Re: [RFC][PATCH] tracing: Replace '-' with '_' in event system names

From: Steven Rostedt
Date: Wed Apr 01 2015 - 13:06:45 EST


On Wed, 1 Apr 2015 12:36:57 +0200
Cornelia Huck <cornelia.huck@xxxxxxxxxx> wrote:


> The only direct dependency for kvm-s390 I'm aware of is in
> perf/tests/parse-events.c, added because parsing an event with '-' in
> the name was broken.
>
> Otherwise, I'm not aware of things that should break, excluding local
> scripts and so on of course.

I don't like the fact that this changes what userspace sees. This is
the work around that I'm leaning towards:

-- Steve

diff --git a/arch/s390/kvm/trace-s390.h b/arch/s390/kvm/trace-s390.h
index 653a7ec09ef5..707a3e08639f 100644
--- a/arch/s390/kvm/trace-s390.h
+++ b/arch/s390/kvm/trace-s390.h
@@ -10,6 +10,13 @@
#define TRACE_INCLUDE_FILE trace-s390

/*
+ * The TRACE_SYSTEM_VAR defaults to TRACE_SYSTEM, but must be a
+ * legitimate C variable. It is not exported to user space.
+ */
+#undef TRACE_SYSTEM_VAR
+#define TRACE_SYSTEM_VAR trace_s390
+
+/*
* Trace point for the creation of the kvm instance.
*/
TRACE_EVENT(kvm_s390_create_vm,
diff --git a/drivers/usb/host/xhci-trace.h b/drivers/usb/host/xhci-trace.h
index dde3959b7a33..f44be8293217 100644
--- a/drivers/usb/host/xhci-trace.h
+++ b/drivers/usb/host/xhci-trace.h
@@ -14,6 +14,13 @@
#undef TRACE_SYSTEM
#define TRACE_SYSTEM xhci-hcd

+/*
+ * The TRACE_SYSTEM_VAR defaults to TRACE_SYSTEM, but must be a
+ * legitimate C variable. It is not exported to user space.
+ */
+#undef TRACE_SYSTEM_VAR
+#define TRACE_SYSTEM_VAR xhci_hcd
+
#if !defined(__XHCI_TRACE_H) || defined(TRACE_HEADER_MULTI_READ)
#define __XHCI_TRACE_H

diff --git a/include/trace/events/intel-sst.h b/include/trace/events/intel-sst.h
index 76c72d3f1902..a4705d7e549c 100644
--- a/include/trace/events/intel-sst.h
+++ b/include/trace/events/intel-sst.h
@@ -1,6 +1,13 @@
#undef TRACE_SYSTEM
#define TRACE_SYSTEM intel-sst

+/*
+ * The TRACE_SYSTEM_VAR defaults to TRACE_SYSTEM, but must be a
+ * legitimate C variable. It is not exported to user space.
+ */
+#undef TRACE_SYSTEM_VAR
+#define TRACE_SYSTEM_VAR intel_sst
+
#if !defined(_TRACE_INTEL_SST_H) || defined(TRACE_HEADER_MULTI_READ)
#define _TRACE_INTEL_SST_H

diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 708e2caf8a36..e6c8ed5f6a0c 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -18,11 +18,17 @@

#include <linux/ftrace_event.h>

+#ifndef TRACE_SYSTEM_VAR
+#define TRACE_SYSTEM_VAR TRACE_SYSTEM
+#endif
+
#define __app__(x, y) str__##x##y
#define __app(x, y) __app__(x, y)

+#define TRACE_SYSTEM_STRING __app(TRACE_SYSTEM_VAR,__trace_system_name)
+
#define TRACE_MAKE_SYSTEM_STR() \
- static const char __app(TRACE_SYSTEM,__trace_system_name)[] = \
+ static const char TRACE_SYSTEM_STRING[] = \
__stringify(TRACE_SYSTEM)

TRACE_MAKE_SYSTEM_STR();
@@ -32,7 +38,7 @@ TRACE_MAKE_SYSTEM_STR();
static struct trace_enum_map __used __initdata \
__##TRACE_SYSTEM##_##a = \
{ \
- .system = __app(TRACE_SYSTEM,__trace_system_name), \
+ .system = TRACE_SYSTEM_STRING, \
.enum_string = #a, \
.enum_value = a \
}; \
@@ -127,7 +133,6 @@ TRACE_MAKE_SYSTEM_STR();

#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)

-
/*
* Stage 2 of the trace events.
*
@@ -717,7 +722,7 @@ static inline void ftrace_test_probe_##call(void) \
_TRACE_PERF_PROTO(call, PARAMS(proto)); \
static char print_fmt_##call[] = print; \
static struct ftrace_event_class __used __refdata event_class_##call = { \
- .system = __app(TRACE_SYSTEM,__trace_system_name), \
+ .system = TRACE_SYSTEM_STRING, \
.define_fields = ftrace_define_fields_##call, \
.fields = LIST_HEAD_INIT(event_class_##call.fields),\
.raw_init = trace_event_raw_init, \
@@ -760,6 +765,7 @@ __attribute__((section("_ftrace_events"))) *__event_##call = &event_##call

#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)

+#undef TRACE_SYSTEM_VAR

#ifdef CONFIG_PERF_EVENTS

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