[PATCH net-next v3 06/11] tls: Address behaviour change in multi_chunk_sendfile kselftest

[David Howells <dhowells@redhat.com>]

The multi_chunk_sendfile tests in the TLS kselftest now fail because the
behaviour of sendfile()[*] changed when SPLICE_F_MORE signalling was fixed.
Now MSG_MORE is signalled to the socket until we have read sufficient data
to fulfill the request - which means if we get a short read, MSG_MORE isn't
seen to be dropped and the TLS record remains pending.

[*] This will also affect splice() if SPLICE_F_MORE isn't included in the
    flags.

Fix the TLS multi_chunk_sendfile kselftest to attempt to flush the
outstanding TLS record if we get a short sendfile() by doing a zero-length
send() with MSG_MORE unset.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Chuck Lever <chuck.lever@oracle.com>
cc: Boris Pismenny <borisp@nvidia.com>
cc: John Fastabend <john.fastabend@gmail.com>
cc: Jakub Kicinski <kuba@kernel.org>
cc: Eric Dumazet <edumazet@google.com>
cc: "David S. Miller" <davem@davemloft.net>
cc: Paolo Abeni <pabeni@redhat.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
cc: netdev@vger.kernel.org
---
 tools/testing/selftests/net/tls.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/tls.c b/tools/testing/selftests/net/tls.c
index e699548d4247..8f4bed8aacc0 100644
--- a/tools/testing/selftests/net/tls.c
+++ b/tools/testing/selftests/net/tls.c
@@ -377,7 +377,7 @@ static void chunked_sendfile(struct __test_metadata *_metadata,
 	char buf[TLS_PAYLOAD_MAX_LEN];
 	uint16_t test_payload_size;
 	int size = 0;
-	int ret;
+	int ret = 0;
 	char filename[] = "/tmp/mytemp.XXXXXX";
 	int fd = mkstemp(filename);
 	off_t offset = 0;
@@ -398,6 +398,10 @@ static void chunked_sendfile(struct __test_metadata *_metadata,
 		size -= ret;
 	}
 
+	/* Flush the TLS record on a short read. */
+	if (ret < chunk_size)
+		EXPECT_EQ(send(self->fd, "", 0, 0), 0);
+
 	EXPECT_EQ(recv(self->cfd, buf, test_payload_size, MSG_WAITALL),
 		  test_payload_size);