test/eal: fix loop coverage for alignment macros

[ upstream commit b3e64fe596a3117edf6d3a79a6c5238a9b92dc4f ]

The test loop was much shorter than desired because when
MAX_NUM is defined with out paren's the divide operator /
takes precedence over shift.

But when MAX_NUM is fixed, some tests take too long
and have to be modified to avoid running over full N^2
space of 1<<20.

Note: this is a very old bug, goes back to 2013.

Link: https://pvs-studio.com/en/blog/posts/cpp/1179/
Fixes: 1fb8b07 ("app: add some tests")

Signed-off-by: Stephen Hemminger <[email protected]>
Acked-by: Bruce Richardson <[email protected]>

app/test/test_common.c

@@ -8,11 +8,12 @@
 #include <math.h>
 #include <rte_common.h>
 #include <rte_hexdump.h>
+#include <rte_random.h>
 #include <rte_pause.h>
 
 #include "test.h"
 
-#define MAX_NUM 1 << 20
+#define MAX_NUM (1 << 20)
 
 #define FAIL(x)\
 	{printf(x "() test failed!\n");\
@@ -217,19 +218,21 @@ test_align(void)
 		}
 	}
 
-	for (p = 1; p <= MAX_NUM / 2; p++) {
-		for (i = 1; i <= MAX_NUM / 2; i++) {
-			val = RTE_ALIGN_MUL_CEIL(i, p);
-			if (val % p != 0 || val < i)
-				FAIL_ALIGN("RTE_ALIGN_MUL_CEIL", i, p);
-			val = RTE_ALIGN_MUL_FLOOR(i, p);
-			if (val % p != 0 || val > i)
-				FAIL_ALIGN("RTE_ALIGN_MUL_FLOOR", i, p);
-			val = RTE_ALIGN_MUL_NEAR(i, p);
-			if (val % p != 0 || ((val != RTE_ALIGN_MUL_CEIL(i, p))
-				& (val != RTE_ALIGN_MUL_FLOOR(i, p))))
-				FAIL_ALIGN("RTE_ALIGN_MUL_NEAR", i, p);
-		}
+	/* testing the whole space of 2^20^2 takes too long. */
+	for (j = 1; j <= MAX_NUM ; j++) {
+		i = rte_rand_max(MAX_NUM - 1) + 1;
+		p = rte_rand_max(MAX_NUM - 1) + 1;
+
+		val = RTE_ALIGN_MUL_CEIL(i, p);
+		if (val % p != 0 || val < i)
+			FAIL_ALIGN("RTE_ALIGN_MUL_CEIL", i, p);
+		val = RTE_ALIGN_MUL_FLOOR(i, p);
+		if (val % p != 0 || val > i)
+			FAIL_ALIGN("RTE_ALIGN_MUL_FLOOR", i, p);
+		val = RTE_ALIGN_MUL_NEAR(i, p);
+		if (val % p != 0 || ((val != RTE_ALIGN_MUL_CEIL(i, p))
+				     & (val != RTE_ALIGN_MUL_FLOOR(i, p))))
+			FAIL_ALIGN("RTE_ALIGN_MUL_NEAR", i, p);
 	}
 
 	return 0;