SoW-2020-0002: Trace Hit Counters: trigger error reporting integration
[lttng-tools.git] / src / bin / lttng-sessiond / cmd.c
index 1dec61ea17b6ba7f74e122e37a7df99afa2e07c6..65553a538a1e62a6e570a5edbf127d741ef4c40e 100644 (file)
@@ -1,19 +1,9 @@
 /*
- * Copyright (C) 2012 David Goulet <dgoulet@efficios.com>
- * Copyright (C) 2016 Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ * Copyright (C) 2012 David Goulet <dgoulet@efficios.com>
+ * Copyright (C) 2016 Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License, version 2 only, as
- * published by the Free Software Foundation.
+ * SPDX-License-Identifier: GPL-2.0-only
  *
- * This program is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
- * more details.
- *
- * You should have received a copy of the GNU General Public License along with
- * this program; if not, write to the Free Software Foundation, Inc., 51
- * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
 #define _LGPL_SOURCE
 #include <common/kernel-ctl/kernel-ctl.h>
 #include <common/dynamic-buffer.h>
 #include <common/buffer-view.h>
+#include <common/payload.h>
+#include <common/payload-view.h>
 #include <common/trace-chunk.h>
 #include <lttng/location-internal.h>
 #include <lttng/trigger/trigger-internal.h>
 #include <lttng/condition/condition.h>
+#include <lttng/condition/condition-internal.h>
+#include <lttng/condition/event-rule.h>
+#include <lttng/condition/event-rule-internal.h>
+#include <lttng/event-rule/event-rule.h>
+#include <lttng/event-rule/event-rule-internal.h>
+#include <lttng/event-rule/uprobe-internal.h>
+#include <lttng/event-rule/tracepoint.h>
 #include <lttng/action/action.h>
 #include <lttng/channel.h>
 #include <lttng/channel-internal.h>
@@ -45,6 +44,8 @@
 #include <lttng/session-internal.h>
 #include <lttng/userspace-probe-internal.h>
 #include <lttng/session-descriptor-internal.h>
+#include <lttng/lttng-error.h>
+#include <lttng/tracker.h>
 #include <common/string-utils/string-utils.h>
 
 #include "channel.h"
@@ -64,6 +65,7 @@
 #include "rotation-thread.h"
 #include "timer.h"
 #include "agent-thread.h"
+#include "tracker.h"
 
 #include "cmd.h"
 
@@ -115,7 +117,7 @@ static int cmd_enable_event_internal(struct ltt_session *session,
                const struct lttng_domain *domain,
                char *channel_name, struct lttng_event *event,
                char *filter_expression,
-               struct lttng_filter_bytecode *filter,
+               struct lttng_bytecode *filter,
                struct lttng_event_exclusion *exclusion,
                int wpipe);
 
@@ -400,95 +402,69 @@ end:
        }
 }
 
-static int increment_extended_len(const char *filter_expression,
-               struct lttng_event_exclusion *exclusion,
-               const struct lttng_userspace_probe_location *probe_location,
-               size_t *extended_len)
-{
-       int ret = 0;
-
-       *extended_len += sizeof(struct lttcomm_event_extended_header);
-
-       if (filter_expression) {
-               *extended_len += strlen(filter_expression) + 1;
-       }
-
-       if (exclusion) {
-               *extended_len += exclusion->count * LTTNG_SYMBOL_NAME_LEN;
-       }
-
-       if (probe_location) {
-               ret = lttng_userspace_probe_location_serialize(probe_location,
-                               NULL, NULL);
-               if (ret < 0) {
-                       goto end;
-               }
-               *extended_len += ret;
-       }
-       ret = 0;
-end:
-       return ret;
-}
-
 static int append_extended_info(const char *filter_expression,
                struct lttng_event_exclusion *exclusion,
                struct lttng_userspace_probe_location *probe_location,
-               void **extended_at)
+               struct lttng_payload *payload)
 {
        int ret = 0;
        size_t filter_len = 0;
        size_t nb_exclusions = 0;
        size_t userspace_probe_location_len = 0;
-       struct lttng_dynamic_buffer location_buffer;
-       struct lttcomm_event_extended_header extended_header;
+       struct lttcomm_event_extended_header extended_header = {};
+       struct lttcomm_event_extended_header *p_extended_header;
+       const size_t original_payload_size = payload->buffer.size;
+
+       ret = lttng_dynamic_buffer_append(&payload->buffer, &extended_header,
+                       sizeof(extended_header));
+       if (ret) {
+               goto end;
+       }
 
        if (filter_expression) {
                filter_len = strlen(filter_expression) + 1;
+               ret = lttng_dynamic_buffer_append(&payload->buffer,
+                               filter_expression, filter_len);
+               if (ret) {
+                       goto end;
+               }
        }
 
        if (exclusion) {
+               const size_t len = exclusion->count * LTTNG_SYMBOL_NAME_LEN;
+
                nb_exclusions = exclusion->count;
+
+               ret = lttng_dynamic_buffer_append(
+                               &payload->buffer, &exclusion->names, len);
+               if (ret) {
+                       goto end;
+               }
        }
 
        if (probe_location) {
-               lttng_dynamic_buffer_init(&location_buffer);
+               const size_t size_before_probe = payload->buffer.size;
+
                ret = lttng_userspace_probe_location_serialize(probe_location,
-                               &location_buffer, NULL);
+                               payload);
                if (ret < 0) {
                        ret = -1;
                        goto end;
                }
-               userspace_probe_location_len = location_buffer.size;
-       }
 
-       /* Set header fields */
-       extended_header.filter_len = filter_len;
-       extended_header.nb_exclusions = nb_exclusions;
-       extended_header.userspace_probe_location_len = userspace_probe_location_len;
-
-       /* Copy header */
-       memcpy(*extended_at, &extended_header, sizeof(extended_header));
-       *extended_at += sizeof(extended_header);
-
-       /* Copy filter string */
-       if (filter_expression) {
-               memcpy(*extended_at, filter_expression, filter_len);
-               *extended_at += filter_len;
+               userspace_probe_location_len =
+                               payload->buffer.size - size_before_probe;
        }
 
-       /* Copy exclusion names */
-       if (exclusion) {
-               size_t len = nb_exclusions * LTTNG_SYMBOL_NAME_LEN;
+       /* Set header fields */
+       p_extended_header = (struct lttcomm_event_extended_header *)
+                       (payload->buffer.data + original_payload_size);
 
-               memcpy(*extended_at, &exclusion->names, len);
-               *extended_at += len;
-       }
+       p_extended_header->filter_len = filter_len;
+       p_extended_header->nb_exclusions = nb_exclusions;
+       p_extended_header->userspace_probe_location_len =
+                       userspace_probe_location_len;
 
-       if (probe_location) {
-               memcpy(*extended_at, location_buffer.data, location_buffer.size);
-               *extended_at += location_buffer.size;
-               lttng_dynamic_buffer_reset(&location_buffer);
-       }
        ret = 0;
 end:
        return ret;
@@ -500,89 +476,55 @@ end:
  * Return number of events in list on success or else a negative value.
  */
 static int list_lttng_agent_events(struct agent *agt,
-               struct lttng_event **events, size_t *total_size)
+               struct lttng_payload *payload)
 {
-       int i = 0, ret = 0;
-       unsigned int nb_event = 0;
-       struct agent_event *event;
-       struct lttng_event *tmp_events = NULL;
+       int nb_events = 0, ret = 0;
+       const struct agent_event *agent_event;
        struct lttng_ht_iter iter;
-       size_t extended_len = 0;
-       void *extended_at;
 
        assert(agt);
-       assert(events);
 
        DBG3("Listing agent events");
 
        rcu_read_lock();
-       nb_event = lttng_ht_get_count(agt->events);
-       rcu_read_unlock();
-       if (nb_event == 0) {
-               ret = nb_event;
-               *total_size = 0;
-               goto error;
-       }
-
-       /* Compute required extended infos size */
-       extended_len = nb_event * sizeof(struct lttcomm_event_extended_header);
-
-       /*
-        * This is only valid because the commands which add events are
-        * processed in the same thread as the listing.
-        */
-       rcu_read_lock();
-       cds_lfht_for_each_entry(agt->events->ht, &iter.iter, event, node.node) {
-               ret = increment_extended_len(event->filter_expression, NULL, NULL,
-                               &extended_len);
+       cds_lfht_for_each_entry (
+                       agt->events->ht, &iter.iter, agent_event, node.node) {
+               struct lttng_event event = {
+                       .enabled = agent_event->enabled,
+                       .loglevel = agent_event->loglevel_value,
+                       .loglevel_type = agent_event->loglevel_type,
+               };
+
+               strncpy(event.name, agent_event->name, sizeof(event.name));
+               event.name[sizeof(event.name) - 1] = '\0';
+
+               ret = lttng_dynamic_buffer_append(
+                               &payload->buffer, &event, sizeof(event));
                if (ret) {
-                       DBG("Error computing the length of extended info message");
-                       ret = -LTTNG_ERR_FATAL;
-                       goto error;
+                       ERR("Failed to append event to payload");
+                       ret = -LTTNG_ERR_NOMEM;
+                       goto end;
                }
-       }
-       rcu_read_unlock();
 
-       *total_size = nb_event * sizeof(*tmp_events) + extended_len;
-       tmp_events = zmalloc(*total_size);
-       if (!tmp_events) {
-               PERROR("zmalloc agent events session");
-               ret = -LTTNG_ERR_FATAL;
-               goto error;
+               nb_events++;
        }
 
-       extended_at = ((uint8_t *) tmp_events) +
-               nb_event * sizeof(struct lttng_event);
-
-       rcu_read_lock();
-       cds_lfht_for_each_entry(agt->events->ht, &iter.iter, event, node.node) {
-               strncpy(tmp_events[i].name, event->name, sizeof(tmp_events[i].name));
-               tmp_events[i].name[sizeof(tmp_events[i].name) - 1] = '\0';
-               tmp_events[i].enabled = event->enabled;
-               tmp_events[i].loglevel = event->loglevel_value;
-               tmp_events[i].loglevel_type = event->loglevel_type;
-               i++;
-
-               /* Append extended info */
-               ret = append_extended_info(event->filter_expression, NULL, NULL,
-                               &extended_at);
+       cds_lfht_for_each_entry (
+               agt->events->ht, &iter.iter, agent_event, node.node) {
+               /* Append extended info. */
+               ret = append_extended_info(agent_event->filter_expression, NULL,
+                               NULL, payload);
                if (ret) {
-                       DBG("Error appending extended info message");
-                       ret = -LTTNG_ERR_FATAL;
-                       goto error;
+                       ERR("Failed to append extended event info to payload");
+                       ret = -LTTNG_ERR_NOMEM;
+                       goto end;
                }
        }
 
-       *events = tmp_events;
-       ret = nb_event;
-       assert(nb_event == i);
-
+       ret = nb_events;
 end:
        rcu_read_unlock();
        return ret;
-error:
-       free(tmp_events);
-       goto end;
 }
 
 /*
@@ -590,23 +532,20 @@ error:
  */
 static int list_lttng_ust_global_events(char *channel_name,
                struct ltt_ust_domain_global *ust_global,
-               struct lttng_event **events, size_t *total_size)
+               struct lttng_payload *payload)
 {
-       int i = 0, ret = 0;
-       unsigned int nb_event = 0;
+       int ret = 0;
+       unsigned int nb_events = 0;
        struct lttng_ht_iter iter;
-       struct lttng_ht_node_str *node;
-       struct ltt_ust_channel *uchan;
-       struct ltt_ust_event *uevent;
-       struct lttng_event *tmp;
-       size_t extended_len = 0;
-       void *extended_at;
+       const struct lttng_ht_node_str *node;
+       const struct ltt_ust_channel *uchan;
+       const struct ltt_ust_event *uevent;
 
        DBG("Listing UST global events for channel %s", channel_name);
 
        rcu_read_lock();
 
-       lttng_ht_lookup(ust_global->channels, (void *)channel_name, &iter);
+       lttng_ht_lookup(ust_global->channels, (void *) channel_name, &iter);
        node = lttng_ht_iter_get_node_str(&iter);
        if (node == NULL) {
                ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
@@ -615,99 +554,75 @@ static int list_lttng_ust_global_events(char *channel_name,
 
        uchan = caa_container_of(&node->node, struct ltt_ust_channel, node.node);
 
-       nb_event = lttng_ht_get_count(uchan->events);
-       if (nb_event == 0) {
-               ret = nb_event;
-               *total_size = 0;
-               goto end;
-       }
-
-       DBG3("Listing UST global %d events", nb_event);
+       DBG3("Listing UST global events");
 
-       /* Compute required extended infos size */
        cds_lfht_for_each_entry(uchan->events->ht, &iter.iter, uevent, node.node) {
+               struct lttng_event event = {};
+
                if (uevent->internal) {
-                       nb_event--;
                        continue;
                }
 
-               ret = increment_extended_len(uevent->filter_expression,
-                       uevent->exclusion, NULL, &extended_len);
-               if (ret) {
-                       DBG("Error computing the length of extended info message");
-                       ret = -LTTNG_ERR_FATAL;
-                       goto end;
-               }
-       }
-       if (nb_event == 0) {
-               /* All events are internal, skip. */
-               ret = 0;
-               *total_size = 0;
-               goto end;
-       }
+               strncpy(event.name, uevent->attr.name, sizeof(event.name));
+               event.name[sizeof(event.name) - 1] = '\0';
 
-       *total_size = nb_event * sizeof(struct lttng_event) + extended_len;
-       tmp = zmalloc(*total_size);
-       if (tmp == NULL) {
-               ret = -LTTNG_ERR_FATAL;
-               goto end;
-       }
-
-       extended_at = ((uint8_t *) tmp) + nb_event * sizeof(struct lttng_event);
-
-       cds_lfht_for_each_entry(uchan->events->ht, &iter.iter, uevent, node.node) {
-               if (uevent->internal) {
-                       /* This event should remain hidden from clients */
-                       continue;
-               }
-               strncpy(tmp[i].name, uevent->attr.name, LTTNG_SYMBOL_NAME_LEN);
-               tmp[i].name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
-               tmp[i].enabled = uevent->enabled;
+               event.enabled = uevent->enabled;
 
                switch (uevent->attr.instrumentation) {
                case LTTNG_UST_TRACEPOINT:
-                       tmp[i].type = LTTNG_EVENT_TRACEPOINT;
+                       event.type = LTTNG_EVENT_TRACEPOINT;
                        break;
                case LTTNG_UST_PROBE:
-                       tmp[i].type = LTTNG_EVENT_PROBE;
+                       event.type = LTTNG_EVENT_PROBE;
                        break;
                case LTTNG_UST_FUNCTION:
-                       tmp[i].type = LTTNG_EVENT_FUNCTION;
+                       event.type = LTTNG_EVENT_FUNCTION;
                        break;
                }
 
-               tmp[i].loglevel = uevent->attr.loglevel;
+               event.loglevel = uevent->attr.loglevel;
                switch (uevent->attr.loglevel_type) {
                case LTTNG_UST_LOGLEVEL_ALL:
-                       tmp[i].loglevel_type = LTTNG_EVENT_LOGLEVEL_ALL;
+                       event.loglevel_type = LTTNG_EVENT_LOGLEVEL_ALL;
                        break;
                case LTTNG_UST_LOGLEVEL_RANGE:
-                       tmp[i].loglevel_type = LTTNG_EVENT_LOGLEVEL_RANGE;
+                       event.loglevel_type = LTTNG_EVENT_LOGLEVEL_RANGE;
                        break;
                case LTTNG_UST_LOGLEVEL_SINGLE:
-                       tmp[i].loglevel_type = LTTNG_EVENT_LOGLEVEL_SINGLE;
+                       event.loglevel_type = LTTNG_EVENT_LOGLEVEL_SINGLE;
                        break;
                }
+
                if (uevent->filter) {
-                       tmp[i].filter = 1;
+                       event.filter = 1;
                }
+
                if (uevent->exclusion) {
-                       tmp[i].exclusion = 1;
+                       event.exclusion = 1;
                }
-               i++;
 
-               /* Append extended info */
+               ret = lttng_dynamic_buffer_append(&payload->buffer, &event, sizeof(event));
+               if (ret) {
+                       ERR("Failed to append event to payload");
+                       ret = -LTTNG_ERR_NOMEM;
+                       goto end;
+               }
+
+               nb_events++;
+       }
+
+       cds_lfht_for_each_entry(uchan->events->ht, &iter.iter, uevent, node.node) {
+               /* Append extended info. */
                ret = append_extended_info(uevent->filter_expression,
-                       uevent->exclusion, NULL, &extended_at);
+                               uevent->exclusion, NULL, payload);
                if (ret) {
-                       DBG("Error appending extended info message");
+                       ERR("Failed to append extended event info to payload");
                        ret = -LTTNG_ERR_FATAL;
                        goto end;
                }
        }
 
-       ret = nb_event;
-       *events = tmp;
+       ret = nb_events;
 end:
        rcu_read_unlock();
        return ret;
@@ -718,14 +633,12 @@ end:
  */
 static int list_lttng_kernel_events(char *channel_name,
                struct ltt_kernel_session *kernel_session,
-               struct lttng_event **events, size_t *total_size)
+               struct lttng_payload *payload)
 {
-       int i = 0, ret;
+       int ret;
        unsigned int nb_event;
-       struct ltt_kernel_event *event;
-       struct ltt_kernel_channel *kchan;
-       size_t extended_len = 0;
-       void *extended_at;
+       const struct ltt_kernel_event *kevent;
+       const struct ltt_kernel_channel *kchan;
 
        kchan = trace_kernel_get_channel_by_name(channel_name, kernel_session);
        if (kchan == NULL) {
@@ -737,69 +650,42 @@ static int list_lttng_kernel_events(char *channel_name,
 
        DBG("Listing events for channel %s", kchan->channel->name);
 
-       if (nb_event == 0) {
-               *total_size = 0;
-               *events = NULL;
-               goto end;
-       }
-
-       /* Compute required extended infos size */
-       cds_list_for_each_entry(event, &kchan->events_list.head, list) {
-               ret = increment_extended_len(event->filter_expression, NULL,
-                       event->userspace_probe_location,
-                       &extended_len);
-               if (ret) {
-                       DBG("Error computing the length of extended info message");
-                       ret = -LTTNG_ERR_FATAL;
-                       goto error;
-               }
-       }
-
-       *total_size = nb_event * sizeof(struct lttng_event) + extended_len;
-       *events = zmalloc(*total_size);
-       if (*events == NULL) {
-               ret = -LTTNG_ERR_FATAL;
-               goto error;
-       }
+       /* Kernel channels */
+       cds_list_for_each_entry(kevent, &kchan->events_list.head , list) {
+               struct lttng_event event = {};
 
-       extended_at = ((void *) *events) +
-               nb_event * sizeof(struct lttng_event);
+               strncpy(event.name, kevent->event->name, sizeof(event.name));
+               event.name[sizeof(event.name) - 1] = '\0';
+               event.enabled = kevent->enabled;
+               event.filter = (unsigned char) !!kevent->filter_expression;
 
-       /* Kernel channels */
-       cds_list_for_each_entry(event, &kchan->events_list.head , list) {
-               strncpy((*events)[i].name, event->event->name, LTTNG_SYMBOL_NAME_LEN);
-               (*events)[i].name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
-               (*events)[i].enabled = event->enabled;
-               (*events)[i].filter =
-                               (unsigned char) !!event->filter_expression;
-
-               switch (event->event->instrumentation) {
+               switch (kevent->event->instrumentation) {
                case LTTNG_KERNEL_TRACEPOINT:
-                       (*events)[i].type = LTTNG_EVENT_TRACEPOINT;
+                       event.type = LTTNG_EVENT_TRACEPOINT;
                        break;
                case LTTNG_KERNEL_KRETPROBE:
-                       (*events)[i].type = LTTNG_EVENT_FUNCTION;
-                       memcpy(&(*events)[i].attr.probe, &event->event->u.kprobe,
+                       event.type = LTTNG_EVENT_FUNCTION;
+                       memcpy(&event.attr.probe, &kevent->event->u.kprobe,
                                        sizeof(struct lttng_kernel_kprobe));
                        break;
                case LTTNG_KERNEL_KPROBE:
-                       (*events)[i].type = LTTNG_EVENT_PROBE;
-                       memcpy(&(*events)[i].attr.probe, &event->event->u.kprobe,
+                       event.type = LTTNG_EVENT_PROBE;
+                       memcpy(&event.attr.probe, &kevent->event->u.kprobe,
                                        sizeof(struct lttng_kernel_kprobe));
                        break;
                case LTTNG_KERNEL_UPROBE:
-                       (*events)[i].type = LTTNG_EVENT_USERSPACE_PROBE;
+                       event.type = LTTNG_EVENT_USERSPACE_PROBE;
                        break;
                case LTTNG_KERNEL_FUNCTION:
-                       (*events)[i].type = LTTNG_EVENT_FUNCTION;
-                       memcpy(&((*events)[i].attr.ftrace), &event->event->u.ftrace,
+                       event.type = LTTNG_EVENT_FUNCTION;
+                       memcpy(&event.attr.ftrace, &kevent->event->u.ftrace,
                                        sizeof(struct lttng_kernel_function));
                        break;
                case LTTNG_KERNEL_NOOP:
-                       (*events)[i].type = LTTNG_EVENT_NOOP;
+                       event.type = LTTNG_EVENT_NOOP;
                        break;
                case LTTNG_KERNEL_SYSCALL:
-                       (*events)[i].type = LTTNG_EVENT_SYSCALL;
+                       event.type = LTTNG_EVENT_SYSCALL;
                        break;
                case LTTNG_KERNEL_ALL:
                        /* fall-through. */
@@ -807,11 +693,20 @@ static int list_lttng_kernel_events(char *channel_name,
                        assert(0);
                        break;
                }
-               i++;
 
-               /* Append extended info */
-               ret = append_extended_info(event->filter_expression, NULL,
-                       event->userspace_probe_location, &extended_at);
+               ret = lttng_dynamic_buffer_append(
+                               &payload->buffer, &event, sizeof(event));
+               if (ret) {
+                       ERR("Failed to append event to payload");
+                       ret = -LTTNG_ERR_NOMEM;
+                       goto end;
+               }
+       }
+
+       cds_list_for_each_entry(kevent, &kchan->events_list.head , list) {
+               /* Append extended info. */
+               ret = append_extended_info(kevent->filter_expression, NULL,
+                               kevent->userspace_probe_location, payload);
                if (ret) {
                        DBG("Error appending extended info message");
                        ret = -LTTNG_ERR_FATAL;
@@ -821,10 +716,8 @@ static int list_lttng_kernel_events(char *channel_name,
 
 end:
        return nb_event;
-
 error:
-       /* Negate the error code to differentiate the size from an error */
-       return -ret;
+       return ret;
 }
 
 /*
@@ -998,6 +891,8 @@ static enum lttng_error_code create_connect_relayd(struct lttng_uri *uri,
 
        /* Create socket for control stream. */
        if (uri->stype == LTTNG_STREAM_CONTROL) {
+               uint64_t result_flags;
+
                DBG3("Creating relayd stream socket from URI");
 
                /* Check relayd version */
@@ -1012,6 +907,16 @@ static enum lttng_error_code create_connect_relayd(struct lttng_uri *uri,
                }
                consumer->relay_major_version = rsock->major;
                consumer->relay_minor_version = rsock->minor;
+               ret = relayd_get_configuration(rsock, 0,
+                               &result_flags);
+               if (ret < 0) {
+                       ERR("Unable to get relayd configuration");
+                       status = LTTNG_ERR_RELAYD_CONNECT_FAIL;
+                       goto close_sock;
+               }
+               if (result_flags & LTTCOMM_RELAYD_CONFIGURATION_FLAG_CLEAR_ALLOWED) {
+                       consumer->relay_allows_clear = true;
+               }
        } else if (uri->stype == LTTNG_STREAM_DATA) {
                DBG3("Creating relayd data socket from URI");
        } else {
@@ -1048,7 +953,7 @@ static enum lttng_error_code send_consumer_relayd_socket(
                struct consumer_socket *consumer_sock,
                const char *session_name, const char *hostname,
                const char *base_path, int session_live_timer,
-               const uint64_t *current_chunk_id,
+               const uint64_t *current_chunk_id,
                time_t session_creation_time,
                bool session_name_contains_creation_time)
 {
@@ -1176,15 +1081,16 @@ int cmd_setup_relayd(struct ltt_session *session)
        struct ltt_kernel_session *ksess;
        struct consumer_socket *socket;
        struct lttng_ht_iter iter;
-        LTTNG_OPTIONAL(uint64_t) current_chunk_id = {};
+       LTTNG_OPTIONAL(uint64_t) current_chunk_id = {};
 
-        assert(session);
+       assert(session);
 
        usess = session->ust_session;
        ksess = session->kernel_session;
 
        DBG("Setting relayd for session %s", session->name);
 
+       rcu_read_lock();
        if (session->current_trace_chunk) {
                enum lttng_trace_chunk_status status = lttng_trace_chunk_get_id(
                                session->current_trace_chunk, &current_chunk_id.value);
@@ -1198,8 +1104,6 @@ int cmd_setup_relayd(struct ltt_session *session)
                }
        }
 
-       rcu_read_lock();
-
        if (usess && usess->consumer && usess->consumer->type == CONSUMER_DST_NET
                        && usess->consumer->enabled) {
                /* For each consumer socket, send relayd sockets */
@@ -1225,6 +1129,8 @@ int cmd_setup_relayd(struct ltt_session *session)
                        usess->consumer->relay_major_version;
                session->consumer->relay_minor_version =
                        usess->consumer->relay_minor_version;
+               session->consumer->relay_allows_clear =
+                       usess->consumer->relay_allows_clear;
        }
 
        if (ksess && ksess->consumer && ksess->consumer->type == CONSUMER_DST_NET
@@ -1251,6 +1157,8 @@ int cmd_setup_relayd(struct ltt_session *session)
                        ksess->consumer->relay_major_version;
                session->consumer->relay_minor_version =
                        ksess->consumer->relay_minor_version;
+               session->consumer->relay_allows_clear =
+                       ksess->consumer->relay_allows_clear;
        }
 
 error:
@@ -1261,7 +1169,7 @@ error:
 /*
  * Start a kernel session by opening all necessary streams.
  */
-static int start_kernel_session(struct ltt_kernel_session *ksess)
+int start_kernel_session(struct ltt_kernel_session *ksess)
 {
        int ret;
        struct ltt_kernel_channel *kchan;
@@ -1323,133 +1231,71 @@ error:
        return ret;
 }
 
-/*
- * Command LTTNG_DISABLE_CHANNEL processed by the client thread.
- */
-int cmd_disable_channel(struct ltt_session *session,
-               enum lttng_domain_type domain, char *channel_name)
+int stop_kernel_session(struct ltt_kernel_session *ksess)
 {
+       struct ltt_kernel_channel *kchan;
+       bool error_occurred = false;
        int ret;
-       struct ltt_ust_session *usess;
-
-       usess = session->ust_session;
-
-       rcu_read_lock();
 
-       switch (domain) {
-       case LTTNG_DOMAIN_KERNEL:
-       {
-               ret = channel_kernel_disable(session->kernel_session,
-                               channel_name);
-               if (ret != LTTNG_OK) {
-                       goto error;
-               }
-
-               kernel_wait_quiescent();
-               break;
+       if (!ksess || !ksess->active) {
+               return LTTNG_OK;
        }
-       case LTTNG_DOMAIN_UST:
-       {
-               struct ltt_ust_channel *uchan;
-               struct lttng_ht *chan_ht;
-
-               chan_ht = usess->domain_global.channels;
-
-               uchan = trace_ust_find_channel_by_name(chan_ht, channel_name);
-               if (uchan == NULL) {
-                       ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
-                       goto error;
-               }
+       DBG("Stopping kernel tracing");
 
-               ret = channel_ust_disable(usess, uchan);
-               if (ret != LTTNG_OK) {
-                       goto error;
-               }
-               break;
-       }
-       default:
-               ret = LTTNG_ERR_UNKNOWN_DOMAIN;
+       ret = kernel_stop_session(ksess);
+       if (ret < 0) {
+               ret = LTTNG_ERR_KERN_STOP_FAIL;
                goto error;
        }
 
-       ret = LTTNG_OK;
-
-error:
-       rcu_read_unlock();
-       return ret;
-}
-
-/*
- * Command LTTNG_TRACK_PID processed by the client thread.
- *
- * Called with session lock held.
- */
-int cmd_track_pid(struct ltt_session *session, enum lttng_domain_type domain,
-               int pid)
-{
-       int ret;
-
-       rcu_read_lock();
-
-       switch (domain) {
-       case LTTNG_DOMAIN_KERNEL:
-       {
-               struct ltt_kernel_session *ksess;
-
-               ksess = session->kernel_session;
+       kernel_wait_quiescent();
 
-               ret = kernel_track_pid(ksess, pid);
-               if (ret != LTTNG_OK) {
-                       goto error;
+       /* Flush metadata after stopping (if exists) */
+       if (ksess->metadata_stream_fd >= 0) {
+               ret = kernel_metadata_flush_buffer(ksess->metadata_stream_fd);
+               if (ret < 0) {
+                       ERR("Kernel metadata flush failed");
+                       error_occurred = true;
                }
-
-               kernel_wait_quiescent();
-               break;
        }
-       case LTTNG_DOMAIN_UST:
-       {
-               struct ltt_ust_session *usess;
 
-               usess = session->ust_session;
-
-               ret = trace_ust_track_pid(usess, pid);
-               if (ret != LTTNG_OK) {
-                       goto error;
+       /* Flush all buffers after stopping */
+       cds_list_for_each_entry(kchan, &ksess->channel_list.head, list) {
+               ret = kernel_flush_buffer(kchan);
+               if (ret < 0) {
+                       ERR("Kernel flush buffer error");
+                       error_occurred = true;
                }
-               break;
-       }
-       default:
-               ret = LTTNG_ERR_UNKNOWN_DOMAIN;
-               goto error;
        }
 
-       ret = LTTNG_OK;
-
+       ksess->active = 0;
+       if (error_occurred) {
+               ret = LTTNG_ERR_UNK;
+       } else {
+               ret = LTTNG_OK;
+       }
 error:
-       rcu_read_unlock();
        return ret;
 }
 
 /*
- * Command LTTNG_UNTRACK_PID processed by the client thread.
- *
- * Called with session lock held.
+ * Command LTTNG_DISABLE_CHANNEL processed by the client thread.
  */
-int cmd_untrack_pid(struct ltt_session *session, enum lttng_domain_type domain,
-               int pid)
+int cmd_disable_channel(struct ltt_session *session,
+               enum lttng_domain_type domain, char *channel_name)
 {
        int ret;
+       struct ltt_ust_session *usess;
+
+       usess = session->ust_session;
 
        rcu_read_lock();
 
        switch (domain) {
        case LTTNG_DOMAIN_KERNEL:
        {
-               struct ltt_kernel_session *ksess;
-
-               ksess = session->kernel_session;
-
-               ret = kernel_untrack_pid(ksess, pid);
+               ret = channel_kernel_disable(session->kernel_session,
+                               channel_name);
                if (ret != LTTNG_OK) {
                        goto error;
                }
@@ -1459,11 +1305,18 @@ int cmd_untrack_pid(struct ltt_session *session, enum lttng_domain_type domain,
        }
        case LTTNG_DOMAIN_UST:
        {
-               struct ltt_ust_session *usess;
+               struct ltt_ust_channel *uchan;
+               struct lttng_ht *chan_ht;
 
-               usess = session->ust_session;
+               chan_ht = usess->domain_global.channels;
 
-               ret = trace_ust_untrack_pid(usess, pid);
+               uchan = trace_ust_find_channel_by_name(chan_ht, channel_name);
+               if (uchan == NULL) {
+                       ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
+                       goto error;
+               }
+
+               ret = channel_ust_disable(usess, uchan);
                if (ret != LTTNG_OK) {
                        goto error;
                }
@@ -1652,6 +1505,211 @@ end:
        return ret;
 }
 
+enum lttng_error_code cmd_process_attr_tracker_get_tracking_policy(
+               struct ltt_session *session,
+               enum lttng_domain_type domain,
+               enum lttng_process_attr process_attr,
+               enum lttng_tracking_policy *policy)
+{
+       enum lttng_error_code ret_code = LTTNG_OK;
+       const struct process_attr_tracker *tracker;
+
+       switch (domain) {
+       case LTTNG_DOMAIN_KERNEL:
+               if (!session->kernel_session) {
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               tracker = kernel_get_process_attr_tracker(
+                               session->kernel_session, process_attr);
+               break;
+       case LTTNG_DOMAIN_UST:
+               if (!session->ust_session) {
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               tracker = trace_ust_get_process_attr_tracker(
+                               session->ust_session, process_attr);
+               break;
+       default:
+               ret_code = LTTNG_ERR_UNSUPPORTED_DOMAIN;
+               goto end;
+       }
+       if (tracker) {
+               *policy = process_attr_tracker_get_tracking_policy(tracker);
+       } else {
+               ret_code = LTTNG_ERR_INVALID;
+       }
+end:
+       return ret_code;
+}
+
+enum lttng_error_code cmd_process_attr_tracker_set_tracking_policy(
+               struct ltt_session *session,
+               enum lttng_domain_type domain,
+               enum lttng_process_attr process_attr,
+               enum lttng_tracking_policy policy)
+{
+       enum lttng_error_code ret_code = LTTNG_OK;
+
+       switch (policy) {
+       case LTTNG_TRACKING_POLICY_INCLUDE_SET:
+       case LTTNG_TRACKING_POLICY_EXCLUDE_ALL:
+       case LTTNG_TRACKING_POLICY_INCLUDE_ALL:
+               break;
+       default:
+               ret_code = LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       switch (domain) {
+       case LTTNG_DOMAIN_KERNEL:
+               if (!session->kernel_session) {
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               ret_code = kernel_process_attr_tracker_set_tracking_policy(
+                               session->kernel_session, process_attr, policy);
+               break;
+       case LTTNG_DOMAIN_UST:
+               if (!session->ust_session) {
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               ret_code = trace_ust_process_attr_tracker_set_tracking_policy(
+                               session->ust_session, process_attr, policy);
+               break;
+       default:
+               ret_code = LTTNG_ERR_UNSUPPORTED_DOMAIN;
+               break;
+       }
+end:
+       return ret_code;
+}
+
+enum lttng_error_code cmd_process_attr_tracker_inclusion_set_add_value(
+               struct ltt_session *session,
+               enum lttng_domain_type domain,
+               enum lttng_process_attr process_attr,
+               const struct process_attr_value *value)
+{
+       enum lttng_error_code ret_code = LTTNG_OK;
+
+       switch (domain) {
+       case LTTNG_DOMAIN_KERNEL:
+               if (!session->kernel_session) {
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               ret_code = kernel_process_attr_tracker_inclusion_set_add_value(
+                               session->kernel_session, process_attr, value);
+               break;
+       case LTTNG_DOMAIN_UST:
+               if (!session->ust_session) {
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               ret_code = trace_ust_process_attr_tracker_inclusion_set_add_value(
+                               session->ust_session, process_attr, value);
+               break;
+       default:
+               ret_code = LTTNG_ERR_UNSUPPORTED_DOMAIN;
+               break;
+       }
+end:
+       return ret_code;
+}
+
+enum lttng_error_code cmd_process_attr_tracker_inclusion_set_remove_value(
+               struct ltt_session *session,
+               enum lttng_domain_type domain,
+               enum lttng_process_attr process_attr,
+               const struct process_attr_value *value)
+{
+       enum lttng_error_code ret_code = LTTNG_OK;
+
+       switch (domain) {
+       case LTTNG_DOMAIN_KERNEL:
+               if (!session->kernel_session) {
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               ret_code = kernel_process_attr_tracker_inclusion_set_remove_value(
+                               session->kernel_session, process_attr, value);
+               break;
+       case LTTNG_DOMAIN_UST:
+               if (!session->ust_session) {
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               ret_code = trace_ust_process_attr_tracker_inclusion_set_remove_value(
+                               session->ust_session, process_attr, value);
+               break;
+       default:
+               ret_code = LTTNG_ERR_UNSUPPORTED_DOMAIN;
+               break;
+       }
+end:
+       return ret_code;
+}
+
+enum lttng_error_code cmd_process_attr_tracker_get_inclusion_set(
+               struct ltt_session *session,
+               enum lttng_domain_type domain,
+               enum lttng_process_attr process_attr,
+               struct lttng_process_attr_values **values)
+{
+       enum lttng_error_code ret_code = LTTNG_OK;
+       const struct process_attr_tracker *tracker;
+       enum process_attr_tracker_status status;
+
+       switch (domain) {
+       case LTTNG_DOMAIN_KERNEL:
+               if (!session->kernel_session) {
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               tracker = kernel_get_process_attr_tracker(
+                               session->kernel_session, process_attr);
+               break;
+       case LTTNG_DOMAIN_UST:
+               if (!session->ust_session) {
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               tracker = trace_ust_get_process_attr_tracker(
+                               session->ust_session, process_attr);
+               break;
+       default:
+               ret_code = LTTNG_ERR_UNSUPPORTED_DOMAIN;
+               goto end;
+       }
+
+       if (!tracker) {
+               ret_code = LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       status = process_attr_tracker_get_inclusion_set(tracker, values);
+       switch (status) {
+       case PROCESS_ATTR_TRACKER_STATUS_OK:
+               ret_code = LTTNG_OK;
+               break;
+       case PROCESS_ATTR_TRACKER_STATUS_INVALID_TRACKING_POLICY:
+               ret_code = LTTNG_ERR_PROCESS_ATTR_TRACKER_INVALID_TRACKING_POLICY;
+               break;
+       case PROCESS_ATTR_TRACKER_STATUS_ERROR:
+               ret_code = LTTNG_ERR_NOMEM;
+               break;
+       default:
+               ret_code = LTTNG_ERR_UNK;
+               break;
+       }
+
+end:
+       return ret_code;
+}
+
 /*
  * Command LTTNG_DISABLE_EVENT processed by the client thread.
  */
@@ -2007,7 +2065,7 @@ static int _cmd_enable_event(struct ltt_session *session,
                const struct lttng_domain *domain,
                char *channel_name, struct lttng_event *event,
                char *filter_expression,
-               struct lttng_filter_bytecode *filter,
+               struct lttng_bytecode *filter,
                struct lttng_event_exclusion *exclusion,
                int wpipe, bool internal_event)
 {
@@ -2090,7 +2148,7 @@ static int _cmd_enable_event(struct ltt_session *session,
                case LTTNG_EVENT_ALL:
                {
                        char *filter_expression_a = NULL;
-                       struct lttng_filter_bytecode *filter_a = NULL;
+                       struct lttng_bytecode *filter_a = NULL;
 
                        /*
                         * We need to duplicate filter_expression and filter,
@@ -2237,7 +2295,7 @@ static int _cmd_enable_event(struct ltt_session *session,
                         */
                        ret = validate_ust_event_name(event->name);
                        if (ret) {
-                               WARN("Userspace event name %s failed validation.",
+                               WARN("Userspace event name %s failed validation.",
                                                event->name);
                                ret = LTTNG_ERR_INVALID_EVENT_NAME;
                                goto error;
@@ -2325,11 +2383,11 @@ static int _cmd_enable_event(struct ltt_session *session,
 
                {
                        char *filter_expression_copy = NULL;
-                       struct lttng_filter_bytecode *filter_copy = NULL;
+                       struct lttng_bytecode *filter_copy = NULL;
 
                        if (filter) {
                                const size_t filter_size = sizeof(
-                                               struct lttng_filter_bytecode)
+                                               struct lttng_bytecode)
                                                + filter->len;
 
                                filter_copy = zmalloc(filter_size);
@@ -2405,7 +2463,7 @@ int cmd_enable_event(struct ltt_session *session,
                const struct lttng_domain *domain,
                char *channel_name, struct lttng_event *event,
                char *filter_expression,
-               struct lttng_filter_bytecode *filter,
+               struct lttng_bytecode *filter,
                struct lttng_event_exclusion *exclusion,
                int wpipe)
 {
@@ -2422,7 +2480,7 @@ static int cmd_enable_event_internal(struct ltt_session *session,
                const struct lttng_domain *domain,
                char *channel_name, struct lttng_event *event,
                char *filter_expression,
-               struct lttng_filter_bytecode *filter,
+               struct lttng_bytecode *filter,
                struct lttng_event_exclusion *exclusion,
                int wpipe)
 {
@@ -2510,57 +2568,6 @@ ssize_t cmd_list_syscalls(struct lttng_event **events)
        return syscall_table_list(events);
 }
 
-/*
- * Command LTTNG_LIST_TRACKER_PIDS processed by the client thread.
- *
- * Called with session lock held.
- */
-ssize_t cmd_list_tracker_pids(struct ltt_session *session,
-               enum lttng_domain_type domain, int32_t **pids)
-{
-       int ret;
-       ssize_t nr_pids = 0;
-
-       switch (domain) {
-       case LTTNG_DOMAIN_KERNEL:
-       {
-               struct ltt_kernel_session *ksess;
-
-               ksess = session->kernel_session;
-               nr_pids = kernel_list_tracker_pids(ksess, pids);
-               if (nr_pids < 0) {
-                       ret = LTTNG_ERR_KERN_LIST_FAIL;
-                       goto error;
-               }
-               break;
-       }
-       case LTTNG_DOMAIN_UST:
-       {
-               struct ltt_ust_session *usess;
-
-               usess = session->ust_session;
-               nr_pids = trace_ust_list_tracker_pids(usess, pids);
-               if (nr_pids < 0) {
-                       ret = LTTNG_ERR_UST_LIST_FAIL;
-                       goto error;
-               }
-               break;
-       }
-       case LTTNG_DOMAIN_LOG4J:
-       case LTTNG_DOMAIN_JUL:
-       case LTTNG_DOMAIN_PYTHON:
-       default:
-               ret = LTTNG_ERR_UND;
-               goto error;
-       }
-
-       return nr_pids;
-
-error:
-       /* Return negative value to differentiate return code */
-       return -ret;
-}
-
 /*
  * Command LTTNG_START_TRACE processed by the client thread.
  *
@@ -2572,6 +2579,10 @@ int cmd_start_trace(struct ltt_session *session)
        unsigned long nb_chan = 0;
        struct ltt_kernel_session *ksession;
        struct ltt_ust_session *usess;
+       const bool session_rotated_after_last_stop =
+                       session->rotated_after_last_stop;
+       const bool session_cleared_after_last_stop =
+                       session->cleared_after_last_stop;
 
        assert(session);
 
@@ -2582,6 +2593,23 @@ int cmd_start_trace(struct ltt_session *session)
        /* Is the session already started? */
        if (session->active) {
                ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
+               /* Perform nothing */
+               goto end;
+       }
+
+       if (session->rotation_state == LTTNG_ROTATION_STATE_ONGOING &&
+                       !session->current_trace_chunk) {
+               /*
+                * A rotation was launched while the session was stopped and
+                * it has not been completed yet. It is not possible to start
+                * the session since starting the session here would require a
+                * rotation from "NULL" to a new trace chunk. That rotation
+                * would overlap with the ongoing rotation, which is not
+                * supported.
+                */
+               WARN("Refusing to start session \"%s\" as a rotation launched after the last \"stop\" is still ongoing",
+                               session->name);
+               ret = LTTNG_ERR_ROTATION_PENDING;
                goto error;
        }
 
@@ -2600,21 +2628,47 @@ int cmd_start_trace(struct ltt_session *session)
                goto error;
        }
 
+       session->active = 1;
+       session->rotated_after_last_stop = false;
+       session->cleared_after_last_stop = false;
        if (session->output_traces && !session->current_trace_chunk) {
-               struct lttng_trace_chunk *trace_chunk;
+               if (!session->has_been_started) {
+                       struct lttng_trace_chunk *trace_chunk;
 
-               trace_chunk = session_create_new_trace_chunk(
-                               session, NULL, NULL, NULL);
-               if (!trace_chunk) {
-                       ret = LTTNG_ERR_CREATE_DIR_FAIL;
-                       goto error;
-               }
-               assert(!session->current_trace_chunk);
-               ret = session_set_trace_chunk(session, trace_chunk, NULL);
-               lttng_trace_chunk_put(trace_chunk);
-               if (ret) {
-                       ret = LTTNG_ERR_CREATE_TRACE_CHUNK_FAIL_CONSUMER;
-                       goto error;
+                       DBG("Creating initial trace chunk of session \"%s\"",
+                                       session->name);
+                       trace_chunk = session_create_new_trace_chunk(
+                                       session, NULL, NULL, NULL);
+                       if (!trace_chunk) {
+                               ret = LTTNG_ERR_CREATE_DIR_FAIL;
+                               goto error;
+                       }
+                       assert(!session->current_trace_chunk);
+                       ret = session_set_trace_chunk(session, trace_chunk,
+                                       NULL);
+                       lttng_trace_chunk_put(trace_chunk);
+                       if (ret) {
+                               ret = LTTNG_ERR_CREATE_TRACE_CHUNK_FAIL_CONSUMER;
+                               goto error;
+                       }
+               } else {
+                       DBG("Rotating session \"%s\" from its current \"NULL\" trace chunk to a new chunk",
+                                       session->name);
+                       /*
+                        * Rotate existing streams into the new chunk.
+                        * This is a "quiet" rotation has no client has
+                        * explicitly requested this operation.
+                        *
+                        * There is also no need to wait for the rotation
+                        * to complete as it will happen immediately. No data
+                        * was produced as the session was stopped, so the
+                        * rotation should happen on reception of the command.
+                        */
+                       ret = cmd_rotate_session(session, NULL, true,
+                                       LTTNG_TRACE_CHUNK_COMMAND_TYPE_NO_OPERATION);
+                       if (ret != LTTNG_OK) {
+                               goto error;
+                       }
                }
        }
 
@@ -2637,10 +2691,16 @@ int cmd_start_trace(struct ltt_session *session)
                }
        }
 
-       /* Flag this after a successful start. */
-       session->has_been_started = 1;
-       session->active = 1;
-
+       /*
+        * Open a packet in every stream of the session to ensure that viewers
+        * can correctly identify the boundaries of the periods during which
+        * tracing was active for this session.
+        */
+       ret = session_open_packets(session);
+       if (ret != LTTNG_OK) {
+               goto error;
+       }
+
        /*
         * Clear the flag that indicates that a rotation was done while the
         * session was stopped.
@@ -2661,6 +2721,18 @@ int cmd_start_trace(struct ltt_session *session)
        ret = LTTNG_OK;
 
 error:
+       if (ret == LTTNG_OK) {
+               /* Flag this after a successful start. */
+               session->has_been_started |= 1;
+       } else {
+               session->active = 0;
+               /* Restore initial state on error. */
+               session->rotated_after_last_stop =
+                               session_rotated_after_last_stop;
+               session->cleared_after_last_stop =
+                               session_cleared_after_last_stop;
+       }
+end:
        return ret;
 }
 
@@ -2670,14 +2742,12 @@ error:
 int cmd_stop_trace(struct ltt_session *session)
 {
        int ret;
-       struct ltt_kernel_channel *kchan;
        struct ltt_kernel_session *ksession;
        struct ltt_ust_session *usess;
-       bool error_occurred = false;
 
        assert(session);
 
-       DBG("Begin stop session %s (id %" PRIu64 ")", session->name, session->id);
+       DBG("Begin stop session \"%s\" (id %" PRIu64 ")", session->name, session->id);
        /* Short cut */
        ksession = session->kernel_session;
        usess = session->ust_session;
@@ -2688,39 +2758,9 @@ int cmd_stop_trace(struct ltt_session *session)
                goto error;
        }
 
-       /* Kernel tracer */
-       if (ksession && ksession->active) {
-               DBG("Stop kernel tracing");
-
-               ret = kernel_stop_session(ksession);
-               if (ret < 0) {
-                       ret = LTTNG_ERR_KERN_STOP_FAIL;
-                       goto error;
-               }
-
-               kernel_wait_quiescent();
-
-               /* Flush metadata after stopping (if exists) */
-               if (ksession->metadata_stream_fd >= 0) {
-                       ret = kernel_metadata_flush_buffer(ksession->metadata_stream_fd);
-                       if (ret < 0) {
-                               ERR("Kernel metadata flush failed");
-                               error_occurred = true;
-                       }
-               }
-
-               /* Flush all buffers after stopping */
-               cds_list_for_each_entry(kchan, &ksession->channel_list.head, list) {
-                       ret = kernel_flush_buffer(kchan);
-                       if (ret < 0) {
-                               ERR("Kernel flush buffer error");
-                               error_occurred = true;
-                       }
-               }
-
-               ksession->active = 0;
-               DBG("Kernel session stopped %s (id %" PRIu64 ")", session->name,
-                               session->id);
+       ret = stop_kernel_session(ksession);
+       if (ret != LTTNG_OK) {
+               goto error;
        }
 
        if (usess && usess->active) {
@@ -2731,33 +2771,26 @@ int cmd_stop_trace(struct ltt_session *session)
                }
        }
 
+       DBG("Completed stop session \"%s\" (id %" PRIu64 ")", session->name,
+                       session->id);
        /* Flag inactive after a successful stop. */
        session->active = 0;
-       ret = !error_occurred ? LTTNG_OK : LTTNG_ERR_UNK;
+       ret = LTTNG_OK;
 
 error:
        return ret;
 }
 
 /*
- * Command LTTNG_SET_CONSUMER_URI processed by the client thread.
+ * Set the base_path of the session only if subdir of a control uris is set.
+ * Return LTTNG_OK on success, otherwise LTTNG_ERR_*.
  */
-int cmd_set_consumer_uri(struct ltt_session *session, size_t nb_uri,
+static int set_session_base_path_from_uris(struct ltt_session *session,
+               size_t nb_uri,
                struct lttng_uri *uris)
 {
-       int ret, i;
-       struct ltt_kernel_session *ksess = session->kernel_session;
-       struct ltt_ust_session *usess = session->ust_session;
-
-       assert(session);
-       assert(uris);
-       assert(nb_uri > 0);
-
-       /* Can't set consumer URI if the session is active. */
-       if (session->active) {
-               ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
-               goto error;
-       }
+       int ret;
+       size_t i;
 
        for (i = 0; i < nb_uri; i++) {
                if (uris[i].stype != LTTNG_STREAM_CONTROL ||
@@ -2774,11 +2807,47 @@ int cmd_set_consumer_uri(struct ltt_session *session, size_t nb_uri,
                /* Set session base_path */
                session->base_path = strdup(uris[i].subdir);
                if (!session->base_path) {
-                       PERROR("Copying base path: %s", uris[i].subdir);
+                       PERROR("Failed to copy base path \"%s\" to session \"%s\"",
+                                       uris[i].subdir, session->name);
+                       ret = LTTNG_ERR_NOMEM;
                        goto error;
                }
-               DBG2("Setting base path for session %" PRIu64 ": %s",
-                               session->id, session->base_path);
+               DBG2("Setting base path \"%s\" for session \"%s\"",
+                               session->base_path, session->name);
+       }
+       ret = LTTNG_OK;
+error:
+       return ret;
+}
+
+/*
+ * Command LTTNG_SET_CONSUMER_URI processed by the client thread.
+ */
+int cmd_set_consumer_uri(struct ltt_session *session, size_t nb_uri,
+               struct lttng_uri *uris)
+{
+       int ret, i;
+       struct ltt_kernel_session *ksess = session->kernel_session;
+       struct ltt_ust_session *usess = session->ust_session;
+
+       assert(session);
+       assert(uris);
+       assert(nb_uri > 0);
+
+       /* Can't set consumer URI if the session is active. */
+       if (session->active) {
+               ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
+               goto error;
+       }
+
+       /*
+        * Set the session base path if any. This is done inside
+        * cmd_set_consumer_uri to preserve backward compatibility of the
+        * previous session creation api vs the session descriptor api.
+        */
+       ret = set_session_base_path_from_uris(session, nb_uri, uris);
+       if (ret != LTTNG_OK) {
+               goto error;
        }
 
        /* Set the "global" consumer URIs */
@@ -3015,19 +3084,19 @@ enum lttng_error_code cmd_create_session(struct command_ctx *cmd_ctx, int sock,
        enum lttng_error_code ret_code;
 
        lttng_dynamic_buffer_init(&payload);
-       if (cmd_ctx->lsm->u.create_session.home_dir_size >=
+       if (cmd_ctx->lsm.u.create_session.home_dir_size >=
                        LTTNG_PATH_MAX) {
                ret_code = LTTNG_ERR_INVALID;
                goto error;
        }
-       if (cmd_ctx->lsm->u.create_session.session_descriptor_size >
+       if (cmd_ctx->lsm.u.create_session.session_descriptor_size >
                        LTTNG_SESSION_DESCRIPTOR_MAX_LEN) {
                ret_code = LTTNG_ERR_INVALID;
                goto error;
        }
 
-       payload_size = cmd_ctx->lsm->u.create_session.home_dir_size +
-                       cmd_ctx->lsm->u.create_session.session_descriptor_size;
+       payload_size = cmd_ctx->lsm.u.create_session.home_dir_size +
+                       cmd_ctx->lsm.u.create_session.session_descriptor_size;
        ret = lttng_dynamic_buffer_set_size(&payload, payload_size);
        if (ret) {
                ret_code = LTTNG_ERR_NOMEM;
@@ -3044,11 +3113,11 @@ enum lttng_error_code cmd_create_session(struct command_ctx *cmd_ctx, int sock,
        home_dir_view = lttng_buffer_view_from_dynamic_buffer(
                        &payload,
                        0,
-                       cmd_ctx->lsm->u.create_session.home_dir_size);
+                       cmd_ctx->lsm.u.create_session.home_dir_size);
        session_descriptor_view = lttng_buffer_view_from_dynamic_buffer(
                        &payload,
-                       cmd_ctx->lsm->u.create_session.home_dir_size,
-                       cmd_ctx->lsm->u.create_session.session_descriptor_size);
+                       cmd_ctx->lsm.u.create_session.home_dir_size,
+                       cmd_ctx->lsm.u.create_session.session_descriptor_size);
 
        ret = lttng_session_descriptor_create_from_buffer(
                        &session_descriptor_view, &session_descriptor);
@@ -3102,10 +3171,10 @@ void cmd_destroy_session_reply(const struct ltt_session *session,
        lttng_dynamic_buffer_init(&payload);
 
        ret = lttng_dynamic_buffer_append(&payload, &llm, sizeof(llm));
-        if (ret) {
+       if (ret) {
                ERR("Failed to append session destruction message");
                goto error;
-        }
+       }
 
        cmd_header.rotation_state =
                        (int32_t) (reply_context->implicit_rotation_on_destroy ?
@@ -3216,23 +3285,22 @@ int cmd_destroy_session(struct ltt_session *session,
                session->rotate_size = 0;
        }
 
-       if (session->most_recent_chunk_id.is_set &&
-                       session->most_recent_chunk_id.value != 0 &&
-                       session->current_trace_chunk && session->output_traces) {
+       if (session->rotated && session->current_trace_chunk && session->output_traces) {
                /*
                 * Perform a last rotation on destruction if rotations have
                 * occurred during the session's lifetime.
                 */
-               ret = cmd_rotate_session(session, NULL, false);
+               ret = cmd_rotate_session(session, NULL, false,
+                       LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED);
                if (ret != LTTNG_OK) {
                        ERR("Failed to perform an implicit rotation as part of the destruction of session \"%s\": %s",
                                        session->name, lttng_strerror(-ret));
                        destruction_last_error = -ret;
                }
-                if (reply_context) {
+               if (reply_context) {
                        reply_context->implicit_rotation_on_destroy = true;
-                }
-        } else if (session->has_been_started && session->current_trace_chunk) {
+               }
+       } else if (session->has_been_started && session->current_trace_chunk) {
                /*
                 * The user has not triggered a session rotation. However, to
                 * ensure all data has been consumed, the session is rotated
@@ -3242,10 +3310,19 @@ int cmd_destroy_session(struct ltt_session *session,
                 * emitted and no renaming of the current trace chunk takes
                 * place.
                 */
-               ret = cmd_rotate_session(session, NULL, true);
-               if (ret != LTTNG_OK) {
+               ret = cmd_rotate_session(session, NULL, true,
+                       LTTNG_TRACE_CHUNK_COMMAND_TYPE_NO_OPERATION);
+               /*
+                * Rotation operations may not be supported by the kernel
+                * tracer. Hence, do not consider this implicit rotation as
+                * a session destruction error. The library has already stopped
+                * the session and waited for pending data; there is nothing
+                * left to do but complete the destruction of the session.
+                */
+               if (ret != LTTNG_OK &&
+                               ret != -LTTNG_ERR_ROTATION_NOT_AVAILABLE_KERNEL) {
                        ERR("Failed to perform a quiet rotation as part of the destruction of session \"%s\": %s",
-                                       session->name, lttng_strerror(-ret));
+                           session->name, lttng_strerror(ret));
                        destruction_last_error = -ret;
                }
        }
@@ -3321,8 +3398,8 @@ int cmd_destroy_session(struct ltt_session *session,
                } else {
                        *sock_fd = -1;
                }
-        }
-        ret = LTTNG_OK;
+       }
+       ret = LTTNG_OK;
 end:
        return ret;
 }
@@ -3551,25 +3628,33 @@ end:
  */
 ssize_t cmd_list_events(enum lttng_domain_type domain,
                struct ltt_session *session, char *channel_name,
-               struct lttng_event **events, size_t *total_size)
+               struct lttng_payload *payload)
 {
        int ret = 0;
-       ssize_t nb_event = 0;
+       ssize_t nb_events = 0;
+       struct lttcomm_event_command_header cmd_header = {};
+       const size_t cmd_header_offset = payload->buffer.size;
+
+       ret = lttng_dynamic_buffer_append(
+                       &payload->buffer, &cmd_header, sizeof(cmd_header));
+       if (ret) {
+               ret = LTTNG_ERR_NOMEM;
+               goto error;
+       }
 
        switch (domain) {
        case LTTNG_DOMAIN_KERNEL:
                if (session->kernel_session != NULL) {
-                       nb_event = list_lttng_kernel_events(channel_name,
-                                       session->kernel_session, events,
-                                       total_size);
+                       nb_events = list_lttng_kernel_events(channel_name,
+                                       session->kernel_session, payload);
                }
                break;
        case LTTNG_DOMAIN_UST:
        {
                if (session->ust_session != NULL) {
-                       nb_event = list_lttng_ust_global_events(channel_name,
-                                       &session->ust_session->domain_global, events,
-                                       total_size);
+                       nb_events = list_lttng_ust_global_events(channel_name,
+                                       &session->ust_session->domain_global,
+                                       payload);
                }
                break;
        }
@@ -3584,9 +3669,8 @@ ssize_t cmd_list_events(enum lttng_domain_type domain,
                        cds_lfht_for_each_entry(session->ust_session->agents->ht,
                                        &iter.iter, agt, node.node) {
                                if (agt->domain == domain) {
-                                       nb_event = list_lttng_agent_events(
-                                                       agt, events,
-                                                       total_size);
+                                       nb_events = list_lttng_agent_events(
+                                                       agt, payload);
                                        break;
                                }
                        }
@@ -3598,7 +3682,10 @@ ssize_t cmd_list_events(enum lttng_domain_type domain,
                goto error;
        }
 
-       return nb_event;
+       ((struct lttcomm_event_command_header *) (payload->buffer.data +
+                        cmd_header_offset))->nb_events = (uint32_t) nb_events;
+
+       return nb_events;
 
 error:
        /* Return negative value to differentiate return code */
@@ -3619,7 +3706,7 @@ void cmd_list_lttng_sessions(struct lttng_session *sessions,
        unsigned int i = 0;
        struct ltt_session *session;
        struct ltt_session_list *list = session_get_list();
-        struct lttng_session_extended *extended =
+       struct lttng_session_extended *extended =
                        (typeof(extended)) (&sessions[session_count]);
 
        DBG("Getting all available session for UID %d GID %d",
@@ -3635,7 +3722,7 @@ void cmd_list_lttng_sessions(struct lttng_session *sessions,
                /*
                 * Only list the sessions the user can control.
                 */
-               if (!session_access_ok(session, uid, gid) ||
+               if (!session_access_ok(session, uid) ||
                                session->destroyed) {
                        session_put(session);
                        continue;
@@ -4176,26 +4263,81 @@ end:
        return ret;
 }
 
+/*
+ * On success LTTNG_OK. On error, returns lttng_error code.
+ */
+static enum lttng_error_code prepare_trigger_object(struct lttng_trigger *trigger, const struct lttng_credentials *cmd_creds)
+{
+       enum lttng_error_code ret;
+       /* Internal object of the trigger might have to "generate" and
+        * "populate" internal field e.g filter bytecode
+        */
+       struct lttng_condition *condition = NULL;
+
+       condition = lttng_trigger_get_condition(trigger);
+       if (!condition) {
+               ret = LTTNG_ERR_INVALID_TRIGGER;
+               goto end;
+       }
+
+       switch (lttng_condition_get_type(condition)) {
+       case LTTNG_CONDITION_TYPE_EVENT_RULE_HIT:
+       {
+               struct lttng_event_rule *event_rule;
+               lttng_condition_event_rule_get_rule_mutable(
+                               condition, &event_rule);
+               ret = lttng_event_rule_generate_filter_bytecode(
+                               event_rule, lttng_credentials_get_uid(cmd_creds), lttng_credentials_get_gid(cmd_creds));
+               if (ret != LTTNG_OK) {
+                       goto end;
+               }
+
+               /* Generate the capture bytecode set */
+               ret = lttng_condition_event_rule_generate_capture_descriptor_bytecode_set(
+                               condition, &trigger->capture_bytecode_set);
+               if (ret != LTTNG_OK) {
+                       goto end;
+               }
+
+               ret = LTTNG_OK;
+               break;
+       }
+       default:
+       {
+               ret = LTTNG_OK;
+               break;
+       }
+       }
+
+end:
+       return ret;
+}
+
 int cmd_register_trigger(struct command_ctx *cmd_ctx, int sock,
-               struct notification_thread_handle *notification_thread)
+               struct notification_thread_handle *notification_thread,
+               struct lttng_trigger **return_trigger)
 {
        int ret;
        size_t trigger_len;
        ssize_t sock_recv_len;
        struct lttng_trigger *trigger = NULL;
-       struct lttng_buffer_view view;
-       struct lttng_dynamic_buffer trigger_buffer;
+       struct lttng_payload trigger_payload;
+       struct lttng_credentials cmd_creds = {
+               .uid = LTTNG_OPTIONAL_INIT_VALUE(cmd_ctx->creds.uid),
+               .gid = LTTNG_OPTIONAL_INIT_VALUE(cmd_ctx->creds.gid),
+       };
 
-       lttng_dynamic_buffer_init(&trigger_buffer);
-       trigger_len = (size_t) cmd_ctx->lsm->u.trigger.length;
-       ret = lttng_dynamic_buffer_set_size(&trigger_buffer, trigger_len);
+       lttng_payload_init(&trigger_payload);
+       trigger_len = (size_t) cmd_ctx->lsm.u.trigger.length;
+       ret = lttng_dynamic_buffer_set_size(
+                       &trigger_payload.buffer, trigger_len);
        if (ret) {
                ret = LTTNG_ERR_NOMEM;
                goto end;
        }
 
-       sock_recv_len = lttcomm_recv_unix_sock(sock, trigger_buffer.data,
-                       trigger_len);
+       sock_recv_len = lttcomm_recv_unix_sock(
+                       sock, trigger_payload.buffer.data, trigger_len);
        if (sock_recv_len < 0 || sock_recv_len != trigger_len) {
                ERR("Failed to receive \"register trigger\" command payload");
                /* TODO: should this be a new error enum ? */
@@ -4203,21 +4345,149 @@ int cmd_register_trigger(struct command_ctx *cmd_ctx, int sock,
                goto end;
        }
 
-       view = lttng_buffer_view_from_dynamic_buffer(&trigger_buffer, 0, -1);
-       if (lttng_trigger_create_from_buffer(&view, &trigger) !=
-                       trigger_len) {
-               ERR("Invalid trigger payload received in \"register trigger\" command");
-               ret = LTTNG_ERR_INVALID_TRIGGER;
+       /* Receive fds, if any. */
+       if (cmd_ctx->lsm.fd_count > 0) {
+               ret = lttcomm_recv_payload_fds_unix_sock(
+                               sock, cmd_ctx->lsm.fd_count, &trigger_payload);
+               if (ret > 0 && ret != cmd_ctx->lsm.fd_count * sizeof(int)) {
+                       ret = LTTNG_ERR_INVALID_PROTOCOL;
+                       goto end;
+               } else if (ret <= 0) {
+                       ret = LTTNG_ERR_FATAL;
+                       goto end;
+               }
+       }
+
+       /* Deserialize trigger. */
+       {
+               struct lttng_payload_view view =
+                               lttng_payload_view_from_payload(
+                                               &trigger_payload, 0, -1);
+
+               if (lttng_trigger_create_from_payload(&view, &trigger) !=
+                               trigger_len) {
+                       ERR("Invalid trigger payload received in \"register trigger\" command");
+                       ret = LTTNG_ERR_INVALID_TRIGGER;
+                       goto end;
+               }
+       }
+
+       /*
+        * Validate the trigger credentials against the command credentials.
+        * Only the root user can register a trigger with non-matching
+        * credentials.
+        */
+       if (!lttng_credentials_is_equal_uid(
+                       lttng_trigger_get_credentials(trigger),
+                       &cmd_creds)) {
+               if (lttng_credentials_get_uid(&cmd_creds) != 0) {
+                       ERR("Trigger credentials do not match the command credentials");
+                       ret = LTTNG_ERR_INVALID_TRIGGER;
+                       goto end;
+               }
+       }
+
+       /*
+        * Since we return the trigger object, take a reference to it
+        * Caller is responsible for calling lttng_destroy_trigger on it.
+        * This thread does not OWN the trigger.
+        */
+       lttng_trigger_get(trigger);
+
+       /* Prepare internal trigger object if needed on reception.
+        * Handles also special treatment for certain internal object of the
+        * trigger (e.g uprobe event rule binary fd.
+        */
+       ret = prepare_trigger_object(trigger, &cmd_creds);
+       if (ret != LTTNG_OK) {
                goto end;
        }
 
+       /* Inform the notification thread */
        ret = notification_thread_command_register_trigger(notification_thread,
                        trigger);
-       /* Ownership of trigger was transferred. */
+       if (ret != LTTNG_OK) {
+               goto end;
+       }
+
+       /* Synchronize tracers, only if needed */
+       /* TODO: maybe extract somewhere else */
+       {
+               struct lttng_condition *condition = NULL;
+               condition = lttng_trigger_get_condition(trigger);
+               if (!condition) {
+                       ret = LTTNG_ERR_INVALID_TRIGGER;
+                       goto end;
+               }
+
+               if (lttng_condition_get_type(condition) == LTTNG_CONDITION_TYPE_EVENT_RULE_HIT) {
+                       const struct lttng_event_rule *rule = NULL;
+                       (void) lttng_condition_event_rule_get_rule(condition, &rule);
+                       if (!rule) {
+                               ret = LTTNG_ERR_INVALID_TRIGGER;
+                               goto end;
+                       }
+                       if (lttng_event_rule_get_domain_type(rule) == LTTNG_DOMAIN_KERNEL) {
+                               /* TODO: get the token value from the
+                                * notification thread and only perform an
+                                * enable and a disable.... This is NOT
+                                * OPTIMIZED AT ALL
+                                */
+                               ret = kernel_register_trigger(trigger, &cmd_creds);
+                               if (ret != LTTNG_OK) {
+                                       enum lttng_error_code notif_thread_unregister_ret =
+                                                       notification_thread_command_unregister_trigger(
+                                                                       notification_thread,
+                                                                       trigger);
+                                       if (notif_thread_unregister_ret != LTTNG_OK) {
+                                               ERR("Error unregistering notification thread trigger after kernel registration failure.");
+                                       }
+                                       goto end;
+
+                               }
+                       } else {
+                               /* TODO: get the token value from the
+                                * notification thread and only perform an
+                                * enable and a disable.... This is NOT
+                                * OPTIMIZED AT ALL
+                                */
+                               ust_app_global_update_all_tokens();
+                               /* Agent handling */
+                               if (lttng_event_rule_is_agent(rule)) {
+                                       struct agent *agt;
+                                       const char *pattern;
+                                       enum lttng_domain_type domain_type;
+                                       domain_type = lttng_event_rule_get_domain_type(
+                                                       rule);
+                                       (void) lttng_event_rule_tracepoint_get_pattern(
+                                                       rule, &pattern);
+                                       agt = trigger_find_agent(domain_type);
+                                       if (!agt) {
+                                               agt = agent_create(domain_type);
+                                               if (!agt) {
+                                                       ret = LTTNG_ERR_NOMEM;
+                                                       goto end;
+                                               }
+                                               agent_add(agt, trigger_agents_ht_by_domain);
+                                       }
+
+                                       ret = trigger_agent_enable(
+                                                       trigger, agt);
+                                       if (ret != LTTNG_OK) {
+                                               goto end;
+                                       }
+                               }
+                       }
+               }
+       }
+
+       /* Return an image of the updated object to the client */
+       *return_trigger = trigger;
+       /* Ownership of trigger was transferred to caller. */
        trigger = NULL;
 end:
        lttng_trigger_destroy(trigger);
-       lttng_dynamic_buffer_reset(&trigger_buffer);
+       lttng_payload_reset(&trigger_payload);
        return ret;
 }
 
@@ -4228,19 +4498,23 @@ int cmd_unregister_trigger(struct command_ctx *cmd_ctx, int sock,
        size_t trigger_len;
        ssize_t sock_recv_len;
        struct lttng_trigger *trigger = NULL;
-       struct lttng_buffer_view view;
-       struct lttng_dynamic_buffer trigger_buffer;
+       struct lttng_payload trigger_payload;
+       struct lttng_credentials cmd_creds = {
+               .uid = LTTNG_OPTIONAL_INIT_VALUE(cmd_ctx->creds.uid),
+               .gid = LTTNG_OPTIONAL_INIT_VALUE(cmd_ctx->creds.gid),
+       };
 
-       lttng_dynamic_buffer_init(&trigger_buffer);
-       trigger_len = (size_t) cmd_ctx->lsm->u.trigger.length;
-       ret = lttng_dynamic_buffer_set_size(&trigger_buffer, trigger_len);
+       lttng_payload_init(&trigger_payload);
+       trigger_len = (size_t) cmd_ctx->lsm.u.trigger.length;
+       ret = lttng_dynamic_buffer_set_size(
+                       &trigger_payload.buffer, trigger_len);
        if (ret) {
                ret = LTTNG_ERR_NOMEM;
                goto end;
        }
 
-       sock_recv_len = lttcomm_recv_unix_sock(sock, trigger_buffer.data,
-                       trigger_len);
+       sock_recv_len = lttcomm_recv_unix_sock(
+                       sock, trigger_payload.buffer.data, trigger_len);
        if (sock_recv_len < 0 || sock_recv_len != trigger_len) {
                ERR("Failed to receive \"unregister trigger\" command payload");
                /* TODO: should this be a new error enum ? */
@@ -4248,22 +4522,140 @@ int cmd_unregister_trigger(struct command_ctx *cmd_ctx, int sock,
                goto end;
        }
 
-       view = lttng_buffer_view_from_dynamic_buffer(&trigger_buffer, 0, -1);
-       if (lttng_trigger_create_from_buffer(&view, &trigger) !=
-                       trigger_len) {
-               ERR("Invalid trigger payload received in \"unregister trigger\" command");
-               ret = LTTNG_ERR_INVALID_TRIGGER;
+       /* Receive fds, if any. */
+       if (cmd_ctx->lsm.fd_count > 0) {
+               ret = lttcomm_recv_payload_fds_unix_sock(
+                               sock, cmd_ctx->lsm.fd_count, &trigger_payload);
+               if (ret > 0 && ret != cmd_ctx->lsm.fd_count * sizeof(int)) {
+                       ret = LTTNG_ERR_INVALID_PROTOCOL;
+                       goto end;
+               } else if (ret <= 0) {
+                       ret = LTTNG_ERR_FATAL;
+                       goto end;
+               }
+       }
+
+       {
+               struct lttng_payload_view view =
+                               lttng_payload_view_from_payload(
+                                               &trigger_payload, 0, -1);
+
+               if (lttng_trigger_create_from_payload(&view, &trigger) !=
+                               trigger_len) {
+                       ERR("Invalid trigger payload received in \"unregister trigger\" command");
+                       ret = LTTNG_ERR_INVALID_TRIGGER;
+                       goto end;
+               }
+       }
+
+       /*
+        * Validate the trigger credentials against the command credentials.
+        * Only the root user can unregister a trigger with non-matching
+        * credentials.
+        */
+       if (!lttng_credentials_is_equal_uid(
+                       lttng_trigger_get_credentials(trigger),
+                       &cmd_creds)) {
+               if (lttng_credentials_get_uid(&cmd_creds) != 0) {
+                       ERR("Trigger credentials do not match the command credentials");
+                       ret = LTTNG_ERR_INVALID_TRIGGER;
+                       goto end;
+               }
+       }
+
+       ret = prepare_trigger_object(trigger, &cmd_creds);
+       if (ret != LTTNG_OK) {
                goto end;
        }
 
        ret = notification_thread_command_unregister_trigger(notification_thread,
                        trigger);
+
+       /* Synchronize tracers, only if needed */
+       /* TODO: maybe extract somewhere else */
+       {
+               struct lttng_condition *condition = NULL;
+               condition = lttng_trigger_get_condition(trigger);
+               if (!condition) {
+                       ret = LTTNG_ERR_INVALID_TRIGGER;
+                       goto end;
+               }
+
+               if (lttng_condition_get_type(condition) == LTTNG_CONDITION_TYPE_EVENT_RULE_HIT) {
+                       const struct lttng_event_rule *rule = NULL;
+                       (void) lttng_condition_event_rule_get_rule(condition, &rule);
+                       if (!rule) {
+                               ret = LTTNG_ERR_INVALID_TRIGGER;
+                               goto end;
+                       }
+                       if (lttng_event_rule_get_domain_type(rule) == LTTNG_DOMAIN_KERNEL) {
+                               /* TODO: get the token value from the
+                                * notification thread and only perform an
+                                * enable and a disable.... This is NOT
+                                * OPTIMIZED AT ALL
+                                */
+                               ret = kernel_unregister_trigger(trigger);
+                       } else {
+                               /* TODO: get the token value from the
+                                * notification thread and only perform an
+                                * enable and a disable.... This is NOT
+                                * OPTIMIZED AT ALL
+                                */
+                               ust_app_global_update_all_tokens();
+                               if (lttng_event_rule_is_agent(rule)) {
+                                       struct agent *agt;
+                                       const char *pattern;
+                                       enum lttng_domain_type domain_type;
+
+                                       domain_type = lttng_event_rule_get_domain_type(
+                                                       rule);
+                                       (void) lttng_event_rule_tracepoint_get_pattern(
+                                                       rule, &pattern);
+
+                                       agt = trigger_find_agent(domain_type);
+                                       if (!agt) {
+                                               ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
+                                               goto end;
+                                       }
+                                       ret = trigger_agent_disable(
+                                                       trigger, agt);
+                                       if (ret != LTTNG_OK) {
+                                               goto end;
+                                       }
+                               }
+                       }
+               }
+       }
+
 end:
        lttng_trigger_destroy(trigger);
-       lttng_dynamic_buffer_reset(&trigger_buffer);
+       lttng_payload_reset(&trigger_payload);
        return ret;
 }
 
+int cmd_list_triggers(struct command_ctx *cmd_ctx,
+               struct notification_thread_handle *notification_thread,
+               struct lttng_triggers **return_triggers)
+{
+       int ret = 0;
+       enum lttng_error_code ret_code;
+       struct lttng_triggers *triggers = NULL;
+
+       /* Get list of token trigger from the notification thread here */
+       ret_code = notification_thread_command_list_triggers(notification_thread, cmd_ctx->creds.uid, &triggers);
+       if (ret_code != LTTNG_OK) {
+               ret = ret_code;
+               goto end;
+       }
+
+       /* Return a "view" of the current triggers */
+       *return_triggers = triggers;
+       triggers = NULL;
+       ret = LTTNG_OK;
+end:
+       lttng_triggers_destroy(triggers);
+       return ret;
+}
 /*
  * Send relayd sockets from snapshot output to consumer. Ignore request if the
  * snapshot output is *not* set with a remote destination.
@@ -4467,7 +4859,7 @@ int64_t get_session_nb_packets_per_stream(const struct ltt_session *session,
                }
                cur_nb_packets++;
        }
-       if (!cur_nb_packets) {
+       if (!cur_nb_packets && size_left != max_size) {
                /* Not enough room to grab one packet of each stream, error. */
                return -1;
        }
@@ -4580,7 +4972,7 @@ enum lttng_error_code snapshot_record(struct ltt_session *session,
                        snapshot_output->max_size);
        if (nb_packets_per_stream < 0) {
                ret_code = LTTNG_ERR_MAX_SIZE_INVALID;
-               goto error;
+               goto error_close_trace_chunk;
        }
 
        if (session->kernel_session) {
@@ -4588,7 +4980,7 @@ enum lttng_error_code snapshot_record(struct ltt_session *session,
                                snapshot_kernel_consumer_output, session,
                                wait, nb_packets_per_stream);
                if (ret_code != LTTNG_OK) {
-                       goto error;
+                       goto error_close_trace_chunk;
                }
        }
 
@@ -4597,12 +4989,19 @@ enum lttng_error_code snapshot_record(struct ltt_session *session,
                                snapshot_ust_consumer_output, session,
                                wait, nb_packets_per_stream);
                if (ret_code != LTTNG_OK) {
-                       goto error;
+                       goto error_close_trace_chunk;
                }
        }
 
-       if (session_close_trace_chunk(
-                           session, session->current_trace_chunk, NULL, NULL)) {
+error_close_trace_chunk:
+       if (session_set_trace_chunk(session, NULL, &snapshot_trace_chunk)) {
+               ERR("Failed to release the current trace chunk of session \"%s\"",
+                               session->name);
+               ret_code = LTTNG_ERR_UNK;
+       }
+
+       if (session_close_trace_chunk(session, snapshot_trace_chunk,
+                       LTTNG_TRACE_CHUNK_COMMAND_TYPE_NO_OPERATION, NULL)) {
                /*
                 * Don't goto end; make sure the chunk is closed for the session
                 * to allow future snapshots.
@@ -4611,11 +5010,6 @@ enum lttng_error_code snapshot_record(struct ltt_session *session,
                                session->name);
                ret_code = LTTNG_ERR_CLOSE_TRACE_CHUNK_FAIL_CONSUMER;
        }
-       if (session_set_trace_chunk(session, NULL, NULL)) {
-               ERR("Failed to release the current trace chunk of session \"%s\"",
-                               session->name);
-               ret_code = LTTNG_ERR_UNK;
-       }
 error:
        if (original_ust_consumer_output) {
                session->ust_session->consumer = original_ust_consumer_output;
@@ -4796,7 +5190,8 @@ int cmd_set_session_shm_path(struct ltt_session *session,
  */
 int cmd_rotate_session(struct ltt_session *session,
                struct lttng_rotate_session_return *rotate_return,
-               bool quiet_rotation)
+               bool quiet_rotation,
+               enum lttng_trace_chunk_command_type command)
 {
        int ret;
        uint64_t ongoing_rotation_chunk_id;
@@ -4834,6 +5229,12 @@ int cmd_rotate_session(struct ltt_session *session,
                goto end;
        }
 
+       /* Unsupported feature in lttng-modules before 2.8 (lack of sequence number). */
+       if (session->kernel_session && !kernel_supports_ring_buffer_packet_sequence_number()) {
+               cmd_ret = LTTNG_ERR_ROTATION_NOT_AVAILABLE_KERNEL;
+               goto end;
+       }
+
        if (session->rotation_state == LTTNG_ROTATION_STATE_ONGOING) {
                DBG("Refusing to launch a rotation; a rotation is already in progress for session %s",
                                session->name);
@@ -4852,7 +5253,16 @@ int cmd_rotate_session(struct ltt_session *session,
                goto end;
        }
 
-       session->rotation_state = LTTNG_ROTATION_STATE_ONGOING;
+       /*
+        * After a stop followed by a clear, disallow following rotations a they would
+        * generate empty chunks.
+        */
+       if (session->cleared_after_last_stop) {
+               DBG("Session \"%s\" was already cleared after stop, refusing rotation",
+                               session->name);
+               cmd_ret = LTTNG_ERR_ROTATION_AFTER_STOP_CLEAR;
+               goto end;
+       }
 
        if (session->active) {
                new_trace_chunk = session_create_new_trace_chunk(session, NULL,
@@ -4861,7 +5271,7 @@ int cmd_rotate_session(struct ltt_session *session,
                        cmd_ret = LTTNG_ERR_CREATE_DIR_FAIL;
                        goto error;
                }
-        }
+       }
 
        /*
         * The current trace chunk becomes the chunk being archived.
@@ -4877,11 +5287,6 @@ int cmd_rotate_session(struct ltt_session *session,
                goto error;
        }
 
-       assert(chunk_being_archived);
-       chunk_status = lttng_trace_chunk_get_id(chunk_being_archived,
-                       &ongoing_rotation_chunk_id);
-       assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
-
        if (session->kernel_session) {
                cmd_ret = kernel_rotate_session(session);
                if (cmd_ret != LTTNG_OK) {
@@ -4897,12 +5302,28 @@ int cmd_rotate_session(struct ltt_session *session,
                }
        }
 
+       if (!session->active) {
+               session->rotated_after_last_stop = true;
+       }
+
+       if (!chunk_being_archived) {
+               DBG("Rotating session \"%s\" from a \"NULL\" trace chunk to a new trace chunk, skipping completion check",
+                               session->name);
+               if (failed_to_rotate) {
+                       cmd_ret = rotation_fail_code;
+                       goto error;
+               }
+               cmd_ret = LTTNG_OK;
+               goto end;
+       }
+
+       session->rotation_state = LTTNG_ROTATION_STATE_ONGOING;
+       chunk_status = lttng_trace_chunk_get_id(chunk_being_archived,
+                       &ongoing_rotation_chunk_id);
+       assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
+
        ret = session_close_trace_chunk(session, chunk_being_archived,
-                       quiet_rotation ?
-                                       NULL :
-                                       &((enum lttng_trace_chunk_command_type){
-                                                       LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED}),
-                       session->last_chunk_path);
+               command, session->last_chunk_path);
        if (ret) {
                cmd_ret = LTTNG_ERR_CLOSE_TRACE_CHUNK_FAIL_CONSUMER;
                goto error;
@@ -4921,10 +5342,6 @@ int cmd_rotate_session(struct ltt_session *session,
                goto error;
        }
 
-       if (!session->active) {
-               session->rotated_after_last_stop = true;
-       }
-
        if (rotate_return) {
                rotate_return->rotation_id = ongoing_rotation_chunk_id;
        }
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