[lttng-dev] [PATCH lttng-ust v2 1/2] Add ust_baddr_statedump start and end events

[Antoine Busque]

These events mark the beginning and end of base addresses state dump,
which happens once per traced application per session. Note that for a
given (process, session) pair, begin/end events are serialized and
will match. However, in a session, statedumps from different processes
may be interleaved. The vpid context should be used to identify which
events belong to which process.

Signed-off-by: Antoine Busque <abusque at efficios.com>
---
 liblttng-ust/lttng-ust-baddr.c     | 59 ++++++++++++++++++++++++++++++++++++++
 liblttng-ust/ust_baddr_statedump.h | 10 +++++++
 2 files changed, 69 insertions(+)

diff --git a/liblttng-ust/lttng-ust-baddr.c b/liblttng-ust/lttng-ust-baddr.c
index 922899b..bd3bdcb 100644
--- a/liblttng-ust/lttng-ust-baddr.c
+++ b/liblttng-ust/lttng-ust-baddr.c
@@ -89,6 +89,54 @@ int trace_baddr(void *base_addr_ptr,
 }
 
 static
+int trace_statedump_start(void *owner)
+{
+	struct cds_list_head *sessionsp;
+	struct lttng_session *session;
+
+	if (ust_lock()) {
+		ust_unlock();
+		return 1;
+	}
+
+	sessionsp = _lttng_get_sessions();
+	cds_list_for_each_entry(session, sessionsp, node) {
+		if (session->owner != owner)
+			continue;
+		if (!session->statedump_pending)
+			continue;
+		tracepoint(ust_baddr_statedump, start,
+				session);
+	}
+	ust_unlock();
+	return 0;
+}
+
+static
+int trace_statedump_end(void *owner)
+{
+	struct cds_list_head *sessionsp;
+	struct lttng_session *session;
+
+	if (ust_lock()) {
+		ust_unlock();
+		return 1;
+	}
+
+	sessionsp = _lttng_get_sessions();
+	cds_list_for_each_entry(session, sessionsp, node) {
+		if (session->owner != owner)
+			continue;
+		if (!session->statedump_pending)
+			continue;
+		tracepoint(ust_baddr_statedump, end,
+				session);
+	}
+	ust_unlock();
+	return 0;
+}
+
+static
 int extract_soinfo_events(struct dl_phdr_info *info, size_t size, void *_data)
 {
 	int j;
@@ -172,6 +220,15 @@ void dump_exec_baddr(struct extract_data *data)
 	trace_baddr(base_addr_ptr, exe_path, 0, owner);
 }
 
+/*
+ * Generate a statedump of base addresses of all shared objects loaded
+ * by the traced application, as well as for the application's
+ * executable itself. A statedump is delimited by start and end
+ * events. For a given (process, session) pair, begin/end events are
+ * serialized and will match. However, in a session, statedumps from
+ * different processes may be interleaved. The vpid context should be
+ * used to identify which events belong to which process.
+ */
 int lttng_ust_baddr_statedump(void *owner)
 {
 	struct extract_data data;
@@ -179,6 +236,7 @@ int lttng_ust_baddr_statedump(void *owner)
 	if (getenv("LTTNG_UST_WITHOUT_BADDR_STATEDUMP"))
 		return 0;
 
+	trace_statedump_start(owner);
 	data.owner = owner;
 	data.exec_baddr = NULL;
 	/*
@@ -194,6 +252,7 @@ int lttng_ust_baddr_statedump(void *owner)
 	 * iteration.
 	 */
 	dump_exec_baddr(&data);
+	trace_statedump_end(owner);
 	return 0;
 }
 
diff --git a/liblttng-ust/ust_baddr_statedump.h b/liblttng-ust/ust_baddr_statedump.h
index 77a9af4..99fb849 100644
--- a/liblttng-ust/ust_baddr_statedump.h
+++ b/liblttng-ust/ust_baddr_statedump.h
@@ -37,6 +37,11 @@ extern "C" {
 #define LTTNG_UST_BADDR_STATEDUMP_PROVIDER
 #include <lttng/tracepoint.h>
 
+TRACEPOINT_EVENT(ust_baddr_statedump, start,
+	TP_ARGS(struct lttng_session *, session),
+	TP_FIELDS()
+)
+
 TRACEPOINT_EVENT(ust_baddr_statedump, soinfo,
 	TP_ARGS(struct lttng_session *, session, void *, baddr, const char*, sopath, int64_t, size, int64_t, mtime),
 	TP_FIELDS(
@@ -47,6 +52,11 @@ TRACEPOINT_EVENT(ust_baddr_statedump, soinfo,
 	)
 )
 
+TRACEPOINT_EVENT(ust_baddr_statedump, end,
+	TP_ARGS(struct lttng_session *, session),
+	TP_FIELDS()
+)
+
 #endif /* _TRACEPOINT_UST_BADDR_STATEDUMP_H */
 
 #undef TRACEPOINT_INCLUDE
-- 
2.4.1