[PATCH v2 2/2] tests/intel/xe_sysfs_timeslice_duration: Restore preempt timeout

[Kamil Konieczny]

Hi Jonathan,
On 2024-10-31 at 16:31:22 +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.
> 
> v2: Also restore preempt_timeout_us on test failure (Kamil)
> 
> 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>
> CC: Kamil Konieczny <kamil.konieczny at linux.intel.com>
> ---
>  tests/intel/xe_sysfs_timeslice_duration.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/tests/intel/xe_sysfs_timeslice_duration.c b/tests/intel/xe_sysfs_timeslice_duration.c
> index 914575a282..576be98ede 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));

Imho '_lt' - zero is an error?!

> +	igt_sysfs_scanf(engine, "preempt_timeout_us", "%u", &saved);
> +	igt_assert_eq(saved, old_pt);
>  }
>  
>  igt_main
> @@ -158,7 +162,7 @@ igt_main
>  	int gt_count = 0;
>  	int fd = -1, sys_fd, gt;
>  	int engines_fd[8], gt_fd[8];
> -	unsigned int tds[8];
> +	unsigned int tds[8], pts[8];
>  
>  	igt_fixture {
>  		fd = drm_open_driver(DRIVER_XE);
> @@ -176,6 +180,9 @@ igt_main
>  			igt_assert(igt_sysfs_scanf(engines_fd[gt_count],
>  						   "timeslice_duration_us",
>  						   "%u", &tds[gt_count]) == 1);
> +			igt_assert(igt_sysfs_scanf(engines_fd[gt_count],

imho igt_require should be enough.

> +						   "preempt_timeout_us",
> +						   "%u", &pts[gt_count]) == 1);
>  			gt_count++;
>  		}
>  	}
> @@ -194,6 +201,8 @@ igt_main
>  	}
>  	igt_fixture {
>  		for (int i = gt_count - 1; i >= 0; i--) {
> +			igt_assert_lte(0, igt_sysfs_printf(engines_fd[i], "preempt_timeout_us",

This should be '> 0' as printf return number of bytes written,
also in case of error imho better use igt_abort()
We do not want proceed with any test after a failure.

Maybe add also check here if old value was really restored?

> +							   "%u", pts[i]));
>  			set_timeslice_duration(engines_fd[i], tds[i]);

Same problem is here, function makes checks and uses igt_assert(),
instead of calling it, open code restoration and abort on error.

Or code that function to return bool instead of asserting?

Same goes for restoration in patch 1.

Regards,
Kamil

>  			close(engines_fd[i]);
>  			close(gt_fd[i]);
> -- 
> 2.43.0
>