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, 4 insertions, 3 deletions

diff --git a/tools/perf/ui/browser.c b/tools/perf/ui/browser.c
index 1818a531f1d3..4aeb7d5df939 100644
--- a/tools/perf/ui/browser.c
+++ b/tools/perf/ui/browser.c
@@ -269,7 +269,7 @@ int ui_browser__show(struct ui_browser *browser, const char *title,
 	return err ? 0 : -1;
 }
 
-void ui_browser__hide(struct ui_browser *browser __used)
+void ui_browser__hide(struct ui_browser *browser __maybe_unused)
 {
 	pthread_mutex_lock(&ui__lock);
 	ui_helpline__pop();
@@ -518,7 +518,7 @@ static struct ui_browser__colorset {
 
 
 static int ui_browser__color_config(const char *var, const char *value,
-				    void *data __used)
+				    void *data __maybe_unused)
 {
 	char *fg = NULL, *bg;
 	int i;
@@ -602,7 +602,8 @@ void __ui_browser__vline(struct ui_browser *browser, unsigned int column,
 	SLsmg_set_char_set(0);
 }
 
-void ui_browser__write_graph(struct ui_browser *browser __used, int graph)
+void ui_browser__write_graph(struct ui_browser *browser __maybe_unused,
+			     int graph)
 {
 	SLsmg_set_char_set(1);
 	SLsmg_write_char(graph);