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From:   Thiago Jung Bauermann <bauerman@linux.ibm.com>
To:     linux-kselftest@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org, Shuah Khan <shuah@kernel.org>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>,
        Prakash Sangappa <prakash.sangappa@oracle.com>,
        Thiago Jung Bauermann <bauerman@linux.ibm.com>
Subject: [PATCH v2 2/4] userfaultfd: selftest: Skip test if userfaultfd() syscall not supported
Date:   Fri,  3 Aug 2018 19:00:44 -0300
In-Reply-To: <20180803220046.4019-1-bauerman@linux.ibm.com>
References: <20180803220046.4019-1-bauerman@linux.ibm.com>
Message-Id: <20180803220046.4019-3-bauerman@linux.ibm.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Since there's no point in doing anything in this case, immediately exit the
process.

And take the opportunity to improve the error message.

Before:

  # ./userfaultfd shmem 10 10
  nr_pages: 160, nr_pages_per_cpu: 40
  userfaultfd syscall not available in this kernel
  # echo $?
  1

After:

  # ./userfaultfd shmem 10 10
  nr_pages: 160, nr_pages_per_cpu: 40
  userfaultfd syscall not available in this kernel: Function not implemented
  # echo $?
  4

Suggested-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
---
 tools/testing/selftests/vm/userfaultfd.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c
index e4099afe7557..d728bd1cb33c 100644
--- a/tools/testing/selftests/vm/userfaultfd.c
+++ b/tools/testing/selftests/vm/userfaultfd.c
@@ -636,9 +636,11 @@ static int userfaultfd_open(int features)
 
 	uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
 	if (uffd < 0) {
-		fprintf(stderr,
-			"userfaultfd syscall not available in this kernel\n");
-		return 1;
+		int errnum = errno;
+
+		perror("userfaultfd syscall not available in this kernel");
+
+		exit(errnum == ENOSYS ? KSFT_SKIP : 1);
 	}
 	uffd_flags = fcntl(uffd, F_GETFD, NULL);