Since cpumask_first() on the cpu_possible_mask must return at most
nr_cpu_ids - 1 for a valid result, cpumask_last() cannot return anything
larger than this value.  As test_cpumask_weight() also verifies that the
total weight of cpu_possible_mask must equal nr_cpu_ids, the last bit
set in this mask must be at nr_cpu_ids - 1.

Fixes: c41e8866c28c ("lib/test: introduce cpumask KUnit test suite")
Link: https://lore.kernel.org/lkml/346cb279-8e75-24b0-7d12-9803f2b41c73@riseup.net/
Reported-by: Maíra Canal <mairacanal@riseup.net>
Signed-off-by: Sander Vanheule <sander@svanheule.net>
Cc: David Gow <davidgow@google.com>
---
 lib/test_cpumask.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/test_cpumask.c b/lib/test_cpumask.c
index 4ebf9f5805f3..4d353614d853 100644
--- a/lib/test_cpumask.c
+++ b/lib/test_cpumask.c
@@ -73,7 +73,7 @@ static void test_cpumask_first(struct kunit *test)
 static void test_cpumask_last(struct kunit *test)
 {
 	KUNIT_EXPECT_LE(test, nr_cpumask_bits, cpumask_last(&mask_empty));
-	KUNIT_EXPECT_EQ(test, nr_cpumask_bits - 1, cpumask_last(cpu_possible_mask));
+	KUNIT_EXPECT_EQ(test, nr_cpu_ids - 1, cpumask_last(cpu_possible_mask));
 }
 
 static void test_cpumask_next(struct kunit *test)
-- 
2.37.1

On Wed, Aug 10, 2022 at 2:09 AM Sander Vanheule <sander@svanheule.net> wrote:
>
> Since cpumask_first() on the cpu_possible_mask must return at most
> nr_cpu_ids - 1 for a valid result, cpumask_last() cannot return anything
> larger than this value.  As test_cpumask_weight() also verifies that the
> total weight of cpu_possible_mask must equal nr_cpu_ids, the last bit
> set in this mask must be at nr_cpu_ids - 1.
>
> Fixes: c41e8866c28c ("lib/test: introduce cpumask KUnit test suite")
> Link: https://lore.kernel.org/lkml/346cb279-8e75-24b0-7d12-9803f2b41c73@riseup.net/
> Reported-by: Maíra Canal <mairacanal@riseup.net>
> Signed-off-by: Sander Vanheule <sander@svanheule.net>
> Cc: David Gow <davidgow@google.com>
> ---

Much better, thanks.

Reviewed-by: David Gow <davidgow@google.com>

Cheers,
-- David


>  lib/test_cpumask.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/test_cpumask.c b/lib/test_cpumask.c
> index 4ebf9f5805f3..4d353614d853 100644
> --- a/lib/test_cpumask.c
> +++ b/lib/test_cpumask.c
> @@ -73,7 +73,7 @@ static void test_cpumask_first(struct kunit *test)
>  static void test_cpumask_last(struct kunit *test)
>  {
>         KUNIT_EXPECT_LE(test, nr_cpumask_bits, cpumask_last(&mask_empty));
> -       KUNIT_EXPECT_EQ(test, nr_cpumask_bits - 1, cpumask_last(cpu_possible_mask));
> +       KUNIT_EXPECT_EQ(test, nr_cpu_ids - 1, cpumask_last(cpu_possible_mask));
>  }
>
>  static void test_cpumask_next(struct kunit *test)
> --
> 2.37.1
>

On 8/9/22 15:08, Sander Vanheule wrote:
> Since cpumask_first() on the cpu_possible_mask must return at most
> nr_cpu_ids - 1 for a valid result, cpumask_last() cannot return anything
> larger than this value.  As test_cpumask_weight() also verifies that the
> total weight of cpu_possible_mask must equal nr_cpu_ids, the last bit
> set in this mask must be at nr_cpu_ids - 1.
> 
> Fixes: c41e8866c28c ("lib/test: introduce cpumask KUnit test suite")
> Link: https://lore.kernel.org/lkml/346cb279-8e75-24b0-7d12-9803f2b41c73@riseup.net/
> Reported-by: Maíra Canal <mairacanal@riseup.net>
> Signed-off-by: Sander Vanheule <sander@svanheule.net>

Tested-by: Maíra Canal <mairacanal@riseup.net>

> Cc: David Gow <davidgow@google.com>
> ---
>  lib/test_cpumask.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/test_cpumask.c b/lib/test_cpumask.c
> index 4ebf9f5805f3..4d353614d853 100644
> --- a/lib/test_cpumask.c
> +++ b/lib/test_cpumask.c
> @@ -73,7 +73,7 @@ static void test_cpumask_first(struct kunit *test)
>  static void test_cpumask_last(struct kunit *test)
>  {
>  	KUNIT_EXPECT_LE(test, nr_cpumask_bits, cpumask_last(&mask_empty));
> -	KUNIT_EXPECT_EQ(test, nr_cpumask_bits - 1, cpumask_last(cpu_possible_mask));
> +	KUNIT_EXPECT_EQ(test, nr_cpu_ids - 1, cpumask_last(cpu_possible_mask));
>  }
>  
>  static void test_cpumask_next(struct kunit *test)