Previously, the xsk code did not record which umem was bound to a specific queue id. This was not required if all drivers were zero-copy enabled as this had to be recorded in the driver anyway. So if a user tried to bind two umems to the same queue, the driver would say no. But if copy-mode was first enabled and then zero-copy mode (or the reverse order), we mistakenly enabled both of them on the same umem leading to buggy behavior. The main culprit for this is that we did not store the association of umem to queue id in the copy case and only relied on the driver reporting this. As this relation was not stored in the driver for copy mode (it does not rely on the AF_XDP NDOs), this obviously could not work.
This patch fixes the problem by always recording the umem to queue id relationship in the netdev_queue and netdev_rx_queue structs. This way we always know what kind of umem has been bound to a queue id and can act appropriately at bind time. Patch 1: Introduces a umem reference in the netdev_rx_queue and netdev_queue structs. Patch 2: Records which queue_id is bound to which umem and make sure that you cannot bind two different umems to the same queue_id. I based this patch set on bpf-next commit 70e88c758a6b ("selftests/bpf: fix bpf_flow.c build") Thanks: Magnus Magnus Karlsson (2): net: add umem reference in netdev{_rx}_queue xsk: fix bug when trying to use both copy and zero-copy on one queue id include/linux/netdevice.h | 6 ++++ net/xdp/xdp_umem.c | 87 ++++++++++++++++++++++++++++++++++++++--------- net/xdp/xdp_umem.h | 2 +- 3 files changed, 77 insertions(+), 18 deletions(-) -- 2.7.4