Code that checks dstate is unaware of SystemTap and LTTng UST dstate, so
the following trace event will not fire when solely enabled by SystemTap
or LTTng UST:
if (trace_event_get_state(TRACE_MY_EVENT)) {
str = g_strdup_printf("Expensive string to generate ...",
...);
trace_my_event(str);
g_free(str);
}
Most users of trace_event_get_state() want to know both QEMU and backend
dstate for the event. Update the macro to include backend dstate.
Introduce trace_event_get_state_qemu() for those callers who really only
want QEMU dstate. This includes the trace backends (like 'log') which
should only trigger when event are enabled via QEMU.
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
---
trace/control.h | 20 ++++++++++++++++++--
scripts/tracetool/backend/ftrace.py | 2 +-
scripts/tracetool/backend/log.py | 3 ++-
scripts/tracetool/backend/simple.py | 2 +-
scripts/tracetool/backend/syslog.py | 3 ++-
5 files changed, 24 insertions(+), 6 deletions(-)
diff --git a/trace/control.h b/trace/control.h
index b931824d60..b996c34c08 100644
--- a/trace/control.h
+++ b/trace/control.h
@@ -93,16 +93,32 @@ static bool trace_event_is_vcpu(TraceEvent *ev);
static const char * trace_event_get_name(TraceEvent *ev);
/**
+ * trace_event_get_state_qemu:
+ * @id: Event identifier name.
+ *
+ * Get the tracing state of an event, both static and the QEMU dynamic state.
+ * Note that some backends maintain their own dynamic state, use
+ * trace_event_get_state() instead if you wish to include it.
+ *
+ * If the event has the disabled property, the check will have no performance
+ * impact.
+ */
+#define trace_event_get_state_qemu(id) \
+ ((id ##_ENABLED) && trace_event_get_state_dynamic_by_id(id))
+
+/**
* trace_event_get_state:
* @id: Event identifier name.
*
- * Get the tracing state of an event (both static and dynamic).
+ * Get the tracing state of an event (both static and dynamic). Both QEMU and
+ * backend-specific dynamic state are included.
*
* If the event has the disabled property, the check will have no performance
* impact.
*/
#define trace_event_get_state(id) \
- ((id ##_ENABLED) && trace_event_get_state_dynamic_by_id(id))
+ ((id ##_ENABLED) && (trace_event_get_state_dynamic_by_id(id) || \
+ id ##_BACKEND_DSTATE()))
/**
* trace_event_get_vcpu_state:
diff --git a/scripts/tracetool/backend/ftrace.py
b/scripts/tracetool/backend/ftrace.py
index dd0eda4441..fba637b376 100644
--- a/scripts/tracetool/backend/ftrace.py
+++ b/scripts/tracetool/backend/ftrace.py
@@ -33,7 +33,7 @@ def generate_h(event, group):
' char ftrace_buf[MAX_TRACE_STRLEN];',
' int unused __attribute__ ((unused));',
' int trlen;',
- ' if (trace_event_get_state(%(event_id)s)) {',
+ ' if (trace_event_get_state_qemu(%(event_id)s)) {',
' trlen = snprintf(ftrace_buf, MAX_TRACE_STRLEN,',
' "%(name)s " %(fmt)s "\\n"
%(argnames)s);',
' trlen = MIN(trlen, MAX_TRACE_STRLEN - 1);',
diff --git a/scripts/tracetool/backend/log.py b/scripts/tracetool/backend/log.py
index 54f0a69886..4562b9d12d 100644
--- a/scripts/tracetool/backend/log.py
+++ b/scripts/tracetool/backend/log.py
@@ -33,7 +33,8 @@ def generate_h(event, group):
# already checked on the generic format code
cond = "true"
else:
- cond = "trace_event_get_state(%s)" % ("TRACE_" + event.name.upper())
+ cond = "trace_event_get_state_qemu(%s)" % \
+ ("TRACE_" + event.name.upper())
out(' if (%(cond)s) {',
' struct timeval _now;',
diff --git a/scripts/tracetool/backend/simple.py
b/scripts/tracetool/backend/simple.py
index f983670ee1..a39bbdc5c6 100644
--- a/scripts/tracetool/backend/simple.py
+++ b/scripts/tracetool/backend/simple.py
@@ -73,7 +73,7 @@ def generate_c(event, group):
# already checked on the generic format code
cond = "true"
else:
- cond = "trace_event_get_state(%s)" % event_id
+ cond = "trace_event_get_state_qemu(%s)" % event_id
out('',
' if (!%(cond)s) {',
diff --git a/scripts/tracetool/backend/syslog.py
b/scripts/tracetool/backend/syslog.py
index 1ce627f0fc..3ee07bf7fd 100644
--- a/scripts/tracetool/backend/syslog.py
+++ b/scripts/tracetool/backend/syslog.py
@@ -33,7 +33,8 @@ def generate_h(event, group):
# already checked on the generic format code
cond = "true"
else:
- cond = "trace_event_get_state(%s)" % ("TRACE_" + event.name.upper())
+ cond = "trace_event_get_state_qemu(%s)" % \
+ ("TRACE_" + event.name.upper())
out(' if (%(cond)s) {',
' syslog(LOG_INFO, "%(name)s " %(fmt)s %(argnames)s);',
--
2.13.3
