utils: Add logic to check for hardcoded tracefs paths first

The logic we added previously was to use '/proc/mounts'
to find the tracefs path.

However, the logic can be simplified even further by
using the canonical ftrace path, as per commit from
torvalds/linux@2455f0e.

Link: https://git.kernel.org/torvalds/c/2455f0e124d3
Signed-off-by: Gichoel Choi <gichoel3101@gmail.com>

utils/tracefs.c

@@ -1,23 +1,34 @@
 #include <fcntl.h>
+#include <linux/magic.h>
 #include <mntent.h>
 #include <stdio.h>
 #include <string.h>
+#include <sys/vfs.h>
 
 #include "utils/tracefs.h"
 #include "utils/utils.h"
 
 #define PROC_MOUNTS_DIR_PATH "/proc/mounts"
+#define TRACEFS_DIR_PATH "/sys/kernel/tracing"
+#define OLD_TRACEFS_DIR_PATH "/sys/kernel/debug/tracing"
 
 static char *TRACING_DIR = NULL;
 
 static bool find_tracing_dir(void)
 {
 	FILE *fp;
 	struct mntent *ent;
+	struct statfs fs;
 
 	if (TRACING_DIR)
 		return true;
 
+	if ((!statfs(TRACEFS_DIR_PATH, &fs) && fs.f_type == TRACEFS_MAGIC) ||
+	    (!statfs(OLD_TRACEFS_DIR_PATH, &fs) && fs.f_type == TRACEFS_MAGIC)) {
+		xasprintf(&TRACING_DIR, "%s", TRACEFS_DIR_PATH);
+		return true;
+	}
+
 	fp = setmntent(PROC_MOUNTS_DIR_PATH, "r");
 	if (fp == NULL)
 		return false;