X-Git-Url: http://git.efficios.com/?a=blobdiff_plain;f=src%2Fbin%2Flttng-sessiond%2Fkernel.c;h=a72fe7f5c977ac76cd351555ec170b5781977191;hb=de04bbc88637bb336255f6cc7c7e4f4ea179f40d;hp=d52d9aa62f4e997b327fe2d1ec336ed5414392f8;hpb=2f77fc4b3720dc8f75847130498c2d4aad7c03ec;p=lttng-tools.git

diff --git a/src/bin/lttng-sessiond/kernel.c b/src/bin/lttng-sessiond/kernel.c
index d52d9aa62..a72fe7f5c 100644
--- a/src/bin/lttng-sessiond/kernel.c
+++ b/src/bin/lttng-sessiond/kernel.c
@@ -15,8 +15,7 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#define _GNU_SOURCE
-#include <errno.h>
+#define _LGPL_SOURCE
 #include <fcntl.h>
 #include <stdlib.h>
 #include <stdio.h>
@@ -26,72 +25,55 @@
 
 #include <common/common.h>
 #include <common/kernel-ctl/kernel-ctl.h>
+#include <common/kernel-ctl/kernel-ioctl.h>
 #include <common/sessiond-comm/sessiond-comm.h>
 
 #include "consumer.h"
 #include "kernel.h"
+#include "kernel-consumer.h"
 #include "kern-modules.h"
+#include "utils.h"
 
 /*
  * Add context on a kernel channel.
+ *
+ * Assumes the ownership of ctx.
  */
 int kernel_add_channel_context(struct ltt_kernel_channel *chan,
-		struct lttng_kernel_context *ctx)
+		struct ltt_kernel_context *ctx)
 {
 	int ret;
 
+	assert(chan);
+	assert(ctx);
+
 	DBG("Adding context to channel %s", chan->channel->name);
-	ret = kernctl_add_context(chan->fd, ctx);
+	ret = kernctl_add_context(chan->fd, &ctx->ctx);
 	if (ret < 0) {
-		if (errno != EEXIST) {
-			PERROR("add context ioctl");
-		} else {
+		switch (-ret) {
+		case ENOSYS:
+			/* Exists but not available for this kernel */
+			ret = LTTNG_ERR_KERN_CONTEXT_UNAVAILABLE;
+			goto error;
+		case EEXIST:
 			/* If EEXIST, we just ignore the error */
 			ret = 0;
+			goto end;
+		default:
+			PERROR("add context ioctl");
+			ret = LTTNG_ERR_KERN_CONTEXT_FAIL;
+			goto error;
 		}
-		goto error;
 	}
 
-	chan->ctx = zmalloc(sizeof(struct lttng_kernel_context));
-	if (chan->ctx == NULL) {
-		PERROR("zmalloc event context");
-		goto error;
-	}
-
-	memcpy(chan->ctx, ctx, sizeof(struct lttng_kernel_context));
-
-	return 0;
-
+end:
+	cds_list_add_tail(&ctx->list, &chan->ctx_list);
+	ctx->in_list = true;
+	ctx = NULL;
 error:
-	return ret;
-}
-
-/*
- * Add context on a kernel event.
- */
-int kernel_add_event_context(struct ltt_kernel_event *event,
-		struct lttng_kernel_context *ctx)
-{
-	int ret;
-
-	DBG("Adding context to event %s", event->event->name);
-	ret = kernctl_add_context(event->fd, ctx);
-	if (ret < 0) {
-		PERROR("add context ioctl");
-		goto error;
-	}
-
-	event->ctx = zmalloc(sizeof(struct lttng_kernel_context));
-	if (event->ctx == NULL) {
-		PERROR("zmalloc event context");
-		goto error;
+	if (ctx) {
+		trace_kernel_destroy_context(ctx);
 	}
-
-	memcpy(event->ctx, ctx, sizeof(struct lttng_kernel_context));
-
-	return 0;
-
-error:
 	return ret;
 }
 
@@ -104,8 +86,10 @@ int kernel_create_session(struct ltt_session *session, int tracer_fd)
 	int ret;
 	struct ltt_kernel_session *lks;
 
+	assert(session);
+
 	/* Allocate data structure */
-	lks = trace_kernel_create_session(session->path);
+	lks = trace_kernel_create_session();
 	if (lks == NULL) {
 		ret = -1;
 		goto error;
@@ -125,6 +109,7 @@ int kernel_create_session(struct ltt_session *session, int tracer_fd)
 		PERROR("fcntl session fd");
 	}
 
+	lks->id = session->id;
 	lks->consumer_fds_sent = 0;
 	session->kernel_session = lks;
 
@@ -133,6 +118,9 @@ int kernel_create_session(struct ltt_session *session, int tracer_fd)
 	return 0;
 
 error:
+	if (lks) {
+		trace_kernel_destroy_session(lks);
+	}
 	return ret;
 }
 
@@ -141,22 +129,25 @@ error:
  * kernel session.
  */
 int kernel_create_channel(struct ltt_kernel_session *session,
-		struct lttng_channel *chan, char *path)
+		struct lttng_channel *chan)
 {
 	int ret;
 	struct ltt_kernel_channel *lkc;
 
+	assert(session);
+	assert(chan);
+
 	/* Allocate kernel channel */
-	lkc = trace_kernel_create_channel(chan, path);
+	lkc = trace_kernel_create_channel(chan);
 	if (lkc == NULL) {
 		goto error;
 	}
 
-	DBG3("Kernel create channel %s in %s with attr: %d, %" PRIu64 ", %" PRIu64 ", %u, %u, %d",
-			chan->name, path, lkc->channel->attr.overwrite,
+	DBG3("Kernel create channel %s with attr: %d, %" PRIu64 ", %" PRIu64 ", %u, %u, %d, %d",
+			chan->name, lkc->channel->attr.overwrite,
 			lkc->channel->attr.subbuf_size, lkc->channel->attr.num_subbuf,
 			lkc->channel->attr.switch_timer_interval, lkc->channel->attr.read_timer_interval,
-			lkc->channel->attr.output);
+			lkc->channel->attr.live_timer_interval, lkc->channel->attr.output);
 
 	/* Kernel tracer channel creation */
 	ret = kernctl_create_channel(session->fd, &lkc->channel->attr);
@@ -176,26 +167,39 @@ int kernel_create_channel(struct ltt_kernel_session *session,
 	/* Add channel to session */
 	cds_list_add(&lkc->list, &session->channel_list.head);
 	session->channel_count++;
+	lkc->session = session;
 
 	DBG("Kernel channel %s created (fd: %d)", lkc->channel->name, lkc->fd);
 
 	return 0;
 
 error:
+	if (lkc) {
+		free(lkc->channel);
+		free(lkc);
+	}
 	return -1;
 }
 
 /*
  * Create a kernel event, enable it to the kernel tracer and add it to the
  * channel event list of the kernel session.
+ * We own filter_expression and filter.
  */
 int kernel_create_event(struct lttng_event *ev,
-		struct ltt_kernel_channel *channel)
+		struct ltt_kernel_channel *channel,
+		char *filter_expression,
+		struct lttng_filter_bytecode *filter)
 {
 	int ret;
 	struct ltt_kernel_event *event;
 
-	event = trace_kernel_create_event(ev);
+	assert(ev);
+	assert(channel);
+
+	/* We pass ownership of filter_expression and filter */
+	event = trace_kernel_create_event(ev, filter_expression,
+			filter);
 	if (event == NULL) {
 		ret = -1;
 		goto error;
@@ -203,32 +207,22 @@ int kernel_create_event(struct lttng_event *ev,
 
 	ret = kernctl_create_event(channel->fd, event->event);
 	if (ret < 0) {
-		switch (errno) {
+		switch (-ret) {
 		case EEXIST:
 			break;
 		case ENOSYS:
 			WARN("Event type not implemented");
 			break;
+		case ENOENT:
+			WARN("Event %s not found!", ev->name);
+			break;
 		default:
 			PERROR("create event ioctl");
 		}
-		ret = -errno;
 		goto free_event;
 	}
 
-	/*
-	 * LTTNG_KERNEL_SYSCALL event creation will return 0 on success.
-	 */
-	if (ret == 0 && event->event->instrumentation == LTTNG_KERNEL_SYSCALL) {
-		DBG2("Kernel event syscall creation success");
-		/*
-		 * We use fd == -1 to ensure that we never trigger a close of fd
-		 * 0.
-		 */
-		event->fd = -1;
-		goto add_list;
-	}
-
+	event->type = ev->type;
 	event->fd = ret;
 	/* Prevent fd duplication after execlp() */
 	ret = fcntl(event->fd, F_SETFD, FD_CLOEXEC);
@@ -236,7 +230,26 @@ int kernel_create_event(struct lttng_event *ev,
 		PERROR("fcntl session fd");
 	}
 
-add_list:
+	if (filter) {
+		ret = kernctl_filter(event->fd, filter);
+		if (ret) {
+			goto filter_error;
+		}
+	}
+
+	ret = kernctl_enable(event->fd);
+	if (ret < 0) {
+		switch (-ret) {
+		case EEXIST:
+			ret = LTTNG_ERR_KERN_EVENT_EXIST;
+			break;
+		default:
+			PERROR("enable kernel event");
+			break;
+		}
+		goto enable_error;
+	}
+
 	/* Add event to event list */
 	cds_list_add(&event->list, &channel->events_list.head);
 	channel->event_count++;
@@ -245,6 +258,16 @@ add_list:
 
 	return 0;
 
+enable_error:
+filter_error:
+	{
+		int closeret;
+
+		closeret = close(event->fd);
+		if (closeret) {
+			PERROR("close event fd");
+		}
+	}
 free_event:
 	free(event);
 error:
@@ -258,10 +281,11 @@ int kernel_disable_channel(struct ltt_kernel_channel *chan)
 {
 	int ret;
 
+	assert(chan);
+
 	ret = kernctl_disable(chan->fd);
 	if (ret < 0) {
 		PERROR("disable chan ioctl");
-		ret = errno;
 		goto error;
 	}
 
@@ -281,8 +305,10 @@ int kernel_enable_channel(struct ltt_kernel_channel *chan)
 {
 	int ret;
 
+	assert(chan);
+
 	ret = kernctl_enable(chan->fd);
-	if (ret < 0 && errno != EEXIST) {
+	if (ret < 0 && ret != -EEXIST) {
 		PERROR("Enable kernel chan");
 		goto error;
 	}
@@ -303,11 +329,13 @@ int kernel_enable_event(struct ltt_kernel_event *event)
 {
 	int ret;
 
+	assert(event);
+
 	ret = kernctl_enable(event->fd);
 	if (ret < 0) {
-		switch (errno) {
+		switch (-ret) {
 		case EEXIST:
-			ret = LTTCOMM_KERN_EVENT_EXIST;
+			ret = LTTNG_ERR_KERN_EVENT_EXIST;
 			break;
 		default:
 			PERROR("enable kernel event");
@@ -332,11 +360,13 @@ int kernel_disable_event(struct ltt_kernel_event *event)
 {
 	int ret;
 
+	assert(event);
+
 	ret = kernctl_disable(event->fd);
 	if (ret < 0) {
-		switch (errno) {
+		switch (-ret) {
 		case EEXIST:
-			ret = LTTCOMM_KERN_EVENT_EXIST;
+			ret = LTTNG_ERR_KERN_EVENT_EXIST;
 			break;
 		default:
 			PERROR("disable kernel event");
@@ -354,6 +384,276 @@ error:
 	return ret;
 }
 
+static
+struct lttng_tracker_list *get_id_tracker_list(struct ltt_kernel_session *session,
+		enum lttng_tracker_type tracker_type)
+{
+	switch (tracker_type) {
+	case LTTNG_TRACKER_PID:
+		return session->tracker_list_pid;
+	case LTTNG_TRACKER_VPID:
+		return session->tracker_list_vpid;
+	case LTTNG_TRACKER_UID:
+		return session->tracker_list_uid;
+	case LTTNG_TRACKER_VUID:
+		return session->tracker_list_vuid;
+	case LTTNG_TRACKER_GID:
+		return session->tracker_list_gid;
+	case LTTNG_TRACKER_VGID:
+		return session->tracker_list_vgid;
+	default:
+		return NULL;
+	}
+}
+
+int kernel_track_id(enum lttng_tracker_type tracker_type,
+		struct ltt_kernel_session *session,
+		struct lttng_tracker_id *id)
+{
+	int ret, value;
+	struct lttng_tracker_list *tracker_list;
+	struct lttng_tracker_id *saved_ids;
+	ssize_t saved_ids_count, i;
+
+	ret = lttng_tracker_id_lookup_string(tracker_type,
+			id, &value);
+	if (ret != LTTNG_OK) {
+		return ret;
+	}
+
+	tracker_list = get_id_tracker_list(session, tracker_type);
+	if (!tracker_list) {
+		return LTTNG_ERR_INVALID;
+	}
+	/* Save list for restore on error. */
+	saved_ids_count = lttng_tracker_id_get_list(tracker_list, &saved_ids);
+	if (saved_ids_count < 0) {
+		return LTTNG_ERR_INVALID;
+	}
+	/* Add to list. */
+	ret = lttng_tracker_list_add(tracker_list, id);
+	if (ret != LTTNG_OK) {
+		goto end;
+	}
+
+	switch (tracker_type) {
+	case LTTNG_TRACKER_PID:
+		DBG("Kernel track PID %d for session id %" PRIu64 ".",
+				value, session->id);
+		ret = kernctl_track_pid(session->fd, value);
+		if (!ret) {
+			ret = LTTNG_OK;
+			goto end;
+		}
+		break;
+	case LTTNG_TRACKER_VPID:
+		DBG("Kernel track VPID %d for session id %" PRIu64 ".",
+				value, session->id);
+		ret = kernctl_track_id(session->fd, LTTNG_TRACKER_VPID, value);
+		if (!ret) {
+			ret = LTTNG_OK;
+			goto end;
+		}
+		break;
+	case LTTNG_TRACKER_UID:
+		DBG("Kernel track UID %d for session id %" PRIu64 ".",
+				value, session->id);
+		ret = kernctl_track_id(session->fd, LTTNG_TRACKER_UID, value);
+		if (!ret) {
+			ret = LTTNG_OK;
+			goto end;
+		}
+		break;
+	case LTTNG_TRACKER_GID:
+		DBG("Kernel track GID %d for session id %" PRIu64 ".",
+				value, session->id);
+		ret = kernctl_track_id(session->fd, LTTNG_TRACKER_GID, value);
+		if (!ret) {
+			ret = LTTNG_OK;
+			goto end;
+		}
+		break;
+	case LTTNG_TRACKER_VUID:
+		DBG("Kernel track VUID %d for session id %" PRIu64 ".",
+				value, session->id);
+		ret = kernctl_track_id(session->fd, LTTNG_TRACKER_VUID, value);
+		if (!ret) {
+			ret = LTTNG_OK;
+			goto end;
+		}
+		break;
+	case LTTNG_TRACKER_VGID:
+		DBG("Kernel track VGID %d for session id %" PRIu64 ".",
+				value, session->id);
+		ret = kernctl_track_id(session->fd, LTTNG_TRACKER_VGID, value);
+		if (!ret) {
+			ret = LTTNG_OK;
+			goto end;
+		}
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+	/* Error handling. */
+	switch (-ret) {
+	case EINVAL:
+		ret = LTTNG_ERR_INVALID;
+		break;
+	case ENOMEM:
+		ret = LTTNG_ERR_NOMEM;
+		break;
+	case EEXIST:
+		ret = LTTNG_ERR_ID_TRACKED;
+		break;
+	default:
+		ret = LTTNG_ERR_UNK;
+		break;
+	}
+	if (lttng_tracker_id_set_list(tracker_list, saved_ids, saved_ids_count) != LTTNG_OK) {
+		ERR("Error on tracker add error handling.\n");
+	}
+end:
+	for (i = 0; i < saved_ids_count; i++) {
+		free(saved_ids[i].string);
+	}
+	free(saved_ids);
+	return ret;
+}
+
+int kernel_untrack_id(enum lttng_tracker_type tracker_type,
+		struct ltt_kernel_session *session,
+		struct lttng_tracker_id *id)
+{
+	int ret, value;
+	struct lttng_tracker_list *tracker_list;
+	struct lttng_tracker_id *saved_ids;
+	ssize_t saved_ids_count, i;
+
+	ret = lttng_tracker_id_lookup_string(tracker_type,
+			id, &value);
+	if (ret != LTTNG_OK) {
+		return ret;
+	}
+
+	tracker_list = get_id_tracker_list(session, tracker_type);
+	if (!tracker_list) {
+		return LTTNG_ERR_INVALID;
+	}
+	/* Save list for restore on error. */
+	saved_ids_count = lttng_tracker_id_get_list(tracker_list, &saved_ids);
+	if (saved_ids_count < 0) {
+		return LTTNG_ERR_INVALID;
+	}
+	/* Remove from list. */
+	ret = lttng_tracker_list_remove(tracker_list, id);
+	if (ret != LTTNG_OK) {
+		goto end;
+	}
+
+	switch (tracker_type) {
+	case LTTNG_TRACKER_PID:
+		DBG("Kernel untrack PID %d for session id %" PRIu64 ".",
+				value, session->id);
+		ret = kernctl_untrack_pid(session->fd, value);
+		if (!ret) {
+			ret = LTTNG_OK;
+			goto end;
+		}
+		break;
+	case LTTNG_TRACKER_VPID:
+		DBG("Kernel untrack VPID %d for session id %" PRIu64 ".",
+				value, session->id);
+		ret = kernctl_untrack_id(session->fd, LTTNG_TRACKER_VPID, value);
+		if (!ret) {
+			ret = LTTNG_OK;
+			goto end;
+		}
+		break;
+	case LTTNG_TRACKER_UID:
+		DBG("Kernel untrack UID %d for session id %" PRIu64 ".",
+				value, session->id);
+		ret = kernctl_untrack_id(session->fd, LTTNG_TRACKER_UID, value);
+		if (!ret) {
+			ret = LTTNG_OK;
+			goto end;
+		}
+		break;
+	case LTTNG_TRACKER_GID:
+		DBG("Kernel untrack GID %d for session id %" PRIu64 ".",
+				value, session->id);
+		ret = kernctl_untrack_id(session->fd, LTTNG_TRACKER_GID, value);
+		if (!ret) {
+			ret = LTTNG_OK;
+			goto end;
+		}
+		break;
+	case LTTNG_TRACKER_VUID:
+		DBG("Kernel untrack VUID %d for session id %" PRIu64 ".",
+				value, session->id);
+		ret = kernctl_untrack_id(session->fd, LTTNG_TRACKER_VUID, value);
+		if (!ret) {
+			ret = LTTNG_OK;
+			goto end;
+		}
+		break;
+	case LTTNG_TRACKER_VGID:
+		DBG("Kernel untrack VGID %d for session id %" PRIu64 ".",
+				value, session->id);
+		ret = kernctl_untrack_id(session->fd, LTTNG_TRACKER_VGID, value);
+		if (!ret) {
+			ret = LTTNG_OK;
+			goto end;
+		}
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	/* Error handling. */
+	switch (-ret) {
+	case EINVAL:
+		ret = LTTNG_ERR_INVALID;
+		break;
+	case ENOMEM:
+		ret = LTTNG_ERR_NOMEM;
+		break;
+	case EEXIST:
+		ret = LTTNG_ERR_ID_TRACKED;
+		break;
+	default:
+		ret = LTTNG_ERR_UNK;
+		break;
+	}
+
+	if (lttng_tracker_id_set_list(tracker_list, saved_ids, saved_ids_count) != LTTNG_OK) {
+		ERR("Error on tracker remove error handling.\n");
+	}
+end:
+	for (i = 0; i < saved_ids_count; i++) {
+		free(saved_ids[i].string);
+	}
+	free(saved_ids);
+	return ret;
+}
+
+/*
+ * Called with session lock held.
+ */
+ssize_t kernel_list_tracker_ids(enum lttng_tracker_type tracker_type,
+		struct ltt_kernel_session *session,
+		struct lttng_tracker_id **_ids)
+{
+	struct lttng_tracker_list *tracker_list;
+
+	tracker_list = get_id_tracker_list(session, tracker_type);
+	if (!tracker_list) {
+		return -LTTNG_ERR_INVALID;
+	}
+	return lttng_tracker_id_get_list(tracker_list, _ids);
+}
+
 /*
  * Create kernel metadata, open from the kernel tracer and add it to the
  * kernel session.
@@ -361,7 +661,9 @@ error:
 int kernel_open_metadata(struct ltt_kernel_session *session)
 {
 	int ret;
-	struct ltt_kernel_metadata *lkm;
+	struct ltt_kernel_metadata *lkm = NULL;
+
+	assert(session);
 
 	/* Allocate kernel metadata */
 	lkm = trace_kernel_create_metadata();
@@ -372,7 +674,7 @@ int kernel_open_metadata(struct ltt_kernel_session *session)
 	/* Kernel tracer metadata creation */
 	ret = kernctl_open_metadata(session->fd, &lkm->conf->attr);
 	if (ret < 0) {
-		goto error;
+		goto error_open;
 	}
 
 	lkm->fd = ret;
@@ -388,6 +690,8 @@ int kernel_open_metadata(struct ltt_kernel_session *session)
 
 	return 0;
 
+error_open:
+	trace_kernel_destroy_metadata(lkm);
 error:
 	return -1;
 }
@@ -399,6 +703,8 @@ int kernel_start_session(struct ltt_kernel_session *session)
 {
 	int ret;
 
+	assert(session);
+
 	ret = kernctl_start_session(session->fd);
 	if (ret < 0) {
 		PERROR("ioctl start session");
@@ -429,23 +735,6 @@ void kernel_wait_quiescent(int fd)
 	}
 }
 
-/*
- * Kernel calibrate
- */
-int kernel_calibrate(int fd, struct lttng_kernel_calibrate *calibrate)
-{
-	int ret;
-
-	ret = kernctl_calibrate(fd, calibrate);
-	if (ret < 0) {
-		PERROR("calibrate ioctl");
-		return -1;
-	}
-
-	return 0;
-}
-
-
 /*
  *  Force flush buffer of metadata.
  */
@@ -453,6 +742,8 @@ int kernel_metadata_flush_buffer(int fd)
 {
 	int ret;
 
+	DBG("Kernel flushing metadata buffer on fd %d", fd);
+
 	ret = kernctl_buffer_flush(fd);
 	if (ret < 0) {
 		ERR("Fail to flush metadata buffers %d (ret: %d)", fd, ret);
@@ -469,6 +760,8 @@ int kernel_flush_buffer(struct ltt_kernel_channel *channel)
 	int ret;
 	struct ltt_kernel_stream *stream;
 
+	assert(channel);
+
 	DBG("Flush buffer for channel %s", channel->channel->name);
 
 	cds_list_for_each_entry(stream, &channel->stream_list.head, list) {
@@ -491,6 +784,8 @@ int kernel_stop_session(struct ltt_kernel_session *session)
 {
 	int ret;
 
+	assert(session);
+
 	ret = kernctl_stop_session(session->fd);
 	if (ret < 0) {
 		goto error;
@@ -508,15 +803,22 @@ error:
  * Open stream of channel, register it to the kernel tracer and add it
  * to the stream list of the channel.
  *
+ * Note: given that the streams may appear in random order wrt CPU
+ * number (e.g. cpu hotplug), the index value of the stream number in
+ * the stream name is not necessarily linked to the CPU number.
+ *
  * Return the number of created stream. Else, a negative value.
  */
 int kernel_open_channel_stream(struct ltt_kernel_channel *channel)
 {
-	int ret, count = 0;
+	int ret;
 	struct ltt_kernel_stream *lks;
 
+	assert(channel);
+
 	while ((ret = kernctl_create_stream(channel->fd)) >= 0) {
-		lks = trace_kernel_create_stream(channel->channel->name, count);
+		lks = trace_kernel_create_stream(channel->channel->name,
+				channel->stream_count);
 		if (lks == NULL) {
 			ret = close(ret);
 			if (ret) {
@@ -532,13 +834,13 @@ int kernel_open_channel_stream(struct ltt_kernel_channel *channel)
 			PERROR("fcntl session fd");
 		}
 
-		/* Add stream to channe stream list */
+		lks->tracefile_size = channel->channel->attr.tracefile_size;
+		lks->tracefile_count = channel->channel->attr.tracefile_count;
+
+		/* Add stream to channel stream list */
 		cds_list_add(&lks->list, &channel->stream_list.head);
 		channel->stream_count++;
 
-		/* Increment counter which represent CPU number. */
-		count++;
-
 		DBG("Kernel stream %s created (fd: %d, state: %d)", lks->name, lks->fd,
 				lks->state);
 	}
@@ -556,6 +858,8 @@ int kernel_open_metadata_stream(struct ltt_kernel_session *session)
 {
 	int ret;
 
+	assert(session);
+
 	ret = kernctl_create_stream(session->metadata->fd);
 	if (ret < 0) {
 		PERROR("kernel create metadata stream");
@@ -581,13 +885,14 @@ error:
  */
 ssize_t kernel_list_events(int tracer_fd, struct lttng_event **events)
 {
-	int fd, pos, ret;
+	int fd, ret;
 	char *event;
 	size_t nbmem, count = 0;
-	ssize_t size;
 	FILE *fp;
 	struct lttng_event *elist;
 
+	assert(events);
+
 	fd = kernctl_tracepoint_list(tracer_fd);
 	if (fd < 0) {
 		PERROR("kernel tracepoint list");
@@ -612,15 +917,15 @@ ssize_t kernel_list_events(int tracer_fd, struct lttng_event **events)
 		goto end;
 	}
 
-	while ((size = fscanf(fp, "event { name = %m[^;]; };%n\n", &event, &pos)) == 1) {
+	while (fscanf(fp, "event { name = %m[^;]; };\n", &event) == 1) {
 		if (count >= nbmem) {
 			struct lttng_event *new_elist;
+			size_t new_nbmem;
 
-			DBG("Reallocating event list from %zu to %zu bytes", nbmem,
-					nbmem * 2);
-			/* Double the size */
-			nbmem <<= 1;
-			new_elist = realloc(elist, nbmem * sizeof(struct lttng_event));
+			new_nbmem = nbmem << 1;
+			DBG("Reallocating event list from %zu to %zu bytes",
+					nbmem, new_nbmem);
+			new_elist = realloc(elist, new_nbmem * sizeof(struct lttng_event));
 			if (new_elist == NULL) {
 				PERROR("realloc list events");
 				free(event);
@@ -628,6 +933,10 @@ ssize_t kernel_list_events(int tracer_fd, struct lttng_event **events)
 				count = -ENOMEM;
 				goto end;
 			}
+			/* Zero the new memory */
+			memset(new_elist + nbmem, 0,
+				(new_nbmem - nbmem) * sizeof(struct lttng_event));
+			nbmem = new_nbmem;
 			elist = new_elist;
 		}
 		strncpy(elist[count].name, event, LTTNG_SYMBOL_NAME_LEN);
@@ -662,28 +971,41 @@ int kernel_validate_version(int tracer_fd)
 {
 	int ret;
 	struct lttng_kernel_tracer_version version;
+	struct lttng_kernel_tracer_abi_version abi_version;
 
 	ret = kernctl_tracer_version(tracer_fd, &version);
 	if (ret < 0) {
-		ERR("Failed at getting the lttng-modules version");
+		ERR("Failed to retrieve the lttng-modules version");
 		goto error;
 	}
 
 	/* Validate version */
-	if (version.major != KERN_MODULES_PRE_MAJOR
-		&& version.major != KERN_MODULES_MAJOR) {
+	if (version.major != VERSION_MAJOR) {
+		ERR("Kernel tracer major version (%d) is not compatible with lttng-tools major version (%d)",
+			version.major, VERSION_MAJOR);
 		goto error_version;
 	}
-
-	DBG2("Kernel tracer version validated (major version %d)", version.major);
+	ret = kernctl_tracer_abi_version(tracer_fd, &abi_version);
+	if (ret < 0) {
+		ERR("Failed to retrieve lttng-modules ABI version");
+		goto error;
+	}
+	if (abi_version.major != LTTNG_MODULES_ABI_MAJOR_VERSION) {
+		ERR("Kernel tracer ABI version (%d.%d) does not match the expected ABI major version (%d.*)",
+			abi_version.major, abi_version.minor,
+			LTTNG_MODULES_ABI_MAJOR_VERSION);
+		goto error;
+	}
+	DBG2("Kernel tracer version validated (%d.%d, ABI %d.%d)",
+			version.major, version.minor,
+			abi_version.major, abi_version.minor);
 	return 0;
 
 error_version:
-	ERR("Kernel major version %d is not compatible (supporting <= %d)",
-			version.major, KERN_MODULES_MAJOR)
 	ret = -1;
 
 error:
+	ERR("Kernel tracer version check failed; kernel tracing will not be available");
 	return ret;
 }
 
@@ -732,8 +1054,192 @@ void kernel_destroy_session(struct ltt_kernel_session *ksess)
 
 	DBG("Tearing down kernel session");
 
+	/*
+	 * Destroy channels on the consumer if at least one FD has been sent and we
+	 * are in no output mode because the streams are in *no* monitor mode so we
+	 * have to send a command to clean them up or else they leaked.
+	 */
+	if (!ksess->output_traces && ksess->consumer_fds_sent) {
+		int ret;
+		struct consumer_socket *socket;
+		struct lttng_ht_iter iter;
+
+		/* For each consumer socket. */
+		rcu_read_lock();
+		cds_lfht_for_each_entry(ksess->consumer->socks->ht, &iter.iter,
+				socket, node.node) {
+			struct ltt_kernel_channel *chan;
+
+			/* For each channel, ask the consumer to destroy it. */
+			cds_list_for_each_entry(chan, &ksess->channel_list.head, list) {
+				ret = kernel_consumer_destroy_channel(socket, chan);
+				if (ret < 0) {
+					/* Consumer is probably dead. Use next socket. */
+					continue;
+				}
+			}
+		}
+		rcu_read_unlock();
+	}
+
 	/* Close any relayd session */
 	consumer_output_send_destroy_relayd(ksess->consumer);
 
 	trace_kernel_destroy_session(ksess);
 }
+
+/*
+ * Destroy a kernel channel object. It does not do anything on the tracer side.
+ */
+void kernel_destroy_channel(struct ltt_kernel_channel *kchan)
+{
+	struct ltt_kernel_session *ksess = NULL;
+
+	assert(kchan);
+	assert(kchan->channel);
+
+	DBG3("Kernel destroy channel %s", kchan->channel->name);
+
+	/* Update channel count of associated session. */
+	if (kchan->session) {
+		/* Keep pointer reference so we can update it after the destroy. */
+		ksess = kchan->session;
+	}
+
+	trace_kernel_destroy_channel(kchan);
+
+	/*
+	 * At this point the kernel channel is not visible anymore. This is safe
+	 * since in order to work on a visible kernel session, the tracing session
+	 * lock (ltt_session.lock) MUST be acquired.
+	 */
+	if (ksess) {
+		ksess->channel_count--;
+	}
+}
+
+/*
+ * Take a snapshot for a given kernel session.
+ *
+ * Return 0 on success or else return a LTTNG_ERR code.
+ */
+int kernel_snapshot_record(struct ltt_kernel_session *ksess,
+		struct snapshot_output *output, int wait,
+		uint64_t nb_packets_per_stream)
+{
+	int err, ret, saved_metadata_fd;
+	struct consumer_socket *socket;
+	struct lttng_ht_iter iter;
+	struct ltt_kernel_metadata *saved_metadata;
+
+	assert(ksess);
+	assert(ksess->consumer);
+	assert(output);
+
+	DBG("Kernel snapshot record started");
+
+	/* Save current metadata since the following calls will change it. */
+	saved_metadata = ksess->metadata;
+	saved_metadata_fd = ksess->metadata_stream_fd;
+
+	rcu_read_lock();
+
+	ret = kernel_open_metadata(ksess);
+	if (ret < 0) {
+		ret = LTTNG_ERR_KERN_META_FAIL;
+		goto error;
+	}
+
+	ret = kernel_open_metadata_stream(ksess);
+	if (ret < 0) {
+		ret = LTTNG_ERR_KERN_META_FAIL;
+		goto error_open_stream;
+	}
+
+	/* Send metadata to consumer and snapshot everything. */
+	cds_lfht_for_each_entry(ksess->consumer->socks->ht, &iter.iter,
+			socket, node.node) {
+		struct consumer_output *saved_output;
+		struct ltt_kernel_channel *chan;
+
+		/*
+		 * Temporarly switch consumer output for our snapshot output. As long
+		 * as the session lock is taken, this is safe.
+		 */
+		saved_output = ksess->consumer;
+		ksess->consumer = output->consumer;
+
+		pthread_mutex_lock(socket->lock);
+		/* This stream must not be monitored by the consumer. */
+		ret = kernel_consumer_add_metadata(socket, ksess, 0);
+		pthread_mutex_unlock(socket->lock);
+		/* Put back the saved consumer output into the session. */
+		ksess->consumer = saved_output;
+		if (ret < 0) {
+			ret = LTTNG_ERR_KERN_CONSUMER_FAIL;
+			goto error_consumer;
+		}
+
+		/* For each channel, ask the consumer to snapshot it. */
+		cds_list_for_each_entry(chan, &ksess->channel_list.head, list) {
+			ret = consumer_snapshot_channel(socket, chan->fd, output, 0,
+					ksess->uid, ksess->gid,
+					DEFAULT_KERNEL_TRACE_DIR, wait,
+					nb_packets_per_stream);
+			if (ret < 0) {
+				ret = LTTNG_ERR_KERN_CONSUMER_FAIL;
+				(void) kernel_consumer_destroy_metadata(socket,
+						ksess->metadata);
+				goto error_consumer;
+			}
+		}
+
+		/* Snapshot metadata, */
+		ret = consumer_snapshot_channel(socket, ksess->metadata->fd, output,
+				1, ksess->uid, ksess->gid,
+				DEFAULT_KERNEL_TRACE_DIR, wait, 0);
+		if (ret < 0) {
+			ret = LTTNG_ERR_KERN_CONSUMER_FAIL;
+			goto error_consumer;
+		}
+
+		/*
+		 * The metadata snapshot is done, ask the consumer to destroy it since
+		 * it's not monitored on the consumer side.
+		 */
+		(void) kernel_consumer_destroy_metadata(socket, ksess->metadata);
+	}
+
+	ret = LTTNG_OK;
+
+error_consumer:
+	/* Close newly opened metadata stream. It's now on the consumer side. */
+	err = close(ksess->metadata_stream_fd);
+	if (err < 0) {
+		PERROR("close snapshot kernel");
+	}
+
+error_open_stream:
+	trace_kernel_destroy_metadata(ksess->metadata);
+error:
+	/* Restore metadata state.*/
+	ksess->metadata = saved_metadata;
+	ksess->metadata_stream_fd = saved_metadata_fd;
+
+	rcu_read_unlock();
+	return ret;
+}
+
+/*
+ * Get the syscall mask array from the kernel tracer.
+ *
+ * Return 0 on success else a negative value. In both case, syscall_mask should
+ * be freed.
+ */
+int kernel_syscall_mask(int chan_fd, char **syscall_mask, uint32_t *nr_bits)
+{
+	assert(syscall_mask);
+	assert(nr_bits);
+
+	return kernctl_syscall_mask(chan_fd, syscall_mask, nr_bits);
+}