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, 2 deletions

diff --git a/tools/perf/ui/browsers/annotate.c b/tools/perf/ui/browsers/annotate.c
index 67a2703e666a..8f8cd2d73b3b 100644
--- a/tools/perf/ui/browsers/annotate.c
+++ b/tools/perf/ui/browsers/annotate.c
@@ -54,7 +54,8 @@ static inline struct browser_disasm_line *disasm_line__browser(struct disasm_lin
 	return (struct browser_disasm_line *)(dl + 1);
 }
 
-static bool disasm_line__filter(struct ui_browser *browser __used, void *entry)
+static bool disasm_line__filter(struct ui_browser *browser __maybe_unused,
+				void *entry)
 {
 	if (annotate_browser__opts.hide_src_code) {
 		struct disasm_line *dl = list_entry(entry, struct disasm_line, node);
@@ -928,7 +929,8 @@ static int annotate_config__cmp(const void *name, const void *cfgp)
 	return strcmp(name, cfg->name);
 }
 
-static int annotate__config(const char *var, const char *value, void *data __used)
+static int annotate__config(const char *var, const char *value,
+			    void *data __maybe_unused)
 {
 	struct annotate__config *cfg;
 	const char *name;