2019-12-10 14:33:03

by Colin King

Subject: [PATCH][next] drm/i915/selftests: fix uninitialized variable sum when summing up values

From: Colin Ian King <[email protected]>

Currently the variable sum is not uninitialized and hence will cause an
incorrect result in the summation values. Fix this by initializing
sum to the first item in the summation.

Addresses-Coverity: ("Uninitialized scalar variable")
Fixes: 3c7a44bbbfa7 ("drm/i915/selftests: Perform some basic cycle counting of MI ops")
Signed-off-by: Colin Ian King <[email protected]>
---
drivers/gpu/drm/i915/gt/selftest_engine_cs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/selftest_engine_cs.c b/drivers/gpu/drm/i915/gt/selftest_engine_cs.c
index 761d81f4bd68..f88e445a1cae 100644
--- a/drivers/gpu/drm/i915/gt/selftest_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/selftest_engine_cs.c
@@ -108,7 +108,7 @@ static u32 trifilter(u32 *a)

sort(a, COUNT, sizeof(*a), cmp_u32, NULL);

- sum += mul_u32_u32(a[2], 2);
+ sum = mul_u32_u32(a[2], 2);
sum += a[1];
sum += a[3];

--
2.24.0

2019-12-10 14:36:13

by Chris Wilson

Subject: Re: [PATCH][next] drm/i915/selftests: fix uninitialized variable sum when summing up values

Quoting Colin King (2019-12-10 14:32:05)
> From: Colin Ian King <[email protected]>
>
> Currently the variable sum is not uninitialized and hence will cause an
> incorrect result in the summation values. Fix this by initializing
> sum to the first item in the summation.
>
> Addresses-Coverity: ("Uninitialized scalar variable")
> Fixes: 3c7a44bbbfa7 ("drm/i915/selftests: Perform some basic cycle counting of MI ops")
> Signed-off-by: Colin Ian King <[email protected]>
> ---
> drivers/gpu/drm/i915/gt/selftest_engine_cs.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/selftest_engine_cs.c b/drivers/gpu/drm/i915/gt/selftest_engine_cs.c
> index 761d81f4bd68..f88e445a1cae 100644
> --- a/drivers/gpu/drm/i915/gt/selftest_engine_cs.c
> +++ b/drivers/gpu/drm/i915/gt/selftest_engine_cs.c
> @@ -108,7 +108,7 @@ static u32 trifilter(u32 *a)
>
> sort(a, COUNT, sizeof(*a), cmp_u32, NULL);
>
> - sum += mul_u32_u32(a[2], 2);
> + sum = mul_u32_u32(a[2], 2);

/o\
Reviewed-by: Chris Wilson <[email protected]>
-Chris