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, 5 deletions

diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 1f8d11b4f7ff..97b2e6300f4c 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -223,9 +223,9 @@ static int process_sample_event(struct perf_tool *tool,
 
 static int process_read_event(struct perf_tool *tool,
 			      union perf_event *event,
-			      struct perf_sample *sample __used,
+			      struct perf_sample *sample __maybe_unused,
 			      struct perf_evsel *evsel,
-			      struct machine *machine __used)
+			      struct machine *machine __maybe_unused)
 {
 	struct perf_report *rep = container_of(tool, struct perf_report, tool);
 
@@ -287,7 +287,7 @@ static int perf_report__setup_sample_type(struct perf_report *rep)
 
 extern volatile int session_done;
 
-static void sig_handler(int sig __used)
+static void sig_handler(int sig __maybe_unused)
 {
 	session_done = 1;
 }
@@ -533,13 +533,14 @@ setup:
 }
 
 static int
-parse_branch_mode(const struct option *opt __used, const char *str __used, int unset)
+parse_branch_mode(const struct option *opt __maybe_unused,
+		  const char *str __maybe_unused, int unset)
 {
 	sort__branch_mode = !unset;
 	return 0;
 }
 
-int cmd_report(int argc, const char **argv, const char *prefix __used)
+int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused)
 {
 	struct perf_session *session;
 	struct stat st;