Re: [PATCH 1/3] selftests/mm: check a valid fd with negative value

[David Hildenbrand <david@redhat.com>]

On 16.07.25 10:27, Wei Yang wrote:
> fd 0 is usually occupied by stdin, which is not expected to be returned
> by open(). But 0 is still a valid fd.
> 
> Check the valid fd with negative value like other places.
> 
> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> Cc: Rik van Riel <riel@surriel.com>
> Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Harry Yoo <harry.yoo@oracle.com>
> ---
>   tools/testing/selftests/mm/ksm_functional_tests.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/testing/selftests/mm/ksm_functional_tests.c
> index d8bd1911dfc0..6da5c3340e10 100644
> --- a/tools/testing/selftests/mm/ksm_functional_tests.c
> +++ b/tools/testing/selftests/mm/ksm_functional_tests.c
> @@ -81,7 +81,7 @@ static long get_my_ksm_zero_pages(void)
>   	ssize_t read_size;
>   	unsigned long my_ksm_zero_pages;
>   
> -	if (!proc_self_ksm_stat_fd)
> +	if (proc_self_ksm_stat_fd < 0)
>   		return 0;

Only test_unmerge_zero_pages() calls get_my_ksm_zero_pages(). And there, 
we have

if (proc_self_ksm_stat_fd < 0) {
	ksft_test_result_skip("open(\"/proc/self/ksm_stat\") failed\n");
	return;
}

As the fd is opened after others, we should never get fd=0.

So probably, this should just be handled as part of factoring it out, no 
need for this change upfront AFAIKS.

-- 
Cheers,

David / dhildenb