netdev - Re: [PATCH v3 bpf-next 2/9] bpf, xdp: maintain info on attached XDP BPF programs in net

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Date:   Thu, 16 Jul 2020 13:01:23 -0600
From:   David Ahern <dsahern@...il.com>
To:     Andrii Nakryiko <andriin@...com>, bpf@...r.kernel.org,
        netdev@...r.kernel.org, ast@...com, daniel@...earbox.net
Cc:     andrii.nakryiko@...il.com, kernel-team@...com
Subject: Re: [PATCH v3 bpf-next 2/9] bpf, xdp: maintain info on attached XDP
 BPF programs in net_device

On 7/15/20 10:55 PM, Andrii Nakryiko wrote:
> Instead of delegating to drivers, maintain information about which BPF
> programs are attached in which XDP modes (generic/skb, driver, or hardware)
> locally in net_device. This effectively obsoletes XDP_QUERY_PROG command.
> 
> Such re-organization simplifies existing code already. But it also allows to
> further add bpf_link-based XDP attachments without drivers having to know
> about any of this at all, which seems like a good setup.
> XDP_SETUP_PROG/XDP_SETUP_PROG_HW are just low-level commands to driver to
> install/uninstall active BPF program. All the higher-level concerns about
> prog/link interaction will be contained within generic driver-agnostic logic.
> 
> All the XDP_QUERY_PROG calls to driver in dev_xdp_uninstall() were removed.
> It's not clear for me why dev_xdp_uninstall() were passing previous prog_flags
> when resetting installed programs. That seems unnecessary, plus most drivers
> don't populate prog_flags anyways. Having XDP_SETUP_PROG vs XDP_SETUP_PROG_HW
> should be enough of an indicator of what is required of driver to correctly
> reset active BPF program. dev_xdp_uninstall() is also generalized as an
> iteration over all three supported mode.
> 
> Signed-off-by: Andrii Nakryiko <andriin@...com>
> ---
>  include/linux/netdevice.h |  17 +++-
>  net/core/dev.c            | 158 +++++++++++++++++++++-----------------

Similar to my comment on a v1 patch, this change is doing multiple
things that really should be split into 2 patches - one moving code
around and the second making the change you want. As is the patch is
difficult to properly review.

Given that you need a v4 anyways, can you split this patch into 2?