This patch set generalizes XDP by make the hooks in drivers to be
generic in the same manner of nfhooks. This has a number of
- Allows alternative users of the XDP hooks other than the original
- Allows a means to pipeline XDP programs together
- Reduces the amount of code and complexity needed in drivers to
- Provides a more structured environment that is extensible to new
features while being mostly transparent to the drivers
The generic XDP infrastructure is based on how nfhooks works. The new
xdp_hook_ops structure contains callback functions and private data
structure that can be populated by the user of XDP. The hook ops are
registered either on a netdev or a napi (both maintain a list of XDP
hook ops). Allow per netdev ops makes management of XDP a lot simpler
when the intent is for the hook to apply to the whole driver (as is the
case with XDP_BPF so far). The downside is that we may need per napi
data (such as counters of returned actions).
The xdp_hook_ops contains three fields of interest. The "hook" field is
the function that is run for the hook. This takes a private data field
and the xdp_buff as arguments. "priv" is private data and "put_priv"
is a function called when XDP is done with the private data. In XDP_BPF
terminology the hook field is bpf_prog_run_xdp, "priv" is the xdp_prog,
and "put_priv" is bpf_prog_put.
The meaning of ndo_xdp is also changed. There are two commands for this
nod: XDP_DEV_INIT and XDP_DEV_FINISH. XDP_DEV_INIT is called the first
time an XDP hook is set on a device, this is primarily intended to
allow the device to initialize XDP (allocated the XDP TX queues for
instance). XDP_DEV_FINISH is called when the last XDP hook is
removed from a driver so that the driver can cleanup when XDP is done.
A new net feature is added NETIF_F_XDP so that a driver indicates
that is supports XDP.
The primary modification to a driver to support XDP is that it call
xdp_hook_run in the receive path (equivalent to bpf_prog_run in
previous XDP-BPF). The driver must deal with the four XDP return
actions XDP_PASS, XDP_DROP, XDP_TX, and XDP_ABORT.
xdp.h contains the interface to register and manage XDP hooks.
Created a simple hook that does XDP_PASS and saw it works. A lot more
testing is needed for this.
Tom Herbert (3):
xdp: Infrastructure to generalize XDP
mlx4: Change XDP/BPF to use generic XDP infrastructure
netdevice: Remove obsolete xdp_netdev_command
drivers/net/ethernet/mellanox/mlx4/en_netdev.c | 64 ++------
drivers/net/ethernet/mellanox/mlx4/en_rx.c | 25 ++-
drivers/net/ethernet/mellanox/mlx4/mlx4_en.h | 1 -
include/linux/filter.h | 19 +--
include/linux/netdev_features.h | 3 +-
include/linux/netdevice.h | 24 ++-
include/net/xdp.h | 218 +++++++++++++++++++++++++
include/uapi/linux/bpf.h | 20 ---
include/uapi/linux/xdp.h | 24 +++
net/core/Makefile | 2 +-
net/core/dev.c | 44 ++++-
net/core/filter.c | 7 +-
net/core/rtnetlink.c | 16 +-
net/core/xdp.c | 211 ++++++++++++++++++++++++
14 files changed, 534 insertions(+), 144 deletions(-)
create mode 100644 include/net/xdp.h
create mode 100644 include/uapi/linux/xdp.h
create mode 100644 net/core/xdp.c