libust events: lazy probe binding
[lttng-ust.git] / libust / ltt-events.c
index e68b5a2cdc186b6c1b9232cab597e1fd781cb2f3..39167d4b82ccdcc4f10668d0b8ab2ab09be1f732 100644 (file)
@@ -11,6 +11,7 @@
 #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 <uuid/uuid.h>
 #include <ust/tracepoint.h>
 #include <errno.h>
-#include "usterr_signal_safe.h"
+#include <sys/shm.h>
+#include <sys/ipc.h>
+#include <ust/lttng-events.h>
+#include <ust/usterr-signal-safe.h>
 #include "ust/core.h"
-#include "ltt-events.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);
@@ -38,6 +76,81 @@ int _ltt_event_metadata_statedump(struct ltt_session *session,
 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();
@@ -47,10 +160,10 @@ struct ltt_session *ltt_session_create(void)
 {
        struct ltt_session *session;
 
-       pthread_mutex_lock(&sessions_mutex);
        session = zmalloc(sizeof(struct ltt_session));
        if (!session)
                return NULL;
+       pthread_mutex_lock(&sessions_mutex);
        CDS_INIT_LIST_HEAD(&session->chan);
        CDS_INIT_LIST_HEAD(&session->events);
        uuid_generate(session->uuid);
@@ -194,8 +307,7 @@ struct ltt_channel *ltt_channel_create(struct ltt_session *session,
                                       void *buf_addr,
                                       size_t subbuf_size, size_t num_subbuf,
                                       unsigned int switch_timer_interval,
-                                      unsigned int read_timer_interval,
-                                      int *shmid)
+                                      unsigned int read_timer_interval)
 {
        struct ltt_channel *chan;
        struct ltt_transport *transport;
@@ -219,9 +331,9 @@ struct ltt_channel *ltt_channel_create(struct ltt_session *session,
         * headers. Therefore the "chan" information used as input
         * should be already accessible.
         */
-       chan->chan = transport->ops.channel_create("[lttng]", chan, buf_addr,
+       transport->ops.channel_create("[lttng]", chan, buf_addr,
                        subbuf_size, num_subbuf, switch_timer_interval,
-                       read_timer_interval, shmid);
+                       read_timer_interval);
        if (!chan->chan)
                goto create_error;
        chan->enabled = 1;
@@ -245,7 +357,7 @@ active:
 static
 void _ltt_channel_destroy(struct ltt_channel *chan)
 {
-       chan->ops->channel_destroy(chan->chan);
+       chan->ops->channel_destroy(chan);
        cds_list_del(&chan->list);
        lttng_destroy_context(chan->ctx);
        free(chan);
@@ -262,21 +374,25 @@ struct ltt_event *ltt_event_create(struct ltt_channel *chan,
        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. */
@@ -284,29 +400,44 @@ struct ltt_event *ltt_event_create(struct ltt_channel *chan,
        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:
@@ -325,11 +456,16 @@ int _ltt_event_unregister(struct ltt_event *event)
 
        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);
@@ -345,7 +481,9 @@ void _ltt_event_destroy(struct ltt_event *event)
 {
        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);
@@ -384,10 +522,10 @@ int lttng_metadata_printf(struct ltt_session *session,
 
        for (pos = 0; pos < len; pos += reserve_len) {
                reserve_len = min_t(size_t,
-                               chan->ops->packet_avail_size(chan->chan),
+                               chan->ops->packet_avail_size(chan->chan, chan->handle),
                                len - pos);
                lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL, reserve_len,
-                                        sizeof(char), -1);
+                                        sizeof(char), -1, chan->handle);
                /*
                 * We don't care about metadata buffer's records lost
                 * count, because we always retry here. Report error if
@@ -400,7 +538,7 @@ int lttng_metadata_printf(struct ltt_session *session,
                                ret != -ENOBUFS || !ret;
                        }),
                        LTTNG_METADATA_TIMEOUT_MSEC);
-               if (!waitret || waitret == -EINTR || ret) {
+               if (waitret == -ETIMEDOUT || waitret == -EINTR || ret) {
                        DBG("LTTng: Failure to write metadata to buffers (%s)\n",
                                waitret == -EINTR ? "interrupted" :
                                        (ret == -ENOBUFS ? "timeout" : "I/O error"));
@@ -435,7 +573,20 @@ int _ltt_field_statedump(struct ltt_session *session,
                                        ? "UTF8"
                                        : "ASCII",
                        field->type.u.basic.integer.base,
-#ifdef BIG_ENDIAN
+#ifdef __BIG_ENDIAN
+                       field->type.u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
+#else
+                       field->type.u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
+#endif
+                       field->name);
+               break;
+       case atype_float:
+               ret = lttng_metadata_printf(session,
+                       "               floating_point { exp_dig = %u; mant_dig = %u; align = %u; } %s;\n",
+                       field->type.u.basic._float.exp_dig,
+                       field->type.u.basic._float.mant_dig,
+                       field->type.u.basic._float.alignment,
+#ifdef __BIG_ENDIAN
                        field->type.u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 #else
                        field->type.u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
@@ -464,7 +615,7 @@ int _ltt_field_statedump(struct ltt_session *session,
                                        ? "UTF8"
                                        : "ASCII",
                        elem_type->u.basic.integer.base,
-#ifdef BIG_ENDIAN
+#ifdef __BIG_ENDIAN
                        elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 #else
                        elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
@@ -490,7 +641,7 @@ int _ltt_field_statedump(struct ltt_session *session,
                                        ? "UTF8"
                                        : "ASCII"),
                        length_type->u.basic.integer.base,
-#ifdef BIG_ENDIAN
+#ifdef __BIG_ENDIAN
                        length_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 #else
                        length_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
@@ -510,7 +661,7 @@ int _ltt_field_statedump(struct ltt_session *session,
                                        ? "UTF8"
                                        : "ASCII"),
                        elem_type->u.basic.integer.base,
-#ifdef BIG_ENDIAN
+#ifdef __BIG_ENDIAN
                        elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 #else
                        elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
@@ -583,6 +734,11 @@ int _ltt_event_metadata_statedump(struct ltt_session *session,
                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"
@@ -737,8 +893,8 @@ int _ltt_event_header_declare(struct ltt_session *session)
        "               } extended;\n"
        "       } v;\n"
        "} align(%u);\n\n",
-       ltt_alignof(uint32_t) * CHAR_BIT,
-       ltt_alignof(uint16_t) * CHAR_BIT
+       lttng_alignof(uint32_t) * CHAR_BIT,
+       lttng_alignof(uint16_t) * CHAR_BIT
        );
 }
 
@@ -789,14 +945,14 @@ int _ltt_session_metadata_statedump(struct ltt_session *session)
                "               uint32_t stream_id;\n"
                "       };\n"
                "};\n\n",
-               ltt_alignof(uint8_t) * CHAR_BIT,
-               ltt_alignof(uint16_t) * CHAR_BIT,
-               ltt_alignof(uint32_t) * CHAR_BIT,
-               ltt_alignof(uint64_t) * CHAR_BIT,
+               lttng_alignof(uint8_t) * CHAR_BIT,
+               lttng_alignof(uint16_t) * CHAR_BIT,
+               lttng_alignof(uint32_t) * CHAR_BIT,
+               lttng_alignof(uint64_t) * CHAR_BIT,
                CTF_VERSION_MAJOR,
                CTF_VERSION_MINOR,
                uuid_s,
-#ifdef BIG_ENDIAN
+#ifdef __BIG_ENDIAN
                "be"
 #else
                "le"
@@ -855,8 +1011,7 @@ void ltt_transport_unregister(struct ltt_transport *transport)
        pthread_mutex_unlock(&sessions_mutex);
 }
 
-static
-void __attribute__((destructor)) ltt_events_exit(void)
+void ltt_events_exit(void)
 {
        struct ltt_session *session, *tmpsession;
 
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