X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fbin%2Flttng-sessiond%2Ftrace-kernel.c;h=044fc98d2510ddd17c1bb36353e99f9780b8d933;hp=8fb92f12ab13c08386108c0feddcc3769a1aee95;hb=d42266a417afa6e8ca6024590b8282002aebca07;hpb=799e2c4f4ecb595fcb52c3e6affd3b4ec7b5b24e

diff --git a/src/bin/lttng-sessiond/trace-kernel.c b/src/bin/lttng-sessiond/trace-kernel.c
index 8fb92f12a..044fc98d2 100644
--- a/src/bin/lttng-sessiond/trace-kernel.c
+++ b/src/bin/lttng-sessiond/trace-kernel.c
@@ -1,44 +1,48 @@
 /*
- * Copyright (C)  2011 - David Goulet <david.goulet@polymtl.ca>
+ * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
  *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; only version 2
- * of the License.
+ * 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  */
 
-#define _GNU_SOURCE
+#define _LGPL_SOURCE
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 
+#include <lttng/event.h>
+#include <lttng/lttng-error.h>
+#include <lttng/userspace-probe.h>
+#include <lttng/userspace-probe-internal.h>
+
 #include <common/common.h>
 #include <common/defaults.h>
+#include <common/trace-chunk.h>
+#include <common/macros.h>
 
+#include "consumer.h"
 #include "trace-kernel.h"
+#include "lttng-sessiond.h"
+#include "notification-thread-commands.h"
 
 /*
  * Find the channel name for the given kernel session.
  */
 struct ltt_kernel_channel *trace_kernel_get_channel_by_name(
-		char *name, struct ltt_kernel_session *session)
+		const char *name, struct ltt_kernel_session *session)
 {
 	struct ltt_kernel_channel *chan;
 
-	if (session == NULL) {
-		ERR("Undefine session");
-		goto error;
-	}
+	assert(session);
+	assert(name);
+
+	/*
+	 * If we receive an empty string for channel name, it means the
+	 * default channel name is requested.
+	 */
+	if (name[0] == '\0')
+		name = DEFAULT_CHANNEL_NAME;
 
 	DBG("Trying to find channel %s", name);
 
@@ -49,33 +53,82 @@ struct ltt_kernel_channel *trace_kernel_get_channel_by_name(
 		}
 	}
 
-error:
 	return NULL;
 }
 
+/*
+ * Find the event for the given channel.
+ */
+struct ltt_kernel_event *trace_kernel_find_event(
+		char *name, struct ltt_kernel_channel *channel,
+		enum lttng_event_type type,
+		struct lttng_filter_bytecode *filter)
+{
+	struct ltt_kernel_event *ev;
+	int found = 0;
+
+	assert(name);
+	assert(channel);
+
+	cds_list_for_each_entry(ev, &channel->events_list.head, list) {
+		if (type != LTTNG_EVENT_ALL && ev->type != type) {
+			continue;
+		}
+		if (strcmp(name, ev->event->name)) {
+			continue;
+		}
+		if ((ev->filter && !filter) || (!ev->filter && filter)) {
+			continue;
+		}
+		if (ev->filter && filter) {
+			if (ev->filter->len != filter->len ||
+					memcmp(ev->filter->data, filter->data,
+						filter->len) != 0) {
+				continue;
+			}
+		}
+		found = 1;
+		break;
+	}
+	if (found) {
+		DBG("Found event %s for channel %s", name,
+			channel->channel->name);
+		return ev;
+	} else {
+		return NULL;
+	}
+}
+
 /*
  * Find the event name for the given channel.
  */
 struct ltt_kernel_event *trace_kernel_get_event_by_name(
-		char *name, struct ltt_kernel_channel *channel)
+		char *name, struct ltt_kernel_channel *channel,
+		enum lttng_event_type type)
 {
 	struct ltt_kernel_event *ev;
+	int found = 0;
 
-	if (channel == NULL) {
-		ERR("Undefine channel");
-		goto error;
-	}
+	assert(name);
+	assert(channel);
 
 	cds_list_for_each_entry(ev, &channel->events_list.head, list) {
-		if (strcmp(name, ev->event->name) == 0) {
-			DBG("Found event by name %s for channel %s", name,
-					channel->channel->name);
-			return ev;
+		if (type != LTTNG_EVENT_ALL && ev->type != type) {
+			continue;
+		}
+		if (strcmp(name, ev->event->name)) {
+			continue;
 		}
+		found = 1;
+		break;
+	}
+	if (found) {
+		DBG("Found event %s for channel %s", name,
+			channel->channel->name);
+		return ev;
+	} else {
+		return NULL;
 	}
-
-error:
-	return NULL;
 }
 
 /*
@@ -83,37 +136,66 @@ error:
  *
  * Return pointer to structure or NULL.
  */
-struct ltt_kernel_session *trace_kernel_create_session(char *path)
+struct ltt_kernel_session *trace_kernel_create_session(void)
 {
-	int ret;
-	struct ltt_kernel_session *lks;
+	struct ltt_kernel_session *lks = NULL;
 
 	/* Allocate a new ltt kernel session */
 	lks = zmalloc(sizeof(struct ltt_kernel_session));
 	if (lks == NULL) {
 		PERROR("create kernel session zmalloc");
-		goto error;
+		goto alloc_error;
 	}
 
 	/* Init data structure */
-	lks->fd = 0;
-	lks->metadata_stream_fd = 0;
+	lks->fd = -1;
+	lks->metadata_stream_fd = -1;
 	lks->channel_count = 0;
 	lks->stream_count_global = 0;
 	lks->metadata = NULL;
-	lks->consumer_fd = 0;
 	CDS_INIT_LIST_HEAD(&lks->channel_list.head);
 
-	/* Set session path */
-	ret = asprintf(&lks->trace_path, "%s/kernel", path);
-	if (ret < 0) {
-		PERROR("asprintf kernel traces path");
+	lks->tracker_pid = process_attr_tracker_create();
+	if (!lks->tracker_pid) {
+		goto error;
+	}
+	lks->tracker_vpid = process_attr_tracker_create();
+	if (!lks->tracker_vpid) {
+		goto error;
+	}
+	lks->tracker_uid = process_attr_tracker_create();
+	if (!lks->tracker_uid) {
+		goto error;
+	}
+	lks->tracker_vuid = process_attr_tracker_create();
+	if (!lks->tracker_vuid) {
+		goto error;
+	}
+	lks->tracker_gid = process_attr_tracker_create();
+	if (!lks->tracker_gid) {
+		goto error;
+	}
+	lks->tracker_vgid = process_attr_tracker_create();
+	if (!lks->tracker_vgid) {
+		goto error;
+	}
+	lks->consumer = consumer_create_output(CONSUMER_DST_LOCAL);
+	if (lks->consumer == NULL) {
 		goto error;
 	}
 
 	return lks;
 
 error:
+	process_attr_tracker_destroy(lks->tracker_pid);
+	process_attr_tracker_destroy(lks->tracker_vpid);
+	process_attr_tracker_destroy(lks->tracker_uid);
+	process_attr_tracker_destroy(lks->tracker_vuid);
+	process_attr_tracker_destroy(lks->tracker_gid);
+	process_attr_tracker_destroy(lks->tracker_vgid);
+	free(lks);
+
+alloc_error:
 	return NULL;
 }
 
@@ -122,10 +204,13 @@ error:
  *
  * Return pointer to structure or NULL.
  */
-struct ltt_kernel_channel *trace_kernel_create_channel(struct lttng_channel *chan, char *path)
+struct ltt_kernel_channel *trace_kernel_create_channel(
+		struct lttng_channel *chan)
 {
-	int ret;
 	struct ltt_kernel_channel *lkc;
+	struct lttng_channel_extended *extended = NULL;
+
+	assert(chan);
 
 	lkc = zmalloc(sizeof(struct ltt_kernel_channel));
 	if (lkc == NULL) {
@@ -138,43 +223,119 @@ struct ltt_kernel_channel *trace_kernel_create_channel(struct lttng_channel *cha
 		PERROR("lttng_channel zmalloc");
 		goto error;
 	}
+
+	extended = zmalloc(sizeof(struct lttng_channel_extended));
+	if (!extended) {
+		PERROR("lttng_channel_channel zmalloc");
+		goto error;
+	}
 	memcpy(lkc->channel, chan, sizeof(struct lttng_channel));
+	memcpy(extended, chan->attr.extended.ptr, sizeof(struct lttng_channel_extended));
+	lkc->channel->attr.extended.ptr = extended;
+	extended = NULL;
+
+	/*
+	 * If we receive an empty string for channel name, it means the
+	 * default channel name is requested.
+	 */
+	if (chan->name[0] == '\0') {
+		strncpy(lkc->channel->name, DEFAULT_CHANNEL_NAME,
+			sizeof(lkc->channel->name));
+	}
+	lkc->channel->name[LTTNG_KERNEL_SYM_NAME_LEN - 1] = '\0';
 
-	lkc->fd = 0;
+	lkc->fd = -1;
 	lkc->stream_count = 0;
 	lkc->event_count = 0;
 	lkc->enabled = 1;
-	lkc->ctx = NULL;
+	lkc->published_to_notification_thread = false;
 	/* Init linked list */
 	CDS_INIT_LIST_HEAD(&lkc->events_list.head);
 	CDS_INIT_LIST_HEAD(&lkc->stream_list.head);
-	/* Set default trace output path */
-	ret = asprintf(&lkc->pathname, "%s", path);
-	if (ret < 0) {
-		PERROR("asprintf kernel create channel");
-		goto error;
-	}
+	CDS_INIT_LIST_HEAD(&lkc->ctx_list);
 
 	return lkc;
 
 error:
+	if (lkc) {
+		free(lkc->channel);
+	}
+	free(extended);
+	free(lkc);
 	return NULL;
 }
 
+/*
+ * Allocate and init a kernel context object.
+ *
+ * Return the allocated object or NULL on error.
+ */
+struct ltt_kernel_context *trace_kernel_create_context(
+		struct lttng_kernel_context *ctx)
+{
+	struct ltt_kernel_context *kctx;
+
+	kctx = zmalloc(sizeof(*kctx));
+	if (!kctx) {
+		PERROR("zmalloc kernel context");
+		goto error;
+	}
+
+	if (ctx) {
+		memcpy(&kctx->ctx, ctx, sizeof(kctx->ctx));
+	}
+error:
+	return kctx;
+}
+
+/*
+ * Allocate and init a kernel context object from an existing kernel context
+ * object.
+ *
+ * Return the allocated object or NULL on error.
+ */
+struct ltt_kernel_context *trace_kernel_copy_context(
+		struct ltt_kernel_context *kctx)
+{
+	struct ltt_kernel_context *kctx_copy;
+
+	assert(kctx);
+	kctx_copy = zmalloc(sizeof(*kctx_copy));
+	if (!kctx_copy) {
+		PERROR("zmalloc ltt_kernel_context");
+		goto error;
+	}
+
+	memcpy(kctx_copy, kctx, sizeof(*kctx_copy));
+	memset(&kctx_copy->list, 0, sizeof(kctx_copy->list));
+
+error:
+	return kctx_copy;
+}
+
 /*
  * Allocate and initialize a kernel event. Set name and event type.
+ * We own filter_expression, and filter.
  *
  * Return pointer to structure or NULL.
  */
-struct ltt_kernel_event *trace_kernel_create_event(struct lttng_event *ev)
+enum lttng_error_code trace_kernel_create_event(
+		struct lttng_event *ev, char *filter_expression,
+		struct lttng_filter_bytecode *filter,
+		struct ltt_kernel_event **kernel_event)
 {
-	struct ltt_kernel_event *lke;
+	enum lttng_error_code ret;
 	struct lttng_kernel_event *attr;
+	struct ltt_kernel_event *local_kernel_event;
+	struct lttng_userspace_probe_location *userspace_probe_location = NULL;
+
+	assert(ev);
 
-	lke = zmalloc(sizeof(struct ltt_kernel_event));
+	local_kernel_event = zmalloc(sizeof(struct ltt_kernel_event));
 	attr = zmalloc(sizeof(struct lttng_kernel_event));
-	if (lke == NULL || attr == NULL) {
+	if (local_kernel_event == NULL || attr == NULL) {
 		PERROR("kernel event zmalloc");
+		ret = LTTNG_ERR_NOMEM;
 		goto error;
 	}
 
@@ -187,11 +348,88 @@ struct ltt_kernel_event *trace_kernel_create_event(struct lttng_event *ev)
 				ev->attr.probe.symbol_name, LTTNG_KERNEL_SYM_NAME_LEN);
 		attr->u.kprobe.symbol_name[LTTNG_KERNEL_SYM_NAME_LEN - 1] = '\0';
 		break;
+	case LTTNG_EVENT_USERSPACE_PROBE:
+	{
+		const struct lttng_userspace_probe_location* location = NULL;
+		const struct lttng_userspace_probe_location_lookup_method *lookup = NULL;
+
+		location = lttng_event_get_userspace_probe_location(ev);
+		if (!location) {
+			ret = LTTNG_ERR_PROBE_LOCATION_INVAL;
+			goto error;
+		}
+
+		/*
+		 * From this point on, the specific term 'uprobe' is used
+		 * instead of the generic 'userspace probe' because it's the
+		 * technology used at the moment for this instrumentation.
+		 * LTTng currently implements userspace probes using uprobes.
+		 * In the interactions with the kernel tracer, we use the
+		 * uprobe term.
+		 */
+		attr->instrumentation = LTTNG_KERNEL_UPROBE;
+
+		/*
+		 * Only the elf lookup method is supported at the moment.
+		 */
+		lookup = lttng_userspace_probe_location_get_lookup_method(
+				location);
+		if (!lookup) {
+			ret = LTTNG_ERR_PROBE_LOCATION_INVAL;
+			goto error;
+		}
+
+		/*
+		 * From the kernel tracer's perspective, all userspace probe
+		 * event types are all the same: a file and an offset.
+		 */
+		switch (lttng_userspace_probe_location_lookup_method_get_type(lookup)) {
+		case LTTNG_USERSPACE_PROBE_LOCATION_LOOKUP_METHOD_TYPE_FUNCTION_ELF:
+			/* Get the file descriptor on the target binary. */
+			attr->u.uprobe.fd =
+					lttng_userspace_probe_location_function_get_binary_fd(location);
+
+			/*
+			 * Save a reference to the probe location used during
+			 * the listing of events. Close its FD since it won't
+			 * be needed for listing.
+			 */
+			userspace_probe_location =
+					lttng_userspace_probe_location_copy(location);
+			ret = lttng_userspace_probe_location_function_set_binary_fd(
+					userspace_probe_location, -1);
+			if (ret) {
+				goto error;
+			}
+			break;
+		case LTTNG_USERSPACE_PROBE_LOCATION_LOOKUP_METHOD_TYPE_TRACEPOINT_SDT:
+			/* Get the file descriptor on the target binary. */
+			attr->u.uprobe.fd =
+					lttng_userspace_probe_location_tracepoint_get_binary_fd(location);
+
+			/*
+			 * Save a reference to the probe location used during the listing of
+			 * events. Close its FD since it won't be needed for listing.
+			 */
+			userspace_probe_location =
+					lttng_userspace_probe_location_copy(location);
+			ret = lttng_userspace_probe_location_tracepoint_set_binary_fd(
+					userspace_probe_location, -1);
+			if (ret) {
+				goto error;
+			}
+			break;
+		default:
+			DBG("Unsupported lookup method type");
+			ret = LTTNG_ERR_PROBE_LOCATION_INVAL;
+			goto error;
+		}
+		break;
+	}
 	case LTTNG_EVENT_FUNCTION:
 		attr->instrumentation = LTTNG_KERNEL_KRETPROBE;
 		attr->u.kretprobe.addr = ev->attr.probe.addr;
 		attr->u.kretprobe.offset = ev->attr.probe.offset;
-		attr->u.kretprobe.offset = ev->attr.probe.offset;
 		strncpy(attr->u.kretprobe.symbol_name,
 				ev->attr.probe.symbol_name, LTTNG_KERNEL_SYM_NAME_LEN);
 		attr->u.kretprobe.symbol_name[LTTNG_KERNEL_SYM_NAME_LEN - 1] = '\0';
@@ -213,6 +451,7 @@ struct ltt_kernel_event *trace_kernel_create_event(struct lttng_event *ev)
 		break;
 	default:
 		ERR("Unknown kernel instrumentation type (%d)", ev->type);
+		ret = LTTNG_ERR_INVALID;
 		goto error;
 	}
 
@@ -221,15 +460,23 @@ struct ltt_kernel_event *trace_kernel_create_event(struct lttng_event *ev)
 	attr->name[LTTNG_KERNEL_SYM_NAME_LEN - 1] = '\0';
 
 	/* Setting up a kernel event */
-	lke->fd = 0;
-	lke->event = attr;
-	lke->enabled = 1;
-	lke->ctx = NULL;
+	local_kernel_event->fd = -1;
+	local_kernel_event->event = attr;
+	local_kernel_event->enabled = 1;
+	local_kernel_event->filter_expression = filter_expression;
+	local_kernel_event->filter = filter;
+	local_kernel_event->userspace_probe_location = userspace_probe_location;
+
+	*kernel_event = local_kernel_event;
 
-	return lke;
+	return LTTNG_OK;
 
 error:
-	return NULL;
+	free(filter_expression);
+	free(filter);
+	free(local_kernel_event);
+	free(attr);
+	return ret;
 }
 
 /*
@@ -237,7 +484,7 @@ error:
  *
  * Return pointer to structure or NULL.
  */
-struct ltt_kernel_metadata *trace_kernel_create_metadata(char *path)
+struct ltt_kernel_metadata *trace_kernel_create_metadata(void)
 {
 	int ret;
 	struct ltt_kernel_metadata *lkm;
@@ -250,27 +497,48 @@ struct ltt_kernel_metadata *trace_kernel_create_metadata(char *path)
 		goto error;
 	}
 
+	ret = lttng_strncpy(
+			chan->name, DEFAULT_METADATA_NAME, sizeof(chan->name));
+	if (ret) {
+		ERR("Failed to initialize metadata channel name to `%s`",
+				DEFAULT_METADATA_NAME);
+		goto error;
+	}
+
 	/* Set default attributes */
-	chan->attr.overwrite = DEFAULT_CHANNEL_OVERWRITE;
-	chan->attr.subbuf_size = DEFAULT_METADATA_SUBBUF_SIZE;
+	chan->attr.overwrite = DEFAULT_METADATA_OVERWRITE;
+	chan->attr.subbuf_size = default_get_metadata_subbuf_size();
 	chan->attr.num_subbuf = DEFAULT_METADATA_SUBBUF_NUM;
-	chan->attr.switch_timer_interval = DEFAULT_CHANNEL_SWITCH_TIMER;
-	chan->attr.read_timer_interval = DEFAULT_CHANNEL_READ_TIMER;
-	chan->attr.output = DEFAULT_KERNEL_CHANNEL_OUTPUT;
+	chan->attr.switch_timer_interval = DEFAULT_METADATA_SWITCH_TIMER;
+	chan->attr.read_timer_interval = DEFAULT_METADATA_READ_TIMER;;
+
+
+	/*
+	 * The metadata channel of kernel sessions must use the "mmap"
+	 * back-end since the consumer daemon accumulates complete
+	 * metadata units before sending them to the relay daemon in
+	 * live mode. The consumer daemon also needs to extract the contents
+	 * of the metadata cache when computing a rotation position.
+	 *
+	 * In both cases, it is not possible to rely on the splice
+	 * back-end as the consumer daemon may need to accumulate more
+	 * content than can be backed by the ring buffer's underlying
+	 * pages.
+	 */
+	chan->attr.output = LTTNG_EVENT_MMAP;
+	chan->attr.tracefile_size = 0;
+	chan->attr.tracefile_count = 0;
+	chan->attr.live_timer_interval = 0;
 
 	/* Init metadata */
-	lkm->fd = 0;
+	lkm->fd = -1;
 	lkm->conf = chan;
-	/* Set default metadata path */
-	ret = asprintf(&lkm->pathname, "%s/metadata", path);
-	if (ret < 0) {
-		PERROR("asprintf kernel metadata");
-		goto error;
-	}
 
 	return lkm;
 
 error:
+	free(lkm);
+	free(chan);
 	return NULL;
 }
 
@@ -280,20 +548,32 @@ error:
  *
  * Return pointer to structure or NULL.
  */
-struct ltt_kernel_stream *trace_kernel_create_stream(void)
+struct ltt_kernel_stream *trace_kernel_create_stream(const char *name,
+		unsigned int count)
 {
+	int ret;
 	struct ltt_kernel_stream *lks;
 
+	assert(name);
+
 	lks = zmalloc(sizeof(struct ltt_kernel_stream));
 	if (lks == NULL) {
 		PERROR("kernel stream zmalloc");
 		goto error;
 	}
 
+	/* Set name */
+	ret = snprintf(lks->name, sizeof(lks->name), "%s_%u", name, count);
+	if (ret < 0) {
+		PERROR("snprintf stream name");
+		goto error;
+	}
+	lks->name[sizeof(lks->name) - 1] = '\0';
+
 	/* Init stream */
-	lks->fd = 0;
-	lks->pathname = NULL;
+	lks->fd = -1;
 	lks->state = 0;
+	lks->cpu = count;
 
 	return lks;
 
@@ -306,18 +586,21 @@ error:
  */
 void trace_kernel_destroy_stream(struct ltt_kernel_stream *stream)
 {
-	int ret;
+	assert(stream);
 
 	DBG("[trace] Closing stream fd %d", stream->fd);
 	/* Close kernel fd */
-	ret = close(stream->fd);
-	if (ret) {
-		PERROR("close");
+	if (stream->fd >= 0) {
+		int ret;
+
+		ret = close(stream->fd);
+		if (ret) {
+			PERROR("close");
+		}
 	}
 	/* Remove from stream list */
 	cds_list_del(&stream->list);
 
-	free(stream->pathname);
 	free(stream);
 }
 
@@ -326,9 +609,11 @@ void trace_kernel_destroy_stream(struct ltt_kernel_stream *stream)
  */
 void trace_kernel_destroy_event(struct ltt_kernel_event *event)
 {
-	int ret;
+	assert(event);
 
 	if (event->fd >= 0) {
+		int ret;
+
 		DBG("[trace] Closing event fd %d", event->fd);
 		/* Close kernel fd */
 		ret = close(event->fd);
@@ -342,11 +627,26 @@ void trace_kernel_destroy_event(struct ltt_kernel_event *event)
 	/* Remove from event list */
 	cds_list_del(&event->list);
 
+	free(event->filter_expression);
+	free(event->filter);
+
 	free(event->event);
-	free(event->ctx);
 	free(event);
 }
 
+/*
+ * Cleanup kernel context structure.
+ */
+void trace_kernel_destroy_context(struct ltt_kernel_context *ctx)
+{
+	assert(ctx);
+
+	if (ctx->in_list) {
+		cds_list_del(&ctx->list);
+	}
+	free(ctx);
+}
+
 /*
  * Cleanup kernel channel structure.
  */
@@ -354,13 +654,19 @@ void trace_kernel_destroy_channel(struct ltt_kernel_channel *channel)
 {
 	struct ltt_kernel_stream *stream, *stmp;
 	struct ltt_kernel_event *event, *etmp;
+	struct ltt_kernel_context *ctx, *ctmp;
 	int ret;
+	enum lttng_error_code status;
+
+	assert(channel);
 
 	DBG("[trace] Closing channel fd %d", channel->fd);
 	/* Close kernel fd */
-	ret = close(channel->fd);
-	if (ret) {
-		PERROR("close");
+	if (channel->fd >= 0) {
+		ret = close(channel->fd);
+		if (ret) {
+			PERROR("close");
+		}
 	}
 
 	/* For each stream in the channel list */
@@ -373,12 +679,23 @@ void trace_kernel_destroy_channel(struct ltt_kernel_channel *channel)
 		trace_kernel_destroy_event(event);
 	}
 
+	/* For each context in the channel list */
+	cds_list_for_each_entry_safe(ctx, ctmp, &channel->ctx_list, list) {
+		trace_kernel_destroy_context(ctx);
+	}
+
 	/* Remove from channel list */
 	cds_list_del(&channel->list);
 
-	free(channel->pathname);
+	if (notification_thread_handle
+			&& channel->published_to_notification_thread) {
+		status = notification_thread_command_remove_channel(
+				notification_thread_handle,
+				channel->key, LTTNG_DOMAIN_KERNEL);
+		assert(status == LTTNG_OK);
+	}
+	free(channel->channel->attr.extended.ptr);
 	free(channel->channel);
-	free(channel->ctx);
 	free(channel);
 }
 
@@ -387,36 +704,45 @@ void trace_kernel_destroy_channel(struct ltt_kernel_channel *channel)
  */
 void trace_kernel_destroy_metadata(struct ltt_kernel_metadata *metadata)
 {
-	int ret;
+	assert(metadata);
 
 	DBG("[trace] Closing metadata fd %d", metadata->fd);
 	/* Close kernel fd */
-	ret = close(metadata->fd);
-	if (ret) {
-		PERROR("close");
+	if (metadata->fd >= 0) {
+		int ret;
+
+		ret = close(metadata->fd);
+		if (ret) {
+			PERROR("close");
+		}
 	}
 
 	free(metadata->conf);
-	free(metadata->pathname);
 	free(metadata);
 }
 
 /*
  * Cleanup kernel session structure
+ *
+ * Should *NOT* be called with RCU read-side lock held.
  */
 void trace_kernel_destroy_session(struct ltt_kernel_session *session)
 {
 	struct ltt_kernel_channel *channel, *ctmp;
 	int ret;
 
+	assert(session);
+
 	DBG("[trace] Closing session fd %d", session->fd);
 	/* Close kernel fds */
-	ret = close(session->fd);
-	if (ret) {
-		PERROR("close");
+	if (session->fd >= 0) {
+		ret = close(session->fd);
+		if (ret) {
+			PERROR("close");
+		}
 	}
 
-	if (session->metadata_stream_fd != 0) {
+	if (session->metadata_stream_fd >= 0) {
 		DBG("[trace] Closing metadata stream fd %d", session->metadata_stream_fd);
 		ret = close(session->metadata_stream_fd);
 		if (ret) {
@@ -431,7 +757,20 @@ void trace_kernel_destroy_session(struct ltt_kernel_session *session)
 	cds_list_for_each_entry_safe(channel, ctmp, &session->channel_list.head, list) {
 		trace_kernel_destroy_channel(channel);
 	}
+}
+
+/* Free elements needed by destroy notifiers. */
+void trace_kernel_free_session(struct ltt_kernel_session *session)
+{
+	/* Wipe consumer output object */
+	consumer_output_put(session->consumer);
+
+	process_attr_tracker_destroy(session->tracker_pid);
+	process_attr_tracker_destroy(session->tracker_vpid);
+	process_attr_tracker_destroy(session->tracker_uid);
+	process_attr_tracker_destroy(session->tracker_vuid);
+	process_attr_tracker_destroy(session->tracker_gid);
+	process_attr_tracker_destroy(session->tracker_vgid);
 
-	free(session->trace_path);
 	free(session);
 }