[LTP] [PATCH v2] syscalls/nice01: Add test nice(-1) and nice(-50)

[Zhao Gongyi]

1. Add test verify that the errno is zero when callling of nice
legitimately return -1.(nice(-1), the default nice is usally 0)
2. Add test verify that user of root can decrease the nice value of
the process successfully by passing a lower increment
value (< min. applicable limits) to nice() system call.(nice(-50))

Signed-off-by: Zhao Gongyi <zhaogongyi@huawei.com>
---
 testcases/kernel/syscalls/nice/nice01.c | 29 +++++++++++++++----------
 1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/testcases/kernel/syscalls/nice/nice01.c b/testcases/kernel/syscalls/nice/nice01.c
index 876246180..008c9972c 100644
--- a/testcases/kernel/syscalls/nice/nice01.c
+++ b/testcases/kernel/syscalls/nice/nice01.c
@@ -17,29 +17,32 @@
 #include <sys/resource.h>
 #include "tst_test.h"

-#define	NICEINC		-12
-#define MIN_PRIO	-20
+#define MIN_PRIO        -20

-static void verify_nice(void)
+static int nice_inc[] = {-1, -12, -50};
+
+static void verify_nice(unsigned int i)
 {
 	int new_nice;
 	int orig_nice;
 	int exp_nice;
+	int inc = nice_inc[i];
+	int delta;

 	orig_nice = SAFE_GETPRIORITY(PRIO_PROCESS, 0);

-	TEST(nice(NICEINC));
+	TEST(nice(inc));

-	exp_nice = MAX(MIN_PRIO, (orig_nice + NICEINC));
+	exp_nice = MAX(MIN_PRIO, (orig_nice + inc));

 	if (TST_RET != exp_nice) {
 		tst_res(TFAIL | TTERRNO, "nice(%d) returned %li, expected %i",
-			NICEINC, TST_RET, exp_nice);
+				inc, TST_RET, exp_nice);
 		return;
 	}

 	if (TST_ERR) {
-		tst_res(TFAIL | TTERRNO, "nice(%d) failed", NICEINC);
+		tst_res(TFAIL | TTERRNO, "nice(%d) failed", inc);
 		return;
 	}

@@ -47,18 +50,20 @@ static void verify_nice(void)

 	if (new_nice != exp_nice) {
 		tst_res(TFAIL, "Process priority %i, expected %i",
-				new_nice, orig_nice + NICEINC);
+				new_nice, exp_nice);
 		return;
 	}

-	tst_res(TPASS, "nice(%d) passed", NICEINC);
+	tst_res(TPASS, "nice(%d) passed", inc);

-	TEST(nice(-NICEINC));
+	delta = orig_nice - exp_nice;
+	TEST(nice(delta));
 	if (TST_ERR)
-		tst_brk(TBROK | TTERRNO, "nice(%d) failed", -NICEINC);
+		tst_brk(TBROK | TTERRNO, "nice(%d) failed", delta);
 }

 static struct tst_test test = {
-	.test_all = verify_nice,
 	.needs_root = 1,
+	.test = verify_nice,
+	.tcnt = ARRAY_SIZE(nice_inc),
 };
--
2.17.1