[LTP] [PATCH v1] Correctly check setitimer params in setitimer01

[Andrea Cervesato]

Last test rewrite didn't consider the right expected boundaries when
setitimer syscall was tested. We also introduced counter times as
multiple of clock resolution, to avoid kernel rounding during setitimer
counter increase.

Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
---
 .../kernel/syscalls/setitimer/setitimer01.c   | 42 ++++++++++++++-----
 1 file changed, 32 insertions(+), 10 deletions(-)

diff --git a/testcases/kernel/syscalls/setitimer/setitimer01.c b/testcases/kernel/syscalls/setitimer/setitimer01.c
index f04cb5a69..3fb9250e2 100644
--- a/testcases/kernel/syscalls/setitimer/setitimer01.c
+++ b/testcases/kernel/syscalls/setitimer/setitimer01.c
@@ -8,20 +8,21 @@
 /*\
  * [Description]
  *
- * Check that a setitimer() call pass with timer seting.
- * Check if signal is generated correctly when timer expiration.
+ * Spaw a child and verify that setitimer() syscall passes and it ends up
+ * counting inside expected boundaries. Then verify from parent that our syscall
+ * sent the correct signal to the child.
  */
 
+#include <time.h>
 #include <errno.h>
 #include <sys/time.h>
 #include <stdlib.h>
 #include "tst_test.h"
 #include "lapi/syscalls.h"
-
-#define USEC1	10000
-#define USEC2	20000
+#include "tst_safe_clocks.h"
 
 static struct itimerval *value, *ovalue;
+static unsigned long time_step;
 
 static struct tcase {
 	int which;
@@ -55,6 +56,7 @@ static void verify_setitimer(unsigned int i)
 {
 	pid_t pid;
 	int status;
+	int usec = 3 * time_step;
 	struct tcase *tc = &tcases[i];
 
 	pid = SAFE_FORK();
@@ -64,14 +66,18 @@ static void verify_setitimer(unsigned int i)
 
 		tst_no_corefile(0);
 
-		set_setitimer_value(USEC1, 0);
-		TST_EXP_PASS(sys_setitimer(tc->which, value, NULL));
+		set_setitimer_value(usec, 0);
+		TST_EXP_PASS(sys_setitimer(tc->which, value, 0));
 
-		set_setitimer_value(USEC2, USEC2);
+		set_setitimer_value(5 * time_step, 7 * time_step);
 		TST_EXP_PASS(sys_setitimer(tc->which, value, ovalue));
 
-		if (ovalue->it_value.tv_sec != 0 || ovalue->it_value.tv_usec >= USEC2)
-			tst_brk(TFAIL, "old timer value is not within the expected range");
+		tst_res(TINFO, "tv_sec=%ld, tv_usec=%ld",
+			ovalue->it_value.tv_sec,
+			ovalue->it_value.tv_usec);
+
+		if (ovalue->it_value.tv_sec != 0 || ovalue->it_value.tv_usec > usec)
+			tst_res(TFAIL, "Ending counters are out of range");
 
 		for (;;)
 			;
@@ -85,10 +91,26 @@ static void verify_setitimer(unsigned int i)
 		tst_res(TFAIL, "Child: %s", tst_strstatus(status));
 }
 
+static void setup(void)
+{
+	struct timespec res;
+
+	SAFE_CLOCK_GETRES(CLOCK_MONOTONIC, &res);
+
+	time_step = res.tv_nsec / 1000;
+	if (time_step < 10000)
+		time_step = 10000;
+
+	tst_res(TINFO, "clock resolution: %luns, time step: %luus",
+		res.tv_nsec,
+		time_step);
+}
+
 static struct tst_test test = {
 	.tcnt = ARRAY_SIZE(tcases),
 	.forks_child = 1,
 	.test = verify_setitimer,
+	.setup = setup,
 	.bufs = (struct tst_buffers[]) {
 		{&value,  .size = sizeof(struct itimerval)},
 		{&ovalue, .size = sizeof(struct itimerval)},
-- 
2.35.3