Linux 5.13 Networking Includes BPF Improvements, Optimizations, WWAN + MANA

Last week the big set of networking subsystem updates were submitted and merged for the ongoing Linux 5.13 merge window.

The networking updates this cycle were another hearty mix of new network adapter support, optimizations for performance and reliability, continuing to extend the capabilities of (e)BPF, and more.

- BPF now allows for BPF programs to call kernel functions. This will be important moving forward in opening up new use-cases but for now is just used for reusing the TCP congestion control implementations. BPF also now allows using task-local storage for tracing programs. Libbpf meanwhile has added support for static linking of BPF ELF files and other improvements.

- XDP has seen improvements yielding 4~8% better performance in micro-benchmarks.

- Initial support for RFC 8335 extended PROBE messages.

- Optimizations to avoid the Retpoline mitigation overhead on VLAN and TEB GRO handling.

- The introduction of the WWAN subsystem.

- The VirtIO Bluetooth driver was added.

- Support for the Microchip KSZ8863 and KSZ8873 Ethernet switches.

- Support for the Qualcomm QCN9074 802.11ax WiFi device within the ath11k driver.

- Broadcom BCM4330 and BCM4334 support within the Bluetooth code.

- Realtek RTL8156 and RTL8153D support.

- The Microsoft Azure Network Adapter "MANA" has been added.

- Intel IGC adds network driver queues XDP support.

More details on all of the networking changes for Linux 5.13 via this PR that is already in the mainline tree.