[PATCH v2 11/12] perf tools: Convert to BACKTRACE_SUPPORT

[Namhyung Kim]

From: Namhyung Kim <namhyung.kim@xxxxxxx>

For building perf without stack backtrace debug, we can set
NO_BACKTRACE=1 as a argument of make.  It then defines NO_BACKTRACE
macro for C code to do the proper handling.  However it usually used
in a negative semantics - e.g. #ifndef - so we saw double negations
which can be misleading.  Convert it to a positive form to make it
more readable and add _SUPPORT suffix for consistency.

Cc: Irina Tirdea <irina.tirdea@xxxxxxxxx>
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
 tools/perf/Makefile    |   10 +++++-----
 tools/perf/util/util.c |    4 ++--
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index dd5b9a0507c7..6b3ed863023b 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -45,6 +45,8 @@ include config/utilities.mak
 #
 # Define NO_LIBUNWIND if you do not want libunwind dependency for dwarf
 # backtrace post unwind.
+#
+# Define NO_BACKTRACE if you do not want stack backtrace debug feature
 
 $(OUTPUT)PERF-VERSION-FILE: .FORCE-PERF-VERSION-FILE
 	@$(SHELL_PATH) util/PERF-VERSION-GEN $(OUTPUT)
@@ -750,11 +752,9 @@ else
 	endif
 endif
 
-ifdef NO_BACKTRACE
-       BASIC_CFLAGS += -DNO_BACKTRACE
-else
-       ifneq ($(call try-cc,$(SOURCE_BACKTRACE),),y)
-               BASIC_CFLAGS += -DNO_BACKTRACE
+ifndef NO_BACKTRACE
+       ifeq ($(call try-cc,$(SOURCE_BACKTRACE),),y)
+               BASIC_CFLAGS += -DBACKTRACE_SUPPORT
        endif
 endif
 
diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index 2055cf38041c..99664598bc1a 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -1,7 +1,7 @@
 #include "../perf.h"
 #include "util.h"
 #include <sys/mman.h>
-#ifndef NO_BACKTRACE
+#ifdef BACKTRACE_SUPPORT
 #include <execinfo.h>
 #endif
 #include <stdio.h>
@@ -165,7 +165,7 @@ size_t hex_width(u64 v)
 }
 
 /* Obtain a backtrace and print it to stdout. */
-#ifndef NO_BACKTRACE
+#ifdef BACKTRACE_SUPPORT
 void dump_stack(void)
 {
 	void *array[16];
-- 
1.7.9.2

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