lib: Cache kernel_bits value

This is primarily to avoid printing the uname info two or more
times. Which is increasingly likely with using tst_kernel_bits in
other library functions. Also with features like test variants where
setup may be run multiple times.

Signed-off-by: Richard Palethorpe <rpalethorpe@suse.com>
Reviewed-by: Cyril Hrubis <chrubis@suse.cz>

lib/tst_kernel.c

@@ -37,7 +37,12 @@ static int get_kernel_bits_from_uname(struct utsname *buf)
 int tst_kernel_bits(void)
 {
 	struct utsname buf;
-	int kernel_bits = get_kernel_bits_from_uname(&buf);
+	static int kernel_bits;
+
+	if (kernel_bits)
+		return kernel_bits;
+
+	kernel_bits = get_kernel_bits_from_uname(&buf);
 
 	if (kernel_bits == -1)
 		return -1;