perf tools: Use __maybe_used for unused variables

perf defines both __used and __unused variables to use for marking
unused variables. The variable __used is defined to
__attribute__((__unused__)), which contradicts the kernel definition to
__attribute__((__used__)) for new gcc versions. On Android, __used is
also defined in system headers and this leads to warnings like: warning:
'__used__' attribute ignored

__unused is not defined in the kernel and is not a standard definition.
If __unused is included everywhere instead of __used, this leads to
conflicts with glibc headers, since glibc has a variables with this name
in its headers.

The best approach is to use __maybe_unused, the definition used in the
kernel for __attribute__((unused)). In this way there is only one
definition in perf sources (instead of 2 definitions that point to the
same thing: __used and __unused) and it works on both Linux and Android.
This patch simply replaces all instances of __used and __unused with
__maybe_unused.

Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1347315303-29906-7-git-send-email-irina.tirdea@intel.com
[ committer note: fixed up conflict with a116e05 in builtin-sched.c ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/tools/perf/util/scripting-engines/trace-event-python.c b/tools/perf/util/scripting-engines/trace-event-python.c
index afba09729183..730c6630cba5 100644
--- a/tools/perf/util/scripting-engines/trace-event-python.c
+++ b/tools/perf/util/scripting-engines/trace-event-python.c
@@ -221,10 +221,11 @@ static inline struct event_format *find_cache_event(struct perf_evsel *evsel)
         return event;
 }
 
-static void python_process_tracepoint(union perf_event *perf_event __unused,
+static void python_process_tracepoint(union perf_event *perf_event
+                                      __maybe_unused,
                                  struct perf_sample *sample,
                                  struct perf_evsel *evsel,
-                                 struct machine *machine __unused,
+                                 struct machine *machine __maybe_unused,
                                  struct addr_location *al)
 {
         PyObject *handler, *retval, *context, *t, *obj, *dict = NULL;
@@ -339,10 +340,11 @@ static void python_process_tracepoint(union perf_event *perf_event __unused,
         Py_DECREF(t);
 }
 
-static void python_process_general_event(union perf_event *perf_event __unused,
+static void python_process_general_event(union perf_event *perf_event
+                                         __maybe_unused,
                                          struct perf_sample *sample,
                                          struct perf_evsel *evsel,
-                                         struct machine *machine __unused,
+                                         struct machine *machine __maybe_unused,
                                          struct addr_location *al)
 {
         PyObject *handler, *retval, *t, *dict;