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

[Wei Yang <richard.weiyang@gmail.com>]

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;
 
 	read_size = pread(proc_self_ksm_stat_fd, buf, sizeof(buf) - 1, 0);
-- 
2.34.1