2 * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License, version 2 only,
6 * as published by the Free Software Foundation.
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
13 * You should have received a copy of the GNU General Public License along
14 * with this program; if not, write to the Free Software Foundation, Inc.,
15 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
26 #include <common/common.h>
27 #include <common/kernel-ctl/kernel-ctl.h>
28 #include <common/kernel-ctl/kernel-ioctl.h>
29 #include <common/sessiond-comm/sessiond-comm.h>
33 #include "kernel-consumer.h"
34 #include "kern-modules.h"
39 * Key used to reference a channel between the sessiond and the consumer. This
40 * is only read and updated with the session_list lock held.
42 static uint64_t next_kernel_channel_key
;
45 * Add context on a kernel channel.
47 * Assumes the ownership of ctx.
49 int kernel_add_channel_context(struct ltt_kernel_channel
*chan
,
50 struct ltt_kernel_context
*ctx
)
57 DBG("Adding context to channel %s", chan
->channel
->name
);
58 ret
= kernctl_add_context(chan
->fd
, &ctx
->ctx
);
62 /* Exists but not available for this kernel */
63 ret
= LTTNG_ERR_KERN_CONTEXT_UNAVAILABLE
;
66 /* If EEXIST, we just ignore the error */
70 PERROR("add context ioctl");
71 ret
= LTTNG_ERR_KERN_CONTEXT_FAIL
;
78 cds_list_add_tail(&ctx
->list
, &chan
->ctx_list
);
83 trace_kernel_destroy_context(ctx
);
89 * Create a new kernel session, register it to the kernel tracer and add it to
90 * the session daemon session.
92 int kernel_create_session(struct ltt_session
*session
, int tracer_fd
)
95 struct ltt_kernel_session
*lks
;
99 /* Allocate data structure */
100 lks
= trace_kernel_create_session();
106 /* Kernel tracer session creation */
107 ret
= kernctl_create_session(tracer_fd
);
109 PERROR("ioctl kernel create session");
114 /* Prevent fd duplication after execlp() */
115 ret
= fcntl(lks
->fd
, F_SETFD
, FD_CLOEXEC
);
117 PERROR("fcntl session fd");
120 lks
->id
= session
->id
;
121 lks
->consumer_fds_sent
= 0;
122 session
->kernel_session
= lks
;
124 DBG("Kernel session created (fd: %d)", lks
->fd
);
130 trace_kernel_destroy_session(lks
);
136 * Create a kernel channel, register it to the kernel tracer and add it to the
139 int kernel_create_channel(struct ltt_kernel_session
*session
,
140 struct lttng_channel
*chan
)
143 struct ltt_kernel_channel
*lkc
;
148 /* Allocate kernel channel */
149 lkc
= trace_kernel_create_channel(chan
);
154 DBG3("Kernel create channel %s with attr: %d, %" PRIu64
", %" PRIu64
", %u, %u, %d, %d",
155 chan
->name
, lkc
->channel
->attr
.overwrite
,
156 lkc
->channel
->attr
.subbuf_size
, lkc
->channel
->attr
.num_subbuf
,
157 lkc
->channel
->attr
.switch_timer_interval
, lkc
->channel
->attr
.read_timer_interval
,
158 lkc
->channel
->attr
.live_timer_interval
, lkc
->channel
->attr
.output
);
160 /* Kernel tracer channel creation */
161 ret
= kernctl_create_channel(session
->fd
, &lkc
->channel
->attr
);
163 PERROR("ioctl kernel create channel");
167 /* Setup the channel fd */
169 /* Prevent fd duplication after execlp() */
170 ret
= fcntl(lkc
->fd
, F_SETFD
, FD_CLOEXEC
);
172 PERROR("fcntl session fd");
175 /* Add channel to session */
176 cds_list_add(&lkc
->list
, &session
->channel_list
.head
);
177 session
->channel_count
++;
178 lkc
->session
= session
;
179 lkc
->key
= ++next_kernel_channel_key
;
181 DBG("Kernel channel %s created (fd: %d, key: %" PRIu64
")",
182 lkc
->channel
->name
, lkc
->fd
, lkc
->key
);
195 * Create a kernel event, enable it to the kernel tracer and add it to the
196 * channel event list of the kernel session.
197 * We own filter_expression and filter.
199 int kernel_create_event(struct lttng_event
*ev
,
200 struct ltt_kernel_channel
*channel
,
201 char *filter_expression
,
202 struct lttng_filter_bytecode
*filter
)
205 enum lttng_error_code ret
;
206 struct ltt_kernel_event
*event
;
211 /* We pass ownership of filter_expression and filter */
212 ret
= trace_kernel_create_event(ev
, filter_expression
,
214 if (ret
!= LTTNG_OK
) {
218 fd
= kernctl_create_event(channel
->fd
, event
->event
);
222 ret
= LTTNG_ERR_KERN_EVENT_EXIST
;
225 WARN("Event type not implemented");
226 ret
= LTTNG_ERR_KERN_EVENT_ENOSYS
;
229 WARN("Event %s not found!", ev
->name
);
230 ret
= LTTNG_ERR_KERN_ENABLE_FAIL
;
233 ret
= LTTNG_ERR_KERN_ENABLE_FAIL
;
234 PERROR("create event ioctl");
239 event
->type
= ev
->type
;
241 /* Prevent fd duplication after execlp() */
242 err
= fcntl(event
->fd
, F_SETFD
, FD_CLOEXEC
);
244 PERROR("fcntl session fd");
248 err
= kernctl_filter(event
->fd
, filter
);
252 ret
= LTTNG_ERR_FILTER_NOMEM
;
255 ret
= LTTNG_ERR_FILTER_INVAL
;
262 err
= kernctl_enable(event
->fd
);
266 ret
= LTTNG_ERR_KERN_EVENT_EXIST
;
269 PERROR("enable kernel event");
270 ret
= LTTNG_ERR_KERN_ENABLE_FAIL
;
276 /* Add event to event list */
277 cds_list_add(&event
->list
, &channel
->events_list
.head
);
278 channel
->event_count
++;
280 DBG("Event %s created (fd: %d)", ev
->name
, event
->fd
);
289 closeret
= close(event
->fd
);
291 PERROR("close event fd");
301 * Disable a kernel channel.
303 int kernel_disable_channel(struct ltt_kernel_channel
*chan
)
309 ret
= kernctl_disable(chan
->fd
);
311 PERROR("disable chan ioctl");
316 DBG("Kernel channel %s disabled (fd: %d, key: %" PRIu64
")",
317 chan
->channel
->name
, chan
->fd
, chan
->key
);
326 * Enable a kernel channel.
328 int kernel_enable_channel(struct ltt_kernel_channel
*chan
)
334 ret
= kernctl_enable(chan
->fd
);
335 if (ret
< 0 && ret
!= -EEXIST
) {
336 PERROR("Enable kernel chan");
341 DBG("Kernel channel %s enabled (fd: %d, key: %" PRIu64
")",
342 chan
->channel
->name
, chan
->fd
, chan
->key
);
351 * Enable a kernel event.
353 int kernel_enable_event(struct ltt_kernel_event
*event
)
359 ret
= kernctl_enable(event
->fd
);
363 ret
= LTTNG_ERR_KERN_EVENT_EXIST
;
366 PERROR("enable kernel event");
373 DBG("Kernel event %s enabled (fd: %d)", event
->event
->name
, event
->fd
);
382 * Disable a kernel event.
384 int kernel_disable_event(struct ltt_kernel_event
*event
)
390 ret
= kernctl_disable(event
->fd
);
394 ret
= LTTNG_ERR_KERN_EVENT_EXIST
;
397 PERROR("disable kernel event");
404 DBG("Kernel event %s disabled (fd: %d)", event
->event
->name
, event
->fd
);
413 int kernel_track_pid(struct ltt_kernel_session
*session
, int pid
)
417 DBG("Kernel track PID %d for session id %" PRIu64
".",
419 ret
= kernctl_track_pid(session
->fd
, pid
);
425 return LTTNG_ERR_INVALID
;
427 return LTTNG_ERR_NOMEM
;
429 return LTTNG_ERR_PID_TRACKED
;
431 return LTTNG_ERR_UNK
;
435 int kernel_untrack_pid(struct ltt_kernel_session
*session
, int pid
)
439 DBG("Kernel untrack PID %d for session id %" PRIu64
".",
441 ret
= kernctl_untrack_pid(session
->fd
, pid
);
447 return LTTNG_ERR_INVALID
;
449 return LTTNG_ERR_NOMEM
;
451 return LTTNG_ERR_PID_NOT_TRACKED
;
453 return LTTNG_ERR_UNK
;
457 ssize_t
kernel_list_tracker_pids(struct ltt_kernel_session
*session
,
462 ssize_t nbmem
, count
= 0;
466 fd
= kernctl_list_tracker_pids(session
->fd
);
468 PERROR("kernel tracker pids list");
472 fp
= fdopen(fd
, "r");
474 PERROR("kernel tracker pids list fdopen");
478 nbmem
= KERNEL_TRACKER_PIDS_INIT_LIST_SIZE
;
479 pids
= zmalloc(sizeof(*pids
) * nbmem
);
481 PERROR("alloc list pids");
486 while (fscanf(fp
, "process { pid = %u; };\n", &pid
) == 1) {
487 if (count
>= nbmem
) {
491 new_nbmem
= nbmem
<< 1;
492 DBG("Reallocating pids list from %zu to %zu entries",
494 new_pids
= realloc(pids
, new_nbmem
* sizeof(*new_pids
));
495 if (new_pids
== NULL
) {
496 PERROR("realloc list events");
501 /* Zero the new memory */
502 memset(new_pids
+ nbmem
, 0,
503 (new_nbmem
- nbmem
) * sizeof(*new_pids
));
511 DBG("Kernel list tracker pids done (%zd pids)", count
);
513 ret
= fclose(fp
); /* closes both fp and fd */
529 * Create kernel metadata, open from the kernel tracer and add it to the
532 int kernel_open_metadata(struct ltt_kernel_session
*session
)
535 struct ltt_kernel_metadata
*lkm
= NULL
;
539 /* Allocate kernel metadata */
540 lkm
= trace_kernel_create_metadata();
545 /* Kernel tracer metadata creation */
546 ret
= kernctl_open_metadata(session
->fd
, &lkm
->conf
->attr
);
552 lkm
->key
= ++next_kernel_channel_key
;
553 /* Prevent fd duplication after execlp() */
554 ret
= fcntl(lkm
->fd
, F_SETFD
, FD_CLOEXEC
);
556 PERROR("fcntl session fd");
559 session
->metadata
= lkm
;
561 DBG("Kernel metadata opened (fd: %d)", lkm
->fd
);
566 trace_kernel_destroy_metadata(lkm
);
572 * Start tracing session.
574 int kernel_start_session(struct ltt_kernel_session
*session
)
580 ret
= kernctl_start_session(session
->fd
);
582 PERROR("ioctl start session");
586 DBG("Kernel session started");
595 * Make a kernel wait to make sure in-flight probe have completed.
597 void kernel_wait_quiescent(int fd
)
601 DBG("Kernel quiescent wait on %d", fd
);
603 ret
= kernctl_wait_quiescent(fd
);
605 PERROR("wait quiescent ioctl");
606 ERR("Kernel quiescent wait failed");
611 * Force flush buffer of metadata.
613 int kernel_metadata_flush_buffer(int fd
)
617 DBG("Kernel flushing metadata buffer on fd %d", fd
);
619 ret
= kernctl_buffer_flush(fd
);
621 ERR("Fail to flush metadata buffers %d (ret: %d)", fd
, ret
);
628 * Force flush buffer for channel.
630 int kernel_flush_buffer(struct ltt_kernel_channel
*channel
)
633 struct ltt_kernel_stream
*stream
;
637 DBG("Flush buffer for channel %s", channel
->channel
->name
);
639 cds_list_for_each_entry(stream
, &channel
->stream_list
.head
, list
) {
640 DBG("Flushing channel stream %d", stream
->fd
);
641 ret
= kernctl_buffer_flush(stream
->fd
);
644 ERR("Fail to flush buffer for stream %d (ret: %d)",
653 * Stop tracing session.
655 int kernel_stop_session(struct ltt_kernel_session
*session
)
661 ret
= kernctl_stop_session(session
->fd
);
666 DBG("Kernel session stopped");
675 * Open stream of channel, register it to the kernel tracer and add it
676 * to the stream list of the channel.
678 * Note: given that the streams may appear in random order wrt CPU
679 * number (e.g. cpu hotplug), the index value of the stream number in
680 * the stream name is not necessarily linked to the CPU number.
682 * Return the number of created stream. Else, a negative value.
684 int kernel_open_channel_stream(struct ltt_kernel_channel
*channel
)
687 struct ltt_kernel_stream
*lks
;
691 while ((ret
= kernctl_create_stream(channel
->fd
)) >= 0) {
692 lks
= trace_kernel_create_stream(channel
->channel
->name
,
693 channel
->stream_count
);
703 /* Prevent fd duplication after execlp() */
704 ret
= fcntl(lks
->fd
, F_SETFD
, FD_CLOEXEC
);
706 PERROR("fcntl session fd");
709 lks
->tracefile_size
= channel
->channel
->attr
.tracefile_size
;
710 lks
->tracefile_count
= channel
->channel
->attr
.tracefile_count
;
712 /* Add stream to channel stream list */
713 cds_list_add(&lks
->list
, &channel
->stream_list
.head
);
714 channel
->stream_count
++;
716 DBG("Kernel stream %s created (fd: %d, state: %d)", lks
->name
, lks
->fd
,
720 return channel
->stream_count
;
727 * Open the metadata stream and set it to the kernel session.
729 int kernel_open_metadata_stream(struct ltt_kernel_session
*session
)
735 ret
= kernctl_create_stream(session
->metadata
->fd
);
737 PERROR("kernel create metadata stream");
741 DBG("Kernel metadata stream created (fd: %d)", ret
);
742 session
->metadata_stream_fd
= ret
;
743 /* Prevent fd duplication after execlp() */
744 ret
= fcntl(session
->metadata_stream_fd
, F_SETFD
, FD_CLOEXEC
);
746 PERROR("fcntl session fd");
756 * Get the event list from the kernel tracer and return the number of elements.
758 ssize_t
kernel_list_events(int tracer_fd
, struct lttng_event
**events
)
762 size_t nbmem
, count
= 0;
764 struct lttng_event
*elist
;
768 fd
= kernctl_tracepoint_list(tracer_fd
);
770 PERROR("kernel tracepoint list");
774 fp
= fdopen(fd
, "r");
776 PERROR("kernel tracepoint list fdopen");
781 * Init memory size counter
782 * See kernel-ctl.h for explanation of this value
784 nbmem
= KERNEL_EVENT_INIT_LIST_SIZE
;
785 elist
= zmalloc(sizeof(struct lttng_event
) * nbmem
);
787 PERROR("alloc list events");
792 while (fscanf(fp
, "event { name = %m[^;]; };\n", &event
) == 1) {
793 if (count
>= nbmem
) {
794 struct lttng_event
*new_elist
;
797 new_nbmem
= nbmem
<< 1;
798 DBG("Reallocating event list from %zu to %zu bytes",
800 new_elist
= realloc(elist
, new_nbmem
* sizeof(struct lttng_event
));
801 if (new_elist
== NULL
) {
802 PERROR("realloc list events");
808 /* Zero the new memory */
809 memset(new_elist
+ nbmem
, 0,
810 (new_nbmem
- nbmem
) * sizeof(struct lttng_event
));
814 strncpy(elist
[count
].name
, event
, LTTNG_SYMBOL_NAME_LEN
);
815 elist
[count
].name
[LTTNG_SYMBOL_NAME_LEN
- 1] = '\0';
816 elist
[count
].enabled
= -1;
822 DBG("Kernel list events done (%zu events)", count
);
824 ret
= fclose(fp
); /* closes both fp and fd */
840 * Get kernel version and validate it.
842 int kernel_validate_version(int tracer_fd
,
843 struct lttng_kernel_tracer_version
*version
,
844 struct lttng_kernel_tracer_abi_version
*abi_version
)
848 ret
= kernctl_tracer_version(tracer_fd
, version
);
850 ERR("Failed to retrieve the lttng-modules version");
854 /* Validate version */
855 if (version
->major
!= VERSION_MAJOR
) {
856 ERR("Kernel tracer major version (%d) is not compatible with lttng-tools major version (%d)",
857 version
->major
, VERSION_MAJOR
);
860 ret
= kernctl_tracer_abi_version(tracer_fd
, abi_version
);
862 ERR("Failed to retrieve lttng-modules ABI version");
865 if (abi_version
->major
!= LTTNG_MODULES_ABI_MAJOR_VERSION
) {
866 ERR("Kernel tracer ABI version (%d.%d) does not match the expected ABI major version (%d.*)",
867 abi_version
->major
, abi_version
->minor
,
868 LTTNG_MODULES_ABI_MAJOR_VERSION
);
871 DBG2("Kernel tracer version validated (%d.%d, ABI %d.%d)",
872 version
->major
, version
->minor
,
873 abi_version
->major
, abi_version
->minor
);
880 ERR("Kernel tracer version check failed; kernel tracing will not be available");
885 * Kernel work-arounds called at the start of sessiond main().
887 int init_kernel_workarounds(void)
893 * boot_id needs to be read once before being used concurrently
894 * to deal with a Linux kernel race. A fix is proposed for
895 * upstream, but the work-around is needed for older kernels.
897 fp
= fopen("/proc/sys/kernel/random/boot_id", "r");
904 ret
= fread(buf
, 1, sizeof(buf
), fp
);
906 /* Ignore error, we don't really care */
918 * Complete teardown of a kernel session.
920 void kernel_destroy_session(struct ltt_kernel_session
*ksess
)
923 DBG3("No kernel session when tearing down session");
927 DBG("Tearing down kernel session");
930 * Destroy channels on the consumer if at least one FD has been sent and we
931 * are in no output mode because the streams are in *no* monitor mode so we
932 * have to send a command to clean them up or else they leaked.
934 if (!ksess
->output_traces
&& ksess
->consumer_fds_sent
) {
936 struct consumer_socket
*socket
;
937 struct lttng_ht_iter iter
;
939 /* For each consumer socket. */
941 cds_lfht_for_each_entry(ksess
->consumer
->socks
->ht
, &iter
.iter
,
943 struct ltt_kernel_channel
*chan
;
945 /* For each channel, ask the consumer to destroy it. */
946 cds_list_for_each_entry(chan
, &ksess
->channel_list
.head
, list
) {
947 ret
= kernel_consumer_destroy_channel(socket
, chan
);
949 /* Consumer is probably dead. Use next socket. */
957 /* Close any relayd session */
958 consumer_output_send_destroy_relayd(ksess
->consumer
);
960 trace_kernel_destroy_session(ksess
);
964 * Destroy a kernel channel object. It does not do anything on the tracer side.
966 void kernel_destroy_channel(struct ltt_kernel_channel
*kchan
)
968 struct ltt_kernel_session
*ksess
= NULL
;
971 assert(kchan
->channel
);
973 DBG3("Kernel destroy channel %s", kchan
->channel
->name
);
975 /* Update channel count of associated session. */
976 if (kchan
->session
) {
977 /* Keep pointer reference so we can update it after the destroy. */
978 ksess
= kchan
->session
;
981 trace_kernel_destroy_channel(kchan
);
984 * At this point the kernel channel is not visible anymore. This is safe
985 * since in order to work on a visible kernel session, the tracing session
986 * lock (ltt_session.lock) MUST be acquired.
989 ksess
->channel_count
--;
994 * Take a snapshot for a given kernel session.
996 * Return 0 on success or else return a LTTNG_ERR code.
998 int kernel_snapshot_record(struct ltt_kernel_session
*ksess
,
999 struct snapshot_output
*output
, int wait
,
1000 uint64_t nb_packets_per_stream
)
1002 int err
, ret
, saved_metadata_fd
;
1003 struct consumer_socket
*socket
;
1004 struct lttng_ht_iter iter
;
1005 struct ltt_kernel_metadata
*saved_metadata
;
1006 struct ltt_session
*session
;
1007 uint64_t trace_archive_id
;
1010 assert(ksess
->consumer
);
1013 DBG("Kernel snapshot record started");
1015 session
= session_find_by_id(ksess
->id
);
1017 assert(pthread_mutex_trylock(&session
->lock
));
1018 assert(session_trylock_list());
1019 trace_archive_id
= session
->current_archive_id
;
1021 /* Save current metadata since the following calls will change it. */
1022 saved_metadata
= ksess
->metadata
;
1023 saved_metadata_fd
= ksess
->metadata_stream_fd
;
1027 ret
= kernel_open_metadata(ksess
);
1029 ret
= LTTNG_ERR_KERN_META_FAIL
;
1033 ret
= kernel_open_metadata_stream(ksess
);
1035 ret
= LTTNG_ERR_KERN_META_FAIL
;
1036 goto error_open_stream
;
1039 /* Send metadata to consumer and snapshot everything. */
1040 cds_lfht_for_each_entry(ksess
->consumer
->socks
->ht
, &iter
.iter
,
1041 socket
, node
.node
) {
1042 struct consumer_output
*saved_output
;
1043 struct ltt_kernel_channel
*chan
;
1046 * Temporarly switch consumer output for our snapshot output. As long
1047 * as the session lock is taken, this is safe.
1049 saved_output
= ksess
->consumer
;
1050 ksess
->consumer
= output
->consumer
;
1052 pthread_mutex_lock(socket
->lock
);
1053 /* This stream must not be monitored by the consumer. */
1054 ret
= kernel_consumer_add_metadata(socket
, ksess
, 0);
1055 pthread_mutex_unlock(socket
->lock
);
1056 /* Put back the saved consumer output into the session. */
1057 ksess
->consumer
= saved_output
;
1059 ret
= LTTNG_ERR_KERN_CONSUMER_FAIL
;
1060 goto error_consumer
;
1063 /* For each channel, ask the consumer to snapshot it. */
1064 cds_list_for_each_entry(chan
, &ksess
->channel_list
.head
, list
) {
1065 ret
= consumer_snapshot_channel(socket
, chan
->key
, output
, 0,
1066 ksess
->uid
, ksess
->gid
,
1067 DEFAULT_KERNEL_TRACE_DIR
, wait
,
1068 nb_packets_per_stream
,
1071 ret
= LTTNG_ERR_KERN_CONSUMER_FAIL
;
1072 (void) kernel_consumer_destroy_metadata(socket
,
1074 goto error_consumer
;
1078 /* Snapshot metadata, */
1079 ret
= consumer_snapshot_channel(socket
, ksess
->metadata
->key
, output
,
1080 1, ksess
->uid
, ksess
->gid
,
1081 DEFAULT_KERNEL_TRACE_DIR
, wait
, 0,
1084 ret
= LTTNG_ERR_KERN_CONSUMER_FAIL
;
1085 goto error_consumer
;
1089 * The metadata snapshot is done, ask the consumer to destroy it since
1090 * it's not monitored on the consumer side.
1092 (void) kernel_consumer_destroy_metadata(socket
, ksess
->metadata
);
1098 /* Close newly opened metadata stream. It's now on the consumer side. */
1099 err
= close(ksess
->metadata_stream_fd
);
1101 PERROR("close snapshot kernel");
1105 trace_kernel_destroy_metadata(ksess
->metadata
);
1107 /* Restore metadata state.*/
1108 ksess
->metadata
= saved_metadata
;
1109 ksess
->metadata_stream_fd
= saved_metadata_fd
;
1116 * Get the syscall mask array from the kernel tracer.
1118 * Return 0 on success else a negative value. In both case, syscall_mask should
1121 int kernel_syscall_mask(int chan_fd
, char **syscall_mask
, uint32_t *nr_bits
)
1123 assert(syscall_mask
);
1126 return kernctl_syscall_mask(chan_fd
, syscall_mask
, nr_bits
);
1130 * Check for the support of the RING_BUFFER_SNAPSHOT_SAMPLE_POSITIONS via abi
1133 * Return 1 on success, 0 when feature is not supported, negative value in case
1136 int kernel_supports_ring_buffer_snapshot_sample_positions(int tracer_fd
)
1138 int ret
= 0; // Not supported by default
1139 struct lttng_kernel_tracer_abi_version abi
;
1141 ret
= kernctl_tracer_abi_version(tracer_fd
, &abi
);
1143 ERR("Failed to retrieve lttng-modules ABI version");
1148 * RING_BUFFER_SNAPSHOT_SAMPLE_POSITIONS was introduced in 2.3
1150 if (abi
.major
>= 2 && abi
.minor
>= 3) {
1162 * Rotate a kernel session.
1164 * Return 0 on success or else return a LTTNG_ERR code.
1166 int kernel_rotate_session(struct ltt_session
*session
)
1169 struct consumer_socket
*socket
;
1170 struct lttng_ht_iter iter
;
1171 struct ltt_kernel_session
*ksess
= session
->kernel_session
;
1174 assert(ksess
->consumer
);
1176 DBG("Rotate kernel session %s started (session %" PRIu64
")",
1177 session
->name
, session
->id
);
1182 * Note that this loop will end after one iteration given that there is
1183 * only one kernel consumer.
1185 cds_lfht_for_each_entry(ksess
->consumer
->socks
->ht
, &iter
.iter
,
1186 socket
, node
.node
) {
1187 struct ltt_kernel_channel
*chan
;
1190 * Account the metadata channel first to make sure the
1191 * number of channels waiting for a rotation cannot
1192 * reach 0 before we complete the iteration over all
1195 ret
= rotate_add_channel_pending(ksess
->metadata
->key
,
1196 LTTNG_DOMAIN_KERNEL
, session
);
1198 ret
= LTTNG_ERR_KERN_CONSUMER_FAIL
;
1202 /* For each channel, ask the consumer to rotate it. */
1203 cds_list_for_each_entry(chan
, &ksess
->channel_list
.head
, list
) {
1204 ret
= rotate_add_channel_pending(chan
->key
,
1205 LTTNG_DOMAIN_KERNEL
, session
);
1207 ret
= LTTNG_ERR_KERN_CONSUMER_FAIL
;
1211 DBG("Rotate channel %" PRIu64
", session %s", chan
->key
, session
->name
);
1212 ret
= consumer_rotate_channel(socket
, chan
->key
,
1213 ksess
->uid
, ksess
->gid
, ksess
->consumer
,
1214 ksess
->consumer
->subdir
,
1215 /* is_metadata_channel */ false,
1216 session
->current_archive_id
,
1217 &session
->rotate_pending_relay
);
1219 ret
= LTTNG_ERR_KERN_CONSUMER_FAIL
;
1225 * Rotate the metadata channel.
1227 ret
= consumer_rotate_channel(socket
, ksess
->metadata
->key
,
1228 ksess
->uid
, ksess
->gid
, ksess
->consumer
,
1229 ksess
->consumer
->subdir
,
1230 /* is_metadata_channel */ true,
1231 session
->current_archive_id
,
1232 &session
->rotate_pending_relay
);
1234 ret
= LTTNG_ERR_KERN_CONSUMER_FAIL
;