Re: [PATCH kvm-unit-tests] arm64: timer: Avoid IRQ race in timer test

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On Wed, Jul 26, 2017 at 01:42:49PM +0200, Christoffer Dall wrote:
> The current timer test relies on testing the pending state of the timer
> before the interrupt handler has run which could lower the pending
> signal again (because it masks the timer output signal).
> 
> What we really want is to make sure the output signal from the timer as
> perceived by the virtual interrupt controller is low when the timer is
> programmed some time far in the future.  The proper way to do that is to
> disable the timer interrupt on the distributor and then reading its
> pending state.
> 
> Signed-off-by: Christoffer Dall <cdall@xxxxxxxxxx>
> ---
>  arm/timer.c | 41 ++++++++++++++++++++++++++++++++++-------
>  1 file changed, 34 insertions(+), 7 deletions(-)
>

Hi Christoffer,

With this patch the ptimer "not pending before" test always
fails on KVM for me (tested on mustang and thunderx). Have
you seen that?

Thanks,
drew



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