X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fbin%2Flttng-sessiond%2Fcmd.c;h=11e2885411f69f6fb07325d0364aed8c891e37d1;hp=17091de09ec66d9bd5b6028bbf04b90c7a99d5ff;hb=7c1d2758d663ac5f119eae6849e50b56546a0c48;hpb=ade7ce5245446944d27824943142773f7e4d0674

diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c
index 17091de09..11e288541 100644
--- a/src/bin/lttng-sessiond/cmd.c
+++ b/src/bin/lttng-sessiond/cmd.c
@@ -16,7 +16,9 @@
  */
 
 #define _GNU_SOURCE
+#define _LGPL_SOURCE
 #include <assert.h>
+#include <string.h>
 #include <inttypes.h>
 #include <urcu/list.h>
 #include <urcu/uatomic.h>
@@ -36,6 +38,7 @@
 #include "lttng-sessiond.h"
 #include "utils.h"
 #include "syscall.h"
+#include "agent.h"
 
 #include "cmd.h"
 
@@ -48,21 +51,6 @@
 static pthread_mutex_t relayd_net_seq_idx_lock = PTHREAD_MUTEX_INITIALIZER;
 static uint64_t relayd_net_seq_idx;
 
-/*
- * Both functions below are special case for the Kernel domain when
- * enabling/disabling all events.
- */
-static
-int enable_kevent_all(struct ltt_session *session,
-		struct lttng_domain *domain, char *channel_name,
-		struct lttng_event *event,
-		char *filter_expression,
-		struct lttng_filter_bytecode *filter, int wpipe);
-static
-int disable_kevent_all(struct ltt_session *session, int domain,
-		char *channel_name,
-		struct lttng_event *event);
-
 /*
  * Create a session path used by list_lttng_sessions for the case that the
  * session consumer is on the network.
@@ -219,7 +207,9 @@ static int list_lttng_agent_events(struct agent *agt,
 
 	DBG3("Listing agent events");
 
+	rcu_read_lock();
 	nb_event = lttng_ht_get_count(agt->events);
+	rcu_read_unlock();
 	if (nb_event == 0) {
 		ret = nb_event;
 		goto error;
@@ -908,11 +898,106 @@ int cmd_disable_channel(struct ltt_session *session, int domain,
 		}
 		break;
 	}
-#if 0
-	case LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN:
-	case LTTNG_DOMAIN_UST_EXEC_NAME:
-	case LTTNG_DOMAIN_UST_PID:
-#endif
+	default:
+		ret = LTTNG_ERR_UNKNOWN_DOMAIN;
+		goto error;
+	}
+
+	ret = LTTNG_OK;
+
+error:
+	rcu_read_unlock();
+	return ret;
+}
+
+/*
+ * Command LTTNG_TRACK_PID processed by the client thread.
+ *
+ * Called with session lock held.
+ */
+int cmd_track_pid(struct ltt_session *session, int domain, int pid)
+{
+	int ret;
+
+	rcu_read_lock();
+
+	switch (domain) {
+	case LTTNG_DOMAIN_KERNEL:
+	{
+		struct ltt_kernel_session *ksess;
+
+		ksess = session->kernel_session;
+
+		ret = kernel_track_pid(ksess, pid);
+		if (ret != LTTNG_OK) {
+			goto error;
+		}
+
+		kernel_wait_quiescent(kernel_tracer_fd);
+		break;
+	}
+	case LTTNG_DOMAIN_UST:
+	{
+		struct ltt_ust_session *usess;
+
+		usess = session->ust_session;
+
+		ret = trace_ust_track_pid(usess, pid);
+		if (ret != LTTNG_OK) {
+			goto error;
+		}
+		break;
+	}
+	default:
+		ret = LTTNG_ERR_UNKNOWN_DOMAIN;
+		goto error;
+	}
+
+	ret = LTTNG_OK;
+
+error:
+	rcu_read_unlock();
+	return ret;
+}
+
+/*
+ * Command LTTNG_UNTRACK_PID processed by the client thread.
+ *
+ * Called with session lock held.
+ */
+int cmd_untrack_pid(struct ltt_session *session, int domain, int pid)
+{
+	int ret;
+
+	rcu_read_lock();
+
+	switch (domain) {
+	case LTTNG_DOMAIN_KERNEL:
+	{
+		struct ltt_kernel_session *ksess;
+
+		ksess = session->kernel_session;
+
+		ret = kernel_untrack_pid(ksess, pid);
+		if (ret != LTTNG_OK) {
+			goto error;
+		}
+
+		kernel_wait_quiescent(kernel_tracer_fd);
+		break;
+	}
+	case LTTNG_DOMAIN_UST:
+	{
+		struct ltt_ust_session *usess;
+
+		usess = session->ust_session;
+
+		ret = trace_ust_untrack_pid(usess, pid);
+		if (ret != LTTNG_OK) {
+			goto error;
+		}
+		break;
+	}
 	default:
 		ret = LTTNG_ERR_UNKNOWN_DOMAIN;
 		goto error;
@@ -936,11 +1021,21 @@ int cmd_enable_channel(struct ltt_session *session,
 	int ret;
 	struct ltt_ust_session *usess = session->ust_session;
 	struct lttng_ht *chan_ht;
+	size_t len;
 
 	assert(session);
 	assert(attr);
 	assert(domain);
 
+	len = strnlen(attr->name, sizeof(attr->name));
+
+	/* Validate channel name */
+	if (attr->name[0] == '.' ||
+		memchr(attr->name, '/', len) != NULL) {
+		ret = LTTNG_ERR_INVALID_CHANNEL_NAME;
+		goto end;
+	}
+
 	DBG("Enabling channel %s for session %s", attr->name, session->name);
 
 	rcu_read_lock();
@@ -1021,10 +1116,10 @@ int cmd_enable_channel(struct ltt_session *session,
 
 error:
 	rcu_read_unlock();
+end:
 	return ret;
 }
 
-
 /*
  * Command LTTNG_DISABLE_EVENT processed by the client thread.
  */
@@ -1039,14 +1134,11 @@ int cmd_disable_event(struct ltt_session *session, int domain,
 
 	event_name = event->name;
 
-	if (event->loglevel_type || event->loglevel || event->enabled
+	/* Error out on unhandled search criteria */
+	if (event->loglevel_type || event->loglevel != -1 || event->enabled
 			|| event->pid || event->filter || event->exclusion) {
 		return LTTNG_ERR_UNK;
 	}
-	/* Special handling for kernel domain all events. */
-	if (domain == LTTNG_DOMAIN_KERNEL && !strcmp(event_name, "*")) {
-		return disable_kevent_all(session, domain, channel_name, event);
-	}
 
 	rcu_read_lock();
 
@@ -1076,14 +1168,28 @@ int cmd_disable_event(struct ltt_session *session, int domain,
 
 		switch (event->type) {
 		case LTTNG_EVENT_ALL:
-		case LTTNG_EVENT_TRACEPOINT:
-			ret = event_kernel_disable_tracepoint(kchan, event_name);
+			ret = event_kernel_disable_event_all(kchan);
 			if (ret != LTTNG_OK) {
 				goto error;
 			}
 			break;
+		case LTTNG_EVENT_TRACEPOINT:	/* fall-through */
 		case LTTNG_EVENT_SYSCALL:
-			ret = event_kernel_disable_syscall(kchan, event_name);
+			if (!strcmp(event_name, "*")) {
+				ret = event_kernel_disable_event_type(kchan,
+					event->type);
+			} else {
+				ret = event_kernel_disable_event(kchan,
+					event_name);
+			}
+			if (ret != LTTNG_OK) {
+				goto error;
+			}
+			break;
+		case LTTNG_EVENT_PROBE:
+		case LTTNG_EVENT_FUNCTION:
+		case LTTNG_EVENT_FUNCTION_ENTRY:
+			ret = event_kernel_disable_event(kchan, event_name);
 			if (ret != LTTNG_OK) {
 				goto error;
 			}
@@ -1170,80 +1276,6 @@ int cmd_disable_event(struct ltt_session *session, int domain,
 
 		break;
 	}
-#if 0
-	case LTTNG_DOMAIN_UST_EXEC_NAME:
-	case LTTNG_DOMAIN_UST_PID:
-	case LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN:
-#endif
-	default:
-		ret = LTTNG_ERR_UND;
-		goto error;
-	}
-
-	ret = LTTNG_OK;
-
-error:
-	rcu_read_unlock();
-	return ret;
-}
-
-/*
- * Command LTTNG_DISABLE_EVENT for event "*" processed by the client thread.
- */
-static
-int disable_kevent_all(struct ltt_session *session, int domain,
-		char *channel_name,
-		struct lttng_event *event)
-{
-	int ret;
-
-	rcu_read_lock();
-
-	switch (domain) {
-	case LTTNG_DOMAIN_KERNEL:
-	{
-		struct ltt_kernel_session *ksess;
-		struct ltt_kernel_channel *kchan;
-
-		ksess = session->kernel_session;
-
-		/*
-		 * If a non-default channel has been created in the
-		 * session, explicitely require that -c chan_name needs
-		 * to be provided.
-		 */
-		if (ksess->has_non_default_channel && channel_name[0] == '\0') {
-			ret = LTTNG_ERR_NEED_CHANNEL_NAME;
-			goto error;
-		}
-
-		kchan = trace_kernel_get_channel_by_name(channel_name, ksess);
-		if (kchan == NULL) {
-			ret = LTTNG_ERR_KERN_CHAN_NOT_FOUND;
-			goto error;
-		}
-
-		switch (event->type) {
-		case LTTNG_EVENT_ALL:
-			ret = event_kernel_disable_all(kchan);
-			if (ret != LTTNG_OK) {
-				goto error;
-			}
-			break;
-		case LTTNG_EVENT_SYSCALL:
-			ret = event_kernel_disable_syscall(kchan, "");
-			if (ret != LTTNG_OK) {
-				goto error;
-			}
-			break;
-		default:
-			ret = LTTNG_ERR_UNK;
-			goto error;
-		}
-
-		kernel_wait_quiescent(kernel_tracer_fd);
-		break;
-	}
 	default:
 		ret = LTTNG_ERR_UND;
 		goto error;
@@ -1314,11 +1346,6 @@ int cmd_add_context(struct ltt_session *session, int domain,
 		}
 		break;
 	}
-#if 0
-	case LTTNG_DOMAIN_UST_EXEC_NAME:
-	case LTTNG_DOMAIN_UST_PID:
-	case LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN:
-#endif
 	default:
 		ret = LTTNG_ERR_UND;
 		goto error;
@@ -1385,6 +1412,7 @@ end:
 
 /*
  * Command LTTNG_ENABLE_EVENT processed by the client thread.
+ * We own filter, exclusion, and filter_expression.
  */
 int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
 		char *channel_name, struct lttng_event *event,
@@ -1402,12 +1430,6 @@ int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
 
 	DBG("Enable event command for event \'%s\'", event->name);
 
-	/* Special handling for kernel domain all events. */
-	if (domain->type == LTTNG_DOMAIN_KERNEL && !strcmp(event->name, "*")) {
-		return enable_kevent_all(session, domain, channel_name, event,
-				filter_expression, filter, wpipe);
-	}
-
 	ret = validate_event_name(event->name);
 	if (ret) {
 		goto error;
@@ -1463,11 +1485,65 @@ int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
 
 		switch (event->type) {
 		case LTTNG_EVENT_ALL:
+		{
+			char *filter_expression_a = NULL;
+			struct lttng_filter_bytecode *filter_a = NULL;
+
+			/*
+			 * We need to duplicate filter_expression and filter,
+			 * because ownership is passed to first enable
+			 * event.
+			 */
+			if (filter_expression) {
+				filter_expression_a = strdup(filter_expression);
+				if (!filter_expression_a) {
+					ret = LTTNG_ERR_FATAL;
+					goto error;
+				}
+			}
+			if (filter) {
+				filter_a = zmalloc(sizeof(*filter_a) + filter->len);
+				if (!filter_a) {
+					free(filter_expression_a);
+					ret = LTTNG_ERR_FATAL;
+					goto error;
+				}
+				memcpy(filter_a, filter, sizeof(*filter_a) + filter->len);
+			}
+			event->type = LTTNG_EVENT_TRACEPOINT;	/* Hack */
+			ret = event_kernel_enable_event(kchan, event,
+				filter_expression, filter);
+			/* We have passed ownership */
+			filter_expression = NULL;
+			filter = NULL;
+			if (ret != LTTNG_OK) {
+				if (channel_created) {
+					/* Let's not leak a useless channel. */
+					kernel_destroy_channel(kchan);
+				}
+				free(filter_expression_a);
+				free(filter_a);
+				goto error;
+			}
+			event->type = LTTNG_EVENT_SYSCALL;	/* Hack */
+			ret = event_kernel_enable_event(kchan, event,
+				filter_expression_a, filter_a);
+			if (ret != LTTNG_OK) {
+				free(filter_expression_a);
+				free(filter_a);
+				goto error;
+			}
+			break;
+		}
 		case LTTNG_EVENT_PROBE:
 		case LTTNG_EVENT_FUNCTION:
 		case LTTNG_EVENT_FUNCTION_ENTRY:
 		case LTTNG_EVENT_TRACEPOINT:
-			ret = event_kernel_enable_tracepoint(kchan, event);
+			ret = event_kernel_enable_event(kchan, event,
+				filter_expression, filter);
+			/* We have passed ownership */
+			filter_expression = NULL;
+			filter = NULL;
 			if (ret != LTTNG_OK) {
 				if (channel_created) {
 					/* Let's not leak a useless channel. */
@@ -1477,7 +1553,11 @@ int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
 			}
 			break;
 		case LTTNG_EVENT_SYSCALL:
-			ret = event_kernel_enable_syscall(kchan, event->name);
+			ret = event_kernel_enable_event(kchan, event,
+				filter_expression, filter);
+			/* We have passed ownership */
+			filter_expression = NULL;
+			filter = NULL;
 			if (ret != LTTNG_OK) {
 				goto error;
 			}
@@ -1536,6 +1616,10 @@ int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
 		/* At this point, the session and channel exist on the tracer */
 		ret = event_ust_enable_tracepoint(usess, uchan, event,
 				filter_expression, filter, exclusion);
+		/* We have passed ownership */
+		filter_expression = NULL;
+		filter = NULL;
+		exclusion = NULL;
 		if (ret != LTTNG_OK) {
 			goto error;
 		}
@@ -1598,8 +1682,30 @@ int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
 			assert(0);
 		}
 
-		ret = cmd_enable_event(session, &tmp_dom, (char *) default_chan_name,
-			&uevent, filter_expression, filter, NULL, wpipe);
+		{
+			struct lttng_filter_bytecode *filter_copy = NULL;
+
+			if (filter) {
+				filter_copy = zmalloc(
+					sizeof(struct lttng_filter_bytecode)
+					+ filter->len);
+				if (!filter_copy) {
+					goto error;
+				}
+
+				memcpy(filter_copy, filter,
+					sizeof(struct lttng_filter_bytecode)
+					+ filter->len);
+			}
+
+			ret = cmd_enable_event(session, &tmp_dom,
+					(char *) default_chan_name,
+					&uevent, filter_expression, filter_copy,
+					NULL, wpipe);
+			/* We have passed ownership */
+			filter_expression = NULL;
+		}
+
 		if (ret != LTTNG_OK && ret != LTTNG_ERR_UST_EVENT_ENABLED) {
 			goto error;
 		}
@@ -1607,8 +1713,10 @@ int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
 		/* The wild card * means that everything should be enabled. */
 		if (strncmp(event->name, "*", 1) == 0 && strlen(event->name) == 1) {
 			ret = event_agent_enable_all(usess, agt, event, filter);
+			filter = NULL;
 		} else {
 			ret = event_agent_enable(usess, agt, event, filter);
+			filter = NULL;
 		}
 		if (ret != LTTNG_OK) {
 			goto error;
@@ -1616,119 +1724,6 @@ int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
 
 		break;
 	}
-#if 0
-	case LTTNG_DOMAIN_UST_EXEC_NAME:
-	case LTTNG_DOMAIN_UST_PID:
-	case LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN:
-#endif
-	default:
-		ret = LTTNG_ERR_UND;
-		goto error;
-	}
-
-	ret = LTTNG_OK;
-
-error:
-	rcu_read_unlock();
-	return ret;
-}
-
-/*
- * Command LTTNG_ENABLE_EVENT for event "*" processed by the client thread.
- */
-static
-int enable_kevent_all(struct ltt_session *session,
-		struct lttng_domain *domain, char *channel_name,
-		struct lttng_event *event,
-		char *filter_expression,
-		struct lttng_filter_bytecode *filter, int wpipe)
-{
-	int ret;
-	struct lttng_channel *attr;
-
-	assert(session);
-	assert(channel_name);
-
-	rcu_read_lock();
-
-	switch (domain->type) {
-	case LTTNG_DOMAIN_KERNEL:
-	{
-		struct ltt_kernel_channel *kchan;
-
-		assert(session->kernel_session);
-
-		/*
-		 * If a non-default channel has been created in the
-		 * session, explicitely require that -c chan_name needs
-		 * to be provided.
-		 */
-		if (session->kernel_session->has_non_default_channel
-				&& channel_name[0] == '\0') {
-			ret = LTTNG_ERR_NEED_CHANNEL_NAME;
-			goto error;
-		}
-
-		kchan = trace_kernel_get_channel_by_name(channel_name,
-				session->kernel_session);
-		if (kchan == NULL) {
-			/* Create default channel */
-			attr = channel_new_default_attr(LTTNG_DOMAIN_KERNEL,
-					LTTNG_BUFFER_GLOBAL);
-			if (attr == NULL) {
-				ret = LTTNG_ERR_FATAL;
-				goto error;
-			}
-			strncpy(attr->name, channel_name, sizeof(attr->name));
-
-			ret = cmd_enable_channel(session, domain, attr, wpipe);
-			if (ret != LTTNG_OK) {
-				free(attr);
-				goto error;
-			}
-			free(attr);
-
-			/* Get the newly created kernel channel pointer */
-			kchan = trace_kernel_get_channel_by_name(channel_name,
-					session->kernel_session);
-			assert(kchan);
-		}
-
-		switch (event->type) {
-		case LTTNG_EVENT_SYSCALL:
-			ret = event_kernel_enable_syscall(kchan, "");
-			if (ret != LTTNG_OK) {
-				goto error;
-			}
-			break;
-		case LTTNG_EVENT_TRACEPOINT:
-			/*
-			 * This call enables all LTTNG_KERNEL_TRACEPOINTS and
-			 * events already registered to the channel.
-			 */
-			ret = event_kernel_enable_all_tracepoints(kchan, kernel_tracer_fd);
-			break;
-		case LTTNG_EVENT_ALL:
-			/* Enable syscalls and tracepoints */
-			ret = event_kernel_enable_all(kchan, kernel_tracer_fd);
-			break;
-		default:
-			ret = LTTNG_ERR_KERN_ENABLE_FAIL;
-			goto error;
-		}
-
-		/* Manage return value */
-		if (ret != LTTNG_OK) {
-			/*
-			 * On error, cmd_enable_channel call will take care of destroying
-			 * the created channel if it was needed.
-			 */
-			goto error;
-		}
-
-		kernel_wait_quiescent(kernel_tracer_fd);
-		break;
-	}
 	default:
 		ret = LTTNG_ERR_UND;
 		goto error;
@@ -1737,11 +1732,13 @@ int enable_kevent_all(struct ltt_session *session,
 	ret = LTTNG_OK;
 
 error:
+	free(filter_expression);
+	free(filter);
+	free(exclusion);
 	rcu_read_unlock();
 	return ret;
 }
 
-
 /*
  * Command LTTNG_LIST_TRACEPOINTS processed by the client thread.
  */
@@ -1821,8 +1818,61 @@ ssize_t cmd_list_syscalls(struct lttng_event **events)
 	return syscall_table_list(events);
 }
 
+/*
+ * Command LTTNG_LIST_TRACKER_PIDS processed by the client thread.
+ *
+ * Called with session lock held.
+ */
+ssize_t cmd_list_tracker_pids(struct ltt_session *session,
+		int domain, int32_t **pids)
+{
+	int ret;
+	ssize_t nr_pids = 0;
+
+	switch (domain) {
+	case LTTNG_DOMAIN_KERNEL:
+	{
+		struct ltt_kernel_session *ksess;
+
+		ksess = session->kernel_session;
+		nr_pids = kernel_list_tracker_pids(ksess, pids);
+		if (nr_pids < 0) {
+			ret = LTTNG_ERR_KERN_LIST_FAIL;
+			goto error;
+		}
+		break;
+	}
+	case LTTNG_DOMAIN_UST:
+	{
+		struct ltt_ust_session *usess;
+
+		usess = session->ust_session;
+		nr_pids = trace_ust_list_tracker_pids(usess, pids);
+		if (nr_pids < 0) {
+			ret = LTTNG_ERR_UST_LIST_FAIL;
+			goto error;
+		}
+		break;
+	}
+	case LTTNG_DOMAIN_LOG4J:
+	case LTTNG_DOMAIN_JUL:
+	case LTTNG_DOMAIN_PYTHON:
+	default:
+		ret = LTTNG_ERR_UND;
+		goto error;
+	}
+
+	return nr_pids;
+
+error:
+	/* Return negative value to differentiate return code */
+	return -ret;
+}
+
 /*
  * Command LTTNG_START_TRACE processed by the client thread.
+ *
+ * Called with session mutex held.
  */
 int cmd_start_trace(struct ltt_session *session)
 {
@@ -1848,7 +1898,9 @@ int cmd_start_trace(struct ltt_session *session)
 	 * possible to enable channel thus inform the client.
 	 */
 	if (usess && usess->domain_global.channels) {
+		rcu_read_lock();
 		nb_chan += lttng_ht_get_count(usess->domain_global.channels);
+		rcu_read_unlock();
 	}
 	if (ksession) {
 		nb_chan += ksession->channel_count;
@@ -1969,13 +2021,12 @@ error:
 /*
  * Command LTTNG_SET_CONSUMER_URI processed by the client thread.
  */
-int cmd_set_consumer_uri(int domain, struct ltt_session *session,
-		size_t nb_uri, struct lttng_uri *uris)
+int cmd_set_consumer_uri(struct ltt_session *session, size_t nb_uri,
+		struct lttng_uri *uris)
 {
 	int ret, i;
 	struct ltt_kernel_session *ksess = session->kernel_session;
 	struct ltt_ust_session *usess = session->ust_session;
-	struct consumer_output *consumer = NULL;
 
 	assert(session);
 	assert(uris);
@@ -1987,41 +2038,41 @@ int cmd_set_consumer_uri(int domain, struct ltt_session *session,
 		goto error;
 	}
 
-	/*
-	 * This case switch makes sure the domain session has a temporary consumer
-	 * so the URL can be set.
-	 */
-	switch (domain) {
-	case 0:
-		/* Code flow error. A session MUST always have a consumer object */
-		assert(session->consumer);
-		/*
-		 * The URL will be added to the tracing session consumer instead of a
-		 * specific domain consumer.
-		 */
-		consumer = session->consumer;
-		break;
-	case LTTNG_DOMAIN_KERNEL:
-		/* Code flow error if we don't have a kernel session here. */
-		assert(ksess);
-		assert(ksess->consumer);
-		consumer = ksess->consumer;
-		break;
-	case LTTNG_DOMAIN_UST:
-		/* Code flow error if we don't have a kernel session here. */
-		assert(usess);
-		assert(usess->consumer);
-		consumer = usess->consumer;
-		break;
-	}
-
+	/* Set the "global" consumer URIs */
 	for (i = 0; i < nb_uri; i++) {
-		ret = add_uri_to_consumer(consumer, &uris[i], domain, session->name);
+		ret = add_uri_to_consumer(session->consumer,
+				&uris[i], 0, session->name);
 		if (ret != LTTNG_OK) {
 			goto error;
 		}
 	}
 
+	/* Set UST session URIs */
+	if (session->ust_session) {
+		for (i = 0; i < nb_uri; i++) {
+			ret = add_uri_to_consumer(
+					session->ust_session->consumer,
+					&uris[i], LTTNG_DOMAIN_UST,
+					session->name);
+			if (ret != LTTNG_OK) {
+				goto error;
+			}
+		}
+	}
+
+	/* Set kernel session URIs */
+	if (session->kernel_session) {
+		for (i = 0; i < nb_uri; i++) {
+			ret = add_uri_to_consumer(
+					session->kernel_session->consumer,
+					&uris[i], LTTNG_DOMAIN_KERNEL,
+					session->name);
+			if (ret != LTTNG_OK) {
+				goto error;
+			}
+		}
+	}
+
 	/*
 	 * Make sure to set the session in output mode after we set URI since a
 	 * session can be created without URL (thus flagged in no output mode).
@@ -2029,7 +2080,9 @@ int cmd_set_consumer_uri(int domain, struct ltt_session *session,
 	session->output_traces = 1;
 	if (ksess) {
 		ksess->output_traces = 1;
-	} else if (usess) {
+	}
+
+	if (usess) {
 		usess->output_traces = 1;
 	}
 
@@ -2091,7 +2144,7 @@ int cmd_create_session_uri(char *name, struct lttng_uri *uris,
 	}
 
 	if (uris) {
-		ret = cmd_set_consumer_uri(0, session, nb_uri, uris);
+		ret = cmd_set_consumer_uri(session, nb_uri, uris);
 		if (ret != LTTNG_OK) {
 			goto consumer_error;
 		}
@@ -2180,6 +2233,8 @@ error:
 
 /*
  * Command LTTNG_DESTROY_SESSION processed by the client thread.
+ *
+ * Called with session lock held.
  */
 int cmd_destroy_session(struct ltt_session *session, int wpipe)
 {
@@ -2380,12 +2435,14 @@ ssize_t cmd_list_domains(struct ltt_session *session,
 		DBG3("Listing domains found UST global domain");
 		nb_dom++;
 
+		rcu_read_lock();
 		cds_lfht_for_each_entry(session->ust_session->agents->ht, &iter.iter,
 				agt, node.node) {
 			if (agt->being_used) {
 				nb_dom++;
 			}
 		}
+		rcu_read_unlock();
 	}
 
 	if (!nb_dom) {
@@ -2408,6 +2465,7 @@ ssize_t cmd_list_domains(struct ltt_session *session,
 		(*domains)[index].buf_type = session->ust_session->buffer_type;
 		index++;
 
+		rcu_read_lock();
 		cds_lfht_for_each_entry(session->ust_session->agents->ht, &iter.iter,
 				agt, node.node) {
 			if (agt->being_used) {
@@ -2416,6 +2474,7 @@ ssize_t cmd_list_domains(struct ltt_session *session,
 				index++;
 			}
 		}
+		rcu_read_unlock();
 	}
 end:
 	return nb_dom;
@@ -2447,8 +2506,10 @@ ssize_t cmd_list_channels(int domain, struct ltt_session *session,
 		break;
 	case LTTNG_DOMAIN_UST:
 		if (session->ust_session != NULL) {
+			rcu_read_lock();
 			nb_chan = lttng_ht_get_count(
-					session->ust_session->domain_global.channels);
+				session->ust_session->domain_global.channels);
+			rcu_read_unlock();
 		}
 		DBG3("Number of UST global channels %zd", nb_chan);
 		if (nb_chan < 0) {
@@ -2509,10 +2570,12 @@ ssize_t cmd_list_events(int domain, struct ltt_session *session,
 			struct lttng_ht_iter iter;
 			struct agent *agt;
 
+			rcu_read_lock();
 			cds_lfht_for_each_entry(session->ust_session->agents->ht,
 					&iter.iter, agt, node.node) {
 				nb_event = list_lttng_agent_events(agt, events);
 			}
+			rcu_read_unlock();
 		}
 		break;
 	default:
@@ -2761,7 +2824,7 @@ ssize_t cmd_snapshot_list_outputs(struct ltt_session *session,
 		struct lttng_snapshot_output **outputs)
 {
 	int ret, idx = 0;
-	struct lttng_snapshot_output *list;
+	struct lttng_snapshot_output *list = NULL;
 	struct lttng_ht_iter iter;
 	struct snapshot_output *output;
 
@@ -2775,7 +2838,7 @@ ssize_t cmd_snapshot_list_outputs(struct ltt_session *session,
 	 * set in no output mode.
 	 */
 	if (session->output_traces) {
-		ret = LTTNG_ERR_EPERM;
+		ret = -LTTNG_ERR_EPERM;
 		goto error;
 	}
 
@@ -2786,11 +2849,12 @@ ssize_t cmd_snapshot_list_outputs(struct ltt_session *session,
 
 	list = zmalloc(session->snapshot.nb_output * sizeof(*list));
 	if (!list) {
-		ret = LTTNG_ERR_NOMEM;
+		ret = -LTTNG_ERR_NOMEM;
 		goto error;
 	}
 
 	/* Copy list from session to the new list object. */
+	rcu_read_lock();
 	cds_lfht_for_each_entry(session->snapshot.output_ht->ht, &iter.iter,
 			output, node.node) {
 		assert(output->consumer);
@@ -2805,28 +2869,28 @@ ssize_t cmd_snapshot_list_outputs(struct ltt_session *session,
 			ret = uri_to_str_url(&output->consumer->dst.net.control,
 					list[idx].ctrl_url, sizeof(list[idx].ctrl_url));
 			if (ret < 0) {
-				ret = LTTNG_ERR_NOMEM;
-				goto free_error;
+				ret = -LTTNG_ERR_NOMEM;
+				goto error;
 			}
 
 			/* Data URI. */
 			ret = uri_to_str_url(&output->consumer->dst.net.data,
 					list[idx].data_url, sizeof(list[idx].data_url));
 			if (ret < 0) {
-				ret = LTTNG_ERR_NOMEM;
-				goto free_error;
+				ret = -LTTNG_ERR_NOMEM;
+				goto error;
 			}
 		}
 		idx++;
 	}
 
 	*outputs = list;
-	return session->snapshot.nb_output;
-
-free_error:
-	free(list);
+	list = NULL;
+	ret = session->snapshot.nb_output;
 error:
-	return -ret;
+	free(list);
+	rcu_read_unlock();
+	return ret;
 }
 
 /*
@@ -2882,7 +2946,7 @@ error:
  */
 static int record_kernel_snapshot(struct ltt_kernel_session *ksess,
 		struct snapshot_output *output, struct ltt_session *session,
-		int wait, uint64_t max_stream_size)
+		int wait, uint64_t nb_packets_per_stream)
 {
 	int ret;
 
@@ -2913,17 +2977,19 @@ static int record_kernel_snapshot(struct ltt_kernel_session *ksess,
 		goto error_snapshot;
 	}
 
-	ret = kernel_snapshot_record(ksess, output, wait, max_stream_size);
+	ret = kernel_snapshot_record(ksess, output, wait, nb_packets_per_stream);
 	if (ret != LTTNG_OK) {
 		goto error_snapshot;
 	}
 
 	ret = LTTNG_OK;
+	goto end;
 
 error_snapshot:
 	/* Clean up copied sockets so this output can use some other later on. */
 	consumer_destroy_output_sockets(output->consumer);
 error:
+end:
 	return ret;
 }
 
@@ -2934,7 +3000,7 @@ error:
  */
 static int record_ust_snapshot(struct ltt_ust_session *usess,
 		struct snapshot_output *output, struct ltt_session *session,
-		int wait, uint64_t max_stream_size)
+		int wait, uint64_t nb_packets_per_stream)
 {
 	int ret;
 
@@ -2965,7 +3031,7 @@ static int record_ust_snapshot(struct ltt_ust_session *usess,
 		goto error_snapshot;
 	}
 
-	ret = ust_app_snapshot_record(usess, output, wait, max_stream_size);
+	ret = ust_app_snapshot_record(usess, output, wait, nb_packets_per_stream);
 	if (ret < 0) {
 		switch (-ret) {
 		case EINVAL:
@@ -2990,67 +3056,90 @@ error:
 	return ret;
 }
 
-/*
- * Return the biggest subbuffer size of all channels in the given session.
- */
-static uint64_t get_session_max_subbuf_size(struct ltt_session *session)
+static
+uint64_t get_session_size_one_more_packet_per_stream(struct ltt_session *session,
+	uint64_t cur_nr_packets)
 {
-	uint64_t max_size = 0;
-
-	assert(session);
+	uint64_t tot_size = 0;
 
 	if (session->kernel_session) {
 		struct ltt_kernel_channel *chan;
 		struct ltt_kernel_session *ksess = session->kernel_session;
 
-		/*
-		 * For each channel, add to the max size the size of each subbuffer
-		 * multiplied by their sized.
-		 */
 		cds_list_for_each_entry(chan, &ksess->channel_list.head, list) {
-			if (chan->channel->attr.subbuf_size > max_size) {
-				max_size = chan->channel->attr.subbuf_size;
+			if (cur_nr_packets >= chan->channel->attr.num_subbuf) {
+				/*
+				 * Don't take channel into account if we
+				 * already grab all its packets.
+				 */
+				continue;
 			}
+			tot_size += chan->channel->attr.subbuf_size
+				* chan->stream_count;
 		}
 	}
 
 	if (session->ust_session) {
-		struct lttng_ht_iter iter;
-		struct ltt_ust_channel *uchan;
 		struct ltt_ust_session *usess = session->ust_session;
 
-		cds_lfht_for_each_entry(usess->domain_global.channels->ht, &iter.iter,
-				uchan, node.node) {
-			if (uchan->attr.subbuf_size > max_size) {
-				max_size = uchan->attr.subbuf_size;
-			}
-		}
+		tot_size += ust_app_get_size_one_more_packet_per_stream(usess,
+				cur_nr_packets);
 	}
 
-	return max_size;
+	return tot_size;
 }
 
 /*
- * Returns the total number of streams for a session or a negative value
- * on error.
+ * Calculate the number of packets we can grab from each stream that
+ * fits within the overall snapshot max size.
+ *
+ * Returns -1 on error, 0 means infinite number of packets, else > 0 is
+ * the number of packets per stream.
+ *
+ * TODO: this approach is not perfect: we consider the worse case
+ * (packet filling the sub-buffers) as an upper bound, but we could do
+ * better if we do this calculation while we actually grab the packet
+ * content: we would know how much padding we don't actually store into
+ * the file.
+ *
+ * This algorithm is currently bounded by the number of packets per
+ * stream.
+ *
+ * Since we call this algorithm before actually grabbing the data, it's
+ * an approximation: for instance, applications could appear/disappear
+ * in between this call and actually grabbing data.
  */
-static unsigned int get_session_nb_streams(struct ltt_session *session)
+static
+int64_t get_session_nb_packets_per_stream(struct ltt_session *session, uint64_t max_size)
 {
-	unsigned int total_streams = 0;
+	int64_t size_left;
+	uint64_t cur_nb_packets = 0;
 
-	if (session->kernel_session) {
-		struct ltt_kernel_session *ksess = session->kernel_session;
-
-		total_streams += ksess->stream_count_global;
+	if (!max_size) {
+		return 0;	/* Infinite */
 	}
 
-	if (session->ust_session) {
-		struct ltt_ust_session *usess = session->ust_session;
+	size_left = max_size;
+	for (;;) {
+		uint64_t one_more_packet_tot_size;
 
-		total_streams += ust_app_get_nb_stream(usess);
+		one_more_packet_tot_size = get_session_size_one_more_packet_per_stream(session,
+					cur_nb_packets);
+		if (!one_more_packet_tot_size) {
+			/* We are already grabbing all packets. */
+			break;
+		}
+		size_left -= one_more_packet_tot_size;
+		if (size_left < 0) {
+			break;
+		}
+		cur_nb_packets++;
 	}
-
-	return total_streams;
+	if (!cur_nb_packets) {
+		/* Not enough room to grab one packet of each stream, error. */
+		return -1;
+	}
+	return cur_nb_packets;
 }
 
 /*
@@ -3067,8 +3156,7 @@ int cmd_snapshot_record(struct ltt_session *session,
 	int ret = LTTNG_OK;
 	unsigned int use_tmp_output = 0;
 	struct snapshot_output tmp_output;
-	unsigned int nb_streams, snapshot_success = 0;
-	uint64_t session_max_size = 0, max_stream_size = 0;
+	unsigned int snapshot_success = 0;
 
 	assert(session);
 	assert(output);
@@ -3108,44 +3196,20 @@ int cmd_snapshot_record(struct ltt_session *session,
 		use_tmp_output = 1;
 	}
 
-	/*
-	 * Get the session maximum size for a snapshot meaning it will compute the
-	 * size of all streams from all domain.
-	 */
-	max_stream_size = get_session_max_subbuf_size(session);
-
-	nb_streams = get_session_nb_streams(session);
-	if (nb_streams) {
-		/*
-		 * The maximum size of the snapshot is the number of streams multiplied
-		 * by the biggest subbuf size of all channels in a session which is the
-		 * maximum stream size available for each stream. The session max size
-		 * is now checked against the snapshot max size value given by the user
-		 * and if lower, an error is returned.
-		 */
-		session_max_size = max_stream_size * nb_streams;
-	}
-
-	DBG3("Snapshot max size is %" PRIu64 " for max stream size of %" PRIu64,
-			session_max_size, max_stream_size);
-
-	/*
-	 * If we use a temporary output, check right away if the max size fits else
-	 * for each output the max size will be checked.
-	 */
-	if (use_tmp_output &&
-			(tmp_output.max_size != 0 &&
-			tmp_output.max_size < session_max_size)) {
-		ret = LTTNG_ERR_MAX_SIZE_INVALID;
-		goto error;
-	}
-
 	if (session->kernel_session) {
 		struct ltt_kernel_session *ksess = session->kernel_session;
 
 		if (use_tmp_output) {
+			int64_t nb_packets_per_stream;
+
+			nb_packets_per_stream = get_session_nb_packets_per_stream(session,
+					tmp_output.max_size);
+			if (nb_packets_per_stream < 0) {
+				ret = LTTNG_ERR_MAX_SIZE_INVALID;
+				goto error;
+			}
 			ret = record_kernel_snapshot(ksess, &tmp_output, session,
-					wait, max_stream_size);
+					wait, nb_packets_per_stream);
 			if (ret != LTTNG_OK) {
 				goto error;
 			}
@@ -3157,6 +3221,8 @@ int cmd_snapshot_record(struct ltt_session *session,
 			rcu_read_lock();
 			cds_lfht_for_each_entry(session->snapshot.output_ht->ht,
 					&iter.iter, sout, node.node) {
+				int64_t nb_packets_per_stream;
+
 				/*
 				 * Make a local copy of the output and assign the possible
 				 * temporary value given by the caller.
@@ -3164,14 +3230,13 @@ int cmd_snapshot_record(struct ltt_session *session,
 				memset(&tmp_output, 0, sizeof(tmp_output));
 				memcpy(&tmp_output, sout, sizeof(tmp_output));
 
-				/* Use temporary max size. */
 				if (output->max_size != (uint64_t) -1ULL) {
 					tmp_output.max_size = output->max_size;
 				}
 
-				if (tmp_output.max_size != 0 &&
-						tmp_output.max_size < session_max_size) {
-					rcu_read_unlock();
+				nb_packets_per_stream = get_session_nb_packets_per_stream(session,
+						tmp_output.max_size);
+				if (nb_packets_per_stream < 0) {
 					ret = LTTNG_ERR_MAX_SIZE_INVALID;
 					goto error;
 				}
@@ -3185,7 +3250,7 @@ int cmd_snapshot_record(struct ltt_session *session,
 				tmp_output.nb_snapshot = session->snapshot.nb_snapshot;
 
 				ret = record_kernel_snapshot(ksess, &tmp_output,
-						session, wait, max_stream_size);
+						session, wait, nb_packets_per_stream);
 				if (ret != LTTNG_OK) {
 					rcu_read_unlock();
 					goto error;
@@ -3200,8 +3265,16 @@ int cmd_snapshot_record(struct ltt_session *session,
 		struct ltt_ust_session *usess = session->ust_session;
 
 		if (use_tmp_output) {
+			int64_t nb_packets_per_stream;
+
+			nb_packets_per_stream = get_session_nb_packets_per_stream(session,
+					tmp_output.max_size);
+			if (nb_packets_per_stream < 0) {
+				ret = LTTNG_ERR_MAX_SIZE_INVALID;
+				goto error;
+			}
 			ret = record_ust_snapshot(usess, &tmp_output, session,
-					wait, max_stream_size);
+					wait, nb_packets_per_stream);
 			if (ret != LTTNG_OK) {
 				goto error;
 			}
@@ -3213,6 +3286,8 @@ int cmd_snapshot_record(struct ltt_session *session,
 			rcu_read_lock();
 			cds_lfht_for_each_entry(session->snapshot.output_ht->ht,
 					&iter.iter, sout, node.node) {
+				int64_t nb_packets_per_stream;
+
 				/*
 				 * Make a local copy of the output and assign the possible
 				 * temporary value given by the caller.
@@ -3220,15 +3295,15 @@ int cmd_snapshot_record(struct ltt_session *session,
 				memset(&tmp_output, 0, sizeof(tmp_output));
 				memcpy(&tmp_output, sout, sizeof(tmp_output));
 
-				/* Use temporary max size. */
 				if (output->max_size != (uint64_t) -1ULL) {
 					tmp_output.max_size = output->max_size;
 				}
 
-				if (tmp_output.max_size != 0 &&
-						tmp_output.max_size < session_max_size) {
-					rcu_read_unlock();
+				nb_packets_per_stream = get_session_nb_packets_per_stream(session,
+						tmp_output.max_size);
+				if (nb_packets_per_stream < 0) {
 					ret = LTTNG_ERR_MAX_SIZE_INVALID;
+					rcu_read_unlock();
 					goto error;
 				}
 
@@ -3241,7 +3316,7 @@ int cmd_snapshot_record(struct ltt_session *session,
 				tmp_output.nb_snapshot = session->snapshot.nb_snapshot;
 
 				ret = record_ust_snapshot(usess, &tmp_output, session,
-						wait, max_stream_size);
+						wait, nb_packets_per_stream);
 				if (ret != LTTNG_OK) {
 					rcu_read_unlock();
 					goto error;
@@ -3262,6 +3337,29 @@ error:
 	return ret;
 }
 
+/*
+ * Command LTTNG_SET_SESSION_SHM_PATH processed by the client thread.
+ */
+int cmd_set_session_shm_path(struct ltt_session *session,
+		const char *shm_path)
+{
+	/* Safety net */
+	assert(session);
+
+	/*
+	 * Can only set shm path before session is started.
+	 */
+	if (session->has_been_started) {
+		return LTTNG_ERR_SESSION_STARTED;
+	}
+
+	strncpy(session->shm_path, shm_path,
+		sizeof(session->shm_path));
+	session->shm_path[sizeof(session->shm_path) - 1] = '\0';
+
+	return 0;
+}
+
 /*
  * Init command subsystem.
  */