• Toshiaki Makita's avatar
    xdp: Helpers for disabling napi_direct of xdp_return_frame · 2539650f
    Toshiaki Makita authored
    We need some mechanism to disable napi_direct on calling
    xdp_return_frame_rx_napi() from some context.
    When veth gets support of XDP_REDIRECT, it will redirects packets which
    are redirected from other devices. On redirection veth will reuse
    xdp_mem_info of the redirection source device to make return_frame work.
    But in this case .ndo_xdp_xmit() called from veth redirection uses
    xdp_mem_info which is not guarded by NAPI, because the .ndo_xdp_xmit()
    is not called directly from the rxq which owns the xdp_mem_info.
    
    This approach introduces a flag in bpf_redirect_info to indicate that
    napi_direct should be disabled even when _rx_napi variant is used as
    well as helper functions to use it.
    
    A NAPI handler who wants to use this flag needs to call
    xdp_set_return_frame_no_direct() before processing packets, and call
    xdp_clear_return_frame_no_direct() after xdp_do_flush_map() before
    exiting NAPI.
    
    v4:
    - Use bpf_redirect_info for storing the flag instead of xdp_mem_info to
      avoid per-frame copy cost.
    Signed-off-by: default avatarToshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
    Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
    2539650f
xdp.c 9.34 KB