[PATCH] tests/intel/xe_sysfs_timeslice_duration: Restore preempt timeout

[Kamil Konieczny]

Hi Jonathan,
On 2024-10-29 at 21:36:21 +0000, Jonathan Cavitt wrote:
> The subtests of sysfs_timeslice_duration modify the preempt_timeout_us
> and timeslice_duration_us values.  However, while the test does restore
> the timeslice_duration_us value at the end of execution, it does not do
> the same for preempt_timeout_us.  Because the value is not properly
> restored, future tests can end up using the unexpected preempt timeout
> value and thus have unexpected behavior.
> 
> Save and restore the preempt_timeout_us value during the test.
> 
> This fix does not apply to xe_sysfs_preempt_timeout because only the
> preempt_timeout_us is modified during those tests, and the value is
> correcty restored before the tests end.
> 
> Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/2976
> Signed-off-by: Jonathan Cavitt <jonathan.cavitt at intel.com>
> CC: Vinay Belgaumkar <vinay.belgaumkar at intel.com>
> ---
>  tests/intel/xe_sysfs_timeslice_duration.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/tests/intel/xe_sysfs_timeslice_duration.c b/tests/intel/xe_sysfs_timeslice_duration.c
> index cf95a3ac1c..6912f166b4 100644
> --- a/tests/intel/xe_sysfs_timeslice_duration.c
> +++ b/tests/intel/xe_sysfs_timeslice_duration.c
> @@ -115,10 +115,11 @@ static uint64_t __test_timeout(int fd, int engine, unsigned int timeout, uint16_
>  static void test_timeout(int fd, int engine, const char **property, uint16_t class, int gt)
>  {
>  	uint64_t delays[] = { 1000, 50000, 100000, 500000 };
> -	unsigned int saved;
> +	unsigned int saved, old_pt;
>  	uint64_t elapsed;
>  	uint64_t epsilon;
>  
> +	igt_assert(igt_sysfs_scanf(engine, "preempt_timeout_us", "%u", &old_pt) == 1);
>  	igt_require(igt_sysfs_printf(engine, "preempt_timeout_us", "%u", 1) == 1);
>  	igt_assert(igt_sysfs_scanf(engine, property[0], "%u", &saved) == 1);
>  	igt_debug("Initial %s:%u\n", property[0], saved);
> @@ -140,6 +141,9 @@ static void test_timeout(int fd, int engine, const char **property, uint16_t cla
>  	}
>  
>  	set_timeslice_duration(engine, saved);
> +	igt_assert_lte(0, igt_sysfs_printf(engine, "preempt_timeout_us", "%u", old_pt));

Looks good but it will not reach this line if any
igt_assert/require triggers before.

Regards,
Kamil

> +	igt_sysfs_scanf(engine, "preempt_timeout_us", "%u", &saved);
> +	igt_assert_eq(saved, old_pt);
>  }
>  
>  igt_main
> -- 
> 2.43.0
>