/*
- * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
- * Copyright (C) 2016 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
+ * Copyright (C) 2016 Jérémie Galarneau <jeremie.galarneau@efficios.com>
*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License, version 2 only,
- * as published by the Free Software Foundation.
+ * SPDX-License-Identifier: GPL-2.0-only
*
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#define _LGPL_SOURCE
#include <sys/types.h>
#include <unistd.h>
#include <urcu/compiler.h>
-#include <lttng/ust-error.h>
#include <signal.h>
#include <common/common.h>
#include "health-sessiond.h"
#include "ust-app.h"
#include "ust-consumer.h"
-#include "ust-ctl.h"
+#include "lttng-ust-ctl.h"
+#include "lttng-ust-error.h"
#include "utils.h"
#include "session.h"
#include "lttng-sessiond.h"
#include "notification-thread-commands.h"
#include "rotate.h"
+struct lttng_ht *ust_app_ht;
+struct lttng_ht *ust_app_ht_by_sock;
+struct lttng_ht *ust_app_ht_by_notify_sock;
+
static
int ust_app_flush_app_session(struct ust_app *app, struct ust_app_session *ua_sess);
* nullified. The session lock MUST be held unless the application is
* in the destroy path.
*
+ * Do not hold the registry lock while communicating with the consumerd, because
+ * doing so causes inter-process deadlocks between consumerd and sessiond with
+ * the metadata request notification.
+ *
* Return 0 on success else a negative value.
*/
static int close_metadata(struct ust_registry_session *registry,
{
int ret;
struct consumer_socket *socket;
+ uint64_t metadata_key;
+ bool registry_was_already_closed;
assert(registry);
assert(consumer);
rcu_read_lock();
pthread_mutex_lock(®istry->lock);
+ metadata_key = registry->metadata_key;
+ registry_was_already_closed = registry->metadata_closed;
+ if (metadata_key != 0) {
+ /*
+ * Metadata closed. Even on error this means that the consumer
+ * is not responding or not found so either way a second close
+ * should NOT be emit for this registry.
+ */
+ registry->metadata_closed = 1;
+ }
+ pthread_mutex_unlock(®istry->lock);
- if (!registry->metadata_key || registry->metadata_closed) {
+ if (metadata_key == 0 || registry_was_already_closed) {
ret = 0;
goto end;
}
consumer);
if (!socket) {
ret = -1;
- goto error;
+ goto end;
}
- ret = consumer_close_metadata(socket, registry->metadata_key);
+ ret = consumer_close_metadata(socket, metadata_key);
if (ret < 0) {
- goto error;
+ goto end;
}
-error:
- /*
- * Metadata closed. Even on error this means that the consumer is not
- * responding or not found so either way a second close should NOT be emit
- * for this registry.
- */
- registry->metadata_closed = 1;
end:
- pthread_mutex_unlock(®istry->lock);
rcu_read_unlock();
return ret;
}
* Alloc new UST app channel.
*/
static
-struct ust_app_channel *alloc_ust_app_channel(char *name,
+struct ust_app_channel *alloc_ust_app_channel(const char *name,
struct ust_app_session *ua_sess,
struct lttng_ust_channel_attr *attr)
{
/* Init most of the default value by allocating and zeroing */
ua_event = zmalloc(sizeof(struct ust_app_event));
if (ua_event == NULL) {
- PERROR("malloc");
+ PERROR("Failed to allocate ust_app_event structure");
goto error;
}
if (uctx) {
memcpy(&ua_ctx->ctx, uctx, sizeof(ua_ctx->ctx));
if (uctx->ctx == LTTNG_UST_CONTEXT_APP_CONTEXT) {
- char *provider_name = NULL, *ctx_name = NULL;
+ char *provider_name = NULL, *ctx_name = NULL;
provider_name = strdup(uctx->u.app_ctx.provider_name);
ctx_name = strdup(uctx->u.app_ctx.ctx_name);
switch (ua_sess->buffer_type) {
case LTTNG_BUFFER_PER_PID:
ret = snprintf(tmp_shm_path, sizeof(tmp_shm_path),
- DEFAULT_UST_TRACE_PID_PATH "/%s-%d-%s",
+ "/" DEFAULT_UST_TRACE_PID_PATH "/%s-%d-%s",
app->name, app->pid, datetime);
break;
case LTTNG_BUFFER_PER_UID:
ret = snprintf(tmp_shm_path, sizeof(tmp_shm_path),
- DEFAULT_UST_TRACE_UID_PATH,
+ "/" DEFAULT_UST_TRACE_UID_PATH,
app->uid, app->bits_per_long);
break;
default:
app->byte_order, app->version.major, app->version.minor,
reg_pid->root_shm_path, reg_pid->shm_path,
ua_sess->effective_credentials.uid,
- ua_sess->effective_credentials.gid);
+ ua_sess->effective_credentials.gid, ua_sess->tracing_id,
+ app->uid);
if (ret < 0) {
/*
* reg_pid->registry->reg.ust is NULL upon error, so we need to
app->uint64_t_alignment, app->long_alignment,
app->byte_order, app->version.major,
app->version.minor, reg_uid->root_shm_path,
- reg_uid->shm_path, usess->uid, usess->gid);
+ reg_uid->shm_path, usess->uid, usess->gid,
+ ua_sess->tracing_id, app->uid);
if (ret < 0) {
/*
* reg_uid->registry->reg.ust is NULL upon error, so we need to
*/
static
int create_ust_app_channel_context(struct ust_app_channel *ua_chan,
- struct lttng_ust_context_attr *uctx,
+ struct lttng_ust_context_attr *uctx,
struct ust_app *app)
{
int ret = 0;
ua_event = alloc_ust_app_event(uevent->attr.name, &uevent->attr);
if (ua_event == NULL) {
- /* Only malloc can failed so something is really wrong */
+ /* Only failure mode of alloc_ust_app_event(). */
ret = -ENOMEM;
goto end;
}
/* Create it on the tracer side */
ret = create_ust_event(app, ua_sess, ua_chan, ua_event);
if (ret < 0) {
- /* Not found previously means that it does not exist on the tracer */
- assert(ret != -LTTNG_UST_ERR_EXIST);
+ /*
+ * Not found previously means that it does not exist on the
+ * tracer. If the application reports that the event existed,
+ * it means there is a bug in the sessiond or lttng-ust
+ * (or corruption, etc.)
+ */
+ if (ret == -LTTNG_UST_ERR_EXIST) {
+ ERR("Tracer for application reported that an event being created already existed: "
+ "event_name = \"%s\", pid = %d, ppid = %d, uid = %d, gid = %d",
+ uevent->attr.name,
+ app->pid, app->ppid, app->uid,
+ app->gid);
+ }
goto error;
}
ret = ust_app_channel_allocate(ua_sess, uchan,
LTTNG_UST_CHAN_PER_CPU, usess,
&ua_chan);
- if (ret == 0) {
- ret = ust_app_channel_send(app, usess,
- ua_sess, ua_chan);
- } else {
- goto end;
+ if (ret < 0) {
+ goto error;
+ }
+
+ ret = ust_app_channel_send(app, usess,
+ ua_sess, ua_chan);
+ if (ret) {
+ goto error;
}
/* Add contexts. */
ret = create_ust_app_channel_context(ua_chan,
&uctx->ctx, app);
if (ret) {
- goto end;
+ goto error;
}
}
}
+
+error:
if (ret < 0) {
switch (ret) {
case -ENOTCONN:
break;
}
}
-end:
+
if (ret == 0 && _ua_chan) {
/*
* Only return the application's channel on success. Note
return ret;
}
-/*
- * For a specific UST session, create the channel for all registered apps.
- */
-int ust_app_create_channel_glb(struct ltt_ust_session *usess,
- struct ltt_ust_channel *uchan)
-{
- int ret = 0;
- struct cds_lfht_iter iter;
- struct ust_app *app;
-
- assert(usess);
- assert(usess->active);
- assert(uchan);
-
- DBG2("UST app adding channel %s to UST domain for session id %" PRIu64,
- uchan->name, usess->id);
-
- rcu_read_lock();
- /* For every registered applications */
- cds_lfht_for_each_entry(ust_app_ht->ht, &iter, app, pid_n.node) {
- struct ust_app_session *ua_sess;
- int session_was_created = 0;
-
- if (!app->compatible ||
- !trace_ust_pid_tracker_lookup(usess, app->pid)) {
- goto error_rcu_unlock;
- }
-
- /*
- * Create session on the tracer side and add it to app session HT. Note
- * that if session exist, it will simply return a pointer to the ust
- * app session.
- */
- ret = find_or_create_ust_app_session(usess, app, &ua_sess,
- &session_was_created);
- if (ret < 0) {
- switch (ret) {
- case -ENOTCONN:
- /*
- * The application's socket is not valid. Either a bad
- * socket or a timeout on it. We can't inform the caller
- * that for a specific app, the session failed so lets
- * continue here; it is not an error.
- */
- ret = 0;
- goto error_rcu_unlock;
- case -ENOMEM:
- default:
- goto error_rcu_unlock;
- }
- }
-
- if (ua_sess->deleted) {
- continue;
- }
- ret = ust_app_channel_create(usess, ua_sess, uchan, app, NULL);
- if (ret) {
- if (session_was_created) {
- destroy_app_session(app, ua_sess);
- }
- goto error_rcu_unlock;
- }
- }
-
-error_rcu_unlock:
- rcu_read_unlock();
- return ret;
-}
-
/*
* Enable event for a specific session and channel on the tracer.
*/
goto end;
}
+ if (ua_sess->enabled) {
+ pthread_mutex_unlock(&ua_sess->lock);
+ goto end;
+ }
+
/* Upon restart, we skip the setup, already done */
if (ua_sess->started) {
goto skip_setup;
health_code_update();
skip_setup:
- /* This start the UST tracing */
+ /* This starts the UST tracing */
pthread_mutex_lock(&app->sock_lock);
ret = ustctl_start_session(app->sock, ua_sess->handle);
pthread_mutex_unlock(&app->sock_lock);
/* Indicate that the session has been started once */
ua_sess->started = 1;
+ ua_sess->enabled = 1;
pthread_mutex_unlock(&ua_sess->lock);
}
health_code_update();
+ ua_sess->enabled = 0;
/* Quiescent wait after stopping trace */
pthread_mutex_lock(&app->sock_lock);
/*
* The caller must ensure that the application is compatible and is tracked
- * by the PID tracker.
+ * by the process attribute trackers.
*/
static
void ust_app_synchronize(struct ltt_ust_session *usess,
* allocated (if necessary) and sent to the application, and
* all enabled contexts will be added to the channel.
*/
- ret = find_or_create_ust_app_channel(usess, ua_sess,
+ ret = find_or_create_ust_app_channel(usess, ua_sess,
app, uchan, &ua_chan);
if (ret) {
/* Tracer is probably gone or ENOMEM. */
if (!app->compatible) {
return;
}
- if (trace_ust_pid_tracker_lookup(usess, app->pid)) {
+ if (trace_ust_id_tracker_lookup(LTTNG_PROCESS_ATTR_VIRTUAL_PROCESS_ID,
+ usess, app->pid) &&
+ trace_ust_id_tracker_lookup(
+ LTTNG_PROCESS_ATTR_VIRTUAL_USER_ID,
+ usess, app->uid) &&
+ trace_ust_id_tracker_lookup(
+ LTTNG_PROCESS_ATTR_VIRTUAL_GROUP_ID,
+ usess, app->gid)) {
/*
* Synchronize the application's internal tracing configuration
* and start tracing.
enum lttng_error_code status = LTTNG_OK;
struct lttng_ht_iter iter;
struct ust_app *app;
- char pathname[PATH_MAX];
+ char *trace_path = NULL;
assert(usess);
assert(output);
cds_list_for_each_entry(reg, &usess->buffer_reg_uid_list, lnode) {
struct buffer_reg_channel *reg_chan;
struct consumer_socket *socket;
+ char pathname[PATH_MAX];
+ size_t consumer_path_offset = 0;
if (!reg->registry->reg.ust->metadata_key) {
/* Skip since no metadata is present */
}
memset(pathname, 0, sizeof(pathname));
- /*
- * DEFAULT_UST_TRACE_UID_PATH already contains a path
- * separator.
- */
ret = snprintf(pathname, sizeof(pathname),
- DEFAULT_UST_TRACE_DIR DEFAULT_UST_TRACE_UID_PATH,
+ DEFAULT_UST_TRACE_DIR "/" DEFAULT_UST_TRACE_UID_PATH,
reg->uid, reg->bits_per_long);
if (ret < 0) {
PERROR("snprintf snapshot path");
status = LTTNG_ERR_INVALID;
goto error;
}
-
- /* Add the UST default trace dir to path. */
+ /* Free path allowed on previous iteration. */
+ free(trace_path);
+ trace_path = setup_channel_trace_path(usess->consumer, pathname,
+ &consumer_path_offset);
+ if (!trace_path) {
+ status = LTTNG_ERR_INVALID;
+ goto error;
+ }
+ /* Add the UST default trace dir to path. */
cds_lfht_for_each_entry(reg->registry->channels->ht, &iter.iter,
reg_chan, node.node) {
status = consumer_snapshot_channel(socket,
reg_chan->consumer_key,
output, 0, usess->uid,
- usess->gid, pathname, wait,
+ usess->gid, &trace_path[consumer_path_offset], wait,
nb_packets_per_stream);
if (status != LTTNG_OK) {
goto error;
}
status = consumer_snapshot_channel(socket,
reg->registry->reg.ust->metadata_key, output, 1,
- usess->uid, usess->gid, pathname, wait, 0);
+ usess->uid, usess->gid, &trace_path[consumer_path_offset],
+ wait, 0);
if (status != LTTNG_OK) {
goto error;
}
struct ust_app_channel *ua_chan;
struct ust_app_session *ua_sess;
struct ust_registry_session *registry;
+ char pathname[PATH_MAX];
+ size_t consumer_path_offset = 0;
ua_sess = lookup_session_by_app(usess, app);
if (!ua_sess) {
/* Add the UST default trace dir to path. */
memset(pathname, 0, sizeof(pathname));
- ret = snprintf(pathname, sizeof(pathname), DEFAULT_UST_TRACE_DIR "%s",
+ ret = snprintf(pathname, sizeof(pathname), DEFAULT_UST_TRACE_DIR "/%s",
ua_sess->path);
if (ret < 0) {
status = LTTNG_ERR_INVALID;
PERROR("snprintf snapshot path");
goto error;
}
-
- cds_lfht_for_each_entry(ua_sess->channels->ht, &chan_iter.iter,
+ /* Free path allowed on previous iteration. */
+ free(trace_path);
+ trace_path = setup_channel_trace_path(usess->consumer, pathname,
+ &consumer_path_offset);
+ if (!trace_path) {
+ status = LTTNG_ERR_INVALID;
+ goto error;
+ }
+ cds_lfht_for_each_entry(ua_sess->channels->ht, &chan_iter.iter,
ua_chan, node.node) {
status = consumer_snapshot_channel(socket,
ua_chan->key, output, 0,
.uid,
ua_sess->effective_credentials
.gid,
- pathname, wait,
+ &trace_path[consumer_path_offset], wait,
nb_packets_per_stream);
switch (status) {
case LTTNG_OK:
registry->metadata_key, output, 1,
ua_sess->effective_credentials.uid,
ua_sess->effective_credentials.gid,
- pathname, wait, 0);
+ &trace_path[consumer_path_offset], wait, 0);
switch (status) {
case LTTNG_OK:
break;
}
error:
+ free(trace_path);
rcu_read_unlock();
return status;
}
struct buffer_reg_channel *reg_chan;
struct consumer_socket *socket;
+ if (!reg->registry->reg.ust->metadata_key) {
+ /* Skip since no metadata is present */
+ continue;
+ }
+
/* Get consumer socket to use to push the metadata.*/
socket = consumer_find_socket_by_bitness(reg->bits_per_long,
usess->consumer);
cds_list_for_each_entry(reg, &usess->buffer_reg_uid_list, lnode) {
fmt_ret = asprintf(&pathname_index,
- DEFAULT_UST_TRACE_DIR DEFAULT_UST_TRACE_UID_PATH "/" DEFAULT_INDEX_DIR,
+ DEFAULT_UST_TRACE_DIR "/" DEFAULT_UST_TRACE_UID_PATH "/" DEFAULT_INDEX_DIR,
reg->uid, reg->bits_per_long);
if (fmt_ret < 0) {
ERR("Failed to format channel index directory");
{
struct ust_app *app;
+ /*
+ * Create the toplevel ust/ directory in case no apps are running.
+ */
+ chunk_status = lttng_trace_chunk_create_subdirectory(
+ usess->current_trace_chunk,
+ DEFAULT_UST_TRACE_DIR);
+ if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+ ret = LTTNG_ERR_CREATE_DIR_FAIL;
+ goto error;
+ }
+
cds_lfht_for_each_entry(ust_app_ht->ht, &iter.iter, app,
pid_n.node) {
struct ust_app_session *ua_sess;
}
fmt_ret = asprintf(&pathname_index,
- DEFAULT_UST_TRACE_DIR "%s/" DEFAULT_INDEX_DIR,
+ DEFAULT_UST_TRACE_DIR "/%s/" DEFAULT_INDEX_DIR,
ua_sess->path);
if (fmt_ret < 0) {
ERR("Failed to format channel index directory");
rcu_read_unlock();
return ret;
}
+
+/*
+ * Clear all the channels of a session.
+ *
+ * Return LTTNG_OK on success or else an LTTng error code.
+ */
+enum lttng_error_code ust_app_clear_session(struct ltt_session *session)
+{
+ int ret;
+ enum lttng_error_code cmd_ret = LTTNG_OK;
+ struct lttng_ht_iter iter;
+ struct ust_app *app;
+ struct ltt_ust_session *usess = session->ust_session;
+
+ assert(usess);
+
+ rcu_read_lock();
+
+ if (usess->active) {
+ ERR("Expecting inactive session %s (%" PRIu64 ")", session->name, session->id);
+ cmd_ret = LTTNG_ERR_FATAL;
+ goto end;
+ }
+
+ switch (usess->buffer_type) {
+ case LTTNG_BUFFER_PER_UID:
+ {
+ struct buffer_reg_uid *reg;
+
+ cds_list_for_each_entry(reg, &usess->buffer_reg_uid_list, lnode) {
+ struct buffer_reg_channel *reg_chan;
+ struct consumer_socket *socket;
+
+ /* Get consumer socket to use to push the metadata.*/
+ socket = consumer_find_socket_by_bitness(reg->bits_per_long,
+ usess->consumer);
+ if (!socket) {
+ cmd_ret = LTTNG_ERR_INVALID;
+ goto error_socket;
+ }
+
+ /* Clear the data channels. */
+ cds_lfht_for_each_entry(reg->registry->channels->ht, &iter.iter,
+ reg_chan, node.node) {
+ ret = consumer_clear_channel(socket,
+ reg_chan->consumer_key);
+ if (ret < 0) {
+ goto error;
+ }
+ }
+
+ (void) push_metadata(reg->registry->reg.ust, usess->consumer);
+
+ /*
+ * Clear the metadata channel.
+ * Metadata channel is not cleared per se but we still need to
+ * perform a rotation operation on it behind the scene.
+ */
+ ret = consumer_clear_channel(socket,
+ reg->registry->reg.ust->metadata_key);
+ if (ret < 0) {
+ goto error;
+ }
+ }
+ break;
+ }
+ case LTTNG_BUFFER_PER_PID:
+ {
+ cds_lfht_for_each_entry(ust_app_ht->ht, &iter.iter, app, pid_n.node) {
+ struct consumer_socket *socket;
+ struct lttng_ht_iter chan_iter;
+ struct ust_app_channel *ua_chan;
+ struct ust_app_session *ua_sess;
+ struct ust_registry_session *registry;
+
+ ua_sess = lookup_session_by_app(usess, app);
+ if (!ua_sess) {
+ /* Session not associated with this app. */
+ continue;
+ }
+
+ /* Get the right consumer socket for the application. */
+ socket = consumer_find_socket_by_bitness(app->bits_per_long,
+ usess->consumer);
+ if (!socket) {
+ cmd_ret = LTTNG_ERR_INVALID;
+ goto error_socket;
+ }
+
+ registry = get_session_registry(ua_sess);
+ if (!registry) {
+ DBG("Application session is being torn down. Skip application.");
+ continue;
+ }
+
+ /* Clear the data channels. */
+ cds_lfht_for_each_entry(ua_sess->channels->ht, &chan_iter.iter,
+ ua_chan, node.node) {
+ ret = consumer_clear_channel(socket, ua_chan->key);
+ if (ret < 0) {
+ /* Per-PID buffer and application going away. */
+ if (ret == -LTTNG_ERR_CHAN_NOT_FOUND) {
+ continue;
+ }
+ goto error;
+ }
+ }
+
+ (void) push_metadata(registry, usess->consumer);
+
+ /*
+ * Clear the metadata channel.
+ * Metadata channel is not cleared per se but we still need to
+ * perform rotation operation on it behind the scene.
+ */
+ ret = consumer_clear_channel(socket, registry->metadata_key);
+ if (ret < 0) {
+ /* Per-PID buffer and application going away. */
+ if (ret == -LTTNG_ERR_CHAN_NOT_FOUND) {
+ continue;
+ }
+ goto error;
+ }
+ }
+ break;
+ }
+ default:
+ assert(0);
+ break;
+ }
+
+ cmd_ret = LTTNG_OK;
+ goto end;
+
+error:
+ switch (-ret) {
+ case LTTCOMM_CONSUMERD_RELAYD_CLEAR_DISALLOWED:
+ cmd_ret = LTTNG_ERR_CLEAR_RELAY_DISALLOWED;
+ break;
+ default:
+ cmd_ret = LTTNG_ERR_CLEAR_FAIL_CONSUMER;
+ }
+
+error_socket:
+end:
+ rcu_read_unlock();
+ return cmd_ret;
+}
+
+/*
+ * This function skips the metadata channel as the begin/end timestamps of a
+ * metadata packet are useless.
+ *
+ * Moreover, opening a packet after a "clear" will cause problems for live
+ * sessions as it will introduce padding that was not part of the first trace
+ * chunk. The relay daemon expects the content of the metadata stream of
+ * successive metadata trace chunks to be strict supersets of one another.
+ *
+ * For example, flushing a packet at the beginning of the metadata stream of
+ * a trace chunk resulting from a "clear" session command will cause the
+ * size of the metadata stream of the new trace chunk to not match the size of
+ * the metadata stream of the original chunk. This will confuse the relay
+ * daemon as the same "offset" in a metadata stream will no longer point
+ * to the same content.
+ */
+enum lttng_error_code ust_app_open_packets(struct ltt_session *session)
+{
+ enum lttng_error_code ret = LTTNG_OK;
+ struct lttng_ht_iter iter;
+ struct ltt_ust_session *usess = session->ust_session;
+
+ assert(usess);
+
+ rcu_read_lock();
+
+ switch (usess->buffer_type) {
+ case LTTNG_BUFFER_PER_UID:
+ {
+ struct buffer_reg_uid *reg;
+
+ cds_list_for_each_entry (
+ reg, &usess->buffer_reg_uid_list, lnode) {
+ struct buffer_reg_channel *reg_chan;
+ struct consumer_socket *socket;
+
+ socket = consumer_find_socket_by_bitness(
+ reg->bits_per_long, usess->consumer);
+ if (!socket) {
+ ret = LTTNG_ERR_FATAL;
+ goto error;
+ }
+
+ cds_lfht_for_each_entry(reg->registry->channels->ht,
+ &iter.iter, reg_chan, node.node) {
+ const int open_ret =
+ consumer_open_channel_packets(
+ socket,
+ reg_chan->consumer_key);
+
+ if (open_ret < 0) {
+ ret = LTTNG_ERR_UNK;
+ goto error;
+ }
+ }
+ }
+ break;
+ }
+ case LTTNG_BUFFER_PER_PID:
+ {
+ struct ust_app *app;
+
+ cds_lfht_for_each_entry (
+ ust_app_ht->ht, &iter.iter, app, pid_n.node) {
+ struct consumer_socket *socket;
+ struct lttng_ht_iter chan_iter;
+ struct ust_app_channel *ua_chan;
+ struct ust_app_session *ua_sess;
+ struct ust_registry_session *registry;
+
+ ua_sess = lookup_session_by_app(usess, app);
+ if (!ua_sess) {
+ /* Session not associated with this app. */
+ continue;
+ }
+
+ /* Get the right consumer socket for the application. */
+ socket = consumer_find_socket_by_bitness(
+ app->bits_per_long, usess->consumer);
+ if (!socket) {
+ ret = LTTNG_ERR_FATAL;
+ goto error;
+ }
+
+ registry = get_session_registry(ua_sess);
+ if (!registry) {
+ DBG("Application session is being torn down. Skip application.");
+ continue;
+ }
+
+ cds_lfht_for_each_entry(ua_sess->channels->ht,
+ &chan_iter.iter, ua_chan, node.node) {
+ const int open_ret =
+ consumer_open_channel_packets(
+ socket,
+ ua_chan->key);
+
+ if (open_ret < 0) {
+ /*
+ * Per-PID buffer and application going
+ * away.
+ */
+ if (open_ret == -LTTNG_ERR_CHAN_NOT_FOUND) {
+ continue;
+ }
+
+ ret = LTTNG_ERR_UNK;
+ goto error;
+ }
+ }
+ }
+ break;
+ }
+ default:
+ abort();
+ break;
+ }
+
+error:
+ rcu_read_unlock();
+ return ret;
+}