On Wed, Dec 20, 2023 at 9:58 PM Marc Zyngier maz@kernel.org wrote:
On Wed, 20 Dec 2023 13:51:24 +0000, Haibo Xu xiaobo55x@gmail.com wrote:
On Wed, Dec 20, 2023 at 5:00 PM Marc Zyngier maz@kernel.org wrote:
On 2023-12-20 06:50, Haibo Xu wrote:
On Wed, Dec 20, 2023 at 2:22 AM Marc Zyngier maz@kernel.org wrote:
On Tue, 12 Dec 2023 09:31:20 +0000, Haibo Xu haibo1.xu@intel.com wrote:
diff --git a/tools/testing/selftests/kvm/include/timer_test.h b/tools/testing/selftests/kvm/include/timer_test.h index 968257b893a7..b1d405e7157d 100644 --- a/tools/testing/selftests/kvm/include/timer_test.h +++ b/tools/testing/selftests/kvm/include/timer_test.h @@ -22,6 +22,7 @@ struct test_args { int nr_iter; int timer_period_ms; int migration_freq_ms;
int timer_err_margin_us;... except that you are storing it as a signed value. Some consistency wouldn't hurt, really, and would avoid issues when passing large values.
Yes, it's more proper to use an unsigned int for the non-negative error margin. Storing as signed here is just to keep the type consistent with that of timer_period_ms since there will be '+' operation in other places.
tools/testing/selftests/kvm/aarch64/arch_timer.c /* Setup a timeout for the interrupt to arrive */ udelay(msecs_to_usecs(test_args.timer_period_ms) + test_args.timer_err_margin_us);But that's exactly why using a signed quantity is wrong. What does it mean to have a huge *negative* margin?
Hi Marc,
I agree that negative values are meaningless for the margin. If I understand correctly, the negative margin should be filtered by assertion in atoi_non_negative().
No. Please.
atoi_non_negative() returns a uint32_t, which is what it should do. The bug is squarely in the use of an 'int' to store such value, and it is the *storage* that turns a positive value into a negative one.
Thanks for the detailed info!
May I understand that your concern is mainly for a platform with 64bit int type, which may trigger the positive to negative convert?
If so, I think we may need to do a clean up for the test code since several other places have the same issue.
Regards, Haibo
M.-- Without deviation from the norm, progress is not possible.