The RDS selftests create AF_RDS sockets but never selects a transport, so the transport is chosen implicitly based on network topology when the socket is bound. If underlying connection establishment fails, RDS can fall back to another transport (e.g. loopback) and the test still passes, silently bypassing the intended datapath it is meant to exercise.
Set SO_RDS_TRANSPORT to the proper RDS_TRANS_IB or RDS_TRANS_TCP before they are bound, so the test fails loudly if the intended transport is unavailable rather than passing on a different path. Signed-off-by: Allison Henderson <[email protected]> --- tools/testing/selftests/net/rds/test.py | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/tools/testing/selftests/net/rds/test.py b/tools/testing/selftests/net/rds/test.py index 08f2a846a8ab5..9e4df01cb0d4b 100755 --- a/tools/testing/selftests/net/rds/test.py +++ b/tools/testing/selftests/net/rds/test.py @@ -59,6 +59,14 @@ rdma_addrs = [ OP_FLAG_TCP = 0x1 OP_FLAG_RDMA = 0x2 +# from include/uapi/linux/rds.h: SO_RDS_TRANSPORT pins a socket to a +# specific RDS transport so connection setup cannot silently fall back +# to another (e.g. loopback) transport. +SOL_RDS = 276 +SO_RDS_TRANSPORT = 8 +RDS_TRANS_TCP = 2 +RDS_TRANS_IB = 0 + signal_handler_label = "" tap_idx = 0 @@ -214,11 +222,21 @@ def snd_rcv_packets(env): netns_socket(netns_list[0], socket.AF_RDS, socket.SOCK_SEQPACKET), netns_socket(netns_list[1], socket.AF_RDS, socket.SOCK_SEQPACKET), ] + + # Pin the sockets to the TCP transport so it doesn't fail over to a + # different transport during this test + for s in sockets: + s.setsockopt(SOL_RDS, SO_RDS_TRANSPORT, RDS_TRANS_TCP) elif flags & OP_FLAG_RDMA: sockets = [ socket.socket(socket.AF_RDS, socket.SOCK_SEQPACKET), socket.socket(socket.AF_RDS, socket.SOCK_SEQPACKET), ] + + # Pin the sockets to the RDMA transport so it doesn't fail over to a + # different transport during this test + for s in sockets: + s.setsockopt(SOL_RDS, SO_RDS_TRANSPORT, RDS_TRANS_IB) else: raise RuntimeError(f"Invalid transport flag sets no transports: {flags}") -- 2.25.1
