#define _GNU_SOURCE
#include <stdio.h>
#include <urcu/list.h>
+#include <urcu/hlist.h>
#include <pthread.h>
#include <urcu-bp.h>
#include <urcu/compiler.h>
#include <ust/usterr-signal-safe.h>
#include "ust/core.h"
#include "ltt-tracer.h"
+#include "ltt-tracer-core.h"
#include "ust/wait.h"
#include "../libringbuffer/shm.h"
+typedef u32 uint32_t;
+#include <ust/kcompat/jhash.h>
+
+/*
+ * The sessions mutex is the centralized mutex across UST tracing
+ * control and probe registration.
+ */
+static DEFINE_MUTEX(sessions_mutex);
+
+void lock_ust(void)
+{
+ pthread_mutex_lock(&sessions_mutex);
+}
+
+void unlock_ust(void)
+{
+ pthread_mutex_unlock(&sessions_mutex);
+}
+
static CDS_LIST_HEAD(sessions);
static CDS_LIST_HEAD(ltt_transport_list);
-static DEFINE_MUTEX(sessions_mutex);
+
+/*
+ * Pending probes hash table, containing the registered ltt events for
+ * which tracepoint probes are still missing. Protected by the sessions
+ * mutex.
+ */
+#define PENDING_PROBE_HASH_BITS 6
+#define PENDING_PROBE_HASH_SIZE (1 << PENDING_PROBE_HASH_BITS)
+static struct cds_hlist_head pending_probe_table[PENDING_PROBE_HASH_SIZE];
+
+struct ust_pending_probe {
+ struct ltt_event *event;
+ struct cds_hlist_node node;
+ char name[];
+};
static void _ltt_event_destroy(struct ltt_event *event);
static void _ltt_channel_destroy(struct ltt_channel *chan);
static
int _ltt_session_metadata_statedump(struct ltt_session *session);
+/*
+ * called at event creation if probe is missing.
+ * called with session mutex held.
+ */
+static
+int add_pending_probe(struct ltt_event *event, const char *name)
+{
+ struct cds_hlist_head *head;
+ struct cds_hlist_node *node;
+ struct ust_pending_probe *e;
+ size_t name_len = strlen(name) + 1;
+ u32 hash = jhash(name, name_len - 1, 0);
+
+ head = &pending_probe_table[hash & (PENDING_PROBE_HASH_SIZE - 1)];
+ e = zmalloc(sizeof(struct ust_pending_probe) + name_len);
+ if (!e)
+ return -ENOMEM;
+ memcpy(&e->name[0], name, name_len);
+ cds_hlist_add_head(&e->node, head);
+ e->event = event;
+ event->pending_probe = e;
+ return 0;
+}
+
+/*
+ * remove a pending probe. called when at event teardown and when an
+ * event is fixed (probe is loaded).
+ * called with session mutex held.
+ */
+static
+void remove_pending_probe(struct ust_pending_probe *e)
+{
+ if (!e)
+ return;
+ cds_hlist_del(&e->node);
+ free(e);
+}
+
+/*
+ * Called at library load: connect the probe on the events pending on
+ * probe load.
+ * called with session mutex held.
+ */
+int pending_probe_fix_events(const struct lttng_event_desc *desc)
+{
+ struct cds_hlist_head *head;
+ struct cds_hlist_node *node, *p;
+ struct ust_pending_probe *e;
+ const char *name = desc->name;
+ size_t name_len = strlen(name) + 1;
+ u32 hash = jhash(name, name_len - 1, 0);
+ int ret = 0;
+
+ head = &pending_probe_table[hash & (PENDING_PROBE_HASH_SIZE - 1)];
+ cds_hlist_for_each_entry_safe(e, node, p, head, node) {
+ struct ltt_event *event;
+ struct ltt_channel *chan;
+
+ if (strcmp(name, e->name))
+ continue;
+ event = e->event;
+ chan = event->chan;
+ assert(!event->desc);
+ event->desc = desc;
+ event->pending_probe = NULL;
+ remove_pending_probe(e);
+ ret |= __tracepoint_probe_register(name,
+ event->desc->probe_callback,
+ event);
+ ret |= _ltt_event_metadata_statedump(chan->session, chan,
+ event);
+ }
+ return ret;
+}
+
void synchronize_trace(void)
{
synchronize_rcu();
int ret;
pthread_mutex_lock(&sessions_mutex);
- if (chan->free_event_id == -1UL)
+ if (chan->used_event_id == -1UL)
goto full;
/*
* This is O(n^2) (for each event, the loop is called at event
* creation). Might require a hash if we have lots of events.
*/
cds_list_for_each_entry(event, &chan->session->events, list)
- if (!strcmp(event->desc->name, event_param->name))
+ if (event->desc && !strcmp(event->desc->name, event_param->name))
goto exist;
event = zmalloc(sizeof(struct ltt_event));
if (!event)
goto cache_error;
event->chan = chan;
event->filter = filter;
- event->id = chan->free_event_id++;
+ /*
+ * used_event_id counts the maximum number of event IDs that can
+ * register if all probes register.
+ */
+ chan->used_event_id++;
event->enabled = 1;
event->instrumentation = event_param->instrumentation;
/* Populate ltt_event structure before tracepoint registration. */
switch (event_param->instrumentation) {
case LTTNG_UST_TRACEPOINT:
event->desc = ltt_event_get(event_param->name);
- if (!event->desc)
- goto register_error;
- ret = __tracepoint_probe_register(event_param->name,
- event->desc->probe_callback,
- event);
- if (ret)
- goto register_error;
+ if (event->desc) {
+ ret = __tracepoint_probe_register(event_param->name,
+ event->desc->probe_callback,
+ event);
+ if (ret)
+ goto register_error;
+ event->id = chan->free_event_id++;
+ } else {
+ /*
+ * If the probe is not present, event->desc stays NULL,
+ * waiting for the probe to register, and the event->id
+ * stays unallocated.
+ */
+ ret = add_pending_probe(event, event_param->name);
+ if (ret)
+ goto add_pending_error;
+ }
break;
default:
WARN_ON_ONCE(1);
}
- ret = _ltt_event_metadata_statedump(chan->session, chan, event);
- if (ret)
- goto statedump_error;
+ if (event->desc) {
+ ret = _ltt_event_metadata_statedump(chan->session, chan, event);
+ if (ret)
+ goto statedump_error;
+ }
cds_list_add(&event->list, &chan->session->events);
pthread_mutex_unlock(&sessions_mutex);
return event;
statedump_error:
- WARN_ON_ONCE(__tracepoint_probe_unregister(event_param->name,
- event->desc->probe_callback,
- event));
- ltt_event_put(event->desc);
+ if (event->desc) {
+ WARN_ON_ONCE(__tracepoint_probe_unregister(event_param->name,
+ event->desc->probe_callback,
+ event));
+ ltt_event_put(event->desc);
+ }
+add_pending_error:
register_error:
free(event);
cache_error:
switch (event->instrumentation) {
case LTTNG_UST_TRACEPOINT:
- ret = __tracepoint_probe_unregister(event->desc->name,
- event->desc->probe_callback,
- event);
- if (ret)
- return ret;
+ if (event->desc) {
+ ret = __tracepoint_probe_unregister(event->desc->name,
+ event->desc->probe_callback,
+ event);
+ if (ret)
+ return ret;
+ } else {
+ remove_pending_probe(event->pending_probe);
+ ret = 0;
+ }
break;
default:
WARN_ON_ONCE(1);
{
switch (event->instrumentation) {
case LTTNG_UST_TRACEPOINT:
- ltt_event_put(event->desc);
+ if (event->desc) {
+ ltt_event_put(event->desc);
+ }
break;
default:
WARN_ON_ONCE(1);
return 0;
if (chan == session->metadata)
return 0;
+ /*
+ * Don't print events for which probe load is pending.
+ */
+ if (!event->desc)
+ return 0;
ret = lttng_metadata_printf(session,
"event {\n"
projects / lttng-ust.git / blobdiff