selftests/xsk: Preserve UMEM view in BIDIRECTIONAL test

The UMEM state refactor made __send_pkts() use xsk->umem for Tx
address generation. At the same time, the shared-UMEM Tx setup copies the
Rx UMEM state into a Tx-local state object and resets base_addr and
next_buffer before configuring the Tx socket.

Passing that Tx-local object to xsk_configure() makes xsk->umem point to
the zero-based Tx allocator state. This breaks the BIDIRECTIONAL test once
the roles are switched: the same socket is then used for Rx validation, but
received descriptors from the other logical UMEM half are checked against
base_addr == 0. With the new UMEM bounds check, a valid address such as
base_addr + XDP_PACKET_HEADROOM is rejected as being outside the UMEM
window.

Keep xsk->umem as the shared/Rx UMEM view used for socket configuration
and Rx validation. Use the ifobject-local UMEM copy only for Tx descriptor
address generation, preserving the BIDIRECTIONAL test's intent of using
the proper logical UMEM half after the direction switch.

Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Reviewed-by: Tushar Vyavahare <tushar.vyavahare@intel.com>
Tested-by: Tushar Vyavahare <tushar.vyavahare@intel.com>
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://patch.msgid.link/20260629191221.2700-1-maciej.fijalkowski@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/test_xsk.c b/tools/testing/selftests/bpf/prog_tests/test_xsk.c
index 6eb9096d084c..477aedbb01ba 100644
--- a/tools/testing/selftests/bpf/prog_tests/test_xsk.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_xsk.c
@@ -1164,8 +1164,8 @@ static int __send_pkts(struct ifobject *ifobject, struct xsk_socket_info *xsk,
 		       bool test_timeout)
 {
 	u32 i, idx = 0, valid_pkts = 0, valid_frags = 0, buffer_len;
+	struct xsk_umem_info *umem = ifobject->xsk_arr[0].umem_real;
 	struct pkt_stream *pkt_stream = xsk->pkt_stream;
-	struct xsk_umem_info *umem = xsk->umem;
 	bool use_poll = ifobject->use_poll;
 	struct pollfd fds = { };
 	int ret;
@@ -1514,7 +1514,7 @@ static int thread_common_ops_tx(struct test_spec *test, struct ifobject *ifobjec
 	umem_tx->base_addr = 0;
 	umem_tx->next_buffer = 0;
 
-	ret = xsk_configure(test, ifobject, umem_tx, true);
+	ret = xsk_configure(test, ifobject, umem_rx, true);
 	if (ret)
 		return ret;
 	ifobject->xsk = &ifobject->xsk_arr[0];