diff mbox series

times03: don't assume process initial [us]time is 0

Message ID 8385516ec732e57976aeef8789480c6bf0199bcb.1520411634.git.jstancek@redhat.com
State Superseded
Headers show
Series times03: don't assume process initial [us]time is 0 | expand

Commit Message

Jan Stancek March 7, 2018, 8:34 a.m. UTC
times() runs immediately after fork(), but syscall alone
seems to be enough for some systems to already account ticks.

For example on arm64 with 4.14:
  tst_test.c:980: INFO: Timeout per run is 0h 05m 00s
  times03.c:102: PASS: buf1.tms_utime = 0
  times03.c:105: FAIL: buf1.tms_stime = 1
  ...

This patch drops the initial zero check for [us]time.

Signed-off-by: Jan Stancek <jstancek@redhat.com>
---
 testcases/kernel/syscalls/times/times03.c | 10 ----------
 1 file changed, 10 deletions(-)

Comments

Li Wang March 7, 2018, 9:13 a.m. UTC | #1
On Wed, Mar 7, 2018 at 4:34 PM, Jan Stancek <jstancek@redhat.com> wrote:

> times() runs immediately after fork(), but syscall alone
> seems to be enough for some systems to already account ticks.
>
> For example on arm64 with 4.14:
>   tst_test.c:980: INFO: Timeout per run is 0h 05m 00s
>   times03.c:102: PASS: buf1.tms_utime = 0
>   times03.c:105: FAIL: buf1.tms_stime = 1
>   ...
>
> This patch drops the initial zero check for [us]time.
>

‚ÄčAcked-by: Li Wang <liwang@redhat.com>‚Äč
Cyril Hrubis March 7, 2018, 10:42 a.m. UTC | #2
Hi!
> times() runs immediately after fork(), but syscall alone
> seems to be enough for some systems to already account ticks.
> 
> For example on arm64 with 4.14:
>   tst_test.c:980: INFO: Timeout per run is 0h 05m 00s
>   times03.c:102: PASS: buf1.tms_utime = 0
>   times03.c:105: FAIL: buf1.tms_stime = 1
>   ...
> 
> This patch drops the initial zero check for [us]time.

I wonder if we should drop only the system time counter check, since
agruably the user time should be zero. Or if we should check that these
values are small enough, i.e. < 5 (which should be somewhere between 5ms
and 50ms depending on CONFIG_HZ).
Jan Stancek March 7, 2018, 12:17 p.m. UTC | #3
----- Original Message -----
> Hi!
> > times() runs immediately after fork(), but syscall alone
> > seems to be enough for some systems to already account ticks.
> > 
> > For example on arm64 with 4.14:
> >   tst_test.c:980: INFO: Timeout per run is 0h 05m 00s
> >   times03.c:102: PASS: buf1.tms_utime = 0
> >   times03.c:105: FAIL: buf1.tms_stime = 1
> >   ...
> > 
> > This patch drops the initial zero check for [us]time.
> 
> I wonder if we should drop only the system time counter check, since
> agruably the user time should be zero.

Current fork()/times() is likely not doing much in user-space, but
I'd rather not rely on that. If you want to keep the check, I'd
prefer to check for some small values.

Regards,
Jan

> Or if we should check that these
> values are small enough, i.e. < 5 (which should be somewhere between 5ms
> and 50ms depending on CONFIG_HZ).
> 
> 
> --
> Cyril Hrubis
> chrubis@suse.cz
>
diff mbox series

Patch

diff --git a/testcases/kernel/syscalls/times/times03.c b/testcases/kernel/syscalls/times/times03.c
index 78d72d259ec1..c23ea541ab34 100644
--- a/testcases/kernel/syscalls/times/times03.c
+++ b/testcases/kernel/syscalls/times/times03.c
@@ -96,16 +96,6 @@  static void verify_times(void)
 	if (times(&buf1) == -1)
 		tst_brk(TBROK | TERRNO, "times()");
 
-	if (buf1.tms_utime != 0)
-		tst_res(TFAIL, "buf1.tms_utime = %li", buf1.tms_utime);
-	else
-		tst_res(TPASS, "buf1.tms_utime = 0");
-
-	if (buf1.tms_stime != 0)
-		tst_res(TFAIL, "buf1.tms_stime = %li", buf1.tms_stime);
-	else
-		tst_res(TPASS, "buf1.tms_stime = 0");
-
 	generate_utime();
 	generate_stime();