X-Git-Url: http://git.lttng.org/?p=ust.git;a=blobdiff_plain;f=libust%2Ftracectl.c;h=7a5cf9562282ce7fe90cc3d5e4c405d3bf44b8c6;hp=83109a14c222d9f8719dc3710726f1a35a9544b6;hb=f51d84eac11907346fa02e33da358aad171ac80a;hpb=d9ce395d9a7d0d6628d6f495e4bacb912abfcba9

diff --git a/libust/tracectl.c b/libust/tracectl.c
index 83109a1..7a5cf95 100644
--- a/libust/tracectl.c
+++ b/libust/tracectl.c
@@ -17,26 +17,26 @@
 
 #define _GNU_SOURCE
 #include <stdio.h>
+#include <stdlib.h>
 #include <stdint.h>
+#include <pthread.h>
 #include <signal.h>
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <sys/un.h>
-#include <sched.h>
 #include <fcntl.h>
 #include <poll.h>
 #include <regex.h>
+#include <urcu/uatomic_arch.h>
 
-#include <urcu.h>
-
-#include "marker.h"
+#include <ust/marker.h>
+#include <ust/tracectl.h>
 #include "tracer.h"
-#include "localerr.h"
+#include "usterr.h"
 #include "ustcomm.h"
-#include "relay.h" /* FIXME: remove */
+#include "buffers.h"
 #include "marker-control.h"
-
-//#define USE_CLONE
+#include "multipoll.h"
 
 #define USTSIGNAL SIGIO
 
@@ -44,8 +44,6 @@
 #define MSG_NOTIF 1
 #define MSG_REGISTER_NOTIF 2
 
-char consumer_stack[10000];
-
 /* This should only be accessed by the constructor, before the creation
  * of the listener, and then only by the listener.
  */
@@ -61,11 +59,7 @@ struct tracecmd { /* no padding */
 };
 
 /* volatile because shared between the listener and the main thread */
-volatile sig_atomic_t buffers_to_export = 0;
-
-//struct listener_arg {
-//	int pipe_fd;
-//};
+int buffers_to_export = 0;
 
 struct trctl_msg {
 	/* size: the size of all the fields except size itself */
@@ -91,9 +85,8 @@ struct blocked_consumer {
 	struct ustcomm_server server;
 	struct ustcomm_source src;
 
-	/* args to ltt_do_get_subbuf */
-	struct rchan_buf *rbuf;
-	struct ltt_channel_buf_struct *lttbuf;
+	/* args to ust_buffers_get_subbuf */
+	struct ust_buffer *buf;
 
 	struct list_head list;
 };
@@ -121,7 +114,7 @@ static void print_markers(FILE *fp)
 	marker_iter_start(&iter);
 
 	while(iter.marker) {
-		fprintf(fp, "marker: %s_%s %d \"%s\"\n", iter.marker->channel, iter.marker->name, (int)imv_read(iter.marker->state), iter.marker->format);
+		fprintf(fp, "marker: %s/%s %d \"%s\" %p\n", iter.marker->channel, iter.marker->name, (int)imv_read(iter.marker->state), iter.marker->format, iter.marker->location);
 		marker_iter_next(&iter);
 	}
 	unlock_markers();
@@ -129,37 +122,6 @@ static void print_markers(FILE *fp)
 
 static int init_socket(void);
 
-/* This needs to be called whenever a new thread is created. It notifies
- * liburcu of the new thread.
- */
-
-void ust_register_thread(void)
-{
-	rcu_register_thread();
-}
-
-int fd_notif = -1;
-void notif_cb(void)
-{
-	int result;
-	struct trctl_msg msg;
-
-	/* FIXME: fd_notif should probably be protected by a spinlock */
-
-	if(fd_notif == -1)
-		return;
-
-	msg.type = MSG_NOTIF;
-	msg.size = sizeof(msg.type);
-
-	/* FIXME: don't block here */
-	result = write(fd_notif, &msg, msg.size+sizeof(msg.size));
-	if(result == -1) {
-		PERROR("write");
-		return;
-	}
-}
-
 /* Ask the daemon to collect a trace called trace_name and being
  * produced by this pid.
  *
@@ -169,8 +131,8 @@ void notif_cb(void)
 
 static void inform_consumer_daemon(const char *trace_name)
 {
-	int i;
-	struct ltt_trace_struct *trace;
+	int i,j;
+	struct ust_trace *trace;
 	pid_t pid = getpid();
 	int result;
 
@@ -183,677 +145,931 @@ static void inform_consumer_daemon(const char *trace_name)
 	}
 
 	for(i=0; i < trace->nr_channels; i++) {
-		result = ustcomm_request_consumer(pid, trace->channels[i].channel_name);
-		if(result == -1) {
-			WARN("Failed to request collection for channel %s. Is the daemon available?", trace->channels[i].channel_name);
-			/* continue even if fail */
+		if(trace->channels[i].request_collection) {
+			/* iterate on all cpus */
+			for(j=0; j<trace->channels[i].n_cpus; j++) {
+				char *buf;
+				asprintf(&buf, "%s_%d", trace->channels[i].channel_name, j);
+				result = ustcomm_request_consumer(pid, buf);
+				if(result == -1) {
+					WARN("Failed to request collection for channel %s. Is the daemon available?", trace->channels[i].channel_name);
+					/* continue even if fail */
+				}
+				free(buf);
+				STORE_SHARED(buffers_to_export, LOAD_SHARED(buffers_to_export)+1);
+			}
 		}
-		buffers_to_export++;
 	}
 
 	finish:
 	ltt_unlock_traces();
 }
 
-void process_blocked_consumers(void)
+int process_blkd_consumer_act(void *priv, int fd, short events)
 {
-	int n_fds = 0;
-	struct pollfd *fds;
-	struct blocked_consumer *bc;
-	int idx = 0;
-	char inbuf;
 	int result;
+	long consumed_old = 0;
+	char *reply;
+	struct blocked_consumer *bc = (struct blocked_consumer *) priv;
+	char inbuf;
 
-	list_for_each_entry(bc, &blocked_consumers, list) {
-		n_fds++;
+	result = read(bc->fd_producer, &inbuf, 1);
+	if(result == -1) {
+		PERROR("read");
+		return -1;
 	}
+	if(result == 0) {
+		int res;
+		DBG("listener: got messsage that a buffer ended");
 
-	fds = (struct pollfd *) malloc(n_fds * sizeof(struct pollfd));
-	if(fds == NULL) {
-		ERR("malloc returned NULL");
-		return;
+		res = close(bc->fd_producer);
+		if(res == -1) {
+			PERROR("close");
+		}
+
+		list_del(&bc->list);
+
+		result = ustcomm_send_reply(&bc->server, "END", &bc->src);
+		if(result < 0) {
+			ERR("ustcomm_send_reply failed");
+			return -1;
+		}
+
+		return 0;
 	}
 
+	result = ust_buffers_get_subbuf(bc->buf, &consumed_old);
+	if(result == -EAGAIN) {
+		WARN("missed buffer?");
+		return 0;
+	}
+	else if(result < 0) {
+		ERR("ust_buffers_get_subbuf: error: %s", strerror(-result));
+	}
+	asprintf(&reply, "%s %ld", "OK", consumed_old);
+	result = ustcomm_send_reply(&bc->server, reply, &bc->src);
+	if(result < 0) {
+		ERR("ustcomm_send_reply failed");
+		free(reply);
+		return -1;
+	}
+	free(reply);
+
+	list_del(&bc->list);
+
+	return 0;
+}
+
+void blocked_consumers_add_to_mp(struct mpentries *ent)
+{
+	struct blocked_consumer *bc;
+
 	list_for_each_entry(bc, &blocked_consumers, list) {
-		fds[idx].fd = bc->fd_producer;
-		fds[idx].events = POLLIN;
-		bc->tmp_poll_idx = idx;
-		idx++;
+		multipoll_add(ent, bc->fd_producer, POLLIN, process_blkd_consumer_act, bc, NULL);
 	}
 
-	while((result = poll(fds, n_fds, 0)) == -1 && errno == EINTR)
-		/* nothing */;
-	if(result == -1) {
-		PERROR("poll");
-		return;
+}
+
+void seperate_channel_cpu(const char *channel_and_cpu, char **channel, int *cpu)
+{
+	const char *sep;
+
+	sep = rindex(channel_and_cpu, '_');
+	if(sep == NULL) {
+		*cpu = -1;
+		sep = channel_and_cpu + strlen(channel_and_cpu);
+	}
+	else {
+		*cpu = atoi(sep+1);
 	}
 
-	list_for_each_entry(bc, &blocked_consumers, list) {
-		if(fds[bc->tmp_poll_idx].revents) {
-			long consumed_old = 0;
-			char *reply;
+	asprintf(channel, "%.*s", (int)(sep-channel_and_cpu), channel_and_cpu);
+}
 
-			result = read(bc->fd_producer, &inbuf, 1);
-			if(result == -1) {
-				PERROR("read");
-				continue;
-			}
-			if(result == 0) {
-				DBG("PRODUCER END");
+static int do_cmd_get_shmid(const char *recvbuf, struct ustcomm_source *src)
+{
+	int retval = 0;
+	struct ust_trace *trace;
+	char trace_name[] = "auto";
+	int i;
+	char *channel_and_cpu;
+	int found = 0;
+	int result;
+	char *ch_name;
+	int ch_cpu;
 
-				close(bc->fd_producer);
+	DBG("get_shmid");
 
-				list_del(&bc->list);
+	channel_and_cpu = nth_token(recvbuf, 1);
+	if(channel_and_cpu == NULL) {
+		ERR("cannot parse channel");
+		goto end;
+	}
 
-				result = ustcomm_send_reply(&bc->server, "END", &bc->src);
-				if(result < 0) {
-					ERR("ustcomm_send_reply failed");
-					continue;
-				}
+	seperate_channel_cpu(channel_and_cpu, &ch_name, &ch_cpu);
+	if(ch_cpu == -1) {
+		ERR("problem parsing channel name");
+		goto free_short_chan_name;
+	}
 
-				continue;
-			}
+	ltt_lock_traces();
+	trace = _ltt_trace_find(trace_name);
+	ltt_unlock_traces();
 
-			result = ltt_do_get_subbuf(bc->rbuf, bc->lttbuf, &consumed_old);
-			if(result == -EAGAIN) {
-				WARN("missed buffer?");
-				continue;
-			}
-			else if(result < 0) {
-				DBG("ltt_do_get_subbuf: error: %s", strerror(-result));
-			}
-			asprintf(&reply, "%s %ld", "OK", consumed_old);
-			result = ustcomm_send_reply(&bc->server, reply, &bc->src);
-			if(result < 0) {
+	if(trace == NULL) {
+		ERR("cannot find trace!");
+		retval = -1;
+		goto free_short_chan_name;
+	}
+
+	for(i=0; i<trace->nr_channels; i++) {
+		struct ust_channel *channel = &trace->channels[i];
+		struct ust_buffer *buf = channel->buf[ch_cpu];
+
+		if(!strcmp(trace->channels[i].channel_name, ch_name)) {
+			char *reply;
+
+//			DBG("the shmid for the requested channel is %d", buf->shmid);
+//			DBG("the shmid for its buffer structure is %d", channel->buf_struct_shmids);
+			asprintf(&reply, "%d %d", buf->shmid, channel->buf_struct_shmids[ch_cpu]);
+
+			result = ustcomm_send_reply(&ustcomm_app.server, reply, src);
+			if(result) {
 				ERR("ustcomm_send_reply failed");
 				free(reply);
-				continue;
+				retval = -1;
+				goto free_short_chan_name;
 			}
+
 			free(reply);
 
-			list_del(&bc->list);
+			found = 1;
+			break;
 		}
 	}
 
+	if(!found) {
+		ERR("channel not found (%s)", channel_and_cpu);
+	}
+
+	free_short_chan_name:
+	free(ch_name);
+
+	end:
+	return retval;
 }
 
-void *listener_main(void *p)
+static int do_cmd_get_n_subbufs(const char *recvbuf, struct ustcomm_source *src)
 {
+	int retval = 0;
+	struct ust_trace *trace;
+	char trace_name[] = "auto";
+	int i;
+	char *channel_and_cpu;
+	int found = 0;
 	int result;
+	char *ch_name;
+	int ch_cpu;
 
-	ust_register_thread();
+	DBG("get_n_subbufs");
 
-	DBG("LISTENER");
+	channel_and_cpu = nth_token(recvbuf, 1);
+	if(channel_and_cpu == NULL) {
+		ERR("cannot parse channel");
+		goto end;
+	}
 
-	for(;;) {
-		char trace_name[] = "auto";
-		char trace_type[] = "ustrelay";
-		char *recvbuf;
-		int len;
-		struct ustcomm_source src;
+	seperate_channel_cpu(channel_and_cpu, &ch_name, &ch_cpu);
+	if(ch_cpu == -1) {
+		ERR("problem parsing channel name");
+		goto free_short_chan_name;
+	}
 
-		process_blocked_consumers();
+	ltt_lock_traces();
+	trace = _ltt_trace_find(trace_name);
+	ltt_unlock_traces();
 
-		result = ustcomm_app_recv_message(&ustcomm_app, &recvbuf, &src, 5);
-		if(result < 0) {
-			WARN("error in ustcomm_app_recv_message");
-			continue;
-		}
-		else if(result == 0) {
-			/* no message */
-			continue;
-		}
+	if(trace == NULL) {
+		ERR("cannot find trace!");
+		retval = -1;
+		goto free_short_chan_name;
+	}
 
-		DBG("received a message! it's: %s", recvbuf);
-		len = strlen(recvbuf);
+	for(i=0; i<trace->nr_channels; i++) {
+		struct ust_channel *channel = &trace->channels[i];
 
-		if(!strcmp(recvbuf, "print_markers")) {
-			print_markers(stderr);
-		}
-		else if(!strcmp(recvbuf, "list_markers")) {
-			char *ptr;
-			size_t size;
-			FILE *fp;
+		if(!strcmp(trace->channels[i].channel_name, ch_name)) {
+			char *reply;
 
-			fp = open_memstream(&ptr, &size);
-			print_markers(fp);
-			fclose(fp);
+			DBG("the n_subbufs for the requested channel is %d", channel->subbuf_cnt);
+			asprintf(&reply, "%d", channel->subbuf_cnt);
 
-			result = ustcomm_send_reply(&ustcomm_app.server, ptr, &src);
+			result = ustcomm_send_reply(&ustcomm_app.server, reply, src);
+			if(result) {
+				ERR("ustcomm_send_reply failed");
+				free(reply);
+				retval = -1;
+				goto free_short_chan_name;
+			}
 
-			free(ptr);
+			free(reply);
+			found = 1;
+			break;
 		}
-		else if(!strcmp(recvbuf, "start")) {
-			/* start is an operation that setups the trace, allocates it and starts it */
-			result = ltt_trace_setup(trace_name);
-			if(result < 0) {
-				ERR("ltt_trace_setup failed");
-				return (void *)1;
-			}
+	}
+	if(found == 0) {
+		ERR("unable to find channel");
+	}
 
-			result = ltt_trace_set_type(trace_name, trace_type);
-			if(result < 0) {
-				ERR("ltt_trace_set_type failed");
-				return (void *)1;
-			}
+	free_short_chan_name:
+	free(ch_name);
 
-			result = ltt_trace_alloc(trace_name);
-			if(result < 0) {
-				ERR("ltt_trace_alloc failed");
-				return (void *)1;
-			}
+	end:
+	return retval;
+}
 
-			inform_consumer_daemon(trace_name);
+static int do_cmd_get_subbuf_size(const char *recvbuf, struct ustcomm_source *src)
+{
+	int retval = 0;
+	struct ust_trace *trace;
+	char trace_name[] = "auto";
+	int i;
+	char *channel_and_cpu;
+	int found = 0;
+	int result;
+	char *ch_name;
+	int ch_cpu;
 
-			result = ltt_trace_start(trace_name);
-			if(result < 0) {
-				ERR("ltt_trace_start failed");
-				continue;
-			}
-		}
-		else if(!strcmp(recvbuf, "trace_setup")) {
-			DBG("trace setup");
+	DBG("get_subbuf_size");
 
-			result = ltt_trace_setup(trace_name);
-			if(result < 0) {
-				ERR("ltt_trace_setup failed");
-				return (void *)1;
-			}
+	channel_and_cpu = nth_token(recvbuf, 1);
+	if(channel_and_cpu == NULL) {
+		ERR("cannot parse channel");
+		goto end;
+	}
 
-			result = ltt_trace_set_type(trace_name, trace_type);
-			if(result < 0) {
-				ERR("ltt_trace_set_type failed");
-				return (void *)1;
-			}
-		}
-		else if(!strcmp(recvbuf, "trace_alloc")) {
-			DBG("trace alloc");
+	seperate_channel_cpu(channel_and_cpu, &ch_name, &ch_cpu);
+	if(ch_cpu == -1) {
+		ERR("problem parsing channel name");
+		goto free_short_chan_name;
+	}
 
-			result = ltt_trace_alloc(trace_name);
-			if(result < 0) {
-				ERR("ltt_trace_alloc failed");
-				return (void *)1;
-			}
-		}
-		else if(!strcmp(recvbuf, "trace_start")) {
-			DBG("trace start");
+	ltt_lock_traces();
+	trace = _ltt_trace_find(trace_name);
+	ltt_unlock_traces();
 
-			result = ltt_trace_start(trace_name);
-			if(result < 0) {
-				ERR("ltt_trace_start failed");
-				continue;
-			}
-		}
-		else if(!strcmp(recvbuf, "trace_stop")) {
-			DBG("trace stop");
+	if(trace == NULL) {
+		ERR("cannot find trace!");
+		retval = -1;
+		goto free_short_chan_name;
+	}
 
-			result = ltt_trace_stop(trace_name);
-			if(result < 0) {
-				ERR("ltt_trace_stop failed");
-				return (void *)1;
-			}
-		}
-		else if(!strcmp(recvbuf, "trace_destroy")) {
+	for(i=0; i<trace->nr_channels; i++) {
+		struct ust_channel *channel = &trace->channels[i];
 
-			DBG("trace destroy");
+		if(!strcmp(trace->channels[i].channel_name, ch_name)) {
+			char *reply;
 
-			result = ltt_trace_destroy(trace_name);
-			if(result < 0) {
-				ERR("ltt_trace_destroy failed");
-				return (void *)1;
+			DBG("the subbuf_size for the requested channel is %zd", channel->subbuf_size);
+			asprintf(&reply, "%zd", channel->subbuf_size);
+
+			result = ustcomm_send_reply(&ustcomm_app.server, reply, src);
+			if(result) {
+				ERR("ustcomm_send_reply failed");
+				free(reply);
+				retval = -1;
+				goto free_short_chan_name;
 			}
+
+			free(reply);
+			found = 1;
+			break;
 		}
-		else if(nth_token_is(recvbuf, "get_shmid", 0) == 1) {
-			struct ltt_trace_struct *trace;
-			char trace_name[] = "auto";
-			int i;
-			char *channel_name;
-
-			DBG("get_shmid");
-
-			channel_name = nth_token(recvbuf, 1);
-			if(channel_name == NULL) {
-				ERR("get_shmid: cannot parse channel");
-				goto next_cmd;
-			}
+	}
+	if(found == 0) {
+		ERR("unable to find channel");
+	}
 
-			ltt_lock_traces();
-			trace = _ltt_trace_find(trace_name);
-			ltt_unlock_traces();
+	free_short_chan_name:
+	free(ch_name);
 
-			if(trace == NULL) {
-				ERR("cannot find trace!");
-				return (void *)1;
-			}
+	end:
+	return retval;
+}
 
-			for(i=0; i<trace->nr_channels; i++) {
-				struct rchan *rchan = trace->channels[i].trans_channel_data;
-				struct rchan_buf *rbuf = rchan->buf;
-				struct ltt_channel_struct *ltt_channel = (struct ltt_channel_struct *)rchan->private_data;
+/* Return the power of two which is equal or higher to v */
 
-				if(!strcmp(trace->channels[i].channel_name, channel_name)) {
-					char *reply;
+static unsigned int pow2_higher_or_eq(unsigned int v)
+{
+	int hb = fls(v);
+	int hbm1 = hb-1;
+	int retval = 1<<(hb-1);
+
+	if(v-retval == 0)
+		return retval;
+	else
+		return retval<<1;
+}
+
+static int do_cmd_set_subbuf_size(const char *recvbuf, struct ustcomm_source *src)
+{
+	char *channel_slash_size;
+	char ch_name[256]="";
+	unsigned int size, power;
+	int retval = 0;
+	struct ust_trace *trace;
+	char trace_name[] = "auto";
+	int i;
+	int found = 0;
 
-					DBG("the shmid for the requested channel is %d", rbuf->shmid);
-					DBG("the shmid for its buffer structure is %d", ltt_channel->buf_shmid);
-					asprintf(&reply, "%d %d", rbuf->shmid, ltt_channel->buf_shmid);
+	DBG("set_subbuf_size");
 
-					result = ustcomm_send_reply(&ustcomm_app.server, reply, &src);
-					if(result) {
-						ERR("listener: get_shmid: ustcomm_send_reply failed");
-						goto next_cmd;
-					}
+	channel_slash_size = nth_token(recvbuf, 1);
+	sscanf(channel_slash_size, "%255[^/]/%u", ch_name, &size);
 
-					free(reply);
+	if(ch_name == NULL) {
+		ERR("cannot parse channel");
+		goto end;
+	}
 
-					break;
-				}
-			}
+	power = pow2_higher_or_eq(size);
+	power = max_t(unsigned int, 2u, power);
+	if (power != size)
+		WARN("using the next power of two for buffer size = %u\n", power);
+
+	ltt_lock_traces();
+	trace = _ltt_trace_find_setup(trace_name);
+	if(trace == NULL) {
+		ERR("cannot find trace!");
+		retval = -1;
+		goto end;
+	}
+
+	for(i = 0; i < trace->nr_channels; i++) {
+		struct ust_channel *channel = &trace->channels[i];
+
+		if(!strcmp(trace->channels[i].channel_name, ch_name)) {
+
+			channel->subbuf_size = power;
+			DBG("the set_subbuf_size for the requested channel is %zd", channel->subbuf_size);
 
-			buffers_to_export--;
+			found = 1;
+			break;
 		}
-		else if(nth_token_is(recvbuf, "get_n_subbufs", 0) == 1) {
-			struct ltt_trace_struct *trace;
-			char trace_name[] = "auto";
-			int i;
-			char *channel_name;
-
-			DBG("get_n_subbufs");
-
-			channel_name = nth_token(recvbuf, 1);
-			if(channel_name == NULL) {
-				ERR("get_n_subbufs: cannot parse channel");
-				goto next_cmd;
-			}
+	}
+	if(found == 0) {
+		ERR("unable to find channel");
+	}
 
-			ltt_lock_traces();
-			trace = _ltt_trace_find(trace_name);
-			ltt_unlock_traces();
+	end:
+	ltt_unlock_traces();
+	return retval;
+}
 
-			if(trace == NULL) {
-				ERR("cannot find trace!");
-				return (void *)1;
-			}
+static int do_cmd_set_subbuf_num(const char *recvbuf, struct ustcomm_source *src)
+{
+	char *channel_slash_num;
+	char ch_name[256]="";
+	unsigned int num;
+	int retval = 0;
+	struct ust_trace *trace;
+	char trace_name[] = "auto";
+	int i;
+	int found = 0;
 
-			for(i=0; i<trace->nr_channels; i++) {
-				struct rchan *rchan = trace->channels[i].trans_channel_data;
+	DBG("set_subbuf_num");
 
-				if(!strcmp(trace->channels[i].channel_name, channel_name)) {
-					char *reply;
+	channel_slash_num = nth_token(recvbuf, 1);
+	sscanf(channel_slash_num, "%255[^/]/%u", ch_name, &num);
 
-					DBG("the n_subbufs for the requested channel is %zd", rchan->n_subbufs);
-					asprintf(&reply, "%zd", rchan->n_subbufs);
+	if(ch_name == NULL) {
+		ERR("cannot parse channel");
+		goto end;
+	}
+	if (num < 2) {
+		ERR("subbuffer count should be greater than 2");
+		goto end;
+	}
 
-					result = ustcomm_send_reply(&ustcomm_app.server, reply, &src);
-					if(result) {
-						ERR("listener: get_n_subbufs: ustcomm_send_reply failed");
-						goto next_cmd;
-					}
+	ltt_lock_traces();
+	trace = _ltt_trace_find_setup(trace_name);
+	if(trace == NULL) {
+		ERR("cannot find trace!");
+		retval = -1;
+		goto end;
+	}
 
-					free(reply);
+	for(i = 0; i < trace->nr_channels; i++) {
+		struct ust_channel *channel = &trace->channels[i];
 
-					break;
-				}
-			}
+		if(!strcmp(trace->channels[i].channel_name, ch_name)) {
+
+			channel->subbuf_cnt = num;
+			DBG("the set_subbuf_cnt for the requested channel is %zd", channel->subbuf_cnt);
+
+			found = 1;
+			break;
 		}
-		else if(nth_token_is(recvbuf, "get_subbuf_size", 0) == 1) {
-			struct ltt_trace_struct *trace;
-			char trace_name[] = "auto";
-			int i;
-			char *channel_name;
-
-			DBG("get_subbuf_size");
-
-			channel_name = nth_token(recvbuf, 1);
-			if(channel_name == NULL) {
-				ERR("get_subbuf_size: cannot parse channel");
-				goto next_cmd;
-			}
+	}
+	if(found == 0) {
+		ERR("unable to find channel");
+	}
 
-			ltt_lock_traces();
-			trace = _ltt_trace_find(trace_name);
-			ltt_unlock_traces();
+	end:
+	ltt_unlock_traces();
+	return retval;
+}
 
-			if(trace == NULL) {
-				ERR("cannot find trace!");
-				return (void *)1;
-			}
+static int do_cmd_get_subbuffer(const char *recvbuf, struct ustcomm_source *src)
+{
+	int retval = 0;
+	struct ust_trace *trace;
+	char trace_name[] = "auto";
+	int i;
+	char *channel_and_cpu;
+	int found = 0;
+	char *ch_name;
+	int ch_cpu;
 
-			for(i=0; i<trace->nr_channels; i++) {
-				struct rchan *rchan = trace->channels[i].trans_channel_data;
+	DBG("get_subbuf");
 
-				if(!strcmp(trace->channels[i].channel_name, channel_name)) {
-					char *reply;
+	channel_and_cpu = nth_token(recvbuf, 1);
+	if(channel_and_cpu == NULL) {
+		ERR("cannot parse channel");
+		goto end;
+	}
 
-					DBG("the subbuf_size for the requested channel is %zd", rchan->subbuf_size);
-					asprintf(&reply, "%zd", rchan->subbuf_size);
+	seperate_channel_cpu(channel_and_cpu, &ch_name, &ch_cpu);
+	if(ch_cpu == -1) {
+		ERR("problem parsing channel name");
+		goto free_short_chan_name;
+	}
 
-					result = ustcomm_send_reply(&ustcomm_app.server, reply, &src);
-					if(result) {
-						ERR("listener: get_subbuf_size: ustcomm_send_reply failed");
-						goto next_cmd;
-					}
+	ltt_lock_traces();
+	trace = _ltt_trace_find(trace_name);
 
-					free(reply);
+	if(trace == NULL) {
+		int result;
+
+		DBG("Cannot find trace. It was likely destroyed by the user.");
+		result = ustcomm_send_reply(&ustcomm_app.server, "NOTFOUND", src);
+		if(result) {
+			ERR("ustcomm_send_reply failed");
+			retval = -1;
+			goto unlock_traces;
+		}
 
-					break;
-				}
+		goto unlock_traces;
+	}
+
+	for(i=0; i<trace->nr_channels; i++) {
+		struct ust_channel *channel = &trace->channels[i];
+
+		if(!strcmp(trace->channels[i].channel_name, ch_name)) {
+			struct ust_buffer *buf = channel->buf[ch_cpu];
+			struct blocked_consumer *bc;
+
+			found = 1;
+
+			bc = (struct blocked_consumer *) malloc(sizeof(struct blocked_consumer));
+			if(bc == NULL) {
+				ERR("malloc returned NULL");
+				goto unlock_traces;
 			}
+			bc->fd_consumer = src->fd;
+			bc->fd_producer = buf->data_ready_fd_read;
+			bc->buf = buf;
+			bc->src = *src;
+			bc->server = ustcomm_app.server;
+
+			list_add(&bc->list, &blocked_consumers);
+
+			/* Being here is the proof the daemon has mapped the buffer in its
+			 * memory. We may now decrement buffers_to_export.
+			 */
+			if(uatomic_read(&buf->consumed) == 0) {
+				DBG("decrementing buffers_to_export");
+				STORE_SHARED(buffers_to_export, LOAD_SHARED(buffers_to_export)-1);
+			}
+
+			break;
 		}
-		else if(nth_token_is(recvbuf, "load_probe_lib", 0) == 1) {
-			char *libfile;
+	}
+	if(found == 0) {
+		ERR("unable to find channel");
+	}
+
+	unlock_traces:
+	ltt_unlock_traces();
+
+	free_short_chan_name:
+	free(ch_name);
+
+	end:
+	return retval;
+}
+
+static int do_cmd_put_subbuffer(const char *recvbuf, struct ustcomm_source *src)
+{
+	int retval = 0;
+	struct ust_trace *trace;
+	char trace_name[] = "auto";
+	int i;
+	char *channel_and_cpu;
+	int found = 0;
+	int result;
+	char *ch_name;
+	int ch_cpu;
+	long consumed_old;
+	char *consumed_old_str;
+	char *endptr;
+	char *reply = NULL;
+
+	DBG("put_subbuf");
+
+	channel_and_cpu = strdup(nth_token(recvbuf, 1));
+	if(channel_and_cpu == NULL) {
+		ERR("cannot parse channel");
+		retval = -1;
+		goto end;
+	}
+
+	consumed_old_str = strdup(nth_token(recvbuf, 2));
+	if(consumed_old_str == NULL) {
+		ERR("cannot parse consumed_old");
+		retval = -1;
+		goto free_channel_and_cpu;
+	}
+	consumed_old = strtol(consumed_old_str, &endptr, 10);
+	if(*endptr != '\0') {
+		ERR("invalid value for consumed_old");
+		retval = -1;
+		goto free_consumed_old_str;
+	}
+
+	seperate_channel_cpu(channel_and_cpu, &ch_name, &ch_cpu);
+	if(ch_cpu == -1) {
+		ERR("problem parsing channel name");
+		retval = -1;
+		goto free_short_chan_name;
+	}
 
-			libfile = nth_token(recvbuf, 1);
+	ltt_lock_traces();
+	trace = _ltt_trace_find(trace_name);
 
-			DBG("load_probe_lib loading %s", libfile);
+	if(trace == NULL) {
+		DBG("Cannot find trace. It was likely destroyed by the user.");
+		result = ustcomm_send_reply(&ustcomm_app.server, "NOTFOUND", src);
+		if(result) {
+			ERR("ustcomm_send_reply failed");
+			retval = -1;
+			goto unlock_traces;
 		}
-		else if(nth_token_is(recvbuf, "get_subbuffer", 0) == 1) {
-			struct ltt_trace_struct *trace;
-			char trace_name[] = "auto";
-			int i;
-			char *channel_name;
-
-			DBG("get_subbuf");
-
-			channel_name = nth_token(recvbuf, 1);
-			if(channel_name == NULL) {
-				ERR("get_subbuf: cannot parse channel");
-				goto next_cmd;
-			}
 
-			ltt_lock_traces();
-			trace = _ltt_trace_find(trace_name);
-			ltt_unlock_traces();
+		goto unlock_traces;
+	}
 
-			if(trace == NULL) {
-				ERR("cannot find trace!");
-				return (void *)1;
-			}
+	for(i=0; i<trace->nr_channels; i++) {
+		struct ust_channel *channel = &trace->channels[i];
 
-			for(i=0; i<trace->nr_channels; i++) {
-				struct rchan *rchan = trace->channels[i].trans_channel_data;
-
-				if(!strcmp(trace->channels[i].channel_name, channel_name)) {
-					struct rchan_buf *rbuf = rchan->buf;
-					struct ltt_channel_buf_struct *lttbuf = trace->channels[i].buf;
-					struct blocked_consumer *bc;
-
-					bc = (struct blocked_consumer *) malloc(sizeof(struct blocked_consumer));
-					if(bc == NULL) {
-						ERR("malloc returned NULL");
-						goto next_cmd;
-					}
-					bc->fd_consumer = src.fd;
-					bc->fd_producer = lttbuf->data_ready_fd_read;
-					bc->rbuf = rbuf;
-					bc->lttbuf = lttbuf;
-					bc->src = src;
-					bc->server = ustcomm_app.server;
-
-					list_add(&bc->list, &blocked_consumers);
-
-					break;
-				}
+		if(!strcmp(trace->channels[i].channel_name, ch_name)) {
+			struct ust_buffer *buf = channel->buf[ch_cpu];
+
+			found = 1;
+
+			result = ust_buffers_put_subbuf(buf, consumed_old);
+			if(result < 0) {
+				WARN("ust_buffers_put_subbuf: error (subbuf=%s)", channel_and_cpu);
+				asprintf(&reply, "%s", "ERROR");
 			}
-		}
-		else if(nth_token_is(recvbuf, "put_subbuffer", 0) == 1) {
-			struct ltt_trace_struct *trace;
-			char trace_name[] = "auto";
-			int i;
-			char *channel_name;
-			long consumed_old;
-			char *consumed_old_str;
-			char *endptr;
-
-			DBG("put_subbuf");
-
-			channel_name = strdup_malloc(nth_token(recvbuf, 1));
-			if(channel_name == NULL) {
-				ERR("put_subbuf_size: cannot parse channel");
-				goto next_cmd;
+			else {
+				DBG("ust_buffers_put_subbuf: success (subbuf=%s)", channel_and_cpu);
+				asprintf(&reply, "%s", "OK");
 			}
 
-			consumed_old_str = strdup_malloc(nth_token(recvbuf, 2));
-			if(consumed_old_str == NULL) {
-				ERR("put_subbuf: cannot parse consumed_old");
-				goto next_cmd;
-			}
-			consumed_old = strtol(consumed_old_str, &endptr, 10);
-			if(*endptr != '\0') {
-				ERR("put_subbuf: invalid value for consumed_old");
-				goto next_cmd;
+			result = ustcomm_send_reply(&ustcomm_app.server, reply, src);
+			if(result) {
+				ERR("ustcomm_send_reply failed");
+				free(reply);
+				retval = -1;
+				goto unlock_traces;
 			}
 
-			ltt_lock_traces();
-			trace = _ltt_trace_find(trace_name);
-			ltt_unlock_traces();
+			free(reply);
+			break;
+		}
+	}
+	if(found == 0) {
+		ERR("unable to find channel");
+	}
 
-			if(trace == NULL) {
-				ERR("cannot find trace!");
-				return (void *)1;
-			}
+	unlock_traces:
+	ltt_unlock_traces();
+	free_short_chan_name:
+	free(ch_name);
+	free_consumed_old_str:
+	free(consumed_old_str);
+	free_channel_and_cpu:
+	free(channel_and_cpu);
+
+	end:
+	return retval;
+}
 
-			for(i=0; i<trace->nr_channels; i++) {
-				struct rchan *rchan = trace->channels[i].trans_channel_data;
-
-				if(!strcmp(trace->channels[i].channel_name, channel_name)) {
-					struct rchan_buf *rbuf = rchan->buf;
-					struct ltt_channel_buf_struct *lttbuf = trace->channels[i].buf;
-					char *reply;
-					long consumed_old=0;
-
-					result = ltt_do_put_subbuf(rbuf, lttbuf, consumed_old);
-					if(result < 0) {
-						WARN("ltt_do_put_subbuf: error (subbuf=%s)", channel_name);
-						asprintf(&reply, "%s", "ERROR");
-					}
-					else {
-						DBG("ltt_do_put_subbuf: success (subbuf=%s)", channel_name);
-						asprintf(&reply, "%s", "OK");
-					}
-
-					result = ustcomm_send_reply(&ustcomm_app.server, reply, &src);
-					if(result) {
-						ERR("listener: put_subbuf: ustcomm_send_reply failed");
-						goto next_cmd;
-					}
-
-					free(reply);
-
-					break;
-				}
-			}
+static void listener_cleanup(void *ptr)
+{
+	ustcomm_fini_app(&ustcomm_app, 0);
+}
+
+int process_client_cmd(char *recvbuf, struct ustcomm_source *src)
+{
+	int result;
+	char trace_name[] = "auto";
+	char trace_type[] = "ustrelay";
+	int len;
+
+	DBG("received a message! it's: %s", recvbuf);
+	len = strlen(recvbuf);
+
+	if(!strcmp(recvbuf, "print_markers")) {
+		print_markers(stderr);
+	}
+	else if(!strcmp(recvbuf, "list_markers")) {
+		char *ptr;
+		size_t size;
+		FILE *fp;
 
-			free(channel_name);
-			free(consumed_old_str);
+		fp = open_memstream(&ptr, &size);
+		print_markers(fp);
+		fclose(fp);
+
+		result = ustcomm_send_reply(&ustcomm_app.server, ptr, src);
+
+		free(ptr);
+	}
+	else if(!strcmp(recvbuf, "start")) {
+		/* start is an operation that setups the trace, allocates it and starts it */
+		result = ltt_trace_setup(trace_name);
+		if(result < 0) {
+			ERR("ltt_trace_setup failed");
+			return -1;
 		}
-		else if(nth_token_is(recvbuf, "enable_marker", 0) == 1) {
-			char *channel_slash_name = nth_token(recvbuf, 1);
-			char channel_name[256]="";
-			char marker_name[256]="";
 
-			result = sscanf(channel_slash_name, "%255[^/]/%255s", channel_name, marker_name);
+		result = ltt_trace_set_type(trace_name, trace_type);
+		if(result < 0) {
+			ERR("ltt_trace_set_type failed");
+			return -1;
+		}
 
-			if(channel_name == NULL || marker_name == NULL) {
-				WARN("invalid marker name");
-				goto next_cmd;
-			}
-			printf("%s %s\n", channel_name, marker_name);
+		result = ltt_trace_alloc(trace_name);
+		if(result < 0) {
+			ERR("ltt_trace_alloc failed");
+			return -1;
+		}
 
-			result = ltt_marker_connect(channel_name, marker_name, "default");
-			if(result < 0) {
-				WARN("could not enable marker; channel=%s, name=%s", channel_name, marker_name);
-			}
+		inform_consumer_daemon(trace_name);
+
+		result = ltt_trace_start(trace_name);
+		if(result < 0) {
+			ERR("ltt_trace_start failed");
+			return -1;
 		}
-		else if(nth_token_is(recvbuf, "disable_marker", 0) == 1) {
-			char *channel_slash_name = nth_token(recvbuf, 1);
-			char *marker_name;
-			char *channel_name;
+	}
+	else if(!strcmp(recvbuf, "trace_setup")) {
+		DBG("trace setup");
 
-			result = sscanf(channel_slash_name, "%a[^/]/%as", &channel_name, &marker_name);
+		result = ltt_trace_setup(trace_name);
+		if(result < 0) {
+			ERR("ltt_trace_setup failed");
+			return -1;
+		}
 
-			if(marker_name == NULL) {
-			}
-			printf("%s %s\n", channel_name, marker_name);
+		result = ltt_trace_set_type(trace_name, trace_type);
+		if(result < 0) {
+			ERR("ltt_trace_set_type failed");
+			return -1;
+		}
+	}
+	else if(!strcmp(recvbuf, "trace_alloc")) {
+		DBG("trace alloc");
 
-			result = ltt_marker_disconnect(channel_name, marker_name, "default");
-			if(result < 0) {
-				WARN("could not disable marker; channel=%s, name=%s", channel_name, marker_name);
-			}
+		result = ltt_trace_alloc(trace_name);
+		if(result < 0) {
+			ERR("ltt_trace_alloc failed");
+			return -1;
 		}
-		else if(nth_token_is(recvbuf, "get_pidunique", 0) == 1) {
-			char *reply;
+		inform_consumer_daemon(trace_name);
+	}
+	else if(!strcmp(recvbuf, "trace_create")) {
+		DBG("trace create");
 
-			asprintf(&reply, "%lld", pidunique);
+		result = ltt_trace_setup(trace_name);
+		if(result < 0) {
+			ERR("ltt_trace_setup failed");
+			return -1;
+		}
 
-			result = ustcomm_send_reply(&ustcomm_app.server, reply, &src);
-			if(result) {
-				ERR("listener: get_pidunique: ustcomm_send_reply failed");
-				goto next_cmd;
-			}
+		result = ltt_trace_set_type(trace_name, trace_type);
+		if(result < 0) {
+			ERR("ltt_trace_set_type failed");
+			return -1;
+		}
+	}
+	else if(!strcmp(recvbuf, "trace_start")) {
+		DBG("trace start");
 
-			free(reply);
+		result = ltt_trace_alloc(trace_name);
+		if(result < 0) {
+			ERR("ltt_trace_alloc failed");
+			return -1;
 		}
-//		else if(nth_token_is(recvbuf, "get_notifications", 0) == 1) {
-//			struct ltt_trace_struct *trace;
-//			char trace_name[] = "auto";
-//			int i;
-//			char *channel_name;
-//
-//			DBG("get_notifications");
-//
-//			channel_name = strdup_malloc(nth_token(recvbuf, 1));
-//			if(channel_name == NULL) {
-//				ERR("put_subbuf_size: cannot parse channel");
-//				goto next_cmd;
-//			}
-//
-//			ltt_lock_traces();
-//			trace = _ltt_trace_find(trace_name);
-//			ltt_unlock_traces();
-//
-//			if(trace == NULL) {
-//				ERR("cannot find trace!");
-//				return (void *)1;
-//			}
-//
-//			for(i=0; i<trace->nr_channels; i++) {
-//				struct rchan *rchan = trace->channels[i].trans_channel_data;
-//				int fd;
-//
-//				if(!strcmp(trace->channels[i].channel_name, channel_name)) {
-//					struct rchan_buf *rbuf = rchan->buf;
-//					struct ltt_channel_buf_struct *lttbuf = trace->channels[i].buf;
-//
-//					result = fd = ustcomm_app_detach_client(&ustcomm_app, &src);
-//					if(result == -1) {
-//						ERR("ustcomm_app_detach_client failed");
-//						goto next_cmd;
-//					}
-//
-//					lttbuf->wake_consumer_arg = (void *) fd;
-//
-//					smp_wmb();
-//
-//					lttbuf->call_wake_consumer = 1;
-//
-//					break;
-//				}
-//			}
-//
-//			free(channel_name);
-//		}
-		else {
-			ERR("unable to parse message: %s", recvbuf);
+		if(!result) {
+			inform_consumer_daemon(trace_name);
 		}
 
-	next_cmd:
-		free(recvbuf);
+		result = ltt_trace_start(trace_name);
+		if(result < 0) {
+			ERR("ltt_trace_start failed");
+			return -1;
+		}
 	}
-}
+	else if(!strcmp(recvbuf, "trace_stop")) {
+		DBG("trace stop");
 
-int have_listener = 0;
+		result = ltt_trace_stop(trace_name);
+		if(result < 0) {
+			ERR("ltt_trace_stop failed");
+			return -1;
+		}
+	}
+	else if(!strcmp(recvbuf, "trace_destroy")) {
 
-void create_listener(void)
-{
-#ifdef USE_CLONE
-	static char listener_stack[16384];
-#else
-	pthread_t thread;
-#endif
+		DBG("trace destroy");
 
-	if(have_listener)
-		return;
+		result = ltt_trace_destroy(trace_name, 0);
+		if(result < 0) {
+			ERR("ltt_trace_destroy failed");
+			return -1;
+		}
+	}
+	else if(nth_token_is(recvbuf, "get_shmid", 0) == 1) {
+		do_cmd_get_shmid(recvbuf, src);
+	}
+	else if(nth_token_is(recvbuf, "get_n_subbufs", 0) == 1) {
+		do_cmd_get_n_subbufs(recvbuf, src);
+	}
+	else if(nth_token_is(recvbuf, "get_subbuf_size", 0) == 1) {
+		do_cmd_get_subbuf_size(recvbuf, src);
+	}
+	else if(nth_token_is(recvbuf, "load_probe_lib", 0) == 1) {
+		char *libfile;
 
-#ifdef USE_CLONE
-	result = clone(listener_main, listener_stack+sizeof(listener_stack)-1, CLONE_FS | CLONE_FILES | CLONE_VM | CLONE_SIGHAND | CLONE_THREAD, NULL);
-	if(result == -1) {
-		perror("clone");
-		return;
+		libfile = nth_token(recvbuf, 1);
+
+		DBG("load_probe_lib loading %s", libfile);
+
+		free(libfile);
+	}
+	else if(nth_token_is(recvbuf, "get_subbuffer", 0) == 1) {
+		do_cmd_get_subbuffer(recvbuf, src);
+	}
+	else if(nth_token_is(recvbuf, "put_subbuffer", 0) == 1) {
+		do_cmd_put_subbuffer(recvbuf, src);
 	}
-#else
+	else if(nth_token_is(recvbuf, "set_subbuf_size", 0) == 1) {
+		do_cmd_set_subbuf_size(recvbuf, src);
+	}
+	else if(nth_token_is(recvbuf, "set_subbuf_num", 0) == 1) {
+		do_cmd_set_subbuf_num(recvbuf, src);
+	}
+	else if(nth_token_is(recvbuf, "enable_marker", 0) == 1) {
+		char *channel_slash_name = nth_token(recvbuf, 1);
+		char channel_name[256]="";
+		char marker_name[256]="";
 
-	pthread_create(&thread, NULL, listener_main, NULL);
-#endif
+		result = sscanf(channel_slash_name, "%255[^/]/%255s", channel_name, marker_name);
 
-	have_listener = 1;
-}
+		if(channel_name == NULL || marker_name == NULL) {
+			WARN("invalid marker name");
+			goto next_cmd;
+		}
+
+		result = ltt_marker_connect(channel_name, marker_name, "default");
+		if(result < 0) {
+			WARN("could not enable marker; channel=%s, name=%s", channel_name, marker_name);
+		}
+	}
+	else if(nth_token_is(recvbuf, "disable_marker", 0) == 1) {
+		char *channel_slash_name = nth_token(recvbuf, 1);
+		char *marker_name;
+		char *channel_name;
 
-/* The signal handler itself. Signals must be setup so there cannot be
-   nested signals. */
+		result = sscanf(channel_slash_name, "%a[^/]/%as", &channel_name, &marker_name);
 
-void sighandler(int sig)
-{
-	static char have_listener = 0;
-	DBG("sighandler");
+		if(marker_name == NULL) {
+		}
 
-	if(!have_listener) {
-		create_listener();
-		have_listener = 1;
+		result = ltt_marker_disconnect(channel_name, marker_name, "default");
+		if(result < 0) {
+			WARN("could not disable marker; channel=%s, name=%s", channel_name, marker_name);
+		}
 	}
-}
+	else if(nth_token_is(recvbuf, "get_pidunique", 0) == 1) {
+		char *reply;
 
-/* Called by the app signal handler to chain it to us. */
+		asprintf(&reply, "%lld", pidunique);
 
-void chain_signal(void)
-{
-	sighandler(USTSIGNAL);
+		result = ustcomm_send_reply(&ustcomm_app.server, reply, src);
+		if(result) {
+			ERR("listener: get_pidunique: ustcomm_send_reply failed");
+			goto next_cmd;
+		}
+
+		free(reply);
+	}
+	else {
+		ERR("unable to parse message: %s", recvbuf);
+	}
+
+next_cmd:
+
+	return 0;
 }
 
-static int init_socket(void)
+void *listener_main(void *p)
 {
-	return ustcomm_init_app(getpid(), &ustcomm_app);
+	int result;
+
+	DBG("LISTENER");
+
+	pthread_cleanup_push(listener_cleanup, NULL);
+
+	for(;;) {
+		struct mpentries mpent;
+
+		multipoll_init(&mpent);
+
+		blocked_consumers_add_to_mp(&mpent);
+		ustcomm_mp_add_app_clients(&mpent, &ustcomm_app, process_client_cmd);
+
+		result = multipoll_poll(&mpent, -1);
+		if(result == -1) {
+			ERR("error in multipoll_poll");
+		}
+
+		multipoll_destroy(&mpent);
+	}
+
+	pthread_cleanup_pop(1);
 }
 
-static int init_signal_handler(void)
-{
-	/* Attempt to handler SIGIO. If the main program wants to
-	 * handle it, fine, it'll override us. They it'll have to
-	 * use the chaining function.
-	 */
+/* These should only be accessed in the parent thread,
+ * not the listener.
+ */
+static volatile sig_atomic_t have_listener = 0;
+static pthread_t listener_thread;
 
+void create_listener(void)
+{
 	int result;
-	struct sigaction act;
+	sigset_t sig_all_blocked;
+	sigset_t orig_parent_mask;
 
-	result = sigemptyset(&act.sa_mask);
-	if(result == -1) {
-		PERROR("sigemptyset");
-		return -1;
+	if(have_listener) {
+		WARN("not creating listener because we already had one");
+		return;
 	}
 
-	act.sa_handler = sighandler;
-	act.sa_flags = SA_RESTART;
-
-	/* Only defer ourselves. Also, try to restart interrupted
-	 * syscalls to disturb the traced program as little as possible.
+	/* A new thread created by pthread_create inherits the signal mask
+	 * from the parent. To avoid any signal being received by the
+	 * listener thread, we block all signals temporarily in the parent,
+	 * while we create the listener thread.
 	 */
-	result = sigaction(SIGIO, &act, NULL);
+
+	sigfillset(&sig_all_blocked);
+
+	result = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_parent_mask);
+	if(result) {
+		PERROR("pthread_sigmask: %s", strerror(result));
+	}
+
+	result = pthread_create(&listener_thread, NULL, listener_main, NULL);
 	if(result == -1) {
-		PERROR("sigaction");
-		return -1;
+		PERROR("pthread_create");
 	}
 
-	return 0;
+	/* Restore original signal mask in parent */
+	result = pthread_sigmask(SIG_SETMASK, &orig_parent_mask, NULL);
+	if(result) {
+		PERROR("pthread_sigmask: %s", strerror(result));
+	}
+
+	have_listener = 1;
+}
+
+static int init_socket(void)
+{
+	return ustcomm_init_app(getpid(), &ustcomm_app);
 }
 
 #define AUTOPROBE_DISABLED      0
@@ -890,11 +1106,11 @@ static void auto_probe_connect(struct marker *m)
 	if(result && result != -EEXIST)
 		ERR("ltt_marker_connect (marker = %s/%s, errno = %d)", m->channel, m->name, -result);
 
-	DBG("auto connected marker %s %s to probe default", m->channel, m->name);
+	DBG("auto connected marker %s (addr: %p) %s to probe default", m->channel, m, m->name);
 
 }
 
-static void __attribute__((constructor(1000))) init()
+static void __attribute__((constructor)) init()
 {
 	int result;
 	char* autoprobe_val = NULL;
@@ -904,26 +1120,15 @@ static void __attribute__((constructor(1000))) init()
 	 */
 	pidunique = make_pidunique();
 
-	/* Initialize RCU in case the constructor order is not good. */
-	urcu_init();
-
-	/* It is important to do this before events start to be generated. */
-	ust_register_thread();
-
 	DBG("Tracectl constructor");
 
-	/* Must create socket before signal handler to prevent races.
-         */
 	result = init_socket();
 	if(result == -1) {
 		ERR("init_socket error");
 		return;
 	}
-	result = init_signal_handler();
-	if(result == -1) {
-		ERR("init_signal_handler error");
-		return;
-	}
+
+	create_listener();
 
 	autoprobe_val = getenv("UST_AUTOPROBE");
 	if(autoprobe_val) {
@@ -972,6 +1177,26 @@ static void __attribute__((constructor(1000))) init()
 		}
 	}
 
+	if(getenv("UST_OVERWRITE")) {
+		int val = atoi(getenv("UST_OVERWRITE"));
+		if(val == 0 || val == 1) {
+			STORE_SHARED(ust_channels_overwrite_by_default, val);
+		}
+		else {
+			WARN("invalid value for UST_OVERWRITE");
+		}
+	}
+
+	if(getenv("UST_AUTOCOLLECT")) {
+		int val = atoi(getenv("UST_AUTOCOLLECT"));
+		if(val == 0 || val == 1) {
+			STORE_SHARED(ust_channels_request_collection_by_default, val);
+		}
+		else {
+			WARN("invalid value for UST_AUTOCOLLECT");
+		}
+	}
+
 	if(getenv("UST_TRACE")) {
 		char trace_name[] = "auto";
 		char trace_type[] = "ustrelay";
@@ -981,13 +1206,32 @@ static void __attribute__((constructor(1000))) init()
 		/* Ensure marker control is initialized */
 		init_marker_control();
 
-		/* Ensure relay is initialized */
-		init_ustrelay_transport();
-
 		/* Ensure markers are initialized */
 		init_markers();
 
-		/* In case. */
+		/* Ensure buffers are initialized, for the transport to be available.
+		 * We are about to set a trace type and it will fail without this.
+		 */
+		init_ustrelay_transport();
+
+		/* FIXME: When starting early tracing (here), depending on the
+		 * order of constructors, it is very well possible some marker
+		 * sections are not yet registered. Because of this, some
+		 * channels may not be registered. Yet, we are about to ask the
+		 * daemon to collect the channels. Channels which are not yet
+		 * registered will not be collected.
+		 *
+		 * Currently, in LTTng, there is no way to add a channel after
+		 * trace start. The reason for this is that it induces complex
+		 * concurrency issues on the trace structures, which can only
+		 * be resolved using RCU. This has not been done yet. As a
+		 * workaround, we are forcing the registration of the "ust"
+		 * channel here. This is the only channel (apart from metadata)
+		 * that can be reliably used in early tracing.
+		 *
+		 * Non-early tracing does not have this problem and can use
+		 * arbitrary channel names.
+		 */
 		ltt_channels_register("ust");
 
 		result = ltt_trace_setup(trace_name);
@@ -1008,13 +1252,15 @@ static void __attribute__((constructor(1000))) init()
 			return;
 		}
 
-		inform_consumer_daemon(trace_name);
-
 		result = ltt_trace_start(trace_name);
 		if(result < 0) {
 			ERR("ltt_trace_start failed");
 			return;
 		}
+
+		/* Do this after the trace is started in order to avoid creating confusion
+		 * if the trace fails to start. */
+		inform_consumer_daemon(trace_name);
 	}
 
 
@@ -1048,7 +1294,7 @@ static void destroy_traces(void)
 		ERR("ltt_trace_stop error");
 	}
 
-	result = ltt_trace_destroy("auto");
+	result = ltt_trace_destroy("auto", 0);
 	if(result == -1) {
 		ERR("ltt_trace_destroy error");
 	}
@@ -1057,7 +1303,7 @@ static void destroy_traces(void)
 static int trace_recording(void)
 {
 	int retval = 0;
-	struct ltt_trace_struct *trace;
+	struct ust_trace *trace;
 
 	ltt_lock_traces();
 
@@ -1095,6 +1341,20 @@ int restarting_usleep(useconds_t usecs)
 	return result;
 }
 
+static void stop_listener()
+{
+	int result;
+
+	result = pthread_cancel(listener_thread);
+	if(result != 0) {
+		ERR("pthread_cancel: %s", strerror(result));
+	}
+	result = pthread_join(listener_thread, NULL);
+	if(result != 0) {
+		ERR("pthread_join: %s", strerror(result));
+	}
+}
+
 /* This destructor keeps the process alive for a few seconds in order
  * to leave time to ustd to connect to its buffers. This is necessary
  * for programs whose execution is very short. It is also useful in all
@@ -1107,10 +1367,10 @@ int restarting_usleep(useconds_t usecs)
 
 static void __attribute__((destructor)) keepalive()
 {
-	if(trace_recording() && buffers_to_export) {
+	if(trace_recording() && LOAD_SHARED(buffers_to_export)) {
 		int total = 0;
 		DBG("Keeping process alive for consumer daemon...");
-		while(buffers_to_export) {
+		while(LOAD_SHARED(buffers_to_export)) {
 			const int interv = 200000;
 			restarting_usleep(interv);
 			total += interv;
@@ -1125,13 +1385,16 @@ static void __attribute__((destructor)) keepalive()
 
 	destroy_traces();
 
-	ustcomm_fini_app(&ustcomm_app);
+	/* Ask the listener to stop and clean up. */
+	stop_listener();
 }
 
 void ust_potential_exec(void)
 {
 	trace_mark(ust, potential_exec, MARK_NOARGS);
 
+	DBG("test");
+
 	keepalive();
 }
 
@@ -1139,32 +1402,47 @@ void ust_potential_exec(void)
  * the new process, anytime a process whose memory is not shared with
  * the parent is created. If this function is not called, the events
  * of the new process will not be collected.
+ *
+ * Signals should be disabled before the fork and reenabled only after
+ * this call in order to guarantee tracing is not started before ust_fork()
+ * sanitizes the new process.
  */
 
-void ust_fork(void)
+static void ust_fork(void)
 {
 	struct blocked_consumer *bc;
 	struct blocked_consumer *deletable_bc = NULL;
 	int result;
 
+	/* FIXME: technically, the locks could have been taken before the fork */
 	DBG("ust: forking");
+
+	/* break lock if necessary */
+	ltt_unlock_traces();
+
 	ltt_trace_stop("auto");
-	ltt_trace_destroy("auto");
+	ltt_trace_destroy("auto", 1);
 	/* Delete all active connections */
 	ustcomm_close_all_connections(&ustcomm_app.server);
 
 	/* Delete all blocked consumers */
 	list_for_each_entry(bc, &blocked_consumers, list) {
-		close(bc->fd_producer);
-		close(bc->fd_consumer);
+		result = close(bc->fd_producer);
+		if(result == -1) {
+			PERROR("close");
+		}
 		free(deletable_bc);
 		deletable_bc = bc;
 		list_del(&bc->list);
 	}
 
+	/* free app, keeping socket file */
+	ustcomm_fini_app(&ustcomm_app, 1);
+
+	STORE_SHARED(buffers_to_export, 0);
 	have_listener = 0;
-	create_listener();
 	init_socket();
+	create_listener();
 	ltt_trace_setup("auto");
 	result = ltt_trace_set_type("auto", "ustrelay");
 	if(result < 0) {
@@ -1177,3 +1455,54 @@ void ust_fork(void)
 	inform_consumer_daemon("auto");
 }
 
+void ust_before_fork(ust_fork_info_t *fork_info)
+{
+        /* Disable signals. This is to avoid that the child
+         * intervenes before it is properly setup for tracing. It is
+         * safer to disable all signals, because then we know we are not
+         * breaking anything by restoring the original mask.
+         */
+	sigset_t all_sigs;
+	int result;
+
+        /* FIXME:
+                - only do this if tracing is active
+        */
+
+        /* Disable signals */
+        sigfillset(&all_sigs);
+        result = sigprocmask(SIG_BLOCK, &all_sigs, &fork_info->orig_sigs);
+        if(result == -1) {
+                PERROR("sigprocmask");
+                return;
+        }
+}
+
+/* Don't call this function directly in a traced program */
+static void ust_after_fork_common(ust_fork_info_t *fork_info)
+{
+	int result;
+
+        /* Restore signals */
+        result = sigprocmask(SIG_SETMASK, &fork_info->orig_sigs, NULL);
+        if(result == -1) {
+                PERROR("sigprocmask");
+                return;
+        }
+}
+
+void ust_after_fork_parent(ust_fork_info_t *fork_info)
+{
+	/* Reenable signals */
+	ust_after_fork_common(fork_info);
+}
+
+void ust_after_fork_child(ust_fork_info_t *fork_info)
+{
+	/* First sanitize the child */
+	ust_fork();
+
+	/* Then reenable interrupts */
+	ust_after_fork_common(fork_info);
+}
+