3 * LTTng userspace tracer buffering system
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)
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.
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.
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
28 #include <ust/kernelcompat.h>
29 #include <kcompat/kref.h>
34 #include "tracercore.h"
37 struct ltt_reserve_switch_offsets
{
39 long begin_switch
, end_switch_current
, end_switch_old
;
40 size_t before_hdr_pad
, size
;
44 static DEFINE_MUTEX(ust_buffers_channels_mutex
);
45 static LIST_HEAD(ust_buffers_channels
);
47 static int get_n_cpus(void)
50 static int n_cpus
= 0;
53 /* On Linux, when some processors are offline
54 * _SC_NPROCESSORS_CONF counts the offline
55 * processors, whereas _SC_NPROCESSORS_ONLN
56 * does not. If we used _SC_NPROCESSORS_ONLN,
57 * getcpu() could return a value greater than
58 * this sysconf, in which case the arrays
59 * indexed by processor would overflow.
61 result
= sysconf(_SC_NPROCESSORS_CONF
);
72 /* _ust_buffers_write()
74 * @buf: destination buffer
75 * @offset: offset in destination
77 * @len: length of source
78 * @cpy: already copied
81 void _ust_buffers_write(struct ust_buffer
*buf
, size_t offset
,
82 const void *src
, size_t len
, ssize_t cpy
)
89 WARN_ON(offset
>= buf
->buf_size
);
91 cpy
= min_t(size_t, len
, buf
->buf_size
- offset
);
92 ust_buffers_do_copy(buf
->buf_data
+ offset
, src
, cpy
);
93 } while (unlikely(len
!= cpy
));
96 static int ust_buffers_init_buffer(struct ust_trace
*trace
,
97 struct ust_channel
*ltt_chan
,
98 struct ust_buffer
*buf
,
99 unsigned int n_subbufs
);
101 static int ust_buffers_alloc_buf(struct ust_buffer
*buf
, size_t *size
)
106 *size
= PAGE_ALIGN(*size
);
108 result
= buf
->shmid
= shmget(getpid(), *size
, IPC_CREAT
| IPC_EXCL
| 0700);
109 if(result
== -1 && errno
== EINVAL
) {
110 ERR("shmget() returned EINVAL; maybe /proc/sys/kernel/shmmax should be increased.");
113 else if(result
== -1) {
118 /* FIXME: should have matching call to shmdt */
119 ptr
= shmat(buf
->shmid
, NULL
, 0);
120 if(ptr
== (void *) -1) {
125 /* Already mark the shared memory for destruction. This will occur only
126 * when all users have detached.
128 result
= shmctl(buf
->shmid
, IPC_RMID
, NULL
);
135 buf
->buf_size
= *size
;
140 result
= shmctl(buf
->shmid
, IPC_RMID
, NULL
);
148 int ust_buffers_create_buf(struct ust_channel
*channel
, int cpu
)
151 struct ust_buffer
*buf
= channel
->buf
[cpu
];
154 result
= ust_buffers_alloc_buf(buf
, &channel
->alloc_size
);
159 kref_get(&channel
->kref
);
163 static void ust_buffers_destroy_channel(struct kref
*kref
)
165 struct ust_channel
*chan
= container_of(kref
, struct ust_channel
, kref
);
169 static void ust_buffers_destroy_buf(struct ust_buffer
*buf
)
171 struct ust_channel
*chan
= buf
->chan
;
174 result
= munmap(buf
->buf_data
, buf
->buf_size
);
179 //ust// chan->buf[buf->cpu] = NULL;
181 kref_put(&chan
->kref
, ust_buffers_destroy_channel
);
184 /* called from kref_put */
185 static void ust_buffers_remove_buf(struct kref
*kref
)
187 struct ust_buffer
*buf
= container_of(kref
, struct ust_buffer
, kref
);
188 ust_buffers_destroy_buf(buf
);
191 int ust_buffers_open_buf(struct ust_channel
*chan
, int cpu
)
195 result
= ust_buffers_create_buf(chan
, cpu
);
199 kref_init(&chan
->buf
[cpu
]->kref
);
201 result
= ust_buffers_init_buffer(chan
->trace
, chan
, chan
->buf
[cpu
], chan
->subbuf_cnt
);
207 /* FIXME: decrementally destroy on error? */
211 * ust_buffers_close_buf - close a channel buffer
214 static void ust_buffers_close_buf(struct ust_buffer
*buf
)
216 kref_put(&buf
->kref
, ust_buffers_remove_buf
);
219 int ust_buffers_channel_open(struct ust_channel
*chan
, size_t subbuf_size
, size_t subbuf_cnt
)
224 if(subbuf_size
== 0 || subbuf_cnt
== 0)
227 /* Check that the subbuffer size is larger than a page. */
228 WARN_ON_ONCE(subbuf_size
< PAGE_SIZE
);
231 * Make sure the number of subbuffers and subbuffer size are power of 2.
233 WARN_ON_ONCE(hweight32(subbuf_size
) != 1);
234 WARN_ON(hweight32(subbuf_cnt
) != 1);
236 chan
->version
= UST_CHANNEL_VERSION
;
237 chan
->subbuf_cnt
= subbuf_cnt
;
238 chan
->subbuf_size
= subbuf_size
;
239 chan
->subbuf_size_order
= get_count_order(subbuf_size
);
240 chan
->alloc_size
= subbuf_size
* subbuf_cnt
;
242 kref_init(&chan
->kref
);
244 mutex_lock(&ust_buffers_channels_mutex
);
245 for(i
=0; i
<chan
->n_cpus
; i
++) {
246 result
= ust_buffers_open_buf(chan
, i
);
250 list_add(&chan
->list
, &ust_buffers_channels
);
251 mutex_unlock(&ust_buffers_channels_mutex
);
255 /* Jump directly inside the loop to close the buffers that were already
258 ust_buffers_close_buf(chan
->buf
[i
]);
263 kref_put(&chan
->kref
, ust_buffers_destroy_channel
);
264 mutex_unlock(&ust_buffers_channels_mutex
);
268 void ust_buffers_channel_close(struct ust_channel
*chan
)
274 mutex_lock(&ust_buffers_channels_mutex
);
275 for(i
=0; i
<chan
->n_cpus
; i
++) {
276 /* FIXME: if we make it here, then all buffers were necessarily allocated. Moreover, we don't
277 * initialize to NULL so we cannot use this check. Should we? */
278 //ust// if (chan->buf[i])
279 ust_buffers_close_buf(chan
->buf
[i
]);
282 list_del(&chan
->list
);
283 kref_put(&chan
->kref
, ust_buffers_destroy_channel
);
284 mutex_unlock(&ust_buffers_channels_mutex
);
291 static void ust_buffers_destroy_buffer(struct ust_channel
*ltt_chan
, int cpu
);
293 static void ltt_force_switch(struct ust_buffer
*buf
,
294 enum force_switch_mode mode
);
299 static void ltt_buffer_begin(struct ust_buffer
*buf
,
300 u64 tsc
, unsigned int subbuf_idx
)
302 struct ust_channel
*channel
= buf
->chan
;
303 struct ltt_subbuffer_header
*header
=
304 (struct ltt_subbuffer_header
*)
305 ust_buffers_offset_address(buf
,
306 subbuf_idx
* buf
->chan
->subbuf_size
);
308 header
->cycle_count_begin
= tsc
;
309 header
->data_size
= 0xFFFFFFFF; /* for recognizing crashed buffers */
310 header
->sb_size
= 0xFFFFFFFF; /* for recognizing crashed buffers */
311 /* FIXME: add memory barrier? */
312 ltt_write_trace_header(channel
->trace
, header
);
316 * offset is assumed to never be 0 here : never deliver a completely empty
317 * subbuffer. The lost size is between 0 and subbuf_size-1.
319 static notrace
void ltt_buffer_end(struct ust_buffer
*buf
,
320 u64 tsc
, unsigned int offset
, unsigned int subbuf_idx
)
322 struct ltt_subbuffer_header
*header
=
323 (struct ltt_subbuffer_header
*)
324 ust_buffers_offset_address(buf
,
325 subbuf_idx
* buf
->chan
->subbuf_size
);
326 u32 data_size
= SUBBUF_OFFSET(offset
- 1, buf
->chan
) + 1;
328 header
->data_size
= data_size
;
329 header
->sb_size
= PAGE_ALIGN(data_size
);
330 header
->cycle_count_end
= tsc
;
331 header
->events_lost
= uatomic_read(&buf
->events_lost
);
332 header
->subbuf_corrupt
= uatomic_read(&buf
->corrupted_subbuffers
);
333 if(unlikely(header
->events_lost
> 0)) {
334 DBG("Some events (%d) were lost in %s_%d", header
->events_lost
, buf
->chan
->channel_name
, buf
->cpu
);
339 * This function should not be called from NMI interrupt context
341 static notrace
void ltt_buf_unfull(struct ust_buffer
*buf
,
342 unsigned int subbuf_idx
,
348 * Promote compiler barrier to a smp_mb().
349 * For the specific LTTng case, this IPI call should be removed if the
350 * architecture does not reorder writes. This should eventually be provided by
351 * a separate architecture-specific infrastructure.
353 //ust// static void remote_mb(void *info)
358 int ust_buffers_get_subbuf(struct ust_buffer
*buf
, long *consumed
)
360 struct ust_channel
*channel
= buf
->chan
;
361 long consumed_old
, consumed_idx
, commit_count
, write_offset
;
364 consumed_old
= uatomic_read(&buf
->consumed
);
365 consumed_idx
= SUBBUF_INDEX(consumed_old
, buf
->chan
);
366 commit_count
= uatomic_read(&buf
->commit_count
[consumed_idx
].cc_sb
);
368 * Make sure we read the commit count before reading the buffer
369 * data and the write offset. Correct consumed offset ordering
370 * wrt commit count is insured by the use of cmpxchg to update
371 * the consumed offset.
372 * smp_call_function_single can fail if the remote CPU is offline,
373 * this is OK because then there is no wmb to execute there.
374 * If our thread is executing on the same CPU as the on the buffers
375 * belongs to, we don't have to synchronize it at all. If we are
376 * migrated, the scheduler will take care of the memory barriers.
377 * Normally, smp_call_function_single() should ensure program order when
378 * executing the remote function, which implies that it surrounds the
379 * function execution with :
390 * However, smp_call_function_single() does not seem to clearly execute
391 * such barriers. It depends on spinlock semantic to provide the barrier
392 * before executing the IPI and, when busy-looping, csd_lock_wait only
393 * executes smp_mb() when it has to wait for the other CPU.
395 * I don't trust this code. Therefore, let's add the smp_mb() sequence
396 * required ourself, even if duplicated. It has no performance impact
399 * smp_mb() is needed because smp_rmb() and smp_wmb() only order read vs
400 * read and write vs write. They do not ensure core synchronization. We
401 * really have to ensure total order between the 3 barriers running on
404 //ust// #ifdef LTT_NO_IPI_BARRIER
406 * Local rmb to match the remote wmb to read the commit count before the
407 * buffer data and the write offset.
411 //ust// if (raw_smp_processor_id() != buf->cpu) {
412 //ust// smp_mb(); /* Total order with IPI handler smp_mb() */
413 //ust// smp_call_function_single(buf->cpu, remote_mb, NULL, 1);
414 //ust// smp_mb(); /* Total order with IPI handler smp_mb() */
418 write_offset
= uatomic_read(&buf
->offset
);
420 * Check that the subbuffer we are trying to consume has been
421 * already fully committed.
423 if (((commit_count
- buf
->chan
->subbuf_size
)
424 & channel
->commit_count_mask
)
425 - (BUFFER_TRUNC(consumed_old
, buf
->chan
)
426 >> channel
->n_subbufs_order
)
431 * Check that we are not about to read the same subbuffer in
432 * which the writer head is.
434 if ((SUBBUF_TRUNC(write_offset
, buf
->chan
)
435 - SUBBUF_TRUNC(consumed_old
, buf
->chan
))
440 /* FIXME: is this ok to disable the reading feature? */
441 //ust// retval = update_read_sb_index(buf, consumed_idx);
443 //ust// return retval;
445 *consumed
= consumed_old
;
450 int ust_buffers_put_subbuf(struct ust_buffer
*buf
, unsigned long uconsumed_old
)
452 long consumed_new
, consumed_old
;
454 consumed_old
= uatomic_read(&buf
->consumed
);
455 consumed_old
= consumed_old
& (~0xFFFFFFFFL
);
456 consumed_old
= consumed_old
| uconsumed_old
;
457 consumed_new
= SUBBUF_ALIGN(consumed_old
, buf
->chan
);
459 //ust// spin_lock(<t_buf->full_lock);
460 if (uatomic_cmpxchg(&buf
->consumed
, consumed_old
,
463 /* We have been pushed by the writer : the last
464 * buffer read _is_ corrupted! It can also
465 * happen if this is a buffer we never got. */
466 //ust// spin_unlock(<t_buf->full_lock);
469 /* tell the client that buffer is now unfull */
472 index
= SUBBUF_INDEX(consumed_old
, buf
->chan
);
473 data
= BUFFER_OFFSET(consumed_old
, buf
->chan
);
474 ltt_buf_unfull(buf
, index
, data
);
475 //ust// spin_unlock(<t_buf->full_lock);
480 //ust// static void switch_buffer(unsigned long data)
482 //ust// struct ltt_channel_buf_struct *ltt_buf =
483 //ust// (struct ltt_channel_buf_struct *)data;
484 //ust// struct rchan_buf *buf = ltt_buf->rbuf;
487 //ust// ltt_force_switch(buf, FORCE_ACTIVE);
489 //ust// ltt_buf->switch_timer.expires += ltt_buf->switch_timer_interval;
490 //ust// add_timer_on(<t_buf->switch_timer, smp_processor_id());
493 //ust// static void start_switch_timer(struct ltt_channel_struct *ltt_channel)
495 //ust// struct rchan *rchan = ltt_channel->trans_channel_data;
498 //ust// if (!ltt_channel->switch_timer_interval)
501 //ust// // TODO : hotplug
502 //ust// for_each_online_cpu(cpu) {
503 //ust// struct ltt_channel_buf_struct *ltt_buf;
504 //ust// struct rchan_buf *buf;
506 //ust// buf = rchan->buf[cpu];
507 //ust// ltt_buf = buf->chan_private;
508 //ust// buf->random_access = 1;
509 //ust// ltt_buf->switch_timer_interval =
510 //ust// ltt_channel->switch_timer_interval;
511 //ust// init_timer(<t_buf->switch_timer);
512 //ust// ltt_buf->switch_timer.function = switch_buffer;
513 //ust// ltt_buf->switch_timer.expires = jiffies +
514 //ust// ltt_buf->switch_timer_interval;
515 //ust// ltt_buf->switch_timer.data = (unsigned long)ltt_buf;
516 //ust// add_timer_on(<t_buf->switch_timer, cpu);
521 //ust// * Cannot use del_timer_sync with add_timer_on, so use an IPI to locally
522 //ust// * delete the timer.
524 //ust// static void stop_switch_timer_ipi(void *info)
526 //ust// struct ltt_channel_buf_struct *ltt_buf =
527 //ust// (struct ltt_channel_buf_struct *)info;
529 //ust// del_timer(<t_buf->switch_timer);
532 //ust// static void stop_switch_timer(struct ltt_channel_struct *ltt_channel)
534 //ust// struct rchan *rchan = ltt_channel->trans_channel_data;
537 //ust// if (!ltt_channel->switch_timer_interval)
540 //ust// // TODO : hotplug
541 //ust// for_each_online_cpu(cpu) {
542 //ust// struct ltt_channel_buf_struct *ltt_buf;
543 //ust// struct rchan_buf *buf;
545 //ust// buf = rchan->buf[cpu];
546 //ust// ltt_buf = buf->chan_private;
547 //ust// smp_call_function(stop_switch_timer_ipi, ltt_buf, 1);
548 //ust// buf->random_access = 0;
552 //ust// static void ust_buffers_print_written(struct ust_channel *chan,
553 //ust// long cons_off, unsigned int cpu)
555 //ust// struct ust_buffer *buf = chan->buf[cpu];
556 //ust// long cons_idx, events_count;
558 //ust// cons_idx = SUBBUF_INDEX(cons_off, chan);
559 //ust// events_count = uatomic_read(&buf->commit_count[cons_idx].events);
561 //ust// if (events_count)
562 //ust// printk(KERN_INFO
563 //ust// "channel %s: %lu events written (cpu %u, index %lu)\n",
564 //ust// chan->channel_name, events_count, cpu, cons_idx);
567 static void ltt_relay_print_subbuffer_errors(
568 struct ust_channel
*channel
,
569 long cons_off
, int cpu
)
571 struct ust_buffer
*ltt_buf
= channel
->buf
[cpu
];
572 long cons_idx
, commit_count
, commit_count_sb
, write_offset
;
574 cons_idx
= SUBBUF_INDEX(cons_off
, channel
);
575 commit_count
= uatomic_read(<t_buf
->commit_count
[cons_idx
].cc
);
576 commit_count_sb
= uatomic_read(<t_buf
->commit_count
[cons_idx
].cc_sb
);
579 * No need to order commit_count and write_offset reads because we
580 * execute after trace is stopped when there are no readers left.
582 write_offset
= uatomic_read(<t_buf
->offset
);
583 WARN( "LTT : unread channel %s offset is %ld "
584 "and cons_off : %ld (cpu %d)\n",
585 channel
->channel_name
, write_offset
, cons_off
, cpu
);
586 /* Check each sub-buffer for non filled commit count */
587 if (((commit_count
- channel
->subbuf_size
) & channel
->commit_count_mask
)
588 - (BUFFER_TRUNC(cons_off
, channel
) >> channel
->n_subbufs_order
) != 0) {
589 ERR("LTT : %s : subbuffer %lu has non filled "
590 "commit count [cc, cc_sb] [%lu,%lu].\n",
591 channel
->channel_name
, cons_idx
, commit_count
, commit_count_sb
);
593 ERR("LTT : %s : commit count : %lu, subbuf size %zd\n",
594 channel
->channel_name
, commit_count
,
595 channel
->subbuf_size
);
598 static void ltt_relay_print_errors(struct ust_trace
*trace
,
599 struct ust_channel
*channel
, int cpu
)
601 struct ust_buffer
*ltt_buf
= channel
->buf
[cpu
];
605 * Can be called in the error path of allocation when
606 * trans_channel_data is not yet set.
611 //ust// for (cons_off = 0; cons_off < rchan->alloc_size;
612 //ust// cons_off = SUBBUF_ALIGN(cons_off, rchan))
613 //ust// ust_buffers_print_written(ltt_chan, cons_off, cpu);
614 for (cons_off
= uatomic_read(<t_buf
->consumed
);
615 (SUBBUF_TRUNC(uatomic_read(<t_buf
->offset
),
618 cons_off
= SUBBUF_ALIGN(cons_off
, channel
))
619 ltt_relay_print_subbuffer_errors(channel
, cons_off
, cpu
);
622 static void ltt_relay_print_buffer_errors(struct ust_channel
*channel
, int cpu
)
624 struct ust_trace
*trace
= channel
->trace
;
625 struct ust_buffer
*ltt_buf
= channel
->buf
[cpu
];
627 if (uatomic_read(<t_buf
->events_lost
))
628 ERR("channel %s: %ld events lost (cpu %d)",
629 channel
->channel_name
,
630 uatomic_read(<t_buf
->events_lost
), cpu
);
631 if (uatomic_read(<t_buf
->corrupted_subbuffers
))
632 ERR("channel %s : %ld corrupted subbuffers (cpu %d)",
633 channel
->channel_name
,
634 uatomic_read(<t_buf
->corrupted_subbuffers
), cpu
);
636 ltt_relay_print_errors(trace
, channel
, cpu
);
639 static void ltt_relay_release_channel(struct kref
*kref
)
641 struct ust_channel
*ltt_chan
= container_of(kref
,
642 struct ust_channel
, kref
);
649 //ust// static int ltt_relay_create_buffer(struct ust_trace *trace,
650 //ust// struct ltt_channel_struct *ltt_chan, struct rchan_buf *buf,
651 //ust// unsigned int cpu, unsigned int n_subbufs)
653 //ust// struct ltt_channel_buf_struct *ltt_buf =
654 //ust// percpu_ptr(ltt_chan->buf, cpu);
655 //ust// unsigned int j;
657 //ust// ltt_buf->commit_count =
658 //ust// kzalloc_node(sizeof(ltt_buf->commit_count) * n_subbufs,
659 //ust// GFP_KERNEL, cpu_to_node(cpu));
660 //ust// if (!ltt_buf->commit_count)
661 //ust// return -ENOMEM;
662 //ust// kref_get(&trace->kref);
663 //ust// kref_get(&trace->ltt_transport_kref);
664 //ust// kref_get(<t_chan->kref);
665 //ust// uatomic_set(<t_buf->offset, ltt_subbuffer_header_size());
666 //ust// uatomic_set(<t_buf->consumed, 0);
667 //ust// uatomic_set(<t_buf->active_readers, 0);
668 //ust// for (j = 0; j < n_subbufs; j++)
669 //ust// uatomic_set(<t_buf->commit_count[j], 0);
670 //ust// init_waitqueue_head(<t_buf->write_wait);
671 //ust// uatomic_set(<t_buf->wakeup_readers, 0);
672 //ust// spin_lock_init(<t_buf->full_lock);
674 //ust// ltt_buffer_begin_callback(buf, trace->start_tsc, 0);
675 //ust// /* atomic_add made on local variable on data that belongs to
676 //ust// * various CPUs : ok because tracing not started (for this cpu). */
677 //ust// uatomic_add(<t_buf->commit_count[0], ltt_subbuffer_header_size());
679 //ust// uatomic_set(<t_buf->events_lost, 0);
680 //ust// uatomic_set(<t_buf->corrupted_subbuffers, 0);
685 static int ust_buffers_init_buffer(struct ust_trace
*trace
,
686 struct ust_channel
*ltt_chan
, struct ust_buffer
*buf
,
687 unsigned int n_subbufs
)
694 zmalloc(sizeof(*buf
->commit_count
) * n_subbufs
);
695 if (!buf
->commit_count
)
697 kref_get(&trace
->kref
);
698 kref_get(&trace
->ltt_transport_kref
);
699 kref_get(<t_chan
->kref
);
700 uatomic_set(&buf
->offset
, ltt_subbuffer_header_size());
701 uatomic_set(&buf
->consumed
, 0);
702 uatomic_set(&buf
->active_readers
, 0);
703 for (j
= 0; j
< n_subbufs
; j
++) {
704 uatomic_set(&buf
->commit_count
[j
].cc
, 0);
705 uatomic_set(&buf
->commit_count
[j
].cc_sb
, 0);
707 //ust// init_waitqueue_head(&buf->write_wait);
708 //ust// uatomic_set(&buf->wakeup_readers, 0);
709 //ust// spin_lock_init(&buf->full_lock);
711 ltt_buffer_begin(buf
, trace
->start_tsc
, 0);
713 uatomic_add(&buf
->commit_count
[0].cc
, ltt_subbuffer_header_size());
715 uatomic_set(&buf
->events_lost
, 0);
716 uatomic_set(&buf
->corrupted_subbuffers
, 0);
723 buf
->data_ready_fd_read
= fds
[0];
724 buf
->data_ready_fd_write
= fds
[1];
726 /* FIXME: do we actually need this? */
727 result
= fcntl(fds
[0], F_SETFL
, O_NONBLOCK
);
732 //ust// buf->commit_seq = malloc(sizeof(buf->commit_seq) * n_subbufs);
733 //ust// if(!ltt_buf->commit_seq) {
736 memset(buf
->commit_seq
, 0, sizeof(buf
->commit_seq
[0]) * n_subbufs
);
738 /* FIXME: decrementally destroy on error */
743 /* FIXME: use this function */
744 static void ust_buffers_destroy_buffer(struct ust_channel
*ltt_chan
, int cpu
)
746 struct ust_trace
*trace
= ltt_chan
->trace
;
747 struct ust_buffer
*ltt_buf
= ltt_chan
->buf
[cpu
];
749 kref_put(<t_chan
->trace
->ltt_transport_kref
,
750 ltt_release_transport
);
751 ltt_relay_print_buffer_errors(ltt_chan
, cpu
);
752 //ust// free(ltt_buf->commit_seq);
753 free(ltt_buf
->commit_count
);
754 ltt_buf
->commit_count
= NULL
;
755 kref_put(<t_chan
->kref
, ltt_relay_release_channel
);
756 kref_put(&trace
->kref
, ltt_release_trace
);
757 //ust// wake_up_interruptible(&trace->kref_wq);
760 static int ust_buffers_alloc_channel_buf_structs(struct ust_channel
*chan
)
767 size
= PAGE_ALIGN(1);
769 for(i
=0; i
<chan
->n_cpus
; i
++) {
771 result
= chan
->buf_struct_shmids
[i
] = shmget(getpid(), size
, IPC_CREAT
| IPC_EXCL
| 0700);
774 goto destroy_previous
;
777 /* FIXME: should have matching call to shmdt */
778 ptr
= shmat(chan
->buf_struct_shmids
[i
], NULL
, 0);
779 if(ptr
== (void *) -1) {
784 /* Already mark the shared memory for destruction. This will occur only
785 * when all users have detached.
787 result
= shmctl(chan
->buf_struct_shmids
[i
], IPC_RMID
, NULL
);
790 goto destroy_previous
;
798 /* Jumping inside this loop occurs from within the other loop above with i as
799 * counter, so it unallocates the structures for the cpu = current_i down to
803 result
= shmctl(chan
->buf_struct_shmids
[i
], IPC_RMID
, NULL
);
818 static int ust_buffers_create_channel(const char *trace_name
, struct ust_trace
*trace
,
819 const char *channel_name
, struct ust_channel
*ltt_chan
,
820 unsigned int subbuf_size
, unsigned int n_subbufs
, int overwrite
)
824 kref_init(<t_chan
->kref
);
826 ltt_chan
->trace
= trace
;
827 ltt_chan
->overwrite
= overwrite
;
828 ltt_chan
->n_subbufs_order
= get_count_order(n_subbufs
);
829 ltt_chan
->commit_count_mask
= (~0UL >> ltt_chan
->n_subbufs_order
);
830 ltt_chan
->n_cpus
= get_n_cpus();
831 //ust// ltt_chan->buf = percpu_alloc_mask(sizeof(struct ltt_channel_buf_struct), GFP_KERNEL, cpu_possible_map);
832 ltt_chan
->buf
= (void *) malloc(ltt_chan
->n_cpus
* sizeof(void *));
833 if(ltt_chan
->buf
== NULL
) {
836 ltt_chan
->buf_struct_shmids
= (int *) malloc(ltt_chan
->n_cpus
* sizeof(int));
837 if(ltt_chan
->buf_struct_shmids
== NULL
)
840 result
= ust_buffers_alloc_channel_buf_structs(ltt_chan
);
842 goto free_buf_struct_shmids
;
845 result
= ust_buffers_channel_open(ltt_chan
, subbuf_size
, n_subbufs
);
847 ERR("Cannot open channel for trace %s", trace_name
);
848 goto unalloc_buf_structs
;
854 /* FIXME: put a call here to unalloc the buf structs! */
856 free_buf_struct_shmids
:
857 free(ltt_chan
->buf_struct_shmids
);
867 * LTTng channel flush function.
869 * Must be called when no tracing is active in the channel, because of
870 * accesses across CPUs.
872 static notrace
void ltt_relay_buffer_flush(struct ust_buffer
*buf
)
876 //ust// buf->finalized = 1;
877 ltt_force_switch(buf
, FORCE_FLUSH
);
879 result
= write(buf
->data_ready_fd_write
, "1", 1);
881 PERROR("write (in ltt_relay_buffer_flush)");
882 ERR("this should never happen!");
886 static void ltt_relay_async_wakeup_chan(struct ust_channel
*ltt_channel
)
888 //ust// unsigned int i;
889 //ust// struct rchan *rchan = ltt_channel->trans_channel_data;
891 //ust// for_each_possible_cpu(i) {
892 //ust// struct ltt_channel_buf_struct *ltt_buf =
893 //ust// percpu_ptr(ltt_channel->buf, i);
895 //ust// if (uatomic_read(<t_buf->wakeup_readers) == 1) {
896 //ust// uatomic_set(<t_buf->wakeup_readers, 0);
897 //ust// wake_up_interruptible(&rchan->buf[i]->read_wait);
902 static void ltt_relay_finish_buffer(struct ust_channel
*channel
, unsigned int cpu
)
906 if (channel
->buf
[cpu
]) {
907 struct ust_buffer
*buf
= channel
->buf
[cpu
];
908 ltt_relay_buffer_flush(buf
);
909 //ust// ltt_relay_wake_writers(ltt_buf);
910 /* closing the pipe tells the consumer the buffer is finished */
912 //result = write(ltt_buf->data_ready_fd_write, "D", 1);
914 // PERROR("write (in ltt_relay_finish_buffer)");
915 // ERR("this should never happen!");
917 close(buf
->data_ready_fd_write
);
922 static void ltt_relay_finish_channel(struct ust_channel
*channel
)
926 for(i
=0; i
<channel
->n_cpus
; i
++) {
927 ltt_relay_finish_buffer(channel
, i
);
931 static void ltt_relay_remove_channel(struct ust_channel
*channel
)
933 ust_buffers_channel_close(channel
);
934 kref_put(&channel
->kref
, ltt_relay_release_channel
);
940 //ust// * !0 if execution must be aborted.
942 //ust// static inline int ltt_relay_try_reserve(
943 //ust// struct ust_channel *channel, struct ust_buffer *buf,
944 //ust// struct ltt_reserve_switch_offsets *offsets, size_t data_size,
945 //ust// u64 *tsc, unsigned int *rflags, int largest_align)
947 //ust// offsets->begin = uatomic_read(&buf->offset);
948 //ust// offsets->old = offsets->begin;
949 //ust// offsets->begin_switch = 0;
950 //ust// offsets->end_switch_current = 0;
951 //ust// offsets->end_switch_old = 0;
953 //ust// *tsc = trace_clock_read64();
954 //ust// if (last_tsc_overflow(buf, *tsc))
955 //ust// *rflags = LTT_RFLAG_ID_SIZE_TSC;
957 //ust// if (SUBBUF_OFFSET(offsets->begin, buf->chan) == 0) {
958 //ust// offsets->begin_switch = 1; /* For offsets->begin */
960 //ust// offsets->size = ust_get_header_size(channel,
961 //ust// offsets->begin, data_size,
962 //ust// &offsets->before_hdr_pad, *rflags);
963 //ust// offsets->size += ltt_align(offsets->begin + offsets->size,
964 //ust// largest_align)
966 //ust// if ((SUBBUF_OFFSET(offsets->begin, buf->chan) + offsets->size)
967 //ust// > buf->chan->subbuf_size) {
968 //ust// offsets->end_switch_old = 1; /* For offsets->old */
969 //ust// offsets->begin_switch = 1; /* For offsets->begin */
972 //ust// if (offsets->begin_switch) {
973 //ust// long subbuf_index;
975 //ust// if (offsets->end_switch_old)
976 //ust// offsets->begin = SUBBUF_ALIGN(offsets->begin,
978 //ust// offsets->begin = offsets->begin + ltt_subbuffer_header_size();
979 //ust// /* Test new buffer integrity */
980 //ust// subbuf_index = SUBBUF_INDEX(offsets->begin, buf->chan);
981 //ust// offsets->reserve_commit_diff =
982 //ust// (BUFFER_TRUNC(offsets->begin, buf->chan)
983 //ust// >> channel->n_subbufs_order)
984 //ust// - (uatomic_read(&buf->commit_count[subbuf_index])
985 //ust// & channel->commit_count_mask);
986 //ust// if (offsets->reserve_commit_diff == 0) {
987 //ust// long consumed;
989 //ust// consumed = uatomic_read(&buf->consumed);
991 //ust// /* Next buffer not corrupted. */
992 //ust// if (!channel->overwrite &&
993 //ust// (SUBBUF_TRUNC(offsets->begin, buf->chan)
994 //ust// - SUBBUF_TRUNC(consumed, buf->chan))
995 //ust// >= channel->alloc_size) {
997 //ust// long consumed_idx = SUBBUF_INDEX(consumed, buf->chan);
998 //ust// long commit_count = uatomic_read(&buf->commit_count[consumed_idx]);
999 //ust// if(((commit_count - buf->chan->subbuf_size) & channel->commit_count_mask) - (BUFFER_TRUNC(consumed, buf->chan) >> channel->n_subbufs_order) != 0) {
1000 //ust// WARN("Event dropped. Caused by non-committed event.");
1003 //ust// WARN("Event dropped. Caused by non-consumed buffer.");
1006 //ust// * We do not overwrite non consumed buffers
1007 //ust// * and we are full : event is lost.
1009 //ust// uatomic_inc(&buf->events_lost);
1013 //ust// * next buffer not corrupted, we are either in
1014 //ust// * overwrite mode or the buffer is not full.
1015 //ust// * It's safe to write in this new subbuffer.
1020 //ust// * Next subbuffer corrupted. Force pushing reader even
1021 //ust// * in normal mode. It's safe to write in this new
1022 //ust// * subbuffer.
1025 //ust// offsets->size = ust_get_header_size(channel,
1026 //ust// offsets->begin, data_size,
1027 //ust// &offsets->before_hdr_pad, *rflags);
1028 //ust// offsets->size += ltt_align(offsets->begin + offsets->size,
1029 //ust// largest_align)
1030 //ust// + data_size;
1031 //ust// if ((SUBBUF_OFFSET(offsets->begin, buf->chan) + offsets->size)
1032 //ust// > buf->chan->subbuf_size) {
1034 //ust// * Event too big for subbuffers, report error, don't
1035 //ust// * complete the sub-buffer switch.
1037 //ust// uatomic_inc(&buf->events_lost);
1041 //ust// * We just made a successful buffer switch and the event
1042 //ust// * fits in the new subbuffer. Let's write.
1047 //ust// * Event fits in the current buffer and we are not on a switch
1048 //ust// * boundary. It's safe to write.
1051 //ust// offsets->end = offsets->begin + offsets->size;
1053 //ust// if ((SUBBUF_OFFSET(offsets->end, buf->chan)) == 0) {
1055 //ust// * The offset_end will fall at the very beginning of the next
1056 //ust// * subbuffer.
1058 //ust// offsets->end_switch_current = 1; /* For offsets->begin */
1066 //ust// * !0 if execution must be aborted.
1068 //ust// static inline int ltt_relay_try_switch(
1069 //ust// enum force_switch_mode mode,
1070 //ust// struct ust_channel *channel,
1071 //ust// struct ust_buffer *buf,
1072 //ust// struct ltt_reserve_switch_offsets *offsets,
1075 //ust// long subbuf_index;
1077 //ust// offsets->begin = uatomic_read(&buf->offset);
1078 //ust// offsets->old = offsets->begin;
1079 //ust// offsets->begin_switch = 0;
1080 //ust// offsets->end_switch_old = 0;
1082 //ust// *tsc = trace_clock_read64();
1084 //ust// if (SUBBUF_OFFSET(offsets->begin, buf->chan) != 0) {
1085 //ust// offsets->begin = SUBBUF_ALIGN(offsets->begin, buf->chan);
1086 //ust// offsets->end_switch_old = 1;
1088 //ust// /* we do not have to switch : buffer is empty */
1091 //ust// if (mode == FORCE_ACTIVE)
1092 //ust// offsets->begin += ltt_subbuffer_header_size();
1094 //ust// * Always begin_switch in FORCE_ACTIVE mode.
1095 //ust// * Test new buffer integrity
1097 //ust// subbuf_index = SUBBUF_INDEX(offsets->begin, buf->chan);
1098 //ust// offsets->reserve_commit_diff =
1099 //ust// (BUFFER_TRUNC(offsets->begin, buf->chan)
1100 //ust// >> channel->n_subbufs_order)
1101 //ust// - (uatomic_read(&buf->commit_count[subbuf_index])
1102 //ust// & channel->commit_count_mask);
1103 //ust// if (offsets->reserve_commit_diff == 0) {
1104 //ust// /* Next buffer not corrupted. */
1105 //ust// if (mode == FORCE_ACTIVE
1106 //ust// && !channel->overwrite
1107 //ust// && offsets->begin - uatomic_read(&buf->consumed)
1108 //ust// >= channel->alloc_size) {
1110 //ust// * We do not overwrite non consumed buffers and we are
1111 //ust// * full : ignore switch while tracing is active.
1117 //ust// * Next subbuffer corrupted. Force pushing reader even in normal
1121 //ust// offsets->end = offsets->begin;
1125 //ust// static inline void ltt_reserve_push_reader(
1126 //ust// struct ust_channel *channel,
1127 //ust// struct ust_buffer *buf,
1128 //ust// struct ltt_reserve_switch_offsets *offsets)
1130 //ust// long consumed_old, consumed_new;
1133 //ust// consumed_old = uatomic_read(&buf->consumed);
1135 //ust// * If buffer is in overwrite mode, push the reader consumed
1136 //ust// * count if the write position has reached it and we are not
1137 //ust// * at the first iteration (don't push the reader farther than
1138 //ust// * the writer). This operation can be done concurrently by many
1139 //ust// * writers in the same buffer, the writer being at the farthest
1140 //ust// * write position sub-buffer index in the buffer being the one
1141 //ust// * which will win this loop.
1142 //ust// * If the buffer is not in overwrite mode, pushing the reader
1143 //ust// * only happens if a sub-buffer is corrupted.
1145 //ust// if ((SUBBUF_TRUNC(offsets->end-1, buf->chan)
1146 //ust// - SUBBUF_TRUNC(consumed_old, buf->chan))
1147 //ust// >= channel->alloc_size)
1148 //ust// consumed_new = SUBBUF_ALIGN(consumed_old, buf->chan);
1150 //ust// consumed_new = consumed_old;
1153 //ust// } while (uatomic_cmpxchg(&buf->consumed, consumed_old,
1154 //ust// consumed_new) != consumed_old);
1156 //ust// if (consumed_old != consumed_new) {
1158 //ust// * Reader pushed : we are the winner of the push, we can
1159 //ust// * therefore reequilibrate reserve and commit. Atomic increment
1160 //ust// * of the commit count permits other writers to play around
1161 //ust// * with this variable before us. We keep track of
1162 //ust// * corrupted_subbuffers even in overwrite mode :
1163 //ust// * we never want to write over a non completely committed
1164 //ust// * sub-buffer : possible causes : the buffer size is too low
1165 //ust// * compared to the unordered data input, or there is a writer
1166 //ust// * that died between the reserve and the commit.
1168 //ust// if (offsets->reserve_commit_diff) {
1170 //ust// * We have to alter the sub-buffer commit count.
1171 //ust// * We do not deliver the previous subbuffer, given it
1172 //ust// * was either corrupted or not consumed (overwrite
1175 //ust// uatomic_add(&buf->commit_count[SUBBUF_INDEX(offsets->begin, buf->chan)],
1176 //ust// offsets->reserve_commit_diff);
1177 //ust// if (!channel->overwrite
1178 //ust// || offsets->reserve_commit_diff
1179 //ust// != channel->subbuf_size) {
1181 //ust// * The reserve commit diff was not subbuf_size :
1182 //ust// * it means the subbuffer was partly written to
1183 //ust// * and is therefore corrupted. If it is multiple
1184 //ust// * of subbuffer size and we are in flight
1185 //ust// * recorder mode, we are skipping over a whole
1186 //ust// * subbuffer.
1188 //ust// uatomic_inc(&buf->corrupted_subbuffers);
1195 //ust// * ltt_relay_reserve_slot - Atomic slot reservation in a LTTng buffer.
1196 //ust// * @trace: the trace structure to log to.
1197 //ust// * @ltt_channel: channel structure
1198 //ust// * @transport_data: data structure specific to ltt relay
1199 //ust// * @data_size: size of the variable length data to log.
1200 //ust// * @slot_size: pointer to total size of the slot (out)
1201 //ust// * @buf_offset : pointer to reserved buffer offset (out)
1202 //ust// * @tsc: pointer to the tsc at the slot reservation (out)
1203 //ust// * @cpu: cpuid
1205 //ust// * Return : -ENOSPC if not enough space, else returns 0.
1206 //ust// * It will take care of sub-buffer switching.
1208 //ust// static notrace int ltt_relay_reserve_slot(struct ust_trace *trace,
1209 //ust// struct ust_channel *channel, void **transport_data,
1210 //ust// size_t data_size, size_t *slot_size, long *buf_offset, u64 *tsc,
1211 //ust// unsigned int *rflags, int largest_align, int cpu)
1213 //ust// struct ust_buffer *buf = *transport_data = channel->buf[cpu];
1214 //ust// struct ltt_reserve_switch_offsets offsets;
1216 //ust// offsets.reserve_commit_diff = 0;
1217 //ust// offsets.size = 0;
1220 //ust// * Perform retryable operations.
1222 //ust// if (ltt_nesting > 4) {
1223 //ust// uatomic_inc(&buf->events_lost);
1224 //ust// return -EPERM;
1227 //ust// if (ltt_relay_try_reserve(channel, buf, &offsets, data_size, tsc, rflags,
1228 //ust// largest_align))
1229 //ust// return -ENOSPC;
1230 //ust// } while (uatomic_cmpxchg(&buf->offset, offsets.old,
1231 //ust// offsets.end) != offsets.old);
1234 //ust// * Atomically update last_tsc. This update races against concurrent
1235 //ust// * atomic updates, but the race will always cause supplementary full TSC
1236 //ust// * events, never the opposite (missing a full TSC event when it would be
1239 //ust// save_last_tsc(buf, *tsc);
1242 //ust// * Push the reader if necessary
1244 //ust// ltt_reserve_push_reader(channel, buf, &offsets);
1247 //ust// * Switch old subbuffer if needed.
1249 //ust// if (offsets.end_switch_old)
1250 //ust// ltt_reserve_switch_old_subbuf(channel, buf, &offsets, tsc);
1253 //ust// * Populate new subbuffer.
1255 //ust// if (offsets.begin_switch)
1256 //ust// ltt_reserve_switch_new_subbuf(channel, buf, &offsets, tsc);
1258 //ust// if (offsets.end_switch_current)
1259 //ust// ltt_reserve_end_switch_current(channel, buf, &offsets, tsc);
1261 //ust// *slot_size = offsets.size;
1262 //ust// *buf_offset = offsets.begin + offsets.before_hdr_pad;
1267 //ust// * Force a sub-buffer switch for a per-cpu buffer. This operation is
1268 //ust// * completely reentrant : can be called while tracing is active with
1269 //ust// * absolutely no lock held.
1271 //ust// static notrace void ltt_force_switch(struct ust_buffer *buf,
1272 //ust// enum force_switch_mode mode)
1274 //ust// struct ust_channel *channel = buf->chan;
1275 //ust// struct ltt_reserve_switch_offsets offsets;
1278 //ust// offsets.reserve_commit_diff = 0;
1279 //ust// offsets.size = 0;
1282 //ust// * Perform retryable operations.
1285 //ust// if (ltt_relay_try_switch(mode, channel, buf, &offsets, &tsc))
1287 //ust// } while (uatomic_cmpxchg(&buf->offset, offsets.old,
1288 //ust// offsets.end) != offsets.old);
1291 //ust// * Atomically update last_tsc. This update races against concurrent
1292 //ust// * atomic updates, but the race will always cause supplementary full TSC
1293 //ust// * events, never the opposite (missing a full TSC event when it would be
1296 //ust// save_last_tsc(buf, tsc);
1299 //ust// * Push the reader if necessary
1301 //ust// if (mode == FORCE_ACTIVE)
1302 //ust// ltt_reserve_push_reader(channel, buf, &offsets);
1305 //ust// * Switch old subbuffer if needed.
1307 //ust// if (offsets.end_switch_old)
1308 //ust// ltt_reserve_switch_old_subbuf(channel, buf, &offsets, &tsc);
1311 //ust// * Populate new subbuffer.
1313 //ust// if (mode == FORCE_ACTIVE)
1314 //ust// ltt_reserve_switch_new_subbuf(channel, buf, &offsets, &tsc);
1318 * ltt_reserve_switch_old_subbuf: switch old subbuffer
1320 * Concurrency safe because we are the last and only thread to alter this
1321 * sub-buffer. As long as it is not delivered and read, no other thread can
1322 * alter the offset, alter the reserve_count or call the
1323 * client_buffer_end_callback on this sub-buffer.
1325 * The only remaining threads could be the ones with pending commits. They will
1326 * have to do the deliver themselves. Not concurrency safe in overwrite mode.
1327 * We detect corrupted subbuffers with commit and reserve counts. We keep a
1328 * corrupted sub-buffers count and push the readers across these sub-buffers.
1330 * Not concurrency safe if a writer is stalled in a subbuffer and another writer
1331 * switches in, finding out it's corrupted. The result will be than the old
1332 * (uncommited) subbuffer will be declared corrupted, and that the new subbuffer
1333 * will be declared corrupted too because of the commit count adjustment.
1335 * Note : offset_old should never be 0 here.
1337 static void ltt_reserve_switch_old_subbuf(
1338 struct ust_channel
*chan
, struct ust_buffer
*buf
,
1339 struct ltt_reserve_switch_offsets
*offsets
, u64
*tsc
)
1341 long oldidx
= SUBBUF_INDEX(offsets
->old
- 1, chan
);
1342 long commit_count
, padding_size
;
1344 padding_size
= chan
->subbuf_size
1345 - (SUBBUF_OFFSET(offsets
->old
- 1, chan
) + 1);
1346 ltt_buffer_end(buf
, *tsc
, offsets
->old
, oldidx
);
1349 * Must write slot data before incrementing commit count.
1350 * This compiler barrier is upgraded into a smp_wmb() by the IPI
1351 * sent by get_subbuf() when it does its smp_rmb().
1354 uatomic_add(&buf
->commit_count
[oldidx
].cc
, padding_size
);
1355 commit_count
= uatomic_read(&buf
->commit_count
[oldidx
].cc
);
1356 ltt_check_deliver(chan
, buf
, offsets
->old
- 1, commit_count
, oldidx
);
1357 ltt_write_commit_counter(chan
, buf
, oldidx
,
1358 offsets
->old
, commit_count
, padding_size
);
1362 * ltt_reserve_switch_new_subbuf: Populate new subbuffer.
1364 * This code can be executed unordered : writers may already have written to the
1365 * sub-buffer before this code gets executed, caution. The commit makes sure
1366 * that this code is executed before the deliver of this sub-buffer.
1368 static void ltt_reserve_switch_new_subbuf(
1369 struct ust_channel
*chan
, struct ust_buffer
*buf
,
1370 struct ltt_reserve_switch_offsets
*offsets
, u64
*tsc
)
1372 long beginidx
= SUBBUF_INDEX(offsets
->begin
, chan
);
1375 ltt_buffer_begin(buf
, *tsc
, beginidx
);
1378 * Must write slot data before incrementing commit count.
1379 * This compiler barrier is upgraded into a smp_wmb() by the IPI
1380 * sent by get_subbuf() when it does its smp_rmb().
1383 uatomic_add(&buf
->commit_count
[beginidx
].cc
, ltt_subbuffer_header_size());
1384 commit_count
= uatomic_read(&buf
->commit_count
[beginidx
].cc
);
1385 /* Check if the written buffer has to be delivered */
1386 ltt_check_deliver(chan
, buf
, offsets
->begin
, commit_count
, beginidx
);
1387 ltt_write_commit_counter(chan
, buf
, beginidx
,
1388 offsets
->begin
, commit_count
, ltt_subbuffer_header_size());
1392 * ltt_reserve_end_switch_current: finish switching current subbuffer
1394 * Concurrency safe because we are the last and only thread to alter this
1395 * sub-buffer. As long as it is not delivered and read, no other thread can
1396 * alter the offset, alter the reserve_count or call the
1397 * client_buffer_end_callback on this sub-buffer.
1399 * The only remaining threads could be the ones with pending commits. They will
1400 * have to do the deliver themselves. Not concurrency safe in overwrite mode.
1401 * We detect corrupted subbuffers with commit and reserve counts. We keep a
1402 * corrupted sub-buffers count and push the readers across these sub-buffers.
1404 * Not concurrency safe if a writer is stalled in a subbuffer and another writer
1405 * switches in, finding out it's corrupted. The result will be than the old
1406 * (uncommited) subbuffer will be declared corrupted, and that the new subbuffer
1407 * will be declared corrupted too because of the commit count adjustment.
1409 static void ltt_reserve_end_switch_current(
1410 struct ust_channel
*chan
,
1411 struct ust_buffer
*buf
,
1412 struct ltt_reserve_switch_offsets
*offsets
, u64
*tsc
)
1414 long endidx
= SUBBUF_INDEX(offsets
->end
- 1, chan
);
1415 long commit_count
, padding_size
;
1417 padding_size
= chan
->subbuf_size
1418 - (SUBBUF_OFFSET(offsets
->end
- 1, chan
) + 1);
1420 ltt_buffer_end(buf
, *tsc
, offsets
->end
, endidx
);
1423 * Must write slot data before incrementing commit count.
1424 * This compiler barrier is upgraded into a smp_wmb() by the IPI
1425 * sent by get_subbuf() when it does its smp_rmb().
1428 uatomic_add(&buf
->commit_count
[endidx
].cc
, padding_size
);
1429 commit_count
= uatomic_read(&buf
->commit_count
[endidx
].cc
);
1430 ltt_check_deliver(chan
, buf
,
1431 offsets
->end
- 1, commit_count
, endidx
);
1432 ltt_write_commit_counter(chan
, buf
, endidx
,
1433 offsets
->end
, commit_count
, padding_size
);
1439 * !0 if execution must be aborted.
1441 static int ltt_relay_try_switch_slow(
1442 enum force_switch_mode mode
,
1443 struct ust_channel
*chan
,
1444 struct ust_buffer
*buf
,
1445 struct ltt_reserve_switch_offsets
*offsets
,
1449 long reserve_commit_diff
;
1451 offsets
->begin
= uatomic_read(&buf
->offset
);
1452 offsets
->old
= offsets
->begin
;
1453 offsets
->begin_switch
= 0;
1454 offsets
->end_switch_old
= 0;
1456 *tsc
= trace_clock_read64();
1458 if (SUBBUF_OFFSET(offsets
->begin
, buf
->chan
) != 0) {
1459 offsets
->begin
= SUBBUF_ALIGN(offsets
->begin
, buf
->chan
);
1460 offsets
->end_switch_old
= 1;
1462 /* we do not have to switch : buffer is empty */
1465 if (mode
== FORCE_ACTIVE
)
1466 offsets
->begin
+= ltt_subbuffer_header_size();
1468 * Always begin_switch in FORCE_ACTIVE mode.
1469 * Test new buffer integrity
1471 subbuf_index
= SUBBUF_INDEX(offsets
->begin
, buf
->chan
);
1472 reserve_commit_diff
=
1473 (BUFFER_TRUNC(offsets
->begin
, buf
->chan
)
1474 >> chan
->n_subbufs_order
)
1475 - (uatomic_read(&buf
->commit_count
[subbuf_index
].cc_sb
)
1476 & chan
->commit_count_mask
);
1477 if (reserve_commit_diff
== 0) {
1478 /* Next buffer not corrupted. */
1479 if (mode
== FORCE_ACTIVE
1481 && offsets
->begin
- uatomic_read(&buf
->consumed
)
1482 >= chan
->alloc_size
) {
1484 * We do not overwrite non consumed buffers and we are
1485 * full : ignore switch while tracing is active.
1491 * Next subbuffer corrupted. Force pushing reader even in normal
1495 offsets
->end
= offsets
->begin
;
1500 * Force a sub-buffer switch for a per-cpu buffer. This operation is
1501 * completely reentrant : can be called while tracing is active with
1502 * absolutely no lock held.
1504 void ltt_force_switch_lockless_slow(struct ust_buffer
*buf
,
1505 enum force_switch_mode mode
)
1507 struct ust_channel
*chan
= buf
->chan
;
1508 struct ltt_reserve_switch_offsets offsets
;
1513 DBG("Switching (forced) %s_%d", chan
->channel_name
, buf
->cpu
);
1515 * Perform retryable operations.
1518 if (ltt_relay_try_switch_slow(mode
, chan
, buf
,
1521 } while (uatomic_cmpxchg(&buf
->offset
, offsets
.old
,
1522 offsets
.end
) != offsets
.old
);
1525 * Atomically update last_tsc. This update races against concurrent
1526 * atomic updates, but the race will always cause supplementary full TSC
1527 * events, never the opposite (missing a full TSC event when it would be
1530 save_last_tsc(buf
, tsc
);
1533 * Push the reader if necessary
1535 if (mode
== FORCE_ACTIVE
) {
1536 ltt_reserve_push_reader(chan
, buf
, offsets
.end
- 1);
1537 //ust// ltt_clear_noref_flag(chan, buf, SUBBUF_INDEX(offsets.end - 1, chan));
1541 * Switch old subbuffer if needed.
1543 if (offsets
.end_switch_old
) {
1544 //ust// ltt_clear_noref_flag(rchan, buf, SUBBUF_INDEX(offsets.old - 1, rchan));
1545 ltt_reserve_switch_old_subbuf(chan
, buf
, &offsets
, &tsc
);
1549 * Populate new subbuffer.
1551 if (mode
== FORCE_ACTIVE
)
1552 ltt_reserve_switch_new_subbuf(chan
, buf
, &offsets
, &tsc
);
1558 * !0 if execution must be aborted.
1560 static int ltt_relay_try_reserve_slow(struct ust_channel
*chan
, struct ust_buffer
*buf
,
1561 struct ltt_reserve_switch_offsets
*offsets
, size_t data_size
,
1562 u64
*tsc
, unsigned int *rflags
, int largest_align
)
1564 long reserve_commit_diff
;
1566 offsets
->begin
= uatomic_read(&buf
->offset
);
1567 offsets
->old
= offsets
->begin
;
1568 offsets
->begin_switch
= 0;
1569 offsets
->end_switch_current
= 0;
1570 offsets
->end_switch_old
= 0;
1572 *tsc
= trace_clock_read64();
1573 if (last_tsc_overflow(buf
, *tsc
))
1574 *rflags
= LTT_RFLAG_ID_SIZE_TSC
;
1576 if (unlikely(SUBBUF_OFFSET(offsets
->begin
, buf
->chan
) == 0)) {
1577 offsets
->begin_switch
= 1; /* For offsets->begin */
1579 offsets
->size
= ust_get_header_size(chan
,
1580 offsets
->begin
, data_size
,
1581 &offsets
->before_hdr_pad
, *rflags
);
1582 offsets
->size
+= ltt_align(offsets
->begin
+ offsets
->size
,
1585 if (unlikely((SUBBUF_OFFSET(offsets
->begin
, buf
->chan
) +
1586 offsets
->size
) > buf
->chan
->subbuf_size
)) {
1587 offsets
->end_switch_old
= 1; /* For offsets->old */
1588 offsets
->begin_switch
= 1; /* For offsets->begin */
1591 if (unlikely(offsets
->begin_switch
)) {
1595 * We are typically not filling the previous buffer completely.
1597 if (likely(offsets
->end_switch_old
))
1598 offsets
->begin
= SUBBUF_ALIGN(offsets
->begin
,
1600 offsets
->begin
= offsets
->begin
+ ltt_subbuffer_header_size();
1601 /* Test new buffer integrity */
1602 subbuf_index
= SUBBUF_INDEX(offsets
->begin
, buf
->chan
);
1603 reserve_commit_diff
=
1604 (BUFFER_TRUNC(offsets
->begin
, buf
->chan
)
1605 >> chan
->n_subbufs_order
)
1606 - (uatomic_read(&buf
->commit_count
[subbuf_index
].cc_sb
)
1607 & chan
->commit_count_mask
);
1608 if (likely(reserve_commit_diff
== 0)) {
1609 /* Next buffer not corrupted. */
1610 if (unlikely(!chan
->overwrite
&&
1611 (SUBBUF_TRUNC(offsets
->begin
, buf
->chan
)
1612 - SUBBUF_TRUNC(uatomic_read(
1615 >= chan
->alloc_size
)) {
1617 * We do not overwrite non consumed buffers
1618 * and we are full : event is lost.
1620 uatomic_inc(&buf
->events_lost
);
1624 * next buffer not corrupted, we are either in
1625 * overwrite mode or the buffer is not full.
1626 * It's safe to write in this new subbuffer.
1631 * Next subbuffer corrupted. Drop event in normal and
1632 * overwrite mode. Caused by either a writer OOPS or
1633 * too many nested writes over a reserve/commit pair.
1635 uatomic_inc(&buf
->events_lost
);
1638 offsets
->size
= ust_get_header_size(chan
,
1639 offsets
->begin
, data_size
,
1640 &offsets
->before_hdr_pad
, *rflags
);
1641 offsets
->size
+= ltt_align(offsets
->begin
+ offsets
->size
,
1644 if (unlikely((SUBBUF_OFFSET(offsets
->begin
, buf
->chan
)
1645 + offsets
->size
) > buf
->chan
->subbuf_size
)) {
1647 * Event too big for subbuffers, report error, don't
1648 * complete the sub-buffer switch.
1650 uatomic_inc(&buf
->events_lost
);
1654 * We just made a successful buffer switch and the event
1655 * fits in the new subbuffer. Let's write.
1660 * Event fits in the current buffer and we are not on a switch
1661 * boundary. It's safe to write.
1664 offsets
->end
= offsets
->begin
+ offsets
->size
;
1666 if (unlikely((SUBBUF_OFFSET(offsets
->end
, buf
->chan
)) == 0)) {
1668 * The offset_end will fall at the very beginning of the next
1671 offsets
->end_switch_current
= 1; /* For offsets->begin */
1677 * ltt_relay_reserve_slot_lockless_slow - Atomic slot reservation in a buffer.
1678 * @trace: the trace structure to log to.
1679 * @ltt_channel: channel structure
1680 * @transport_data: data structure specific to ltt relay
1681 * @data_size: size of the variable length data to log.
1682 * @slot_size: pointer to total size of the slot (out)
1683 * @buf_offset : pointer to reserved buffer offset (out)
1684 * @tsc: pointer to the tsc at the slot reservation (out)
1687 * Return : -ENOSPC if not enough space, else returns 0.
1688 * It will take care of sub-buffer switching.
1690 int ltt_reserve_slot_lockless_slow(struct ust_trace
*trace
,
1691 struct ust_channel
*chan
, void **transport_data
,
1692 size_t data_size
, size_t *slot_size
, long *buf_offset
, u64
*tsc
,
1693 unsigned int *rflags
, int largest_align
, int cpu
)
1695 struct ust_buffer
*buf
= chan
->buf
[cpu
];
1696 struct ltt_reserve_switch_offsets offsets
;
1701 if (unlikely(ltt_relay_try_reserve_slow(chan
, buf
, &offsets
,
1702 data_size
, tsc
, rflags
, largest_align
)))
1704 } while (unlikely(uatomic_cmpxchg(&buf
->offset
, offsets
.old
,
1705 offsets
.end
) != offsets
.old
));
1708 * Atomically update last_tsc. This update races against concurrent
1709 * atomic updates, but the race will always cause supplementary full TSC
1710 * events, never the opposite (missing a full TSC event when it would be
1713 save_last_tsc(buf
, *tsc
);
1716 * Push the reader if necessary
1718 ltt_reserve_push_reader(chan
, buf
, offsets
.end
- 1);
1721 * Clear noref flag for this subbuffer.
1723 //ust// ltt_clear_noref_flag(chan, buf, SUBBUF_INDEX(offsets.end - 1, chan));
1726 * Switch old subbuffer if needed.
1728 if (unlikely(offsets
.end_switch_old
)) {
1729 //ust// ltt_clear_noref_flag(chan, buf, SUBBUF_INDEX(offsets.old - 1, chan));
1730 ltt_reserve_switch_old_subbuf(chan
, buf
, &offsets
, tsc
);
1731 DBG("Switching %s_%d", chan
->channel_name
, cpu
);
1735 * Populate new subbuffer.
1737 if (unlikely(offsets
.begin_switch
))
1738 ltt_reserve_switch_new_subbuf(chan
, buf
, &offsets
, tsc
);
1740 if (unlikely(offsets
.end_switch_current
))
1741 ltt_reserve_end_switch_current(chan
, buf
, &offsets
, tsc
);
1743 *slot_size
= offsets
.size
;
1744 *buf_offset
= offsets
.begin
+ offsets
.before_hdr_pad
;
1748 static struct ltt_transport ust_relay_transport
= {
1751 .create_channel
= ust_buffers_create_channel
,
1752 .finish_channel
= ltt_relay_finish_channel
,
1753 .remove_channel
= ltt_relay_remove_channel
,
1754 .wakeup_channel
= ltt_relay_async_wakeup_chan
,
1758 static char initialized
= 0;
1760 void __attribute__((constructor
)) init_ustrelay_transport(void)
1763 ltt_transport_register(&ust_relay_transport
);
1768 static void __attribute__((destructor
)) ust_buffers_exit(void)
1770 ltt_transport_unregister(&ust_relay_transport
);
1773 size_t ltt_write_event_header_slow(struct ust_trace
*trace
,
1774 struct ust_channel
*channel
,
1775 struct ust_buffer
*buf
, long buf_offset
,
1776 u16 eID
, u32 event_size
,
1777 u64 tsc
, unsigned int rflags
)
1779 struct ltt_event_header header
;
1783 case LTT_RFLAG_ID_SIZE_TSC
:
1784 header
.id_time
= 29 << LTT_TSC_BITS
;
1786 case LTT_RFLAG_ID_SIZE
:
1787 header
.id_time
= 30 << LTT_TSC_BITS
;
1790 header
.id_time
= 31 << LTT_TSC_BITS
;
1794 header
.id_time
|= (u32
)tsc
& LTT_TSC_MASK
;
1795 ust_buffers_write(buf
, buf_offset
, &header
, sizeof(header
));
1796 buf_offset
+= sizeof(header
);
1799 case LTT_RFLAG_ID_SIZE_TSC
:
1800 small_size
= (u16
)min_t(u32
, event_size
, LTT_MAX_SMALL_SIZE
);
1801 ust_buffers_write(buf
, buf_offset
,
1803 buf_offset
+= sizeof(u16
);
1804 ust_buffers_write(buf
, buf_offset
,
1805 &small_size
, sizeof(u16
));
1806 buf_offset
+= sizeof(u16
);
1807 if (small_size
== LTT_MAX_SMALL_SIZE
) {
1808 ust_buffers_write(buf
, buf_offset
,
1809 &event_size
, sizeof(u32
));
1810 buf_offset
+= sizeof(u32
);
1812 buf_offset
+= ltt_align(buf_offset
, sizeof(u64
));
1813 ust_buffers_write(buf
, buf_offset
,
1815 buf_offset
+= sizeof(u64
);
1817 case LTT_RFLAG_ID_SIZE
:
1818 small_size
= (u16
)min_t(u32
, event_size
, LTT_MAX_SMALL_SIZE
);
1819 ust_buffers_write(buf
, buf_offset
,
1821 buf_offset
+= sizeof(u16
);
1822 ust_buffers_write(buf
, buf_offset
,
1823 &small_size
, sizeof(u16
));
1824 buf_offset
+= sizeof(u16
);
1825 if (small_size
== LTT_MAX_SMALL_SIZE
) {
1826 ust_buffers_write(buf
, buf_offset
,
1827 &event_size
, sizeof(u32
));
1828 buf_offset
+= sizeof(u32
);
1832 ust_buffers_write(buf
, buf_offset
,
1834 buf_offset
+= sizeof(u16
);