tools lib api: Unexport 'tracing_path' variable

One should use tracing_path_mount() instead, so more things get done
lazily instead of at every 'perf' tool call startup.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-fci4yll35idd9yuslp67vqc2@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/lib/api/fs/tracing_path.c

@@ -14,7 +14,7 @@
 #include "tracing_path.h"
 
 static char tracing_mnt[PATH_MAX]  = "/sys/kernel/debug";
-char tracing_path[PATH_MAX]        = "/sys/kernel/debug/tracing";
+static char tracing_path[PATH_MAX]        = "/sys/kernel/debug/tracing";
 char tracing_events_path[PATH_MAX] = "/sys/kernel/debug/tracing/events";
 
 
@@ -75,7 +75,7 @@ char *get_tracing_file(const char *name)
 {
 	char *file;
 
-	if (asprintf(&file, "%s/%s", tracing_path, name) < 0)
+	if (asprintf(&file, "%s/%s", tracing_path_mount(), name) < 0)
 		return NULL;
 
 	return file;

tools/lib/api/fs/tracing_path.h

@@ -4,7 +4,6 @@
 
 #include <linux/types.h>
 
-extern char tracing_path[];
 extern char tracing_events_path[];
 
 void tracing_path_set(const char *mountpoint);

tools/perf/perf.c

@@ -238,7 +238,7 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
 			(*argc)--;
 		} else if (strstarts(cmd, CMD_DEBUGFS_DIR)) {
 			tracing_path_set(cmd + strlen(CMD_DEBUGFS_DIR));
-			fprintf(stderr, "dir: %s\n", tracing_path);
+			fprintf(stderr, "dir: %s\n", tracing_path_mount());
 			if (envchanged)
 				*envchanged = 1;
 		} else if (!strcmp(cmd, "--list-cmds")) {
@@ -463,9 +463,6 @@ int main(int argc, const char **argv)
 		return err;
 	set_buildid_dir(NULL);
 
-	/* get debugfs/tracefs mount point from /proc/mounts */
-	tracing_path_mount();
-
 	/*
 	 * "perf-xxxx" is the same as "perf xxxx", but we obviously:
 	 *

tools/perf/util/probe-file.c

@@ -84,8 +84,7 @@ int open_trace_file(const char *trace_file, bool readwrite)
 	char buf[PATH_MAX];
 	int ret;
 
-	ret = e_snprintf(buf, PATH_MAX, "%s/%s",
-			 tracing_path, trace_file);
+	ret = e_snprintf(buf, PATH_MAX, "%s/%s", tracing_path_mount(), trace_file);
 	if (ret >= 0) {
 		pr_debug("Opening %s write=%d\n", buf, readwrite);
 		if (readwrite && !probe_event_dry_run)