On Thu, Sep 10, 2020 at 03:35:31PM -0400, Neal Cardwell wrote:
> From: Neal Cardwell <ncardw...@google.com>
>
> This patch series reorganizes TCP congestion control initialization so that if
> EBPF code called by tcp_init_transfer() sets the congestion control algorithm
> by calling setsockopt(TCP_CONGESTION) then the TCP stack initializes the
> congestion control module immediately, instead of having tcp_init_transfer()
> later initialize the congestion control module.
>
> This increases flexibility for the EBPF code that runs at connection
> establishment time, and simplifies the code.
>
> This has the following benefits:
>
> (1) This allows CC module customizations made by the EBPF called in
> tcp_init_transfer() to persist, and not be wiped out by a later
> call to tcp_init_congestion_control() in tcp_init_transfer().
>
> (2) Does not flip the order of EBPF and CC init, to avoid causing bugs
> for existing code upstream that depends on the current order.
>
> (3) Does not cause 2 initializations for for CC in the case where the
> EBPF called in tcp_init_transfer() wants to set the CC to a new CC
> algorithm.
>
> (4) Allows follow-on simplifications to the code in net/core/filter.c
> and net/ipv4/tcp_cong.c, which currently both have some complexity
> to special-case CC initialization to avoid double CC
> initialization if EBPF sets the CC.
>
> changes in v2:
>
> o rebase onto bpf-next
>
> o add another follow-on simplification suggested by Martin KaFai Lau:
> "tcp: simplify tcp_set_congestion_control() load=false case"
>
> changes in v3:
>
> o no change in commits
>
> o resent patch series from @gmail.com, since mail from ncardw...@google.com
> stopped being accepted at netdev@vger.kernel.org mid-way through processing
> the v2 patch series (between patches 2 and 3), confusing patchwork about
> which patches belonged to the v2 patch series
Acked-by: Martin KaFai Lau <ka...@fb.com>
