perf tools: Change perf_mem__lck_scnprintf to return nb of displayed bytes

Moving strncat call into scnprintf to easily track number of displayed
bytes. It will be used in following patch.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1456303616-26926-13-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/mem-events.c

@@ -221,18 +221,20 @@ int perf_mem__snp_scnprintf(char *out, size_t sz, struct mem_info *mem_info)
 	return l;
 }
 
-void perf_mem__lck_scnprintf(char *out, size_t sz __maybe_unused,
-			     struct mem_info *mem_info)
+int perf_mem__lck_scnprintf(char *out, size_t sz, struct mem_info *mem_info)
 {
 	u64 mask = PERF_MEM_LOCK_NA;
+	int l;
 
 	if (mem_info)
 		mask = mem_info->data_src.mem_lock;
 
 	if (mask & PERF_MEM_LOCK_NA)
-		strncat(out, "N/A", 3);
+		l = scnprintf(out, sz, "N/A");
 	else if (mask & PERF_MEM_LOCK_LOCKED)
-		strncat(out, "Yes", 3);
+		l = scnprintf(out, sz, "Yes");
 	else
-		strncat(out, "No", 2);
+		l = scnprintf(out, sz, "No");
+
+	return l;
 }

tools/perf/util/mem-events.h

@@ -28,6 +28,6 @@ struct mem_info;
 int perf_mem__tlb_scnprintf(char *out, size_t sz, struct mem_info *mem_info);
 int perf_mem__lvl_scnprintf(char *out, size_t sz, struct mem_info *mem_info);
 int perf_mem__snp_scnprintf(char *out, size_t sz, struct mem_info *mem_info);
-void perf_mem__lck_scnprintf(char *out, size_t sz, struct mem_info *mem_info);
+int perf_mem__lck_scnprintf(char *out, size_t sz, struct mem_info *mem_info);
 
 #endif /* __PERF_MEM_EVENTS_H */