[Intel-wired-lan] [PATCH intel-net 1/3] i40e: move headroom initialization to i40e_configure_rx_ring

[Bhandare, KiranX]

> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces at osuosl.org> On Behalf Of
> Maciej Fijalkowski
> Sent: Wednesday, March 3, 2021 9:09 PM
> To: intel-wired-lan at lists.osuosl.org
> Cc: netdev at vger.kernel.org; brouer at redhat.com; kuba at kernel.org;
> bpf at vger.kernel.org; Topel, Bjorn <bjorn.topel at intel.com>; Karlsson,
> Magnus <magnus.karlsson at intel.com>
> Subject: [Intel-wired-lan] [PATCH intel-net 1/3] i40e: move headroom
> initialization to i40e_configure_rx_ring
> 
> i40e_rx_offset(), that is supposed to initialize the Rx buffer headroom, relies
> on I40E_RXR_FLAGS_BUILD_SKB_ENABLED flag.
> 
> Currently, the callsite of mentioned function is placed incorrectly within
> i40e_setup_rx_descriptors() where Rx ring's build skb flag is not set yet. This
> causes the XDP_REDIRECT to be partially broken due to inability to create
> xdp_frame in the headroom space, as the headroom is 0.
> 
> For the record, below is the call graph:
> 
> i40e_vsi_open
>  i40e_vsi_setup_rx_resources
>   i40e_setup_rx_descriptors
>    i40e_rx_offset() <-- sets offset to 0 as build_skb flag is set below
> 
>  i40e_vsi_configure_rx
>   i40e_configure_rx_ring
>    set_ring_build_skb_enabled(ring) <-- set build_skb flag
> 
> Fix this by moving i40e_rx_offset() to i40e_configure_rx_ring() after the flag
> setting.
> 
> Fixes: f7bb0d71d658 ("i40e: store the result of i40e_rx_offset() onto
> i40e_ring")
> Reported-by: Jesper Dangaard Brouer <brouer at redhat.com>
> Co-developed-by: Jesper Dangaard Brouer <brouer at redhat.com>
> Signed-off-by: Jesper Dangaard Brouer <brouer at redhat.com>
> Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski at intel.com>
> ---
>  drivers/net/ethernet/intel/i40e/i40e_main.c | 13 +++++++++++++
> drivers/net/ethernet/intel/i40e/i40e_txrx.c | 12 ------------
>  2 files changed, 13 insertions(+), 12 deletions(-)
> 

Tested-by: Kiran Bhandare <kiranx.bhandare at intel.com>  A Contingent Worker at Intel