test_hexdump: replace magic numbers by their meaning

The magic numbers of the length are converted to their actual meaning,
such as end of the buffer with and without ASCII part.

We don't touch the rest of the magic constants that will be removed in the
following commits.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/test_hexdump.c

@@ -137,17 +137,26 @@ static void __init test_hexdump_overflow(size_t buflen, bool ascii)
 {
 	char buf[TEST_HEXDUMP_BUF_SIZE];
 	const char *t = test_data_1_le[0];
+	size_t len = 1;
+	int rs = 16, gs = 1;
+	int ae, he, e, r;
 	bool a;
-	int e, r;
 
 	memset(buf, FILL_CHAR, sizeof(buf));
 
-	r = hex_dump_to_buffer(data_b, 1, 16, 1, buf, buflen, ascii);
+	r = hex_dump_to_buffer(data_b, len, rs, gs, buf, buflen, ascii);
+
+	/*
+	 * Caller must provide the data length multiple of groupsize. The
+	 * calculations below are made with that assumption in mind.
+	 */
+	ae = rs * 2 /* hex */ + rs / gs /* spaces */ + 1 /* space */ + len /* ascii */;
+	he = (gs * 2 /* hex */ + 1 /* space */) * len / gs - 1 /* no trailing space */;
 
 	if (ascii)
-		e = 50;
+		e = ae;
 	else
-		e = 2;
+		e = he;
 	buf[e + 2] = '\0';
 
 	if (!buflen) {