Re: [PATCH v3 bpf-next] bpf: devmap: move drop error path to devmap for XDP_REDIRECT

We want to change the current ndo_xdp_xmit drop semantics 
because
it will allow us to implement better queue overflow handling.
This is working towards the larger goal of a XDP TX queue-hook.
Move XDP_REDIRECT error path handling from each XDP ethernet 
driver to
devmap code. According to the new APIs, the driver running the
ndo_xdp_xmit pointer, will break tx loop whenever the hw reports 
a tx
error and it will just return to devmap caller the number of 
successfully
transmitted frames. It will be devmap responsability to free 
dropped
frames.
Move each XDP ndo_xdp_xmit capable driver to the new APIs:
- veth
- virtio-net
- mvneta
- mvpp2
- socionext
- amazon ena
- bnxt
- freescale (dpaa2, dpaa)
- xen-frontend
- qede
- ice
- igb
- ixgbe
- i40e
- mlx5
- ti (cpsw, cpsw-new)
- tun
- sfc

Acked-by: Edward Cree <ecree.xilinx@gmail.com>
Reviewed-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
More details about the new ndo_xdp_xmit design can be found here 
[0].

[0] 
https://github.com/xdp-project/xdp-project/blob/master/areas/core/redesign01_ndo_xdp_xmit.org

Changes since v2:
- drop wrong comment in ena driver
- simplify drop condition using unlikey in the for condition of 
devmap code
- rebase on top of bpf-next
- collect acked-by/reviewed-by

Changes since v1:
- rebase on top of bpf-next
- add driver maintainers in cc
- add Edward's ack
---
 drivers/net/ethernet/amazon/ena/ena_netdev.c  | 21 
 ++++++-------
 drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c | 20 
 +++++--------
 .../net/ethernet/freescale/dpaa/dpaa_eth.c    | 12 ++++----
 .../net/ethernet/freescale/dpaa2/dpaa2-eth.c  |  2 --
 drivers/net/ethernet/intel/i40e/i40e_txrx.c   | 15 +++++-----
 drivers/net/ethernet/intel/ice/ice_txrx.c     | 15 +++++-----
 drivers/net/ethernet/intel/igb/igb_main.c     | 11 ++++---
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 11 ++++---
 drivers/net/ethernet/marvell/mvneta.c         | 13 ++++----
 .../net/ethernet/marvell/mvpp2/mvpp2_main.c   | 13 ++++----
 .../net/ethernet/mellanox/mlx5/core/en/xdp.c  | 15 ++++------
 drivers/net/ethernet/qlogic/qede/qede_fp.c    | 19 +++++-------
 drivers/net/ethernet/sfc/tx.c                 | 15 +---------
 drivers/net/ethernet/socionext/netsec.c       | 16 +++++-----
 drivers/net/ethernet/ti/cpsw.c                | 14 ++++-----
 drivers/net/ethernet/ti/cpsw_new.c            | 14 ++++-----
 drivers/net/ethernet/ti/cpsw_priv.c           | 11 +++----
 drivers/net/tun.c                             | 15 ++++++----
 drivers/net/veth.c                            | 28 
 +++++++++--------
 drivers/net/virtio_net.c                      | 25 
 ++++++++--------
 drivers/net/xen-netfront.c                    | 18 +++++------
 kernel/bpf/devmap.c                           | 30 
 ++++++++-----------
 22 files changed, 153 insertions(+), 200 deletions(-)

diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c 

b/drivers/net/ethernet/amazon/ena/ena_netdev.c
index 102f2c91fdb8..5c062c51b4cb 100644

--- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
+++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c

@@ -300,7 +300,7 @@ static int ena_xdp_xmit_frame(struct 

ena_ring *xdp_ring,