remove offload_pickup sysctl again

[Bodong Wang]

* Explain the feature
These two sysctls were added because the hardcoded defaults (2 minutes, tcp, 30 seconds, udp) turned out to be too low for some setups.

They appeared in 5.14-rc1 so it should be fine to remove it again.
Note: they patch was introduced before the Linux kernel was released.

Marcelo convinced me that there should be no difference between a flow that was offloaded vs. a flow that was not wrt. timeout handling.
Thus the default is changed to those for TCP established and UDP stream,
5 days and 120 seconds, respectively.

Marcelo also suggested to account for the timeout value used for the offloading, this avoids increase beyond the value in the conntrack-sysctl and will also instantly expire the conntrack entry with altered sysctls.

Example:
   nf_conntrack_udp_timeout_stream=60
   nf_flowtable_udp_timeout=60

This will remove offloaded udp flows after one minute, rather than two.

An earlier version of this patch also cleared the ASSURED bit to allow nf_conntrack to evict the entry via early_drop (i.e., table full).
However, it looks like we can safely assume that connection timed out via HW is still in established state, so this isn't needed.

Quoting Oz:
[..] the hardware sends all packets with a set FIN flags to sw.
[..] Connections that are aged in hardware are expected to be in the established state.

In case it turns out that back-to-sw-path transition can occur for 'dodgy' connections too (e.g., one side disappeared while software-path would have been in RETRANS timeout), we can adjust this later.

* How to test
 Create OVS bridge with 2 devices mlx5 rep devices.
Enable HW offload and configure regular connection tracking OpenFlow rules:

e.g:
    ovs-ofctl del-flows br-ovs
    ovs-ofctl add-flow br-ovs arp,actions=normal
    ovs-ofctl add-flow br-ovs "table=0, ip,ct_state=-trk actions=ct(table=1)"
    ovs-ofctl add-flow br-ovs "table=1, ip,ct_state=+trk+new actions=ct(commit),normal"
    ovs-ofctl add-flow br-ovs "table=1, ip,ct_state=+trk+est, actions=normal"

Establish a TCP and UDP connection and let it reach the hardware aging timeout.
The offload timeout is controlled with the following sysctl parameters:
net.netfilter.nf_flowtable_tcp_timeout = 30 net.netfilter.nf_flowtable_udp_timeout = 30 After the connection has aged it should return to [ASSURED] state with the following timeout:
TCP: net.netfilter.nf_conntrack_tcp_timeout_established (= 432000) - net.netfilter.nf_flowtable_tcp_timeout (=30)
UDP: net.netfilter.nf_conntrack_udp_timeout_stream (= 120) - net.netfilter.nf_flowtable_udp_timeout (= 30)

* What it could break.
N/A

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-bluefield/5.4.0-1042.47 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-focal' to 'verification-done-focal'. If the problem still exists, change the tag 'verification-needed-focal' to 'verification-failed-focal'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux-bluefield - 5.4.0-1042.47

---------------
linux-bluefield (5.4.0-1042.47) focal; urgency=medium

  * focal/linux-bluefield: 5.4.0-1042.47 -proposed tracker (LP: #1979463)

  * Focal update: upstream stable patchset v5.4.192 (LP: #1979014)
    - [Config] bluefield: update configs for NVM

  * flowtable: fix TCP flow teardown (LP: #1975649)
    - netfilter: flowtable: fix TCP flow teardown

  * remove offload_pickup sysctl again (LP: #1975820)
    - netfilter: conntrack: remove offload_pickup sysctl again

  * mlxbf_gige: remove driver-managed interrupt counts (LP: #1975749)
    - mlxbf_gige: remove driver-managed interrupt counts

  [ Ubuntu: 5.4.0-122.138 ]

  * focal/linux: 5.4.0-122.138 -proposed tracker (LP: #1979489)
  * Remove SAUCE patches from test_vxlan_under_vrf.sh in net of
    ubuntu_kernel_selftests (LP: #1975691)
    - Revert "UBUNTU: SAUCE: selftests: net: Don't fail test_vxlan_under_vrf on
      xfail"
    - Revert "UBUNTU: SAUCE: selftests: net: Make test for VXLAN underlay in non-
      default VRF an expected failure"
  * Enable Asus USB-BT500 Bluetooth dongle(0b05:190e) (LP: #1976613)
    - Bluetooth: btusb: Add flag to define wideband speech capability
    - Bluetooth: btrtl: Add support for RTL8761B
    - Bluetooth: btusb: Add 0x0b05:0x190e Realtek 8761BU (ASUS BT500) device.
  * [UBUNTU 20.04] rcu stalls with many storage key guests (LP: #1975582)
    - s390/gmap: voluntarily schedule during key setting
    - s390/mm: use non-quiescing sske for KVM switch to keyed guest
  * Ubuntu 5.4.0-117.132-generic 5.4.189 has BUG: kernel NULL pointer
    dereference, address: 0000000000000034 (LP: #1978719)
    - mm: rmap: explicitly reset vma->anon_vma in unlink_anon_vmas()
  * Focal update: upstream stable patchset v5.4.192 (LP: #1979014)
    - floppy: disable FDRAWCMD by default
    - [Config] updateconfigs for BLK_DEV_FD_RAWCMD
    - hamradio: defer 6pack kfree after unregister_netdev
    - hamradio: remove needs_free_netdev to avoid UAF
    - lightnvm: disable the subsystem
    - [Config] updateconfigs for NVM, NVM_PBLK
    - usb: mtu3: fix USB 3.0 dual-role-switch from device to host
    - USB: quirks: add a Realtek card reader
    - USB: quirks: add STRING quirk for VCOM device
    - USB: serial: whiteheat: fix heap overflow in WHITEHEAT_GET_DTR_RTS
    - USB: serial: cp210x: add PIDs for Kamstrup USB Meter Reader
    - USB: serial: option: add support for Cinterion MV32-WA/MV32-WB
    - USB: serial: option: add Telit 0x1057, 0x1058, 0x1075 compositions
    - xhci: stop polling roothubs after shutdown
    - xhci: increase usb U3 -> U0 link resume timeout from 100ms to 500ms
    - iio: dac: ad5592r: Fix the missing return value.
    - iio: dac: ad5446: Fix read_raw not returning set value
    - iio: magnetometer: ak8975: Fix the error handling in ak8975_power_on()
    - usb: misc: fix improper handling of refcount in uss720_probe()
    - usb: typec: ucsi: Fix role swapping
    - usb: gadget: uvc: Fix crash when encoding data for usb request
    - usb: gadget: configfs: clear deactivation flag in
      configfs_composite_unbind()
    - usb: dwc3: core: Fix tx/rx threshold settings
    - ...