shmids[i] = shmget(getpid(), size, IPC_CREAT | IPC_EXCL | 0700);
773 if(result == -1) {
774 PERROR("shmget");
775 goto destroy_previous;
776 }
b5b073e2 777
204141ee
PMF
778 /* FIXME: should have matching call to shmdt */
779 ptr = shmat(chan->buf_struct_shmids[i], NULL, 0);
780 if(ptr == (void *) -1) {
781 perror("shmat");
782 goto destroy_shm;
783 }
784
785 /* Already mark the shared memory for destruction. This will occur only
786 * when all users have detached.
787 */
788 result = shmctl(chan->buf_struct_shmids[i], IPC_RMID, NULL);
789 if(result == -1) {
790 perror("shmctl");
791 goto destroy_previous;
792 }
793
794 chan->buf[i] = ptr;
b5b073e2
PMF
795 }
796
204141ee 797 return 0;
b5b073e2 798
204141ee
PMF
799 /* Jumping inside this loop occurs from within the other loop above with i as
800 * counter, so it unallocates the structures for the cpu = current_i down to
801 * zero. */
802 for(; i>=0; i--) {
803 destroy_shm:
804 result = shmctl(chan->buf_struct_shmids[i], IPC_RMID, NULL);
805 if(result == -1) {
806 perror("shmctl");
807 }
b5b073e2 808
204141ee
PMF
809 destroy_previous:
810 continue;
b5b073e2
PMF
811 }
812
204141ee 813 return -1;
b5b073e2
PMF
814}
815
816/*
817 * Create channel.
818 */
b73a4c47 819static int ust_buffers_create_channel(const char *trace_name, struct ust_trace *trace,
b5b073e2
PMF
820 const char *channel_name, struct ust_channel *ltt_chan,
821 unsigned int subbuf_size, unsigned int n_subbufs, int overwrite)
822{
b5b073e2
PMF
823 int result;
824
825 kref_init(&ltt_chan->kref);
826
827 ltt_chan->trace = trace;
b5b073e2
PMF
828 ltt_chan->overwrite = overwrite;
829 ltt_chan->n_subbufs_order = get_count_order(n_subbufs);
830 ltt_chan->commit_count_mask = (~0UL >> ltt_chan->n_subbufs_order);
204141ee 831 ltt_chan->n_cpus = get_n_cpus();
b5b073e2 832//ust// ltt_chan->buf = percpu_alloc_mask(sizeof(struct ltt_channel_buf_struct), GFP_KERNEL, cpu_possible_map);
204141ee
PMF
833 ltt_chan->buf = (void *) malloc(ltt_chan->n_cpus * sizeof(void *));
834 if(ltt_chan->buf == NULL) {
835 goto error;
836 }
837 ltt_chan->buf_struct_shmids = (int *) malloc(ltt_chan->n_cpus * sizeof(int));
838 if(ltt_chan->buf_struct_shmids == NULL)
839 goto free_buf;
b5b073e2 840
204141ee
PMF
841 result = ust_buffers_alloc_channel_buf_structs(ltt_chan);
842 if(result != 0) {
843 goto free_buf_struct_shmids;
844 }
b5b073e2 845
b5b073e2 846 result = ust_buffers_channel_open(ltt_chan, subbuf_size, n_subbufs);
204141ee 847 if (result != 0) {
c1f20530 848 ERR("Cannot open channel for trace %s", trace_name);
204141ee 849 goto unalloc_buf_structs;
b5b073e2
PMF
850 }
851
204141ee
PMF
852 return 0;
853
854unalloc_buf_structs:
855 /* FIXME: put a call here to unalloc the buf structs! */
856
857free_buf_struct_shmids:
858 free(ltt_chan->buf_struct_shmids);
b5b073e2 859
204141ee
PMF
860free_buf:
861 free(ltt_chan->buf);
862
863error:
864 return -1;
b5b073e2
PMF
865}
866
867/*
868 * LTTng channel flush function.
869 *
870 * Must be called when no tracing is active in the channel, because of
871 * accesses across CPUs.
872 */
873static notrace void ltt_relay_buffer_flush(struct ust_buffer *buf)
874{
875 int result;
876
877//ust// buf->finalized = 1;
878 ltt_force_switch(buf, FORCE_FLUSH);
879
880 result = write(buf->data_ready_fd_write, "1", 1);
881 if(result == -1) {
882 PERROR("write (in ltt_relay_buffer_flush)");
883 ERR("this should never happen!");
884 }
885}
886
887static void ltt_relay_async_wakeup_chan(struct ust_channel *ltt_channel)
888{
889//ust// unsigned int i;
890//ust// struct rchan *rchan = ltt_channel->trans_channel_data;
891//ust//
892//ust// for_each_possible_cpu(i) {
893//ust// struct ltt_channel_buf_struct *ltt_buf =
894//ust// percpu_ptr(ltt_channel->buf, i);
895//ust//
896//ust// if (atomic_read(&ltt_buf->wakeup_readers) == 1) {
897//ust// atomic_set(&ltt_buf->wakeup_readers, 0);
898//ust// wake_up_interruptible(&rchan->buf[i]->read_wait);
899//ust// }
900//ust// }
901}
902
204141ee 903static void ltt_relay_finish_buffer(struct ust_channel *channel, unsigned int cpu)
b5b073e2
PMF
904{
905// int result;
906
204141ee
PMF
907 if (channel->buf[cpu]) {
908 struct ust_buffer *buf = channel->buf[cpu];
b5b073e2
PMF
909 ltt_relay_buffer_flush(buf);
910//ust// ltt_relay_wake_writers(ltt_buf);
911 /* closing the pipe tells the consumer the buffer is finished */
912
913 //result = write(ltt_buf->data_ready_fd_write, "D", 1);
914 //if(result == -1) {
915 // PERROR("write (in ltt_relay_finish_buffer)");
916 // ERR("this should never happen!");
917 //}
918 close(buf->data_ready_fd_write);
919 }
920}
921
922
923static void ltt_relay_finish_channel(struct ust_channel *channel)
924{
204141ee 925 unsigned int i;
b5b073e2 926
204141ee
PMF
927 for(i=0; i<channel->n_cpus; i++) {
928 ltt_relay_finish_buffer(channel, i);
929 }
b5b073e2
PMF
930}
931
932static void ltt_relay_remove_channel(struct ust_channel *channel)
933{
934 ust_buffers_channel_close(channel);
935 kref_put(&channel->kref, ltt_relay_release_channel);
936}
937
b73a4c47
PMF
938//ust// /*
939//ust// * Returns :
940//ust// * 0 if ok
941//ust// * !0 if execution must be aborted.
942//ust// */
943//ust// static inline int ltt_relay_try_reserve(
944//ust// struct ust_channel *channel, struct ust_buffer *buf,
945//ust// struct ltt_reserve_switch_offsets *offsets, size_t data_size,
946//ust// u64 *tsc, unsigned int *rflags, int largest_align)
947//ust// {
948//ust// offsets->begin = local_read(&buf->offset);
949//ust// offsets->old = offsets->begin;
950//ust// offsets->begin_switch = 0;
951//ust// offsets->end_switch_current = 0;
952//ust// offsets->end_switch_old = 0;
953//ust//
954//ust// *tsc = trace_clock_read64();
955//ust// if (last_tsc_overflow(buf, *tsc))
956//ust// *rflags = LTT_RFLAG_ID_SIZE_TSC;
957//ust//
958//ust// if (SUBBUF_OFFSET(offsets->begin, buf->chan) == 0) {
959//ust// offsets->begin_switch = 1; /* For offsets->begin */
960//ust// } else {
961//ust// offsets->size = ust_get_header_size(channel,
962//ust// offsets->begin, data_size,
963//ust// &offsets->before_hdr_pad, *rflags);
964//ust// offsets->size += ltt_align(offsets->begin + offsets->size,
965//ust// largest_align)
966//ust// + data_size;
967//ust// if ((SUBBUF_OFFSET(offsets->begin, buf->chan) + offsets->size)
968//ust// > buf->chan->subbuf_size) {
969//ust// offsets->end_switch_old = 1; /* For offsets->old */
970//ust// offsets->begin_switch = 1; /* For offsets->begin */
971//ust// }
972//ust// }
973//ust// if (offsets->begin_switch) {
974//ust// long subbuf_index;
975//ust//
976//ust// if (offsets->end_switch_old)
977//ust// offsets->begin = SUBBUF_ALIGN(offsets->begin,
978//ust// buf->chan);
979//ust// offsets->begin = offsets->begin + ltt_subbuffer_header_size();
980//ust// /* Test new buffer integrity */
981//ust// subbuf_index = SUBBUF_INDEX(offsets->begin, buf->chan);
982//ust// offsets->reserve_commit_diff =
983//ust// (BUFFER_TRUNC(offsets->begin, buf->chan)
984//ust// >> channel->n_subbufs_order)
985//ust// - (local_read(&buf->commit_count[subbuf_index])
986//ust// & channel->commit_count_mask);
987//ust// if (offsets->reserve_commit_diff == 0) {
988//ust// long consumed;
989//ust//
990//ust// consumed = atomic_long_read(&buf->consumed);
991//ust//
992//ust// /* Next buffer not corrupted. */
993//ust// if (!channel->overwrite &&
994//ust// (SUBBUF_TRUNC(offsets->begin, buf->chan)
995//ust// - SUBBUF_TRUNC(consumed, buf->chan))
996//ust// >= channel->alloc_size) {
997//ust//
998//ust// long consumed_idx = SUBBUF_INDEX(consumed, buf->chan);
999//ust// long commit_count = local_read(&buf->commit_count[consumed_idx]);
1000//ust// if(((commit_count - buf->chan->subbuf_size) & channel->commit_count_mask) - (BUFFER_TRUNC(consumed, buf->chan) >> channel->n_subbufs_order) != 0) {
1001//ust// WARN("Event dropped. Caused by non-committed event.");
1002//ust// }
1003//ust// else {
1004//ust// WARN("Event dropped. Caused by non-consumed buffer.");
1005//ust// }
1006//ust// /*
1007//ust// * We do not overwrite non consumed buffers
1008//ust// * and we are full : event is lost.
1009//ust// */
1010//ust// local_inc(&buf->events_lost);
1011//ust// return -1;
1012//ust// } else {
1013//ust// /*
1014//ust// * next buffer not corrupted, we are either in
1015//ust// * overwrite mode or the buffer is not full.
1016//ust// * It's safe to write in this new subbuffer.
1017//ust// */
1018//ust// }
1019//ust// } else {
1020//ust// /*
1021//ust// * Next subbuffer corrupted. Force pushing reader even
1022//ust// * in normal mode. It's safe to write in this new
1023//ust// * subbuffer.
1024//ust// */
1025//ust// }
1026//ust// offsets->size = ust_get_header_size(channel,
1027//ust// offsets->begin, data_size,
1028//ust// &offsets->before_hdr_pad, *rflags);
1029//ust// offsets->size += ltt_align(offsets->begin + offsets->size,
1030//ust// largest_align)
1031//ust// + data_size;
1032//ust// if ((SUBBUF_OFFSET(offsets->begin, buf->chan) + offsets->size)
1033//ust// > buf->chan->subbuf_size) {
1034//ust// /*
1035//ust// * Event too big for subbuffers, report error, don't
1036//ust// * complete the sub-buffer switch.
1037//ust// */
1038//ust// local_inc(&buf->events_lost);
1039//ust// return -1;
1040//ust// } else {
1041//ust// /*
1042//ust// * We just made a successful buffer switch and the event
1043//ust// * fits in the new subbuffer. Let's write.
1044//ust// */
1045//ust// }
1046//ust// } else {
1047//ust// /*
1048//ust// * Event fits in the current buffer and we are not on a switch
1049//ust// * boundary. It's safe to write.
1050//ust// */
1051//ust// }
1052//ust// offsets->end = offsets->begin + offsets->size;
1053//ust//
1054//ust// if ((SUBBUF_OFFSET(offsets->end, buf->chan)) == 0) {
1055//ust// /*
1056//ust// * The offset_end will fall at the very beginning of the next
1057//ust// * subbuffer.
1058//ust// */
1059//ust// offsets->end_switch_current = 1; /* For offsets->begin */
1060//ust// }
1061//ust// return 0;
1062//ust// }
1063//ust//
1064//ust// /*
1065//ust// * Returns :
1066//ust// * 0 if ok
1067//ust// * !0 if execution must be aborted.
1068//ust// */
1069//ust// static inline int ltt_relay_try_switch(
1070//ust// enum force_switch_mode mode,
1071//ust// struct ust_channel *channel,
1072//ust// struct ust_buffer *buf,
1073//ust// struct ltt_reserve_switch_offsets *offsets,
1074//ust// u64 *tsc)
1075//ust// {
1076//ust// long subbuf_index;
1077//ust//
1078//ust// offsets->begin = local_read(&buf->offset);
1079//ust// offsets->old = offsets->begin;
1080//ust// offsets->begin_switch = 0;
1081//ust// offsets->end_switch_old = 0;
1082//ust//
1083//ust// *tsc = trace_clock_read64();
1084//ust//
1085//ust// if (SUBBUF_OFFSET(offsets->begin, buf->chan) != 0) {
1086//ust// offsets->begin = SUBBUF_ALIGN(offsets->begin, buf->chan);
1087//ust// offsets->end_switch_old = 1;
1088//ust// } else {
1089//ust// /* we do not have to switch : buffer is empty */
1090//ust// return -1;
1091//ust// }
1092//ust// if (mode == FORCE_ACTIVE)
1093//ust// offsets->begin += ltt_subbuffer_header_size();
1094//ust// /*
1095//ust// * Always begin_switch in FORCE_ACTIVE mode.
1096//ust// * Test new buffer integrity
1097//ust// */
1098//ust// subbuf_index = SUBBUF_INDEX(offsets->begin, buf->chan);
1099//ust// offsets->reserve_commit_diff =
1100//ust// (BUFFER_TRUNC(offsets->begin, buf->chan)
1101//ust// >> channel->n_subbufs_order)
1102//ust// - (local_read(&buf->commit_count[subbuf_index])
1103//ust// & channel->commit_count_mask);
1104//ust// if (offsets->reserve_commit_diff == 0) {
1105//ust// /* Next buffer not corrupted. */
1106//ust// if (mode == FORCE_ACTIVE
1107//ust// && !channel->overwrite
1108//ust// && offsets->begin - atomic_long_read(&buf->consumed)
1109//ust// >= channel->alloc_size) {
1110//ust// /*
1111//ust// * We do not overwrite non consumed buffers and we are
1112//ust// * full : ignore switch while tracing is active.
1113//ust// */
1114//ust// return -1;
1115//ust// }
1116//ust// } else {
1117//ust// /*
1118//ust// * Next subbuffer corrupted. Force pushing reader even in normal
1119//ust// * mode
1120//ust// */
1121//ust// }
1122//ust// offsets->end = offsets->begin;
1123//ust// return 0;
1124//ust// }
1125//ust//
1126//ust// static inline void ltt_reserve_push_reader(
1127//ust// struct ust_channel *channel,
1128//ust// struct ust_buffer *buf,
1129//ust// struct ltt_reserve_switch_offsets *offsets)
1130//ust// {
1131//ust// long consumed_old, consumed_new;
1132//ust//
1133//ust// do {
1134//ust// consumed_old = atomic_long_read(&buf->consumed);
1135//ust// /*
1136//ust// * If buffer is in overwrite mode, push the reader consumed
1137//ust// * count if the write position has reached it and we are not
1138//ust// * at the first iteration (don't push the reader farther than
1139//ust// * the writer). This operation can be done concurrently by many
1140//ust// * writers in the same buffer, the writer being at the farthest
1141//ust// * write position sub-buffer index in the buffer being the one
1142//ust// * which will win this loop.
1143//ust// * If the buffer is not in overwrite mode, pushing the reader
1144//ust// * only happens if a sub-buffer is corrupted.
1145//ust// */
1146//ust// if ((SUBBUF_TRUNC(offsets->end-1, buf->chan)
1147//ust// - SUBBUF_TRUNC(consumed_old, buf->chan))
1148//ust// >= channel->alloc_size)
1149//ust// consumed_new = SUBBUF_ALIGN(consumed_old, buf->chan);
1150//ust// else {
1151//ust// consumed_new = consumed_old;
1152//ust// break;
1153//ust// }
1154//ust// } while (atomic_long_cmpxchg(&buf->consumed, consumed_old,
1155//ust// consumed_new) != consumed_old);
1156//ust//
1157//ust// if (consumed_old != consumed_new) {
1158//ust// /*
1159//ust// * Reader pushed : we are the winner of the push, we can
1160//ust// * therefore reequilibrate reserve and commit. Atomic increment
1161//ust// * of the commit count permits other writers to play around
1162//ust// * with this variable before us. We keep track of
1163//ust// * corrupted_subbuffers even in overwrite mode :
1164//ust// * we never want to write over a non completely committed
1165//ust// * sub-buffer : possible causes : the buffer size is too low
1166//ust// * compared to the unordered data input, or there is a writer
1167//ust// * that died between the reserve and the commit.
1168//ust// */
1169//ust// if (offsets->reserve_commit_diff) {
1170//ust// /*
1171//ust// * We have to alter the sub-buffer commit count.
1172//ust// * We do not deliver the previous subbuffer, given it
1173//ust// * was either corrupted or not consumed (overwrite
1174//ust// * mode).
1175//ust// */
1176//ust// local_add(offsets->reserve_commit_diff,
1177//ust// &buf->commit_count[
1178//ust// SUBBUF_INDEX(offsets->begin,
1179//ust// buf->chan)]);
1180//ust// if (!channel->overwrite
1181//ust// || offsets->reserve_commit_diff
1182//ust// != channel->subbuf_size) {
1183//ust// /*
1184//ust// * The reserve commit diff was not subbuf_size :
1185//ust// * it means the subbuffer was partly written to
1186//ust// * and is therefore corrupted. If it is multiple
1187//ust// * of subbuffer size and we are in flight
1188//ust// * recorder mode, we are skipping over a whole
1189//ust// * subbuffer.
1190//ust// */
1191//ust// local_inc(&buf->corrupted_subbuffers);
1192//ust// }
1193//ust// }
1194//ust// }
1195//ust// }
1196//ust//
1197//ust// /**
1198//ust// * ltt_relay_reserve_slot - Atomic slot reservation in a LTTng buffer.
1199//ust// * @trace: the trace structure to log to.
1200//ust// * @ltt_channel: channel structure
1201//ust// * @transport_data: data structure specific to ltt relay
1202//ust// * @data_size: size of the variable length data to log.
1203//ust// * @slot_size: pointer to total size of the slot (out)
1204//ust// * @buf_offset : pointer to reserved buffer offset (out)
1205//ust// * @tsc: pointer to the tsc at the slot reservation (out)
1206//ust// * @cpu: cpuid
1207//ust// *
1208//ust// * Return : -ENOSPC if not enough space, else returns 0.
1209//ust// * It will take care of sub-buffer switching.
1210//ust// */
1211//ust// static notrace int ltt_relay_reserve_slot(struct ust_trace *trace,
1212//ust// struct ust_channel *channel, void **transport_data,
1213//ust// size_t data_size, size_t *slot_size, long *buf_offset, u64 *tsc,
1214//ust// unsigned int *rflags, int largest_align, int cpu)
1215//ust// {
1216//ust// struct ust_buffer *buf = *transport_data = channel->buf[cpu];
1217//ust// struct ltt_reserve_switch_offsets offsets;
1218//ust//
1219//ust// offsets.reserve_commit_diff = 0;
1220//ust// offsets.size = 0;
1221//ust//
1222//ust// /*
1223//ust// * Perform retryable operations.
1224//ust// */
1225//ust// if (ltt_nesting > 4) {
1226//ust// local_inc(&buf->events_lost);
1227//ust// return -EPERM;
1228//ust// }
1229//ust// do {
1230//ust// if (ltt_relay_try_reserve(channel, buf, &offsets, data_size, tsc, rflags,
1231//ust// largest_align))
1232//ust// return -ENOSPC;
1233//ust// } while (local_cmpxchg(&buf->offset, offsets.old,
1234//ust// offsets.end) != offsets.old);
1235//ust//
1236//ust// /*
1237//ust// * Atomically update last_tsc. This update races against concurrent
1238//ust// * atomic updates, but the race will always cause supplementary full TSC
1239//ust// * events, never the opposite (missing a full TSC event when it would be
1240//ust// * needed).
1241//ust// */
1242//ust// save_last_tsc(buf, *tsc);
1243//ust//
1244//ust// /*
1245//ust// * Push the reader if necessary
1246//ust// */
1247//ust// ltt_reserve_push_reader(channel, buf, &offsets);
1248//ust//
1249//ust// /*
1250//ust// * Switch old subbuffer if needed.
1251//ust// */
1252//ust// if (offsets.end_switch_old)
1253//ust// ltt_reserve_switch_old_subbuf(channel, buf, &offsets, tsc);
1254//ust//
1255//ust// /*
1256//ust// * Populate new subbuffer.
1257//ust// */
1258//ust// if (offsets.begin_switch)
1259//ust// ltt_reserve_switch_new_subbuf(channel, buf, &offsets, tsc);
1260//ust//
1261//ust// if (offsets.end_switch_current)
1262//ust// ltt_reserve_end_switch_current(channel, buf, &offsets, tsc);
1263//ust//
1264//ust// *slot_size = offsets.size;
1265//ust// *buf_offset = offsets.begin + offsets.before_hdr_pad;
1266//ust// return 0;
1267//ust// }
1268//ust//
1269//ust// /*
1270//ust// * Force a sub-buffer switch for a per-cpu buffer. This operation is
1271//ust// * completely reentrant : can be called while tracing is active with
1272//ust// * absolutely no lock held.
1273//ust// *
1274//ust// * Note, however, that as a local_cmpxchg is used for some atomic
1275//ust// * operations, this function must be called from the CPU which owns the buffer
1276//ust// * for a ACTIVE flush.
1277//ust// */
1278//ust// static notrace void ltt_force_switch(struct ust_buffer *buf,
1279//ust// enum force_switch_mode mode)
1280//ust// {
1281//ust// struct ust_channel *channel = buf->chan;
1282//ust// struct ltt_reserve_switch_offsets offsets;
1283//ust// u64 tsc;
1284//ust//
1285//ust// offsets.reserve_commit_diff = 0;
1286//ust// offsets.size = 0;
1287//ust//
1288//ust// /*
1289//ust// * Perform retryable operations.
1290//ust// */
1291//ust// do {
1292//ust// if (ltt_relay_try_switch(mode, channel, buf, &offsets, &tsc))
1293//ust// return;
1294//ust// } while (local_cmpxchg(&buf->offset, offsets.old,
1295//ust// offsets.end) != offsets.old);
1296//ust//
1297//ust// /*
1298//ust// * Atomically update last_tsc. This update races against concurrent
1299//ust// * atomic updates, but the race will always cause supplementary full TSC
1300//ust// * events, never the opposite (missing a full TSC event when it would be
1301//ust// * needed).
1302//ust// */
1303//ust// save_last_tsc(buf, tsc);
1304//ust//
1305//ust// /*
1306//ust// * Push the reader if necessary
1307//ust// */
1308//ust// if (mode == FORCE_ACTIVE)
1309//ust// ltt_reserve_push_reader(channel, buf, &offsets);
1310//ust//
1311//ust// /*
1312//ust// * Switch old subbuffer if needed.
1313//ust// */
1314//ust// if (offsets.end_switch_old)
1315//ust// ltt_reserve_switch_old_subbuf(channel, buf, &offsets, &tsc);
1316//ust//
1317//ust// /*
1318//ust// * Populate new subbuffer.
1319//ust// */
1320//ust// if (mode == FORCE_ACTIVE)
1321//ust// ltt_reserve_switch_new_subbuf(channel, buf, &offsets, &tsc);
1322//ust// }
b5b073e2
PMF
1323
1324/*
b73a4c47
PMF
1325 * ltt_reserve_switch_old_subbuf: switch old subbuffer
1326 *
1327 * Concurrency safe because we are the last and only thread to alter this
1328 * sub-buffer. As long as it is not delivered and read, no other thread can
1329 * alter the offset, alter the reserve_count or call the
1330 * client_buffer_end_callback on this sub-buffer.
1331 *
1332 * The only remaining threads could be the ones with pending commits. They will
1333 * have to do the deliver themselves. Not concurrency safe in overwrite mode.
1334 * We detect corrupted subbuffers with commit and reserve counts. We keep a
1335 * corrupted sub-buffers count and push the readers across these sub-buffers.
1336 *
1337 * Not concurrency safe if a writer is stalled in a subbuffer and another writer
1338 * switches in, finding out it's corrupted. The result will be than the old
1339 * (uncommited) subbuffer will be declared corrupted, and that the new subbuffer
1340 * will be declared corrupted too because of the commit count adjustment.
1341 *
1342 * Note : offset_old should never be 0 here.
b5b073e2 1343 */
b73a4c47
PMF
1344static void ltt_reserve_switch_old_subbuf(
1345 struct ust_channel *chan, struct ust_buffer *buf,
1346 struct ltt_reserve_switch_offsets *offsets, u64 *tsc)
b5b073e2 1347{
b73a4c47
PMF
1348 long oldidx = SUBBUF_INDEX(offsets->old - 1, chan);
1349 long commit_count, padding_size;
b5b073e2 1350
b73a4c47
PMF
1351 padding_size = chan->subbuf_size
1352 - (SUBBUF_OFFSET(offsets->old - 1, chan) + 1);
1353 ltt_buffer_end(buf, *tsc, offsets->old, oldidx);
b5b073e2 1354
b73a4c47
PMF
1355 /*
1356 * Must write slot data before incrementing commit count.
1357 * This compiler barrier is upgraded into a smp_wmb() by the IPI
1358 * sent by get_subbuf() when it does its smp_rmb().
1359 */
1360 barrier();
1361 local_add(padding_size,
1362 &buf->commit_count[oldidx].cc);
1363 commit_count = local_read(&buf->commit_count[oldidx].cc);
1364 ltt_check_deliver(chan, buf, offsets->old - 1, commit_count, oldidx);
1e8c9e7b 1365 ltt_write_commit_counter(chan, buf, oldidx,
b73a4c47
PMF
1366 offsets->old, commit_count, padding_size);
1367}
b5b073e2 1368
b73a4c47
PMF
1369/*
1370 * ltt_reserve_switch_new_subbuf: Populate new subbuffer.
1371 *
1372 * This code can be executed unordered : writers may already have written to the
1373 * sub-buffer before this code gets executed, caution. The commit makes sure
1374 * that this code is executed before the deliver of this sub-buffer.
1375 */
1376static void ltt_reserve_switch_new_subbuf(
1377 struct ust_channel *chan, struct ust_buffer *buf,
1378 struct ltt_reserve_switch_offsets *offsets, u64 *tsc)
1379{
1380 long beginidx = SUBBUF_INDEX(offsets->begin, chan);
1381 long commit_count;
b5b073e2 1382
b73a4c47 1383 ltt_buffer_begin(buf, *tsc, beginidx);
b5b073e2 1384
b73a4c47
PMF
1385 /*
1386 * Must write slot data before incrementing commit count.
1387 * This compiler barrier is upgraded into a smp_wmb() by the IPI
1388 * sent by get_subbuf() when it does its smp_rmb().
1389 */
1390 barrier();
1391 local_add(ltt_subbuffer_header_size(),
1392 &buf->commit_count[beginidx].cc);
1393 commit_count = local_read(&buf->commit_count[beginidx].cc);
1394 /* Check if the written buffer has to be delivered */
1395 ltt_check_deliver(chan, buf, offsets->begin, commit_count, beginidx);
1e8c9e7b 1396 ltt_write_commit_counter(chan, buf, beginidx,
b73a4c47
PMF
1397 offsets->begin, commit_count, ltt_subbuffer_header_size());
1398}
b5b073e2 1399
b73a4c47
PMF
1400/*
1401 * ltt_reserve_end_switch_current: finish switching current subbuffer
1402 *
1403 * Concurrency safe because we are the last and only thread to alter this
1404 * sub-buffer. As long as it is not delivered and read, no other thread can
1405 * alter the offset, alter the reserve_count or call the
1406 * client_buffer_end_callback on this sub-buffer.
1407 *
1408 * The only remaining threads could be the ones with pending commits. They will
1409 * have to do the deliver themselves. Not concurrency safe in overwrite mode.
1410 * We detect corrupted subbuffers with commit and reserve counts. We keep a
1411 * corrupted sub-buffers count and push the readers across these sub-buffers.
1412 *
1413 * Not concurrency safe if a writer is stalled in a subbuffer and another writer
1414 * switches in, finding out it's corrupted. The result will be than the old
1415 * (uncommited) subbuffer will be declared corrupted, and that the new subbuffer
1416 * will be declared corrupted too because of the commit count adjustment.
1417 */
1418static void ltt_reserve_end_switch_current(
1419 struct ust_channel *chan,
1420 struct ust_buffer *buf,
1421 struct ltt_reserve_switch_offsets *offsets, u64 *tsc)
1422{
1423 long endidx = SUBBUF_INDEX(offsets->end - 1, chan);
1424 long commit_count, padding_size;
1425
1426 padding_size = chan->subbuf_size
1427 - (SUBBUF_OFFSET(offsets->end - 1, chan) + 1);
1428
1429 ltt_buffer_end(buf, *tsc, offsets->end, endidx);
1430
1431 /*
1432 * Must write slot data before incrementing commit count.
1433 * This compiler barrier is upgraded into a smp_wmb() by the IPI
1434 * sent by get_subbuf() when it does its smp_rmb().
1435 */
1436 barrier();
1437 local_add(padding_size,
1438 &buf->commit_count[endidx].cc);
1439 commit_count = local_read(&buf->commit_count[endidx].cc);
1440 ltt_check_deliver(chan, buf,
1441 offsets->end - 1, commit_count, endidx);
1e8c9e7b 1442 ltt_write_commit_counter(chan, buf, endidx,
b73a4c47 1443 offsets->end, commit_count, padding_size);
b5b073e2
PMF
1444}
1445
1446/*
1447 * Returns :
1448 * 0 if ok
1449 * !0 if execution must be aborted.
1450 */
b73a4c47 1451static int ltt_relay_try_switch_slow(
b5b073e2 1452 enum force_switch_mode mode,
b73a4c47 1453 struct ust_channel *chan,
b5b073e2
PMF
1454 struct ust_buffer *buf,
1455 struct ltt_reserve_switch_offsets *offsets,
1456 u64 *tsc)
1457{
1458 long subbuf_index;
b73a4c47 1459 long reserve_commit_diff;
b5b073e2
PMF
1460
1461 offsets->begin = local_read(&buf->offset);
1462 offsets->old = offsets->begin;
1463 offsets->begin_switch = 0;
1464 offsets->end_switch_old = 0;
1465
1466 *tsc = trace_clock_read64();
1467
1468 if (SUBBUF_OFFSET(offsets->begin, buf->chan) != 0) {
1469 offsets->begin = SUBBUF_ALIGN(offsets->begin, buf->chan);
1470 offsets->end_switch_old = 1;
1471 } else {
1472 /* we do not have to switch : buffer is empty */
1473 return -1;
1474 }
1475 if (mode == FORCE_ACTIVE)
1476 offsets->begin += ltt_subbuffer_header_size();
1477 /*
1478 * Always begin_switch in FORCE_ACTIVE mode.
1479 * Test new buffer integrity
1480 */
1481 subbuf_index = SUBBUF_INDEX(offsets->begin, buf->chan);
b73a4c47 1482 reserve_commit_diff =
b5b073e2 1483 (BUFFER_TRUNC(offsets->begin, buf->chan)
b73a4c47
PMF
1484 >> chan->n_subbufs_order)
1485 - (local_read(&buf->commit_count[subbuf_index].cc_sb)
1486 & chan->commit_count_mask);
1487 if (reserve_commit_diff == 0) {
b5b073e2
PMF
1488 /* Next buffer not corrupted. */
1489 if (mode == FORCE_ACTIVE
b73a4c47 1490 && !chan->overwrite
b5b073e2 1491 && offsets->begin - atomic_long_read(&buf->consumed)
b73a4c47 1492 >= chan->alloc_size) {
b5b073e2
PMF
1493 /*
1494 * We do not overwrite non consumed buffers and we are
1495 * full : ignore switch while tracing is active.
1496 */
1497 return -1;
1498 }
1499 } else {
1500 /*
1501 * Next subbuffer corrupted. Force pushing reader even in normal
1502 * mode
1503 */
1504 }
1505 offsets->end = offsets->begin;
1506 return 0;
1507}
1508
b5b073e2 1509/*
b73a4c47
PMF
1510 * Force a sub-buffer switch for a per-cpu buffer. This operation is
1511 * completely reentrant : can be called while tracing is active with
1512 * absolutely no lock held.
b5b073e2 1513 *
b73a4c47
PMF
1514 * Note, however, that as a local_cmpxchg is used for some atomic
1515 * operations, this function must be called from the CPU which owns the buffer
1516 * for a ACTIVE flush.
b5b073e2 1517 */
b73a4c47
PMF
1518void ltt_force_switch_lockless_slow(struct ust_buffer *buf,
1519 enum force_switch_mode mode)
b5b073e2 1520{
b73a4c47 1521 struct ust_channel *chan = buf->chan;
b5b073e2 1522 struct ltt_reserve_switch_offsets offsets;
b73a4c47 1523 u64 tsc;
b5b073e2 1524
b5b073e2
PMF
1525 offsets.size = 0;
1526
10dd3941 1527 DBG("Switching (forced) %s_%d", chan->channel_name, buf->cpu);
b5b073e2
PMF
1528 /*
1529 * Perform retryable operations.
1530 */
b5b073e2 1531 do {
b73a4c47
PMF
1532 if (ltt_relay_try_switch_slow(mode, chan, buf,
1533 &offsets, &tsc))
1534 return;
b5b073e2
PMF
1535 } while (local_cmpxchg(&buf->offset, offsets.old,
1536 offsets.end) != offsets.old);
1537
1538 /*
1539 * Atomically update last_tsc. This update races against concurrent
1540 * atomic updates, but the race will always cause supplementary full TSC
1541 * events, never the opposite (missing a full TSC event when it would be
1542 * needed).
1543 */
b73a4c47 1544 save_last_tsc(buf, tsc);
b5b073e2
PMF
1545
1546 /*
1547 * Push the reader if necessary
1548 */
b73a4c47
PMF
1549 if (mode == FORCE_ACTIVE) {
1550 ltt_reserve_push_reader(chan, buf, offsets.end - 1);
1551//ust// ltt_clear_noref_flag(chan, buf, SUBBUF_INDEX(offsets.end - 1, chan));
1552 }
b5b073e2
PMF
1553
1554 /*
1555 * Switch old subbuffer if needed.
1556 */
b73a4c47
PMF
1557 if (offsets.end_switch_old) {
1558//ust// ltt_clear_noref_flag(rchan, buf, SUBBUF_INDEX(offsets.old - 1, rchan));
1559 ltt_reserve_switch_old_subbuf(chan, buf, &offsets, &tsc);
1560 }
b5b073e2
PMF
1561
1562 /*
1563 * Populate new subbuffer.
1564 */
b73a4c47
PMF
1565 if (mode == FORCE_ACTIVE)
1566 ltt_reserve_switch_new_subbuf(chan, buf, &offsets, &tsc);
1567}
b5b073e2 1568
b73a4c47
PMF
1569/*
1570 * Returns :
1571 * 0 if ok
1572 * !0 if execution must be aborted.
1573 */
1574static int ltt_relay_try_reserve_slow(struct ust_channel *chan, struct ust_buffer *buf,
1575 struct ltt_reserve_switch_offsets *offsets, size_t data_size,
1576 u64 *tsc, unsigned int *rflags, int largest_align)
1577{
1578 long reserve_commit_diff;
b5b073e2 1579
b73a4c47
PMF
1580 offsets->begin = local_read(&buf->offset);
1581 offsets->old = offsets->begin;
1582 offsets->begin_switch = 0;
1583 offsets->end_switch_current = 0;
1584 offsets->end_switch_old = 0;
1585
1586 *tsc = trace_clock_read64();
1587 if (last_tsc_overflow(buf, *tsc))
1588 *rflags = LTT_RFLAG_ID_SIZE_TSC;
1589
1590 if (unlikely(SUBBUF_OFFSET(offsets->begin, buf->chan) == 0)) {
1591 offsets->begin_switch = 1; /* For offsets->begin */
1592 } else {
1593 offsets->size = ust_get_header_size(chan,
1594 offsets->begin, data_size,
1595 &offsets->before_hdr_pad, *rflags);
1596 offsets->size += ltt_align(offsets->begin + offsets->size,
1597 largest_align)
1598 + data_size;
1599 if (unlikely((SUBBUF_OFFSET(offsets->begin, buf->chan) +
1600 offsets->size) > buf->chan->subbuf_size)) {
1601 offsets->end_switch_old = 1; /* For offsets->old */
1602 offsets->begin_switch = 1; /* For offsets->begin */
1603 }
1604 }
1605 if (unlikely(offsets->begin_switch)) {
1606 long subbuf_index;
1607
1608 /*
1609 * We are typically not filling the previous buffer completely.
1610 */
1611 if (likely(offsets->end_switch_old))
1612 offsets->begin = SUBBUF_ALIGN(offsets->begin,
1613 buf->chan);
1614 offsets->begin = offsets->begin + ltt_subbuffer_header_size();
1615 /* Test new buffer integrity */
1616 subbuf_index = SUBBUF_INDEX(offsets->begin, buf->chan);
1617 reserve_commit_diff =
1618 (BUFFER_TRUNC(offsets->begin, buf->chan)
1619 >> chan->n_subbufs_order)
1620 - (local_read(&buf->commit_count[subbuf_index].cc_sb)
1621 & chan->commit_count_mask);
1622 if (likely(reserve_commit_diff == 0)) {
1623 /* Next buffer not corrupted. */
1624 if (unlikely(!chan->overwrite &&
1625 (SUBBUF_TRUNC(offsets->begin, buf->chan)
1626 - SUBBUF_TRUNC(atomic_long_read(
1627 &buf->consumed),
1628 buf->chan))
1629 >= chan->alloc_size)) {
1630 /*
1631 * We do not overwrite non consumed buffers
1632 * and we are full : event is lost.
1633 */
1634 local_inc(&buf->events_lost);
1635 return -1;
1636 } else {
1637 /*
1638 * next buffer not corrupted, we are either in
1639 * overwrite mode or the buffer is not full.
1640 * It's safe to write in this new subbuffer.
1641 */
1642 }
1643 } else {
1644 /*
1645 * Next subbuffer corrupted. Drop event in normal and
1646 * overwrite mode. Caused by either a writer OOPS or
1647 * too many nested writes over a reserve/commit pair.
1648 */
1649 local_inc(&buf->events_lost);
1650 return -1;
1651 }
1652 offsets->size = ust_get_header_size(chan,
1653 offsets->begin, data_size,
1654 &offsets->before_hdr_pad, *rflags);
1655 offsets->size += ltt_align(offsets->begin + offsets->size,
1656 largest_align)
1657 + data_size;
1658 if (unlikely((SUBBUF_OFFSET(offsets->begin, buf->chan)
1659 + offsets->size) > buf->chan->subbuf_size)) {
1660 /*
1661 * Event too big for subbuffers, report error, don't
1662 * complete the sub-buffer switch.
1663 */
1664 local_inc(&buf->events_lost);
1665 return -1;
1666 } else {
1667 /*
1668 * We just made a successful buffer switch and the event
1669 * fits in the new subbuffer. Let's write.
1670 */
1671 }
1672 } else {
1673 /*
1674 * Event fits in the current buffer and we are not on a switch
1675 * boundary. It's safe to write.
1676 */
1677 }
1678 offsets->end = offsets->begin + offsets->size;
1679
1680 if (unlikely((SUBBUF_OFFSET(offsets->end, buf->chan)) == 0)) {
1681 /*
1682 * The offset_end will fall at the very beginning of the next
1683 * subbuffer.
1684 */
1685 offsets->end_switch_current = 1; /* For offsets->begin */
1686 }
b5b073e2
PMF
1687 return 0;
1688}
1689
b73a4c47
PMF
1690/**
1691 * ltt_relay_reserve_slot_lockless_slow - Atomic slot reservation in a buffer.
1692 * @trace: the trace structure to log to.
1693 * @ltt_channel: channel structure
1694 * @transport_data: data structure specific to ltt relay
1695 * @data_size: size of the variable length data to log.
1696 * @slot_size: pointer to total size of the slot (out)
1697 * @buf_offset : pointer to reserved buffer offset (out)
1698 * @tsc: pointer to the tsc at the slot reservation (out)
1699 * @cpu: cpuid
b5b073e2 1700 *
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1701 * Return : -ENOSPC if not enough space, else returns 0.
1702 * It will take care of sub-buffer switching.
b5b073e2 1703 */
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1704int ltt_reserve_slot_lockless_slow(struct ust_trace *trace,
1705 struct ust_channel *chan, void **transport_data,
1706 size_t data_size, size_t *slot_size, long *buf_offset, u64 *tsc,
1707 unsigned int *rflags, int largest_align, int cpu)
b5b073e2 1708{
b73a4c47 1709 struct ust_buffer *buf = chan->buf[cpu];
b5b073e2 1710 struct ltt_reserve_switch_offsets offsets;
b5b073e2 1711
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1712 offsets.size = 0;
1713
b5b073e2 1714 do {
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1715 if (unlikely(ltt_relay_try_reserve_slow(chan, buf, &offsets,
1716 data_size, tsc, rflags, largest_align)))
1717 return -ENOSPC;
1718 } while (unlikely(local_cmpxchg(&buf->offset, offsets.old,
1719 offsets.end) != offsets.old));
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1720
1721 /*
1722 * Atomically update last_tsc. This update races against concurrent
1723 * atomic updates, but the race will always cause supplementary full TSC
1724 * events, never the opposite (missing a full TSC event when it would be
1725 * needed).
1726 */
b73a4c47 1727 save_last_tsc(buf, *tsc);
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1728
1729 /*
1730 * Push the reader if necessary
1731 */
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1732 ltt_reserve_push_reader(chan, buf, offsets.end - 1);
1733
1734 /*
1735 * Clear noref flag for this subbuffer.
1736 */
1737//ust// ltt_clear_noref_flag(chan, buf, SUBBUF_INDEX(offsets.end - 1, chan));
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1738
1739 /*
1740 * Switch old subbuffer if needed.
1741 */
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1742 if (unlikely(offsets.end_switch_old)) {
1743//ust// ltt_clear_noref_flag(chan, buf, SUBBUF_INDEX(offsets.old - 1, chan));
1744 ltt_reserve_switch_old_subbuf(chan, buf, &offsets, tsc);
10dd3941 1745 DBG("Switching %s_%d", chan->channel_name, cpu);
b73a4c47 1746 }
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1747
1748 /*
1749 * Populate new subbuffer.
1750 */
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1751 if (unlikely(offsets.begin_switch))
1752 ltt_reserve_switch_new_subbuf(chan, buf, &offsets, tsc);
1753
1754 if (unlikely(offsets.end_switch_current))
1755 ltt_reserve_end_switch_current(chan, buf, &offsets, tsc);
1756
1757 *slot_size = offsets.size;
1758 *buf_offset = offsets.begin + offsets.before_hdr_pad;
1759 return 0;
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1760}
1761
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1762static struct ltt_transport ust_relay_transport = {
1763 .name = "ustrelay",
1764 .ops = {
1765 .create_channel = ust_buffers_create_channel,
1766 .finish_channel = ltt_relay_finish_channel,
1767 .remove_channel = ltt_relay_remove_channel,
1768 .wakeup_channel = ltt_relay_async_wakeup_chan,
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1769 },
1770};
1771
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1772static char initialized = 0;
1773
1774void __attribute__((constructor)) init_ustrelay_transport(void)
1775{
1776 if(!initialized) {
1777 ltt_transport_register(&ust_relay_transport);
1778 initialized = 1;
1779 }
1780}
1781
b73a4c47 1782static void __attribute__((destructor)) ust_buffers_exit(void)
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1783{
1784 ltt_transport_unregister(&ust_relay_transport);
1785}
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1786
1787size_t ltt_write_event_header_slow(struct ust_trace *trace,
1788 struct ust_channel *channel,
1789 struct ust_buffer *buf, long buf_offset,
1790 u16 eID, u32 event_size,
1791 u64 tsc, unsigned int rflags)
1792{
1793 struct ltt_event_header header;
1794 u16 small_size;
1795
1796 switch (rflags) {
1797 case LTT_RFLAG_ID_SIZE_TSC:
1798 header.id_time = 29 << LTT_TSC_BITS;
1799 break;
1800 case LTT_RFLAG_ID_SIZE:
1801 header.id_time = 30 << LTT_TSC_BITS;
1802 break;
1803 case LTT_RFLAG_ID:
1804 header.id_time = 31 << LTT_TSC_BITS;
1805 break;
1806 }
1807
1808 header.id_time |= (u32)tsc & LTT_TSC_MASK;
1809 ust_buffers_write(buf, buf_offset, &header, sizeof(header));
1810 buf_offset += sizeof(header);
1811
1812 switch (rflags) {
1813 case LTT_RFLAG_ID_SIZE_TSC:
1814 small_size = (u16)min_t(u32, event_size, LTT_MAX_SMALL_SIZE);
1815 ust_buffers_write(buf, buf_offset,
1816 &eID, sizeof(u16));
1817 buf_offset += sizeof(u16);
1818 ust_buffers_write(buf, buf_offset,
1819 &small_size, sizeof(u16));
1820 buf_offset += sizeof(u16);
1821 if (small_size == LTT_MAX_SMALL_SIZE) {
1822 ust_buffers_write(buf, buf_offset,
1823 &event_size, sizeof(u32));
1824 buf_offset += sizeof(u32);
1825 }
1826 buf_offset += ltt_align(buf_offset, sizeof(u64));
1827 ust_buffers_write(buf, buf_offset,
1828 &tsc, sizeof(u64));
1829 buf_offset += sizeof(u64);
1830 break;
1831 case LTT_RFLAG_ID_SIZE:
1832 small_size = (u16)min_t(u32, event_size, LTT_MAX_SMALL_SIZE);
1833 ust_buffers_write(buf, buf_offset,
1834 &eID, sizeof(u16));
1835 buf_offset += sizeof(u16);
1836 ust_buffers_write(buf, buf_offset,
1837 &small_size, sizeof(u16));
1838 buf_offset += sizeof(u16);
1839 if (small_size == LTT_MAX_SMALL_SIZE) {
1840 ust_buffers_write(buf, buf_offset,
1841 &event_size, sizeof(u32));
1842 buf_offset += sizeof(u32);
1843 }
1844 break;
1845 case LTT_RFLAG_ID:
1846 ust_buffers_write(buf, buf_offset,
1847 &eID, sizeof(u16));
1848 buf_offset += sizeof(u16);
1849 break;
1850 }
1851
1852 return buf_offset;
1853}
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