• Björn Töpel's avatar
    xsk: proper AF_XDP socket teardown ordering · 541d7fdd
    Björn Töpel authored
    The AF_XDP socket struct can exist in three different, implicit
    states: setup, bound and released. Setup is prior the socket has been
    bound to a device. Bound is when the socket is active for receive and
    send. Released is when the process/userspace side of the socket is
    released, but the sock object is still lingering, e.g. when there is a
    reference to the socket in an XSKMAP after process termination.
    
    The Rx fast-path code uses the "dev" member of struct xdp_sock to
    check whether a socket is bound or relased, and the Tx code uses the
    struct xdp_umem "xsk_list" member in conjunction with "dev" to
    determine the state of a socket.
    
    However, the transition from bound to released did not tear the socket
    down in correct order.
    
    On the Rx side "dev" was cleared after synchronize_net() making the
    synchronization useless. On the Tx side, the internal queues were
    destroyed prior removing them from the "xsk_list".
    
    This commit corrects the cleanup order, and by doing so
    xdp_del_sk_umem() can be simplified and one synchronize_net() can be
    removed.
    
    Fixes: 965a9909 ("xsk: add support for bind for Rx")
    Fixes: ac98d8aa ("xsk: wire upp Tx zero-copy functions")
    Reported-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
    Signed-off-by: default avatarBjörn Töpel <bjorn.topel@intel.com>
    Acked-by: default avatarSong Liu <songliubraving@fb.com>
    Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
    541d7fdd
xsk.c 16.5 KB