userfaultfd/selftests: fix retval check for userfaultfd_open()

userfaultfd_open() returns 1 for errors rather than negatives.  Fix it on
all the callers so when UFFDIO_API failed the test will bail out.

Link: https://lkml.kernel.org/r/20201208024709.7701-3-peterx@redhat.comSigned-off-by: Peter Xu <peterx@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

tools/testing/selftests/vm/userfaultfd.c

@@ -1029,7 +1029,7 @@ static int userfaultfd_zeropage_test(void)
 	if (uffd_test_ops->release_pages(area_dst))
 		return 1;
 
-	if (userfaultfd_open(0) < 0)
+	if (userfaultfd_open(0))
 		return 1;
 	uffdio_register.range.start = (unsigned long) area_dst;
 	uffdio_register.range.len = nr_pages * page_size;
@@ -1079,7 +1079,7 @@ static int userfaultfd_events_test(void)
 
 	features = UFFD_FEATURE_EVENT_FORK | UFFD_FEATURE_EVENT_REMAP |
 		UFFD_FEATURE_EVENT_REMOVE;
-	if (userfaultfd_open(features) < 0)
+	if (userfaultfd_open(features))
 		return 1;
 	fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
 
@@ -1151,7 +1151,7 @@ static int userfaultfd_sig_test(void)
 		return 1;
 
 	features = UFFD_FEATURE_EVENT_FORK|UFFD_FEATURE_SIGBUS;
-	if (userfaultfd_open(features) < 0)
+	if (userfaultfd_open(features))
 		return 1;
 	fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
 
@@ -1231,7 +1231,7 @@ static int userfaultfd_stress(void)
 	if (!area_dst)
 		return 1;
 
-	if (userfaultfd_open(0) < 0)
+	if (userfaultfd_open(0))
 		return 1;
 
 	count_verify = malloc(nr_pages * sizeof(unsigned long long));