Commit 7e107ab85cd4 for kernel

commit 7e107ab85cd40752a06e1788e10b0692fb021cbf
Merge: 82f0e98ba302 c3da92af07ea
Author: Jakub Kicinski <kuba@kernel.org>
Date:   Wed Jul 29 17:12:29 2026 -0700

    Merge branch 'revert-tun-tap-vhost-net-apply-qdisc-backpressure-on-full-ptr_ring-to-reduce-tx-drops'

    Simon Schippers says:

    ====================
    Revert "tun/tap & vhost-net: apply qdisc backpressure on full ptr_ring to reduce TX drops"

    Commit 1d6e569b7d0c ("tun/tap & vhost-net: avoid ptr_ring tail-drop when
    a qdisc is present") did not show a relevant performance regression in my
    testing, but on Brett Sheffield's librecast testbed it causes a
    significant throughput drop in an IPv6 multicast testcase. The regression
    can be pinpointed to multiple iperf3 TCP threads sending: for 8 threads
    the throughput dropped from 13.5 Gbit/s to 9.13 Gbit/s.

    Therefore this series reverts the qdisc backpressure work.

    Making the backpressure opt-in via a new IFF_BACKPRESSURE flag was
    proposed in [1], but a new IFF_* flag needs more review scrutiny than is
    available at the moment, so a revert was requested instead. The opt-in
    will be resubmitted for net-next later.

    [1] Link: https://lore.kernel.org/netdev/20260709095511.168235-1-simon.schippers@tu-dortmund.de/

    Reported-by: Brett Sheffield <brett@librecast.net>
    Closes: https://lore.kernel.org/netdev/akVnoOYQOrt8k-Gu@karahi.librecast.net/
    ====================

    Link: https://patch.msgid.link/20260728092240.250257-1-simon.schippers@tu-dortmund.de
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>