Fix: missing rcu read locking in trigger "unregister all" command
[lttng-tools.git] / src / bin / lttng-sessiond / notification-thread-events.c
index 6a7477aff44a165d1cb5d763526aea8498fde2f8..052689a0ebd8439dbf11db0172df7eb520c68605 100644 (file)
 #include <common/sessiond-comm/sessiond-comm.h>
 #include <common/macros.h>
 #include <lttng/condition/condition.h>
-#include <lttng/action/action.h>
+#include <lttng/action/action-internal.h>
 #include <lttng/notification/notification-internal.h>
 #include <lttng/condition/condition-internal.h>
 #include <lttng/condition/buffer-usage-internal.h>
 #include <lttng/condition/session-consumed-size-internal.h>
+#include <lttng/condition/session-rotation-internal.h>
 #include <lttng/notification/channel-internal.h>
 
 #include <time.h>
 #define CLIENT_POLL_MASK_IN (LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP)
 #define CLIENT_POLL_MASK_IN_OUT (CLIENT_POLL_MASK_IN | LPOLLOUT)
 
+enum lttng_object_type {
+       LTTNG_OBJECT_TYPE_UNKNOWN,
+       LTTNG_OBJECT_TYPE_NONE,
+       LTTNG_OBJECT_TYPE_CHANNEL,
+       LTTNG_OBJECT_TYPE_SESSION,
+};
+
 struct lttng_trigger_list_element {
-       struct lttng_trigger *trigger;
+       /* No ownership of the trigger object is assumed. */
+       const struct lttng_trigger *trigger;
        struct cds_list_head node;
 };
 
 struct lttng_channel_trigger_list {
        struct channel_key channel_key;
+       /* List of struct lttng_trigger_list_element. */
        struct cds_list_head list;
+       /* Node in the channel_triggers_ht */
        struct cds_lfht_node channel_triggers_ht_node;
+       /* call_rcu delayed reclaim. */
+       struct rcu_head rcu_node;
+};
+
+/*
+ * List of triggers applying to a given session.
+ *
+ * See:
+ *   - lttng_session_trigger_list_create()
+ *   - lttng_session_trigger_list_build()
+ *   - lttng_session_trigger_list_destroy()
+ *   - lttng_session_trigger_list_add()
+ */
+struct lttng_session_trigger_list {
+       /*
+        * Not owned by this; points to the session_info structure's
+        * session name.
+        */
+       const char *session_name;
+       /* List of struct lttng_trigger_list_element. */
+       struct cds_list_head list;
+       /* Node in the session_triggers_ht */
+       struct cds_lfht_node session_triggers_ht_node;
+       /*
+        * Weak reference to the notification system's session triggers
+        * hashtable.
+        *
+        * The session trigger list structure structure is owned by
+        * the session's session_info.
+        *
+        * The session_info is kept alive the the channel_infos holding a
+        * reference to it (reference counting). When those channels are
+        * destroyed (at runtime or on teardown), the reference they hold
+        * to the session_info are released. On destruction of session_info,
+        * session_info_destroy() will remove the list of triggers applying
+        * to this session from the notification system's state.
+        *
+        * This implies that the session_triggers_ht must be destroyed
+        * after the channels.
+        */
+       struct cds_lfht *session_triggers_ht;
+       /* Used for delayed RCU reclaim. */
+       struct rcu_head rcu_node;
 };
 
 struct lttng_trigger_ht_element {
        struct lttng_trigger *trigger;
        struct cds_lfht_node node;
+       /* call_rcu delayed reclaim. */
+       struct rcu_head rcu_node;
 };
 
 struct lttng_condition_list_element {
@@ -77,9 +133,11 @@ struct notification_client_list_element {
 };
 
 struct notification_client_list {
-       struct lttng_trigger *trigger;
+       const struct lttng_trigger *trigger;
        struct cds_list_head list;
        struct cds_lfht_node notification_trigger_ht_node;
+       /* call_rcu delayed reclaim. */
+       struct rcu_head rcu_node;
 };
 
 struct notification_client {
@@ -146,6 +204,8 @@ struct notification_client {
                        struct lttng_dynamic_buffer buffer;
                } outbound;
        } communication;
+       /* call_rcu delayed reclaim. */
+       struct rcu_head rcu_node;
 };
 
 struct channel_state_sample {
@@ -154,10 +214,12 @@ struct channel_state_sample {
        uint64_t highest_usage;
        uint64_t lowest_usage;
        uint64_t channel_total_consumed;
+       /* call_rcu delayed reclaim. */
+       struct rcu_head rcu_node;
 };
 
 static unsigned long hash_channel_key(struct channel_key *key);
-static int evaluate_condition(const struct lttng_condition *condition,
+static int evaluate_buffer_condition(const struct lttng_condition *condition,
                struct lttng_evaluation **evaluation,
                const struct notification_thread_state *state,
                const struct channel_state_sample *previous_sample,
@@ -166,13 +228,14 @@ static int evaluate_condition(const struct lttng_condition *condition,
                uint64_t latest_session_consumed_total,
                struct channel_info *channel_info);
 static
-int send_evaluation_to_clients(struct lttng_trigger *trigger,
-               struct lttng_evaluation *evaluation,
+int send_evaluation_to_clients(const struct lttng_trigger *trigger,
+               const struct lttng_evaluation *evaluation,
                struct notification_client_list *client_list,
                struct notification_thread_state *state,
                uid_t channel_uid, gid_t channel_gid);
 
 
+/* session_info API */
 static
 void session_info_destroy(void *_data);
 static
@@ -181,7 +244,9 @@ static
 void session_info_put(struct session_info *session_info);
 static
 struct session_info *session_info_create(const char *name,
-               uid_t uid, gid_t gid);
+               uid_t uid, gid_t gid,
+               struct lttng_session_trigger_list *trigger_list,
+               struct cds_lfht *sessions_ht);
 static
 void session_info_add_channel(struct session_info *session_info,
                struct channel_info *channel_info);
@@ -189,6 +254,23 @@ static
 void session_info_remove_channel(struct session_info *session_info,
                struct channel_info *channel_info);
 
+/* lttng_session_trigger_list API */
+static
+struct lttng_session_trigger_list *lttng_session_trigger_list_create(
+               const char *session_name,
+               struct cds_lfht *session_triggers_ht);
+static
+struct lttng_session_trigger_list *lttng_session_trigger_list_build(
+               const struct notification_thread_state *state,
+               const char *session_name);
+static
+void lttng_session_trigger_list_destroy(
+               struct lttng_session_trigger_list *list);
+static
+int lttng_session_trigger_list_add(struct lttng_session_trigger_list *list,
+               const struct lttng_trigger *trigger);
+
+
 static
 int match_client(struct cds_lfht_node *node, const void *key)
 {
@@ -215,6 +297,18 @@ int match_channel_trigger_list(struct cds_lfht_node *node, const void *key)
                        (channel_key->domain == trigger_list->channel_key.domain));
 }
 
+static
+int match_session_trigger_list(struct cds_lfht_node *node, const void *key)
+{
+       const char *session_name = (const char *) key;
+       struct lttng_session_trigger_list *trigger_list;
+
+       trigger_list = caa_container_of(node, struct lttng_session_trigger_list,
+                       session_triggers_ht_node);
+
+       return !!(strcmp(trigger_list->session_name, session_name) == 0);
+}
+
 static
 int match_channel_state_sample(struct cds_lfht_node *node, const void *key)
 {
@@ -257,49 +351,44 @@ int match_condition(struct cds_lfht_node *node, const void *key)
 }
 
 static
-int match_client_list(struct cds_lfht_node *node, const void *key)
+int match_client_list_condition(struct cds_lfht_node *node, const void *key)
 {
-       struct lttng_trigger *trigger_key = (struct lttng_trigger *) key;
+       struct lttng_condition *condition_key = (struct lttng_condition *) key;
        struct notification_client_list *client_list;
-       struct lttng_condition *condition;
-       struct lttng_condition *condition_key = lttng_trigger_get_condition(
-                       trigger_key);
+       const struct lttng_condition *condition;
 
        assert(condition_key);
 
        client_list = caa_container_of(node, struct notification_client_list,
                        notification_trigger_ht_node);
-       condition = lttng_trigger_get_condition(client_list->trigger);
+       condition = lttng_trigger_get_const_condition(client_list->trigger);
 
        return !!lttng_condition_is_equal(condition_key, condition);
 }
 
 static
-int match_client_list_condition(struct cds_lfht_node *node, const void *key)
+int match_session(struct cds_lfht_node *node, const void *key)
 {
-       struct lttng_condition *condition_key = (struct lttng_condition *) key;
-       struct notification_client_list *client_list;
-       struct lttng_condition *condition;
-
-       assert(condition_key);
-
-       client_list = caa_container_of(node, struct notification_client_list,
-                       notification_trigger_ht_node);
-       condition = lttng_trigger_get_condition(client_list->trigger);
+       const char *name = key;
+       struct session_info *session_info = caa_container_of(
+               node, struct session_info, sessions_ht_node);
 
-       return !!lttng_condition_is_equal(condition_key, condition);
+       return !strcmp(session_info->name, name);
 }
 
 static
 unsigned long lttng_condition_buffer_usage_hash(
-       struct lttng_condition *_condition)
+       const struct lttng_condition *_condition)
 {
-       unsigned long hash = 0;
+       unsigned long hash;
+       unsigned long condition_type;
        struct lttng_condition_buffer_usage *condition;
 
        condition = container_of(_condition,
                        struct lttng_condition_buffer_usage, parent);
 
+       condition_type = (unsigned long) condition->parent.type;
+       hash = hash_key_ulong((void *) condition_type, lttng_ht_seed);
        if (condition->session_name) {
                hash ^= hash_key_str(condition->session_name, lttng_ht_seed);
        }
@@ -327,15 +416,18 @@ unsigned long lttng_condition_buffer_usage_hash(
 
 static
 unsigned long lttng_condition_session_consumed_size_hash(
-       struct lttng_condition *_condition)
+       const struct lttng_condition *_condition)
 {
-       unsigned long hash = 0;
+       unsigned long hash;
+       unsigned long condition_type =
+                       (unsigned long) LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE;
        struct lttng_condition_session_consumed_size *condition;
        uint64_t val;
 
        condition = container_of(_condition,
                        struct lttng_condition_session_consumed_size, parent);
 
+       hash = hash_key_ulong((void *) condition_type, lttng_ht_seed);
        if (condition->session_name) {
                hash ^= hash_key_str(condition->session_name, lttng_ht_seed);
        }
@@ -344,13 +436,29 @@ unsigned long lttng_condition_session_consumed_size_hash(
        return hash;
 }
 
+static
+unsigned long lttng_condition_session_rotation_hash(
+       const struct lttng_condition *_condition)
+{
+       unsigned long hash, condition_type;
+       struct lttng_condition_session_rotation *condition;
+
+       condition = container_of(_condition,
+                       struct lttng_condition_session_rotation, parent);
+       condition_type = (unsigned long) condition->parent.type;
+       hash = hash_key_ulong((void *) condition_type, lttng_ht_seed);
+       assert(condition->session_name);
+       hash ^= hash_key_str(condition->session_name, lttng_ht_seed);
+       return hash;
+}
+
 /*
  * The lttng_condition hashing code is kept in this file (rather than
  * condition.c) since it makes use of GPLv2 code (hashtable utils), which we
  * don't want to link in liblttng-ctl.
  */
 static
-unsigned long lttng_condition_hash(struct lttng_condition *condition)
+unsigned long lttng_condition_hash(const struct lttng_condition *condition)
 {
        switch (condition->type) {
        case LTTNG_CONDITION_TYPE_BUFFER_USAGE_LOW:
@@ -358,6 +466,9 @@ unsigned long lttng_condition_hash(struct lttng_condition *condition)
                return lttng_condition_buffer_usage_hash(condition);
        case LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE:
                return lttng_condition_session_consumed_size_hash(condition);
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING:
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED:
+               return lttng_condition_session_rotation_hash(condition);
        default:
                ERR("[notification-thread] Unexpected condition type caught");
                abort();
@@ -374,6 +485,37 @@ unsigned long hash_channel_key(struct channel_key *key)
        return key_hash ^ domain_hash;
 }
 
+/*
+ * Get the type of object to which a given condition applies. Bindings let
+ * the notification system evaluate a trigger's condition when a given
+ * object's state is updated.
+ *
+ * For instance, a condition bound to a channel will be evaluated everytime
+ * the channel's state is changed by a channel monitoring sample.
+ */
+static
+enum lttng_object_type get_condition_binding_object(
+               const struct lttng_condition *condition)
+{
+       switch (lttng_condition_get_type(condition)) {
+       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_LOW:
+       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_HIGH:
+       case LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE:
+               return LTTNG_OBJECT_TYPE_CHANNEL;
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING:
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED:
+               return LTTNG_OBJECT_TYPE_SESSION;
+       default:
+               return LTTNG_OBJECT_TYPE_UNKNOWN;
+       }
+}
+
+static
+void free_channel_info_rcu(struct rcu_head *node)
+{
+       free(caa_container_of(node, struct channel_info, rcu_node));
+}
+
 static
 void channel_info_destroy(struct channel_info *channel_info)
 {
@@ -389,7 +531,13 @@ void channel_info_destroy(struct channel_info *channel_info)
        if (channel_info->name) {
                free(channel_info->name);
        }
-       free(channel_info);
+       call_rcu(&channel_info->rcu_node, free_channel_info_rcu);
+}
+
+static
+void free_session_info_rcu(struct rcu_head *node)
+{
+       free(caa_container_of(node, struct session_info, rcu_node));
 }
 
 /* Don't call directly, use the ref-counting mechanism. */
@@ -397,13 +545,23 @@ static
 void session_info_destroy(void *_data)
 {
        struct session_info *session_info = _data;
+       int ret;
 
        assert(session_info);
        if (session_info->channel_infos_ht) {
-               cds_lfht_destroy(session_info->channel_infos_ht, NULL);
+               ret = cds_lfht_destroy(session_info->channel_infos_ht, NULL);
+               if (ret) {
+                       ERR("[notification-thread] Failed to destroy channel information hash table");
+               }
        }
+       lttng_session_trigger_list_destroy(session_info->trigger_list);
+
+       rcu_read_lock();
+       cds_lfht_del(session_info->sessions_ht,
+                       &session_info->sessions_ht_node);
+       rcu_read_unlock();
        free(session_info->name);
-       free(session_info);
+       call_rcu(&session_info->rcu_node, free_session_info_rcu);
 }
 
 static
@@ -425,7 +583,9 @@ void session_info_put(struct session_info *session_info)
 }
 
 static
-struct session_info *session_info_create(const char *name, uid_t uid, gid_t gid)
+struct session_info *session_info_create(const char *name, uid_t uid, gid_t gid,
+               struct lttng_session_trigger_list *trigger_list,
+               struct cds_lfht *sessions_ht)
 {
        struct session_info *session_info;
 
@@ -450,6 +610,8 @@ struct session_info *session_info_create(const char *name, uid_t uid, gid_t gid)
        }
        session_info->uid = uid;
        session_info->gid = gid;
+       session_info->trigger_list = trigger_list;
+       session_info->sessions_ht = sessions_ht;
 end:
        return session_info;
 error:
@@ -514,12 +676,34 @@ error:
        return NULL;
 }
 
+/* RCU read lock must be held by the caller. */
+static
+struct notification_client_list *get_client_list_from_condition(
+       struct notification_thread_state *state,
+       const struct lttng_condition *condition)
+{
+       struct cds_lfht_node *node;
+       struct cds_lfht_iter iter;
+
+       cds_lfht_lookup(state->notification_trigger_clients_ht,
+                       lttng_condition_hash(condition),
+                       match_client_list_condition,
+                       condition,
+                       &iter);
+       node = cds_lfht_iter_get_node(&iter);
+
+        return node ? caa_container_of(node,
+                       struct notification_client_list,
+                       notification_trigger_ht_node) : NULL;
+}
+
 /* This function must be called with the RCU read lock held. */
 static
-int evaluate_condition_for_client(struct lttng_trigger *trigger,
-               struct lttng_condition *condition,
-               struct notification_client *client,
-               struct notification_thread_state *state)
+int evaluate_channel_condition_for_client(
+               const struct lttng_condition *condition,
+               struct notification_thread_state *state,
+               struct lttng_evaluation **evaluation,
+               uid_t *session_uid, gid_t *session_gid)
 {
        int ret;
        struct cds_lfht_iter iter;
@@ -528,23 +712,15 @@ int evaluate_condition_for_client(struct lttng_trigger *trigger,
        struct channel_key *channel_key = NULL;
        struct channel_state_sample *last_sample = NULL;
        struct lttng_channel_trigger_list *channel_trigger_list = NULL;
-       struct lttng_evaluation *evaluation = NULL;
-       struct notification_client_list client_list = { 0 };
-       struct notification_client_list_element client_list_element = { 0 };
-
-       assert(trigger);
-       assert(condition);
-       assert(client);
-       assert(state);
 
-       /* Find the channel associated with the trigger. */
+       /* Find the channel associated with the condition. */
        cds_lfht_for_each_entry(state->channel_triggers_ht, &iter,
-                       channel_trigger_list , channel_triggers_ht_node) {
+                       channel_trigger_list, channel_triggers_ht_node) {
                struct lttng_trigger_list_element *element;
 
                cds_list_for_each_entry(element, &channel_trigger_list->list, node) {
-                       struct lttng_condition *current_condition =
-                               lttng_trigger_get_condition(
+                       const struct lttng_condition *current_condition =
+                                       lttng_trigger_get_const_condition(
                                                element->trigger);
 
                        assert(current_condition);
@@ -565,7 +741,7 @@ int evaluate_condition_for_client(struct lttng_trigger *trigger,
 
        if (!channel_key){
                /* No channel found; normal exit. */
-               DBG("[notification-thread] No channel associated with newly subscribed-to condition");
+               DBG("[notification-thread] No known channel associated with newly subscribed-to condition");
                ret = 0;
                goto end;
        }
@@ -599,7 +775,7 @@ int evaluate_condition_for_client(struct lttng_trigger *trigger,
                goto end;
        }
 
-       ret = evaluate_condition(condition, &evaluation, state,
+       ret = evaluate_buffer_condition(condition, evaluation, state,
                        NULL, last_sample,
                        0, channel_info->session_info->consumed_data_size,
                        channel_info);
@@ -608,6 +784,151 @@ int evaluate_condition_for_client(struct lttng_trigger *trigger,
                goto end;
        }
 
+       *session_uid = channel_info->session_info->uid;
+       *session_gid = channel_info->session_info->gid;
+end:
+       return ret;
+}
+
+static
+const char *get_condition_session_name(const struct lttng_condition *condition)
+{
+       const char *session_name = NULL;
+       enum lttng_condition_status status;
+
+       switch (lttng_condition_get_type(condition)) {
+       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_LOW:
+       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_HIGH:
+               status = lttng_condition_buffer_usage_get_session_name(
+                               condition, &session_name);
+               break;
+       case LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE:
+               status = lttng_condition_session_consumed_size_get_session_name(
+                               condition, &session_name);
+               break;
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING:
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED:
+               status = lttng_condition_session_rotation_get_session_name(
+                               condition, &session_name);
+               break;
+       default:
+               abort();
+       }
+       if (status != LTTNG_CONDITION_STATUS_OK) {
+               ERR("[notification-thread] Failed to retrieve session rotation condition's session name");
+               goto end;
+       }
+end:
+       return session_name;
+}
+
+/* This function must be called with the RCU read lock held. */
+static
+int evaluate_session_condition_for_client(
+               const struct lttng_condition *condition,
+               struct notification_thread_state *state,
+               struct lttng_evaluation **evaluation,
+               uid_t *session_uid, gid_t *session_gid)
+{
+       int ret;
+       struct cds_lfht_iter iter;
+       struct cds_lfht_node *node;
+       const char *session_name;
+       struct session_info *session_info = NULL;
+
+       session_name = get_condition_session_name(condition);
+
+       /* Find the session associated with the trigger. */
+       cds_lfht_lookup(state->sessions_ht,
+                       hash_key_str(session_name, lttng_ht_seed),
+                       match_session,
+                       session_name,
+                       &iter);
+       node = cds_lfht_iter_get_node(&iter);
+       if (!node) {
+               DBG("[notification-thread] No known session matching name \"%s\"",
+                               session_name);
+               ret = 0;
+               goto end;
+       }
+
+       session_info = caa_container_of(node, struct session_info,
+                       sessions_ht_node);
+       session_info_get(session_info);
+
+       /*
+        * Evaluation is performed in-line here since only one type of
+        * session-bound condition is handled for the moment.
+        */
+       switch (lttng_condition_get_type(condition)) {
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING:
+               if (!session_info->rotation.ongoing) {
+                       ret = 0;
+                       goto end_session_put;
+               }
+
+               *evaluation = lttng_evaluation_session_rotation_ongoing_create(
+                               session_info->rotation.id);
+               if (!*evaluation) {
+                       /* Fatal error. */
+                       ERR("[notification-thread] Failed to create session rotation ongoing evaluation for session \"%s\"",
+                                       session_info->name);
+                       ret = -1;
+                       goto end_session_put;
+               }
+               ret = 0;
+               break;
+       default:
+               ret = 0;
+               goto end_session_put;
+       }
+
+       *session_uid = session_info->uid;
+       *session_gid = session_info->gid;
+
+end_session_put:
+       session_info_put(session_info);
+end:
+       return ret;
+}
+
+/* This function must be called with the RCU read lock held. */
+static
+int evaluate_condition_for_client(const struct lttng_trigger *trigger,
+               const struct lttng_condition *condition,
+               struct notification_client *client,
+               struct notification_thread_state *state)
+{
+       int ret;
+       struct lttng_evaluation *evaluation = NULL;
+       struct notification_client_list client_list = { 0 };
+       struct notification_client_list_element client_list_element = { 0 };
+       uid_t object_uid = 0;
+       gid_t object_gid = 0;
+
+       assert(trigger);
+       assert(condition);
+       assert(client);
+       assert(state);
+
+       switch (get_condition_binding_object(condition)) {
+       case LTTNG_OBJECT_TYPE_SESSION:
+               ret = evaluate_session_condition_for_client(condition, state,
+                               &evaluation, &object_uid, &object_gid);
+               break;
+       case LTTNG_OBJECT_TYPE_CHANNEL:
+               ret = evaluate_channel_condition_for_client(condition, state,
+                               &evaluation, &object_uid, &object_gid);
+               break;
+       case LTTNG_OBJECT_TYPE_NONE:
+               ret = 0;
+               goto end;
+       case LTTNG_OBJECT_TYPE_UNKNOWN:
+       default:
+               ret = -1;
+               goto end;
+       }
+
        if (!evaluation) {
                /* Evaluation yielded nothing. Normal exit. */
                DBG("[notification-thread] Newly subscribed-to condition evaluated to false, nothing to report to client");
@@ -630,8 +951,7 @@ int evaluate_condition_for_client(struct lttng_trigger *trigger,
        /* Send evaluation result to the newly-subscribed client. */
        DBG("[notification-thread] Newly subscribed-to condition evaluated to true, notifying client");
        ret = send_evaluation_to_clients(trigger, evaluation, &client_list,
-                       state, channel_info->session_info->uid,
-                       channel_info->session_info->gid);
+                       state, object_uid, object_gid);
 
 end:
        return ret;
@@ -644,8 +964,6 @@ int notification_thread_client_subscribe(struct notification_client *client,
                enum lttng_notification_channel_status *_status)
 {
        int ret = 0;
-       struct cds_lfht_iter iter;
-       struct cds_lfht_node *node;
        struct notification_client_list *client_list;
        struct lttng_condition_list_element *condition_list_element = NULL;
        struct notification_client_list_element *client_list_element = NULL;
@@ -684,13 +1002,8 @@ int notification_thread_client_subscribe(struct notification_client *client,
        condition_list_element->condition = condition;
        cds_list_add(&condition_list_element->node, &client->condition_list);
 
-       cds_lfht_lookup(state->notification_trigger_clients_ht,
-                       lttng_condition_hash(condition),
-                       match_client_list_condition,
-                       condition,
-                       &iter);
-       node = cds_lfht_iter_get_node(&iter);
-       if (!node) {
+       client_list = get_client_list_from_condition(state, condition);
+       if (!client_list) {
                /*
                 * No notification-emiting trigger registered with this
                 * condition. We don't evaluate the condition right away
@@ -700,8 +1013,6 @@ int notification_thread_client_subscribe(struct notification_client *client,
                goto end_unlock;
        }
 
-       client_list = caa_container_of(node, struct notification_client_list,
-                       notification_trigger_ht_node);
        /*
         * The condition to which the client just subscribed is evaluated
         * at this point so that conditions that are already TRUE result
@@ -711,6 +1022,7 @@ int notification_thread_client_subscribe(struct notification_client *client,
                        client, state)) {
                WARN("[notification-thread] Evaluation of a condition on client subscription failed, aborting.");
                ret = -1;
+               free(client_list_element);
                goto end_unlock;
        }
 
@@ -742,8 +1054,6 @@ int notification_thread_client_unsubscribe(
                struct notification_thread_state *state,
                enum lttng_notification_channel_status *_status)
 {
-       struct cds_lfht_iter iter;
-       struct cds_lfht_node *node;
        struct notification_client_list *client_list;
        struct lttng_condition_list_element *condition_list_element,
                        *condition_tmp;
@@ -786,18 +1096,11 @@ int notification_thread_client_unsubscribe(
         * matching the condition.
         */
        rcu_read_lock();
-       cds_lfht_lookup(state->notification_trigger_clients_ht,
-                       lttng_condition_hash(condition),
-                       match_client_list_condition,
-                       condition,
-                       &iter);
-       node = cds_lfht_iter_get_node(&iter);
-       if (!node) {
+       client_list = get_client_list_from_condition(state, condition);
+       if (!client_list) {
                goto end_unlock;
        }
 
-       client_list = caa_container_of(node, struct notification_client_list,
-                       notification_trigger_ht_node);
        cds_list_for_each_entry_safe(client_list_element, client_tmp,
                        &client_list->list, node) {
                if (client_list_element->client->socket != client->socket) {
@@ -817,6 +1120,12 @@ end:
        return 0;
 }
 
+static
+void free_notification_client_rcu(struct rcu_head *node)
+{
+       free(caa_container_of(node, struct notification_client, rcu_node));
+}
+
 static
 void notification_client_destroy(struct notification_client *client,
                struct notification_thread_state *state)
@@ -839,7 +1148,7 @@ void notification_client_destroy(struct notification_client *client,
        }
        lttng_dynamic_buffer_reset(&client->communication.inbound.buffer);
        lttng_dynamic_buffer_reset(&client->communication.outbound.buffer);
-       free(client);
+       call_rcu(&client->rcu_node, free_notification_client_rcu);
 }
 
 /*
@@ -872,8 +1181,8 @@ end:
 
 static
 bool buffer_usage_condition_applies_to_channel(
-               struct lttng_condition *condition,
-               struct channel_info *channel_info)
+               const struct lttng_condition *condition,
+               const struct channel_info *channel_info)
 {
        enum lttng_condition_status status;
        enum lttng_domain_type condition_domain;
@@ -909,8 +1218,8 @@ fail:
 
 static
 bool session_consumed_size_condition_applies_to_channel(
-               struct lttng_condition *condition,
-               struct channel_info *channel_info)
+               const struct lttng_condition *condition,
+               const struct channel_info *channel_info)
 {
        enum lttng_condition_status status;
        const char *condition_session_name = NULL;
@@ -929,13 +1238,13 @@ fail:
 }
 
 static
-bool trigger_applies_to_channel(struct lttng_trigger *trigger,
-               struct channel_info *channel_info)
+bool trigger_applies_to_channel(const struct lttng_trigger *trigger,
+               const struct channel_info *channel_info)
 {
-       struct lttng_condition *condition;
+       const struct lttng_condition *condition;
        bool trigger_applies;
 
-       condition = lttng_trigger_get_condition(trigger);
+       condition = lttng_trigger_get_const_condition(trigger);
        if (!condition) {
                goto fail;
        }
@@ -966,26 +1275,209 @@ bool trigger_applies_to_client(struct lttng_trigger *trigger,
        bool applies = false;
        struct lttng_condition_list_element *condition_list_element;
 
-       cds_list_for_each_entry(condition_list_element, &client->condition_list,
-                       node) {
-               applies = lttng_condition_is_equal(
-                               condition_list_element->condition,
-                               lttng_trigger_get_condition(trigger));
-               if (applies) {
-                       break;
+       cds_list_for_each_entry(condition_list_element, &client->condition_list,
+                       node) {
+               applies = lttng_condition_is_equal(
+                               condition_list_element->condition,
+                               lttng_trigger_get_condition(trigger));
+               if (applies) {
+                       break;
+               }
+       }
+       return applies;
+}
+
+/* Must be called with RCU read lock held. */
+static
+struct lttng_session_trigger_list *get_session_trigger_list(
+               struct notification_thread_state *state,
+               const char *session_name)
+{
+       struct lttng_session_trigger_list *list = NULL;
+       struct cds_lfht_node *node;
+       struct cds_lfht_iter iter;
+
+       cds_lfht_lookup(state->session_triggers_ht,
+                       hash_key_str(session_name, lttng_ht_seed),
+                       match_session_trigger_list,
+                       session_name,
+                       &iter);
+       node = cds_lfht_iter_get_node(&iter);
+       if (!node) {
+               /*
+                * Not an error, the list of triggers applying to that session
+                * will be initialized when the session is created.
+                */
+               DBG("[notification-thread] No trigger list found for session \"%s\" as it is not yet known to the notification system",
+                               session_name);
+               goto end;
+       }
+
+        list = caa_container_of(node,
+                       struct lttng_session_trigger_list,
+                       session_triggers_ht_node);
+end:
+       return list;
+}
+
+/*
+ * Allocate an empty lttng_session_trigger_list for the session named
+ * 'session_name'.
+ *
+ * No ownership of 'session_name' is assumed by the session trigger list.
+ * It is the caller's responsability to ensure the session name is alive
+ * for as long as this list is.
+ */
+static
+struct lttng_session_trigger_list *lttng_session_trigger_list_create(
+               const char *session_name,
+               struct cds_lfht *session_triggers_ht)
+{
+       struct lttng_session_trigger_list *list;
+
+       list = zmalloc(sizeof(*list));
+       if (!list) {
+               goto end;
+       }
+       list->session_name = session_name;
+       CDS_INIT_LIST_HEAD(&list->list);
+       cds_lfht_node_init(&list->session_triggers_ht_node);
+       list->session_triggers_ht = session_triggers_ht;
+
+       rcu_read_lock();
+       /* Publish the list through the session_triggers_ht. */
+       cds_lfht_add(session_triggers_ht,
+                       hash_key_str(session_name, lttng_ht_seed),
+                       &list->session_triggers_ht_node);
+       rcu_read_unlock();
+end:
+       return list;
+}
+
+static
+void free_session_trigger_list_rcu(struct rcu_head *node)
+{
+       free(caa_container_of(node, struct lttng_session_trigger_list,
+                       rcu_node));
+}
+
+static
+void lttng_session_trigger_list_destroy(struct lttng_session_trigger_list *list)
+{
+       struct lttng_trigger_list_element *trigger_list_element, *tmp;
+
+       /* Empty the list element by element, and then free the list itself. */
+       cds_list_for_each_entry_safe(trigger_list_element, tmp,
+                       &list->list, node) {
+               cds_list_del(&trigger_list_element->node);
+               free(trigger_list_element);
+       }
+       rcu_read_lock();
+       /* Unpublish the list from the session_triggers_ht. */
+       cds_lfht_del(list->session_triggers_ht,
+                       &list->session_triggers_ht_node);
+       rcu_read_unlock();
+       call_rcu(&list->rcu_node, free_session_trigger_list_rcu);
+}
+
+static
+int lttng_session_trigger_list_add(struct lttng_session_trigger_list *list,
+               const struct lttng_trigger *trigger)
+{
+       int ret = 0;
+       struct lttng_trigger_list_element *new_element =
+                       zmalloc(sizeof(*new_element));
+
+       if (!new_element) {
+               ret = -1;
+               goto end;
+       }
+       CDS_INIT_LIST_HEAD(&new_element->node);
+       new_element->trigger = trigger;
+       cds_list_add(&new_element->node, &list->list);
+end:
+       return ret;
+}
+
+static
+bool trigger_applies_to_session(const struct lttng_trigger *trigger,
+               const char *session_name)
+{
+       bool applies = false;
+       const struct lttng_condition *condition;
+
+       condition = lttng_trigger_get_const_condition(trigger);
+       switch (lttng_condition_get_type(condition)) {
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING:
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED:
+       {
+               enum lttng_condition_status condition_status;
+               const char *condition_session_name;
+
+               condition_status = lttng_condition_session_rotation_get_session_name(
+                       condition, &condition_session_name);
+               if (condition_status != LTTNG_CONDITION_STATUS_OK) {
+                       ERR("[notification-thread] Failed to retrieve session rotation condition's session name");
+                       goto end;
+               }
+
+               assert(condition_session_name);
+               applies = !strcmp(condition_session_name, session_name);
+               break;
+       }
+       default:
+               goto end;
+       }
+end:
+       return applies;
+}
+
+/*
+ * Allocate and initialize an lttng_session_trigger_list which contains
+ * all triggers that apply to the session named 'session_name'.
+ *
+ * No ownership of 'session_name' is assumed by the session trigger list.
+ * It is the caller's responsability to ensure the session name is alive
+ * for as long as this list is.
+ */
+static
+struct lttng_session_trigger_list *lttng_session_trigger_list_build(
+               const struct notification_thread_state *state,
+               const char *session_name)
+{
+       int trigger_count = 0;
+       struct lttng_session_trigger_list *session_trigger_list = NULL;
+       struct lttng_trigger_ht_element *trigger_ht_element = NULL;
+       struct cds_lfht_iter iter;
+
+       session_trigger_list = lttng_session_trigger_list_create(session_name,
+                       state->session_triggers_ht);
+
+       /* Add all triggers applying to the session named 'session_name'. */
+       cds_lfht_for_each_entry(state->triggers_ht, &iter, trigger_ht_element,
+                       node) {
+               int ret;
+
+               if (!trigger_applies_to_session(trigger_ht_element->trigger,
+                               session_name)) {
+                       continue;
+               }
+
+               ret = lttng_session_trigger_list_add(session_trigger_list,
+                               trigger_ht_element->trigger);
+               if (ret) {
+                       goto error;
                }
-       }
-       return applies;
-}
 
-static
-int match_session(struct cds_lfht_node *node, const void *key)
-{
-       const char *name = key;
-       struct session_info *session_info = caa_container_of(
-               node, struct session_info, sessions_ht_node);
+               trigger_count++;
+       }
 
-       return !strcmp(session_info->name, name);
+       DBG("[notification-thread] Found %i triggers that apply to newly created session",
+                       trigger_count);
+       return session_trigger_list;
+error:
+       lttng_session_trigger_list_destroy(session_trigger_list);
+       return NULL;
 }
 
 static
@@ -996,6 +1488,7 @@ struct session_info *find_or_create_session_info(
        struct session_info *session = NULL;
        struct cds_lfht_node *node;
        struct cds_lfht_iter iter;
+       struct lttng_session_trigger_list *trigger_list;
 
        rcu_read_lock();
        cds_lfht_lookup(state->sessions_ht,
@@ -1011,18 +1504,34 @@ struct session_info *find_or_create_session_info(
                                sessions_ht_node);
                assert(session->uid == uid);
                assert(session->gid == gid);
+               session_info_get(session);
                goto end;
        }
 
-       session = session_info_create(name, uid, gid);
+       trigger_list = lttng_session_trigger_list_build(state, name);
+       if (!trigger_list) {
+               goto error;
+       }
+
+       session = session_info_create(name, uid, gid, trigger_list,
+                       state->sessions_ht);
        if (!session) {
                ERR("[notification-thread] Failed to allocation session info for session \"%s\" (uid = %i, gid = %i)",
                                name, uid, gid);
-               goto end;
+               lttng_session_trigger_list_destroy(trigger_list);
+               goto error;
        }
+       trigger_list = NULL;
+
+       cds_lfht_add(state->sessions_ht, hash_key_str(name, lttng_ht_seed),
+                       &session->sessions_ht_node);
 end:
        rcu_read_unlock();
        return session;
+error:
+       rcu_read_unlock();
+       session_info_put(session);
+       return NULL;
 }
 
 static
@@ -1054,7 +1563,7 @@ int handle_notification_thread_command_add_channel(
        session_info = find_or_create_session_info(state, session_name,
                        session_uid, session_gid);
        if (!session_info) {
-               /* Allocation error or an internal error occured. */
+               /* Allocation error or an internal error occurred. */
                goto error;
        }
 
@@ -1064,6 +1573,7 @@ int handle_notification_thread_command_add_channel(
                goto error;
        }
 
+       rcu_read_lock();
        /* Build a list of all triggers applying to the new channel. */
        cds_lfht_for_each_entry(state->triggers_ht, &iter, trigger_ht_element,
                        node) {
@@ -1076,6 +1586,7 @@ int handle_notification_thread_command_add_channel(
 
                new_element = zmalloc(sizeof(*new_element));
                if (!new_element) {
+                       rcu_read_unlock();
                        goto error;
                }
                CDS_INIT_LIST_HEAD(&new_element->node);
@@ -1083,6 +1594,7 @@ int handle_notification_thread_command_add_channel(
                cds_list_add(&new_element->node, &trigger_list);
                trigger_count++;
        }
+       rcu_read_unlock();
 
        DBG("[notification-thread] Found %i triggers that apply to newly added channel",
                        trigger_count);
@@ -1108,6 +1620,7 @@ int handle_notification_thread_command_add_channel(
                        hash_channel_key(&new_channel_info->key),
                        &channel_trigger_list->channel_triggers_ht_node);
        rcu_read_unlock();
+       session_info_put(session_info);
        *cmd_result = LTTNG_OK;
        return 0;
 error:
@@ -1116,6 +1629,20 @@ error:
        return 1;
 }
 
+static
+void free_channel_trigger_list_rcu(struct rcu_head *node)
+{
+       free(caa_container_of(node, struct lttng_channel_trigger_list,
+                       rcu_node));
+}
+
+static
+void free_channel_state_sample_rcu(struct rcu_head *node)
+{
+       free(caa_container_of(node, struct channel_state_sample,
+                       rcu_node));
+}
+
 static
 int handle_notification_thread_command_remove_channel(
        struct notification_thread_state *state,
@@ -1158,7 +1685,7 @@ int handle_notification_thread_command_remove_channel(
                free(trigger_list_element);
        }
        cds_lfht_del(state->channel_triggers_ht, node);
-       free(trigger_list);
+       call_rcu(&trigger_list->rcu_node, free_channel_trigger_list_rcu);
 
        /* Free sampled channel state. */
        cds_lfht_lookup(state->channel_state_ht,
@@ -1177,7 +1704,7 @@ int handle_notification_thread_command_remove_channel(
                                channel_state_ht_node);
 
                cds_lfht_del(state->channel_state_ht, node);
-               free(sample);
+               call_rcu(&sample->rcu_node, free_channel_state_sample_rcu);
        }
 
        /* Remove the channel from the channels_ht and free it. */
@@ -1198,6 +1725,113 @@ end:
        return 0;
 }
 
+static
+int handle_notification_thread_command_session_rotation(
+       struct notification_thread_state *state,
+       enum notification_thread_command_type cmd_type,
+       const char *session_name, uid_t session_uid, gid_t session_gid,
+       uint64_t trace_archive_chunk_id,
+       struct lttng_trace_archive_location *location,
+       enum lttng_error_code *_cmd_result)
+{
+       int ret = 0;
+       enum lttng_error_code cmd_result = LTTNG_OK;
+       struct lttng_session_trigger_list *trigger_list;
+       struct lttng_trigger_list_element *trigger_list_element;
+       struct session_info *session_info;
+
+       rcu_read_lock();
+
+       session_info = find_or_create_session_info(state, session_name,
+                       session_uid, session_gid);
+       if (!session_info) {
+               /* Allocation error or an internal error occurred. */
+               ret = -1;
+               cmd_result = LTTNG_ERR_NOMEM;
+               goto end;
+       }
+
+       session_info->rotation.ongoing =
+                       cmd_type == NOTIFICATION_COMMAND_TYPE_SESSION_ROTATION_ONGOING;
+       session_info->rotation.id = trace_archive_chunk_id;
+       trigger_list = get_session_trigger_list(state, session_name);
+       if (!trigger_list) {
+               DBG("[notification-thread] No triggers applying to session \"%s\" found",
+                               session_name);
+               goto end;
+       }
+
+       cds_list_for_each_entry(trigger_list_element, &trigger_list->list,
+                       node) {
+               const struct lttng_condition *condition;
+               const struct lttng_action *action;
+               const struct lttng_trigger *trigger;
+               struct notification_client_list *client_list;
+               struct lttng_evaluation *evaluation = NULL;
+               enum lttng_condition_type condition_type;
+
+               trigger = trigger_list_element->trigger;
+               condition = lttng_trigger_get_const_condition(trigger);
+               assert(condition);
+               condition_type = lttng_condition_get_type(condition);
+
+               if (condition_type == LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING &&
+                               cmd_type != NOTIFICATION_COMMAND_TYPE_SESSION_ROTATION_ONGOING) {
+                       continue;
+               } else if (condition_type == LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED &&
+                               cmd_type != NOTIFICATION_COMMAND_TYPE_SESSION_ROTATION_COMPLETED) {
+                       continue;
+               }
+
+               action = lttng_trigger_get_const_action(trigger);
+
+               /* Notify actions are the only type currently supported. */
+               assert(lttng_action_get_type_const(action) ==
+                               LTTNG_ACTION_TYPE_NOTIFY);
+
+               client_list = get_client_list_from_condition(state, condition);
+               assert(client_list);
+
+               if (cds_list_empty(&client_list->list)) {
+                       /*
+                        * No clients interested in the evaluation's result,
+                        * skip it.
+                        */
+                       continue;
+               }
+
+               if (cmd_type == NOTIFICATION_COMMAND_TYPE_SESSION_ROTATION_ONGOING) {
+                       evaluation = lttng_evaluation_session_rotation_ongoing_create(
+                                       trace_archive_chunk_id);
+               } else {
+                       evaluation = lttng_evaluation_session_rotation_completed_create(
+                                       trace_archive_chunk_id, location);
+               }
+
+               if (!evaluation) {
+                       /* Internal error */
+                       ret = -1;
+                       cmd_result = LTTNG_ERR_UNK;
+                       goto end;
+               }
+
+               /* Dispatch evaluation result to all clients. */
+               ret = send_evaluation_to_clients(trigger_list_element->trigger,
+                               evaluation, client_list, state,
+                               session_info->uid,
+                               session_info->gid);
+               lttng_evaluation_destroy(evaluation);
+               if (caa_unlikely(ret)) {
+                       goto end;
+               }
+       }
+end:
+       session_info_put(session_info);
+       *_cmd_result = cmd_result;
+       rcu_read_unlock();
+       return ret;
+}
+
 static
 int condition_is_supported(struct lttng_condition *condition)
 {
@@ -1237,13 +1871,105 @@ end:
        return ret;
 }
 
+/* Must be called with RCU read lock held. */
+static
+int bind_trigger_to_matching_session(const struct lttng_trigger *trigger,
+               struct notification_thread_state *state)
+{
+       int ret = 0;
+       const struct lttng_condition *condition;
+       const char *session_name;
+       struct lttng_session_trigger_list *trigger_list;
+
+       condition = lttng_trigger_get_const_condition(trigger);
+       switch (lttng_condition_get_type(condition)) {
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING:
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED:
+       {
+               enum lttng_condition_status status;
+
+               status = lttng_condition_session_rotation_get_session_name(
+                               condition, &session_name);
+               if (status != LTTNG_CONDITION_STATUS_OK) {
+                       ERR("[notification-thread] Failed to bind trigger to session: unable to get 'session_rotation' condition's session name");
+                       ret = -1;
+                       goto end;
+               }
+               break;
+       }
+       default:
+               ret = -1;
+               goto end;
+       }
+
+       trigger_list = get_session_trigger_list(state, session_name);
+       if (!trigger_list) {
+               DBG("[notification-thread] Unable to bind trigger applying to session \"%s\" as it is not yet known to the notification system",
+                               session_name);
+               goto end;
+
+       }
+
+       DBG("[notification-thread] Newly registered trigger bound to session \"%s\"",
+                       session_name);
+       ret = lttng_session_trigger_list_add(trigger_list, trigger);
+end:
+       return ret;
+}
+
+/* Must be called with RCU read lock held. */
+static
+int bind_trigger_to_matching_channels(const struct lttng_trigger *trigger,
+               struct notification_thread_state *state)
+{
+       int ret = 0;
+       struct cds_lfht_node *node;
+       struct cds_lfht_iter iter;
+       struct channel_info *channel;
+
+       cds_lfht_for_each_entry(state->channels_ht, &iter, channel,
+                       channels_ht_node) {
+               struct lttng_trigger_list_element *trigger_list_element;
+               struct lttng_channel_trigger_list *trigger_list;
+               struct cds_lfht_iter lookup_iter;
+
+               if (!trigger_applies_to_channel(trigger, channel)) {
+                       continue;
+               }
+
+               cds_lfht_lookup(state->channel_triggers_ht,
+                               hash_channel_key(&channel->key),
+                               match_channel_trigger_list,
+                               &channel->key,
+                               &lookup_iter);
+               node = cds_lfht_iter_get_node(&lookup_iter);
+               assert(node);
+               trigger_list = caa_container_of(node,
+                               struct lttng_channel_trigger_list,
+                               channel_triggers_ht_node);
+
+               trigger_list_element = zmalloc(sizeof(*trigger_list_element));
+               if (!trigger_list_element) {
+                       ret = -1;
+                       goto end;
+               }
+               CDS_INIT_LIST_HEAD(&trigger_list_element->node);
+               trigger_list_element->trigger = trigger;
+               cds_list_add(&trigger_list_element->node, &trigger_list->list);
+               DBG("[notification-thread] Newly registered trigger bound to channel \"%s\"",
+                               channel->name);
+       }
+end:
+       return ret;
+}
+
 /*
  * FIXME A client's credentials are not checked when registering a trigger, nor
  *       are they stored alongside with the trigger.
  *
  * The effects of this are benign since:
  *     - The client will succeed in registering the trigger, as it is valid,
- *     - The trigger will, internally, be bound to the channel,
+ *     - The trigger will, internally, be bound to the channel/session,
  *     - The notifications will not be sent since the client's credentials
  *       are checked against the channel at that moment.
  *
@@ -1267,7 +1993,6 @@ int handle_notification_thread_command_register_trigger(
        struct notification_client_list_element *client_list_element, *tmp;
        struct cds_lfht_node *node;
        struct cds_lfht_iter iter;
-       struct channel_info *channel;
        bool free_trigger = true;
 
        rcu_read_lock();
@@ -1349,38 +2074,30 @@ int handle_notification_thread_command_register_trigger(
                        lttng_condition_hash(condition),
                        &client_list->notification_trigger_ht_node);
 
-       /*
-        * Add the trigger to list of triggers bound to the channels currently
-        * known.
-        */
-       cds_lfht_for_each_entry(state->channels_ht, &iter, channel,
-                       channels_ht_node) {
-               struct lttng_trigger_list_element *trigger_list_element;
-               struct lttng_channel_trigger_list *trigger_list;
-
-               if (!trigger_applies_to_channel(trigger, channel)) {
-                       continue;
+       switch (get_condition_binding_object(condition)) {
+       case LTTNG_OBJECT_TYPE_SESSION:
+               /* Add the trigger to the list if it matches a known session. */
+               ret = bind_trigger_to_matching_session(trigger, state);
+               if (ret) {
+                       goto error_free_client_list;
                }
-
-               cds_lfht_lookup(state->channel_triggers_ht,
-                               hash_channel_key(&channel->key),
-                               match_channel_trigger_list,
-                               &channel->key,
-                               &iter);
-               node = cds_lfht_iter_get_node(&iter);
-               assert(node);
-               trigger_list = caa_container_of(node,
-                               struct lttng_channel_trigger_list,
-                               channel_triggers_ht_node);
-
-               trigger_list_element = zmalloc(sizeof(*trigger_list_element));
-               if (!trigger_list_element) {
-                       ret = -1;
+               break;
+       case LTTNG_OBJECT_TYPE_CHANNEL:
+               /*
+                * Add the trigger to list of triggers bound to the channels
+                * currently known.
+                */
+               ret = bind_trigger_to_matching_channels(trigger, state);
+               if (ret) {
                        goto error_free_client_list;
                }
-               CDS_INIT_LIST_HEAD(&trigger_list_element->node);
-               trigger_list_element->trigger = trigger;
-               cds_list_add(&trigger_list_element->node, &trigger_list->list);
+               break;
+       case LTTNG_OBJECT_TYPE_NONE:
+               break;
+       default:
+               ERR("[notification-thread] Unknown object type on which to bind a newly registered trigger was encountered");
+               ret = -1;
+               goto error_free_client_list;
        }
 
        /*
@@ -1447,6 +2164,20 @@ error:
        return ret;
 }
 
+static
+void free_notification_client_list_rcu(struct rcu_head *node)
+{
+       free(caa_container_of(node, struct notification_client_list,
+                       rcu_node));
+}
+
+static
+void free_lttng_trigger_ht_element_rcu(struct rcu_head *node)
+{
+       free(caa_container_of(node, struct lttng_trigger_ht_element,
+                       rcu_node));
+}
+
 static
 int handle_notification_thread_command_unregister_trigger(
                struct notification_thread_state *state,
@@ -1454,7 +2185,7 @@ int handle_notification_thread_command_unregister_trigger(
                enum lttng_error_code *_cmd_reply)
 {
        struct cds_lfht_iter iter;
-       struct cds_lfht_node *node, *triggers_ht_node;
+       struct cds_lfht_node *triggers_ht_node;
        struct lttng_channel_trigger_list *trigger_list;
        struct notification_client_list *client_list;
        struct notification_client_list_element *client_list_element, *tmp;
@@ -1486,8 +2217,8 @@ int handle_notification_thread_command_unregister_trigger(
 
                cds_list_for_each_entry_safe(trigger_element, tmp,
                                &trigger_list->list, node) {
-                       struct lttng_condition *current_condition =
-                                       lttng_trigger_get_condition(
+                       const struct lttng_condition *current_condition =
+                                       lttng_trigger_get_const_condition(
                                                trigger_element->trigger);
 
                        assert(current_condition);
@@ -1507,21 +2238,16 @@ int handle_notification_thread_command_unregister_trigger(
         * Remove and release the client list from
         * notification_trigger_clients_ht.
         */
-       cds_lfht_lookup(state->notification_trigger_clients_ht,
-                       lttng_condition_hash(condition),
-                       match_client_list,
-                       trigger,
-                       &iter);
-       node = cds_lfht_iter_get_node(&iter);
-       assert(node);
-       client_list = caa_container_of(node, struct notification_client_list,
-                       notification_trigger_ht_node);
+       client_list = get_client_list_from_condition(state, condition);
+       assert(client_list);
+
        cds_list_for_each_entry_safe(client_list_element, tmp,
                        &client_list->list, node) {
                free(client_list_element);
        }
-       cds_lfht_del(state->notification_trigger_clients_ht, node);
-       free(client_list);
+       cds_lfht_del(state->notification_trigger_clients_ht,
+                       &client_list->notification_trigger_ht_node);
+       call_rcu(&client_list->rcu_node, free_notification_client_list_rcu);
 
        /* Remove trigger from triggers_ht. */
        trigger_ht_element = caa_container_of(triggers_ht_node,
@@ -1533,7 +2259,7 @@ int handle_notification_thread_command_unregister_trigger(
        action = lttng_trigger_get_action(trigger_ht_element->trigger);
        lttng_action_destroy(action);
        lttng_trigger_destroy(trigger_ht_element->trigger);
-       free(trigger_ht_element);
+       call_rcu(&trigger_ht_element->rcu_node, free_lttng_trigger_ht_element_rcu);
 end:
        rcu_read_unlock();
        if (_cmd_reply) {
@@ -1552,9 +2278,9 @@ int handle_notification_thread_command(
        struct notification_thread_command *cmd;
 
        /* Read the event pipe to put it back into a quiescent state. */
-       ret = read(lttng_pipe_get_readfd(handle->cmd_queue.event_pipe), &counter,
+       ret = lttng_read(lttng_pipe_get_readfd(handle->cmd_queue.event_pipe), &counter,
                        sizeof(counter));
-       if (ret == -1) {
+       if (ret != sizeof(counter)) {
                goto error;
        }
 
@@ -1594,6 +2320,21 @@ int handle_notification_thread_command(
                                cmd->parameters.remove_channel.domain,
                                &cmd->reply_code);
                break;
+       case NOTIFICATION_COMMAND_TYPE_SESSION_ROTATION_ONGOING:
+       case NOTIFICATION_COMMAND_TYPE_SESSION_ROTATION_COMPLETED:
+               DBG("[notification-thread] Received session rotation %s command",
+                               cmd->type == NOTIFICATION_COMMAND_TYPE_SESSION_ROTATION_ONGOING ?
+                               "ongoing" : "completed");
+               ret = handle_notification_thread_command_session_rotation(
+                               state,
+                               cmd->type,
+                               cmd->parameters.session_rotation.session_name,
+                               cmd->parameters.session_rotation.uid,
+                               cmd->parameters.session_rotation.gid,
+                               cmd->parameters.session_rotation.trace_archive_chunk_id,
+                               cmd->parameters.session_rotation.location,
+                               &cmd->reply_code);
+               break;
        case NOTIFICATION_COMMAND_TYPE_QUIT:
                DBG("[notification-thread] Received quit command");
                cmd->reply_code = LTTNG_OK;
@@ -1803,6 +2544,7 @@ int handle_notification_thread_trigger_unregister_all(
        struct cds_lfht_iter iter;
        struct lttng_trigger_ht_element *trigger_ht_element;
 
+       rcu_read_lock();
        cds_lfht_for_each_entry(state->triggers_ht, &iter, trigger_ht_element,
                        node) {
                int ret = handle_notification_thread_command_unregister_trigger(
@@ -1811,6 +2553,7 @@ int handle_notification_thread_trigger_unregister_all(
                        error_occurred = true;
                }
        }
+       rcu_read_unlock();
        return error_occurred ? -1 : 0;
 }
 
@@ -2268,7 +3011,7 @@ bool evaluate_session_consumed_size_condition(
 }
 
 static
-int evaluate_condition(const struct lttng_condition *condition,
+int evaluate_buffer_condition(const struct lttng_condition *condition,
                struct lttng_evaluation **evaluation,
                const struct notification_thread_state *state,
                const struct channel_state_sample *previous_sample,
@@ -2339,7 +3082,6 @@ int evaluate_condition(const struct lttng_condition *condition,
                break;
        case LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE:
                *evaluation = lttng_evaluation_session_consumed_size_create(
-                               condition_type,
                                latest_session_consumed_total);
                break;
        default:
@@ -2371,8 +3113,8 @@ int client_enqueue_dropped_notification(struct notification_client *client,
 }
 
 static
-int send_evaluation_to_clients(struct lttng_trigger *trigger,
-               struct lttng_evaluation *evaluation,
+int send_evaluation_to_clients(const struct lttng_trigger *trigger,
+               const struct lttng_evaluation *evaluation,
                struct notification_client_list* client_list,
                struct notification_thread_state *state,
                uid_t channel_uid, gid_t channel_gid)
@@ -2380,51 +3122,33 @@ int send_evaluation_to_clients(struct lttng_trigger *trigger,
        int ret = 0;
        struct lttng_dynamic_buffer msg_buffer;
        struct notification_client_list_element *client_list_element, *tmp;
-       struct lttng_notification *notification;
-       struct lttng_condition *condition;
-       ssize_t expected_notification_size, notification_size;
-       struct lttng_notification_channel_message msg;
+       const struct lttng_notification notification = {
+               .condition = (struct lttng_condition *) lttng_trigger_get_const_condition(trigger),
+               .evaluation = (struct lttng_evaluation *) evaluation,
+       };
+       struct lttng_notification_channel_message msg_header = {
+               .type = (int8_t) LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION,
+       };
 
        lttng_dynamic_buffer_init(&msg_buffer);
 
-       condition = lttng_trigger_get_condition(trigger);
-       assert(condition);
-
-       notification = lttng_notification_create(condition, evaluation);
-       if (!notification) {
-               ret = -1;
-               goto end;
-       }
-
-       expected_notification_size = lttng_notification_serialize(notification,
-                       NULL);
-       if (expected_notification_size < 0) {
-               ERR("[notification-thread] Failed to get size of serialized notification");
-               ret = -1;
-               goto end;
-       }
-
-       msg.type = (int8_t) LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION;
-       msg.size = (uint32_t) expected_notification_size;
-       ret = lttng_dynamic_buffer_append(&msg_buffer, &msg, sizeof(msg));
+       ret = lttng_dynamic_buffer_append(&msg_buffer, &msg_header,
+                       sizeof(msg_header));
        if (ret) {
                goto end;
        }
 
-       ret = lttng_dynamic_buffer_set_size(&msg_buffer,
-                       msg_buffer.size + expected_notification_size);
+       ret = lttng_notification_serialize(&notification, &msg_buffer);
        if (ret) {
-               goto end;
-       }
-
-       notification_size = lttng_notification_serialize(notification,
-                       msg_buffer.data + sizeof(msg));
-       if (notification_size != expected_notification_size) {
                ERR("[notification-thread] Failed to serialize notification");
                ret = -1;
                goto end;
        }
 
+       /* Update payload size. */
+       ((struct lttng_notification_channel_message * ) msg_buffer.data)->size =
+                       (uint32_t) (msg_buffer.size - sizeof(msg_header));
+
        cds_list_for_each_entry_safe(client_list_element, tmp,
                        &client_list->list, node) {
                struct notification_client *client =
@@ -2474,7 +3198,6 @@ int send_evaluation_to_clients(struct lttng_trigger *trigger,
        }
        ret = 0;
 end:
-       lttng_notification_destroy(notification);
        lttng_dynamic_buffer_reset(&msg_buffer);
        return ret;
 }
@@ -2615,36 +3338,27 @@ int handle_notification_thread_channel_sample(
                        channel_triggers_ht_node);
        cds_list_for_each_entry(trigger_list_element, &trigger_list->list,
                        node) {
-               struct lttng_condition *condition;
-               struct lttng_action *action;
-               struct lttng_trigger *trigger;
+               const struct lttng_condition *condition;
+               const struct lttng_action *action;
+               const struct lttng_trigger *trigger;
                struct notification_client_list *client_list;
                struct lttng_evaluation *evaluation = NULL;
 
                trigger = trigger_list_element->trigger;
-               condition = lttng_trigger_get_condition(trigger);
+               condition = lttng_trigger_get_const_condition(trigger);
                assert(condition);
-               action = lttng_trigger_get_action(trigger);
+               action = lttng_trigger_get_const_action(trigger);
 
                /* Notify actions are the only type currently supported. */
-               assert(lttng_action_get_type(action) ==
+               assert(lttng_action_get_type_const(action) ==
                                LTTNG_ACTION_TYPE_NOTIFY);
 
                /*
                 * Check if any client is subscribed to the result of this
                 * evaluation.
                 */
-               cds_lfht_lookup(state->notification_trigger_clients_ht,
-                               lttng_condition_hash(condition),
-                               match_client_list,
-                               trigger,
-                               &iter);
-               node = cds_lfht_iter_get_node(&iter);
-               assert(node);
-
-               client_list = caa_container_of(node,
-                               struct notification_client_list,
-                               notification_trigger_ht_node);
+               client_list = get_client_list_from_condition(state, condition);
+               assert(client_list);
                if (cds_list_empty(&client_list->list)) {
                        /*
                         * No clients interested in the evaluation's result,
@@ -2653,7 +3367,7 @@ int handle_notification_thread_channel_sample(
                        continue;
                }
 
-               ret = evaluate_condition(condition, &evaluation, state,
+               ret = evaluate_buffer_condition(condition, &evaluation, state,
                                previous_sample_available ? &previous_sample : NULL,
                                &latest_sample,
                                previous_session_consumed_total,
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