[Intel-gfx] [PATCH] drm/i915/selftests: Fix compare functions provided for sorting
Chris Wilson
chris at chris-wilson.co.uk
Thu Jul 9 17:02:55 UTC 2020
Quoting Sudeep Holla (2020-07-09 16:49:31)
> Both cmp_u32 and cmp_u64 are comparing the pointers instead of the value
> at those pointers. This will result in incorrect/unsorted list. Fix it
> by deferencing the pointers before comparison.
>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> Signed-off-by: Sudeep Holla <sudeep.holla at arm.com>
> ---
> drivers/gpu/drm/i915/gt/selftest_rps.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> Hi,
>
> I am not sure if I can put 2 fixes tags, but these are the ones affected.
>
> Fixes: 4ba74e53ada3 ("drm/i915/selftests: Verify frequency scaling with RPS")
> Fixes: 8757797ff9c9 ("drm/i915/selftests: Repeat the rps clock frequency measurement")
Might as well tag the fixes, just in case anyone wants to use the tests.
> I made similar mistake and after I fixed it, just looked if there are any
> similar bugs and found this.
>
> Regards,
> Sudeep
>
> diff --git a/drivers/gpu/drm/i915/gt/selftest_rps.c b/drivers/gpu/drm/i915/gt/selftest_rps.c
> index 5049c3dd08a6..c91981e75ebf 100644
> --- a/drivers/gpu/drm/i915/gt/selftest_rps.c
> +++ b/drivers/gpu/drm/i915/gt/selftest_rps.c
> @@ -44,9 +44,9 @@ static int cmp_u64(const void *A, const void *B)
> {
> const u64 *a = A, *b = B;
>
> - if (a < b)
> + if (*a < *b)
> return -1;
> - else if (a > b)
> + else if (*a > *b)
> return 1;
Oh my golly gosh.
Thanks, thanks and thrice thanks.
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
I better double check all my qsort-compare funcs for similar brianfarts.
-Chris
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