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Breaking Down the Entry Barriers on Linux Kernel Networking Stack

Juhee Kang, profile picture
Juhee Kang

The document presents a detailed overview of the Linux kernel networking stack, highlighting the entry barriers for contributions and outlining the contribution process, which differs from typical open-source projects as it requires using a specialized git service rather than GitHub. The speaker, Juhee Kang, emphasizes the complexities involved in kernel contribution, including setup, patch creation, and the various paths of packet processing. The goal is to guide attendees through understanding the kernel development process, thus demystifying the perceived challenges associated with contributing to the Linux kernel.

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UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Breaking Down the Entry Barriers on Linux Kernel Networking Stack Juhee Kang(claudiajkang@gmail.com)
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 2 Speaker Juhee Kang Open-Source Part Frontier Developer Project: Linux Kernel Networking Stack, Kubernetes i18n Interest: Cloud, Network, Backend, etc... Special Lecture at Universities - Open-Source Software Development Mechanism.
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Linux Kernel Networking Stack 1 Step by Step Kernel Contribution 3 3 INDEX Kernel Ecosystem 2
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 4 Let’s think about it Linux Kernel Contribution?
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 5 Linux Kernel Contribution? How do I start?
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 6 Contribution like other open-sources? Maybe, contribute through GitHub? (like any other open source)
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 7 Open-Source Contribution: managed with GitHub File an Issue Create a Branch Make a commit PR (Pull Request) Fetch latest remote repo (pull) merge review clone Original repository forked repository
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 8 Is Kernel Contribution done in the same way?
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 9 Is Kernel Contribution done in the same way? In torvalds/linux Kernel GitHub repository,
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 10 Is Kernel Contribution done in the same way? Pull Request exists just as other open-source.
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 11 Is Kernel Contribution done in the same way? Pull Request 존재 확인 As KernelPRBot replied,
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 12 Is Kernel Contribution done in the same way? Linux Kernel development doesn't happen on GitHub. Read-Only mirror purpose
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 13 Is Kernel Contribution done in the same way? detailed guide for kernel contribution
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 14 Kernel Contribution? - Linux Kernel (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git) Instead of using GitHub, Linux kernel uses its own git service.
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Send Patch mail review 15 Kernel Contribution process? clone Fetch latest remote repo (pull) merge Create a local branch Make a commit Make a Patch linux.git
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Send Patch mail review 16 Kernel Contribution process? clone Fetch latest remote repo (pull) merge Create a local branch Make a commit Make a Patch linux.git
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 17 Kernel Contribution Where to get source code? How to configure build env? What is a patch? Committing by email? Countless barriers before we even started...
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack In this scenario, suppose we fix a bug. 18 Goal of this session $ cd samples/bpf $ make -j $ ./tracex7 sh: 1: Syntax error: word unexpected (expecting ")")
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 19 Goal of this session Step through the Linux kernel contribution to break down contribution barriers.
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 1 Linux Kernel Networking Stack 20
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 21 Linux Kernel Networking Stack Packet Ethernet Frame Preamble Ethernet Frame Inter Frame Gap MAC. Destination MAC. Source Type PAYLOAD (IP/IPv6/ARP…) CRC 8 Bytes 6 Bytes 6 Bytes 2 Bytes 46-1500 Bytes 4 Bytes 12 Bytes 8 64 12
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 22 Linux Kernel Networking Stack Packet Ethernet Frame NIC Network Hardware
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 23 Linux Kernel Networking Stack Packet Ethernet Frame NIC Network Hardware ???
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 24 Linux Kernel Networking Stack Packet Ethernet Frame NIC Network Hardware ??? Userspace Program Userspace Software
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 25 Linux Kernel Networking Stack Packet Ethernet Frame NIC Network Hardware Kernel Linux Kernel Network Stack Userspace Program Userspace Software
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 26 Linux Kernel Networking Stack Packet Receiving Packet Sending Packet Forwarding Packet Filtering Packet Mangling Packet Tunneling Routing NAT TCP HSR UDP AMT
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 27 Basic Packet Path Packet Receiving Packet Sending Packet Forwarding Packet Filtering Packet Mangling Packet Tunneling Routing NAT TCP HSR UDP AMT
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Basic Packet Rx/Tx Path 28
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack ① Receiving Path ② Forwarding Path ③ Sending Path 🖥️ 🖥️ 🖥️ 29 Packet Path
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 30 Packet Receiving Path Packet Kernel Linux Kernel Network Stack Userspace Program Userspace Software NIC Network Hardware
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 31 Packet Receiving Path 🖥️ Host A 192.168.0.1 RX Application Transport (L4) Network (L3) Data Link (L2) NIC Driver Packet NIC Hardware Network Interface Card receives the packet
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 32 Packet Receiving Path 🖥️ Host A 192.168.0.1 RX Application Transport (L4) Network (L3) Data Link (L2) NIC Hardware Packet NIC Driver Rx/Tx Queue From Device Driver, pops the packet from the NIC hardware Queue (RX)
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 33 Packet Receiving Path 🖥️ Host A 192.168.0.1 RX Application Transport (L4) Network (L3) NIC Driver NIC Hardware Packet Data Link (L2) Rx/Tx Queue 📄 struct sk_buff Create a sk_buff structure with this packet.
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 34 Packet Receiving Path 🖥️ Host A 192.168.0.1 RX Application Transport (L4) Data Link (L2) NIC Driver NIC Hardware Packet Network (L3) Rx/Tx Queue 📄 struct sk_buff IP ARP Protocol Handler ICMP Determines which protocol the packet is,
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 35 Packet Receiving Path 🖥️ Host A 192.168.0.1 RX Application Network (L3) Data Link (L2) NIC Driver NIC Hardware Packet Transport (L4) Rx/Tx Queue 📄 struct sk_buff IP ARP UDP TCP Protocol Handler ICMP QUIC Call the appropriate handler function for the protocol
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 36 Packet Receiving Path 🖥️ Host A 192.168.0.1 RX Transport (L4) Network (L3) Data Link (L2) NIC Driver NIC Hardware Packet Application Rx/Tx Queue 📄 struct sk_buff IP ARP UDP TCP Protocol Handler ICMP QUIC Hand over processed packet to user applications
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 37 Linux Kernel Networking Packet Path
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 38 Packet Receiving Path Packet Kernel Linux Kernel Network Stack Userspace Program Userspace Software NIC Network Hardware
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 39 Packet Receiving Path After Network Interface Card receives the packet, Device Driver pops the packet from the NIC hardware Queue (RX)
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 40 Packet Receiving Path Create a sk_buff structure with this packet
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 41 Packet Receiving Path Determine which protocol the packet is and call the appropriate handler function for the protocol
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 42 Packet Receiving Path Lookup the ROUTING table to identify where the packet is headed
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 43 Packet Receiving Path Lookup the ROUTING table to identify where the packet is headed $ route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 _gateway 0.0.0.0 UG 101 0 0 eth0 192.168.0.0 0.0.0.0 255.255.255.0 U 101 0 0 eth0 192.168.0.1 192.168.0.2 255.255.255.255 UGH 0 0 0 veth21 192.168.0.4 192.168.0.3 255.255.255.255 UGH 0 0 0 veth23 _gateway 0.0.0.0 255.255.255.255 UH 101 0 0 eth0
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 44 Packet Receiving Path Preprocess the packet before calling L4 function
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 45 Packet Receiving Path Hand over processed packet to upper layer
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 46 Packet Receiving Path
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Packet Kernel Linux Kernel Network Stack Packet NIC Network Hardware 47 Packet Forwarding Path NIC Network Hardware
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 48 Packet Forwarding Path Lookup the ROUTING table to identify where the packet is headed
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 49 Packet Forwarding Path Lookup the ROUTING table to identify where the packet is headed $ route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 _gateway 0.0.0.0 UG 101 0 0 eth0 192.168.0.0 0.0.0.0 255.255.255.0 U 101 0 0 eth0 192.168.0.1 192.168.0.2 255.255.255.255 UGH 0 0 0 veth21 192.168.0.4 192.168.0.3 255.255.255.255 UGH 0 0 0 veth23 _gateway 0.0.0.0 255.255.255.255 UH 101 0 0 eth0
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 50 Packet Forwarding Path If forwarding is required, send to corresponding interface
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 51 Packet Forwarding Path Determine the MAC address of the destination to send
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 52 Packet Forwarding Path Send the packet to device driver function
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 53 Packet Forwarding Path Transmit packet through the network interface
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 54 Packet Forwarding Path
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Userspace Program Userspace Software Kernel Linux Kernel Network Stack Packet 📦 NIC Network Hardware 55 Packet Sending Path
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 56 Packet Sending Path Packet handed over from upper layer
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 57 Packet Sending Path Check the ROUTING table to see which interface to send packet
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 58 Packet Sending Path Preprocess the packet for the transmission (ex. fragmentation)
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 59 Packet Sending Path Determine the MAC address of the destination to send
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 60 Packet Sending Path Send the packet to device driver function
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 61 Packet Sending Path Transmit packet through the network interface
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 62 Packet Sending Path
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack ① Receiving Path ② Forwarding Path ③ Sending Path 🖥️ 🖥️ 🖥️ 63 Packet Path
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 64 Linux Kernel Networking Stack Packet Receiving Packet Sending Packet Forwarding Packet Filtering Packet Mangling Packet Tunneling Routing NAT TCP HSR UDP AMT
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 65 Packet Processing Packet Receiving Packet Sending Packet Forwarding Packet Filtering Packet Mangling Packet Tunneling Routing NAT TCP HSR UDP AMT
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 66 Network Protocol Packet Receiving Packet Sending Packet Forwarding Packet Filtering Packet Mangling Packet Tunneling Routing NAT TCP HSR UDP AMT
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 2 Kernel Ecosystem 67
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 68 Linux Kernel The core of the Linux Operating System Interface that connects computer hardware to processes Linux Kernel mascot Tux
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 69 Linux Kernel Development The largest open-source project involving developers worldwide https://www.semanticscholar.org/paper/Perpetual-development%3A-A-model-of-the-Linux-kernel- Feitelson/eb7cf446e983e98c1400c8181949f038caf0c8a8/figure/1 Development is done in units called Patch
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack v5.15 v5.16 v5.16-rc1 v5.16-rc2 … v5.16-rc7 Stable (v5.15) LTS Release new kernel released in every 10-11 weeks (2 months), stable kernel released once a week Kernel Release 70 Stable (v5.16) LTS Release Mainline Kernel Release Candidate (RC) Stable Long-term
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack v5.15 v5.16 Kernel Release - 1. Mainline Kernel 71 - released every 9 to 10 weeks - New features introduced, major bug fix patches Mainline Kernel
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack - Switch to stable mode after mainline kernel release - Bug fixes & mainline kernel backporting Stable (v5.15) Kernel Release - 2. Stable 72 Stable (v5.16) Stable v5.15 v5.16
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack LTS Release Kernel Release - 3. LTS Release 73 LTS Release v5.15 v5.16 - provides a critical bug fix among the stable release versions LTS Release
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack v5.15 v5.16 v5.16-rc1 v5.16-rc2 … v5.16-rc7 Kernel Release - 4. Release Candidate (RC) 74 Release Candidate (RC) Commit - "pre-release" of Mainline kernel - For testing new features - This release must be compiled from source - Usually, released up to rc7
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 75 Linux Kernel Release Cycle v5.15 v5.16 5.15 mainline kernel version release
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 76 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) 5.15 mainline kernel version release 5.15 Stable release
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 77 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release 5.15 mainline kernel version release 5.15 Stable release 5.15 LTS release
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 78 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release 5.15 mainline kernel version release 5.15 Stable release 5.15 LTS release
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 79 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release v5.16-rc1 5.15 mainline kernel version release v5.16-rc1 5.15 Stable release 5.15 LTS release
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 80 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release v5.16-rc1 5.15 mainline kernel version release v5.16-rc1 v5.16-rc2 v5.16-rc2 5.15 Stable release 5.15 LTS release
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 81 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release v5.16-rc1 5.15 mainline kernel version release v5.16-rc1 v5.16-rc2 … v5.16-rc2 . . . 5.15 Stable release 5.15 LTS release
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 82 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release v5.16-rc1 5.15 mainline kernel version release v5.16-rc1 v5.16-rc2 … v5.16-rc2 . . . 5.15 Stable release 5.15 LTS release v5.16-rc6
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 83 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release v5.16-rc1 5.15 mainline kernel version release v5.16-rc1 v5.16-rc2 … v5.16-rc7 v5.16-rc2 . . . v5.16-rc7 5.15 Stable release 5.15 LTS release v5.16-rc6
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 84 Linux Kernel Release Cycle http://vger.kernel.org/~davem/net-next.html
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Merge window 85 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release v5.16-rc1 5.15 mainline kernel version release v5.16-rc1 v5.16-rc2 … v5.16-rc7 v5.16-rc2 . . . v5.16-rc7 Merge window 5.15 Stable release 5.15 LTS release v5.16-rc6
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Merge window 86 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release v5.16-rc1 5.15 mainline kernel version release v5.16-rc1 v5.16-rc2 … v5.16-rc7 v5.16-rc2 . . . v5.16-rc7 Merge window v5.16-rc6 * Merge window (2 weeks) - Linux Torvalds receives a pull of code from the maintainer of subsystem and adds it together - New version of the kernel is released after merge window - After period ends, the kernel is developed every two weeks. Naming convention: <mainline kernel version name>-rc-<rc version name>
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Merge window 87 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release v5.16-rc1 5.15 mainline kernel version release v5.16-rc1 v5.16-rc2 … v5.16-rc7 v5.16-rc2 . . . v5.16-rc7 Merge window 5.16 mainline kernel version release 5.15 Stable release 5.15 LTS release v5.16-rc6
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 88 Linux Kernel Release Cycle http://vger.kernel.org/~davem/net-next.html
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Merge window 89 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release v5.16-rc1 5.15 mainline kernel version release v5.16-rc1 v5.16-rc2 … v5.16-rc7 v5.16-rc2 . . . v5.16-rc7 Merge window 5.16 mainline kernel version release Stable (v5.16) 5.15 Stable release 5.15 LTS release 5.16 Stable release v5.16-rc6
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Merge window 90 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release v5.16-rc1 5.15 mainline kernel version release v5.16-rc1 v5.16-rc2 … v5.16-rc7 v5.16-rc2 . . . v5.16-rc7 Merge window 5.16 mainline kernel version release Stable (v5.16) LTS Release 5.15 Stable release 5.15 LTS release 5.16 Stable release 5.16 LTS release v5.16-rc6
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 91 Linux Kernel Subsystem Inside the kernel there are numerous subsystems, http://www.MakeLinux.net/kernel/diagram 5.16 mainline kernel version release
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 92 Linux Kernel Subsystem Inside the kernel there are numerous subsystems, Features developed by each subsystem are combined to be released as the mainline kernel http://www.MakeLinux.net/kernel/diagram 5.16 mainline kernel version release
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 93 Linux Kernel Subsystem Subsystems are developed in each directory of the source code. http://www.MakeLinux.net/kernel/diagram linux $ tree -d -L 1 . ├── arch ├── block ├── certs ├── crypto ├── Documentation ├── drivers ├── fs ├── include ├── init ├── ipc ├── kernel ├── lib ├── LICENSES ├── mm ├── net ├── samples ├── scripts ├── security ├── sound ├── tools ├── usr └── virt
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 94 Linux Kernel Subsystem Network subsystem are developed in net directory of the source code. http://www.MakeLinux.net/kernel/diagram linux $ tree -d -L 1 . ├── arch ├── block => block device subsystem ├── certs ├── crypto ├── Documentation ├── drivers => driver subsystem ├── fs => file system subsystem ├── include ├── init ├── ipc => IPC subsystem ├── kernel ├── lib ├── LICENSES ├── mm => memory management subsystem ├── net => network subsystem ├── samples ├── scripts ├── security ├── sound ├── tools ├── usr └── virt
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 95 Kernel Tree https://git.kernel.org/ kernel code is managed by several major subsystem git repositories, which is called the Kernel Tree
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 96 Kernel Tree Mainline Kernel tree - Managed by Linus Torvalds - Mainline kernel tree & RC release source code * https://www.devcurmudgeon.com/images/mainline-lts-ltsi-genivi-20131025.pdf#page=18
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 97 Kernel Tree Mainline Kernel tree - Managed by Linus Torvalds - Mainline kernel tree & RC release source code Stable Kernel tree - Managed by Greg Kroah-Hartman - stable release branches source code * https://www.devcurmudgeon.com/images/mainline-lts-ltsi-genivi-20131025.pdf#page=18
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 98 Kernel Tree * https://www.devcurmudgeon.com/images/mainline-lts-ltsi-genivi-20131025.pdf#page=18 Mainline Kernel tree - Managed by Linus Torvalds - Mainline kernel tree & RC release source code Stable Kernel tree - Managed by Greg Kroah-Hartman - stable release branches source code linux-next tree - Managed by Stephen Rothwell - Subsystem changes are periodically reflected - Integrated testing of the code is conducted - After testing, pull request is performed with mainline kernel tree
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 99 Linux Kernel Tree Hierarchy Developer Developer net-next Developer Developer driver-core Developer Developer cgroup linux Major subsystems have independent tree
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 100 Linux Kernel Tree Hierarchy Developer Developer Maintainer Developer Developer Maintainer Developer Developer Maintainer Torvalds Each subsystem tree is managed by "Maintainer" netdev/net-next.git torvalds/linux.git gregkh/driver-core.git tj/cgroup.git
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 101 Linux Kernel Tree Hierarchy These maintainers manage the tree for each subsystem, and there are two trees in each subsystem Developer Developer Maintainer Torvalds netdev/net-next.git Mainline Kernel Tree Developer Developer Maintainer Greg netdev/net.git Stable Kernel Tree Networking Subsystem
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 102 Networking Subsystem Tree Developer Developer Maintainer Developer Developer Maintainer Developer Developer Maintainer Greg netdev/net.git git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git stable/linux.git netdev/net.git : netdev Stable Tree Allow only release version of bug fix patch
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 103 Networking Subsystem Tree Developer Developer Maintainer Developer Developer Maintainer Developer Developer Maintainer Torvalds netdev/net-next.git torvalds/linux.git git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git netdev/net-next.git : netdev Mainline Tree Feature Enhancement, Bug-Fix tree
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 104 Subsystem Tree $ cat MAINTAINERS | grep -A 30 'NETWORKING [GENERAL]' NETWORKING [GENERAL] M: "David S. Miller" <davem@davemloft.net> M: Eric Dumazet <edumazet@google.com> M: Jakub Kicinski <kuba@kernel.org> M: Paolo Abeni <pabeni@redhat.com> L: netdev@vger.kernel.org S: Maintained Q: https://patchwork.kernel.org/project/netdevbpf/list/ B: mailto:netdev@vger.kernel.org T: git git://git.kernel.org/.../netdev/net.git T: git git://git.kernel.org/.../netdev/net-next.git F: Documentation/networking/ F: Documentation/process/maintainer-netdev.rst F: include/linux/in.h F: include/linux/net.h F: include/linux/netdevice.h F: include/net/ F: include/uapi/linux/in.h F: include/uapi/linux/net.h F: include/uapi/linux/net_namespace.h F: include/uapi/linux/netdevice.h F: lib/net_utils.c F: lib/random32.c F: net/ F: tools/testing/selftests/net/ Developer Developer Maintainer Developer Developer Maintainer Developer Developer Maintainer Torvalds netdev/net.git
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 105 Mailing List Each subsystem has a mailing list, where contributors submit and discuss patches. $ cat MAINTAINERS | grep -A 30 'NETWORKING [GENERAL]' NETWORKING [GENERAL] M: "David S. Miller" <davem@davemloft.net> M: Eric Dumazet <edumazet@google.com> M: Jakub Kicinski <kuba@kernel.org> M: Paolo Abeni <pabeni@redhat.com> L: netdev@vger.kernel.org S: Maintained http://vger.kernel.org/vger-lists.html
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 106 Patch Contributing units in the kernel
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 107 Patch From 0199215216978b612d4e8be11e878b87bc643033 Mon Sep 17 00:00:00 2001 From: Juhee Kang <claudiajkang@gmail.com> Date: Sun, 10 Oct 2021 13:03:29 +0900 Subject: [PATCH, net-next] mlxsw: spectrum: use netif_is_macsec() instead of open code Open code which is dev->priv_flags & IFF_MACSEC has already defined as netif_is_macsec(). So use netif_is_macsec() instead of open code. This patch doesn't change logic. Signed-off-by: Juhee Kang <claudiajkang@gmail.com> --- include/linux/netdevice.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 15f4a658e436..0723c1314ea2 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -5237,7 +5237,7 @@ static inline void netif_keep_dst(struct net_device *dev) static inline bool netif_reduces_vlan_mtu(struct net_device *dev) { /* TODO: reserve and use an additional IFF bit, if we get more users */ - return dev->priv_flags & IFF_MACSEC; + return netif_is_macsec(dev); } extern struct pernet_operations __net_initdata loopback_net_ops; -- 2.34.1 $ git format-patch -1 --subject-prefix="PATCH, net-next" Contributing units in the kernel Developers make a patch of development
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Contributing units in the kernel Developers make a patch of development and submit it to the mailing list by email 108 Patch $ git format-patch -1 --subject-prefix="PATCH, net-next" $ git send-patch --cc “Network Maintainer <example@email.com>“ --to “Network Mailing List <list@email.com>” *.patch
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 109 Kernel Development Process Developer L: netdev patch 📧 📜 [PATCH net-next] mlxsw: spectrum: use netif_is_macsec() instead of open code Open code which is dev->priv_flags & IFF_MACSEC has already defined as netif_is_macsec(). So use netif_is_macsec() instead of open code. This patch doesn't change logic. Signed-off-by: Juhee Kang <claudiajkang@gmail.com> Contributor create patches $ git format-patch -1 --subject-prefix="PATCH, net-next"
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 110 Kernel Development Process Developer L: netdev 📧 📜 [PATCH net-next] mlxsw: spectrum: use netif_is_macsec() instead of open code Open code which is dev->priv_flags & IFF_MACSEC has already defined as netif_is_macsec(). So use netif_is_macsec() instead of open code. This patch doesn't change logic. Signed-off-by: Juhee Kang <claudiajkang@gmail.com> Contributor sends patches to the mailing list. $ git send-patch --cc “Network Maintainer <example@email.com>“ --to “Network Mailing List <list@email.com>” *.patch
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 111 Kernel Development Process Developer L: netdev patch 📧 📜 From mailing list, review and discussion is conducted. [PATCH net-next] mlxsw: spectrum: use netif_is_macsec() instead of open code Open code which is dev->priv_flags & IFF_MACSEC has already defined as netif_is_macsec(). So use netif_is_macsec() instead of open code. This patch doesn't change logic. Signed-off-by: Juhee Kang <claudiajkang@gmail.com>
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 112 Kernel Development Process Developer L: netdev patch 📧 📜 Once the patch has been accepted, an email will be sent informing that it was reflected in the subsystem [PATCH net-next] mlxsw: spectrum: use netif_is_macsec() instead of open code Open code which is dev->priv_flags & IFF_MACSEC has already defined as netif_is_macsec(). So use netif_is_macsec() instead of open code. This patch doesn't change logic. Signed-off-by: Juhee Kang <claudiajkang@gmail.com> Maintainer 📧 Re: [PATCH net-next] mlxsw: spectrum: use netif_is_macsec() instead of open ode Hello: This series was applied to netdev/net-next.git (master) by David S. Miller <davem@davemloft.net>:
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 113 Kernel Development Process Developer Maintainer Torvalds netdev/net-next.git Patch is reflected in net-next git tree 📧 📜
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 114 Kernel Development Process Developer Developer Maintainer Torvalds netdev/net-next.git 📧 📜 📜 📜 Maintainer will Send Pull Request to Parent Tree torvalds/linux.git
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 115 Kernel Development Process Developer Developer Maintainer Developer Developer Maintainer Developer Developer Maintainer Torvalds netdev/net-next.git Pull Requests are sent from various subsystems to the parent tree 📧 📜 📜 📜 📧 📜 📜 📜 gregkh/driver-core.git tj/cgroup.git torvalds/linux.git
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 116 Kernel Development Process Developer Developer Maintainer Developer Developer Maintainer Developer Developer Maintainer Torvalds netdev/net-next.git Code combined to release as new version of kernel 📧 📜 📜 📜 📧 📜 📜 📜 gregkh/driver-core.git tj/cgroup.git torvalds/linux.git Mainline Kernel Release Candidate (RC)
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack ① Documentation ② Bug-Fix ③ Feature Enhancement ④ etc.. 117 Linux Kernel Contribution
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 118 1. Documentation Improve the documentation - add undocumented or elaborate details
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 119 2. Bug Fix Fixing Bugs - fix code to work as expected
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Adding a new feature - for improved usability 120 3. Feature Enhancement
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Enhance feature - performance improvement 121 3. Feature Enhancement
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Now let's do Contributions to Linux Kernel 122
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 3 Step by Step Kernel Contribution 123
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack In this scenario, suppose we fix a bug. 124 Kernel Patch in Action
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 125 Discover a Bug An error occurred while running the kernel test script. $ cd samples/bpf $ make -j $ ./tracex7 sh: 1: Syntax error: word unexpected (expecting ")")
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 126 Configure Environment: kernel development Fedora Debian OpenSUSE Ubuntu Prepare Linux in VM
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 127 Configure Environment: kernel development # apt-get install build-essential vim git cscope libncurses-dev libssl-dev bison flex bison # systemctl enable serial-getty@ttyS0.service # systemctl start serial-getty@ttyS0.service # systemctl daemon-reload # vim /etc/default/grub # update-grub2 Install development packages on Linux VM
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 128 Configure Environment: kernel development Configure Linux for a debugging # apt-get install build-essential vim git cscope libncurses-dev libssl-dev bison flex bison # systemctl enable serial-getty@ttyS0.service # systemctl start serial-getty@ttyS0.service # systemctl daemon-reload # vim /etc/default/grub # update-grub2
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 129 Configure Environment: get kernel source $ git clone https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git $ cd net-next $ git checkout -f main
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 130 Reproduce Bug: find the cause $ cd samples/bpf $ make -j $ ./tracex7 sh: 1: Syntax error: word unexpected (expecting ")") Maybe Kernel test script has a Bug. An error occurred while running the kernel test script.
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 131 Reproduce Bug: find the cause An error occurred while running the kernel test script. $ cd samples/bpf $ make -j $ ./tracex7 sh: 1: Syntax error: word unexpected (expecting ")") # vim tracex7_user.c Problem caused by failure to check argument at runtime
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 132 Fix source code: resolve problem diff --git a/samples/bpf/test_override_return.sh b/samples/bpf/test_override_return.sh index e68b9ee6814b8b..35db26f736b9d9 100755 --- a/samples/bpf/test_override_return.sh +++ b/samples/bpf/test_override_return.sh @@ -1,5 +1,6 @@ #!/bin/bash +rm -r tmpmnt rm -f testfile.img dd if=/dev/zero of=testfile.img bs=1M seek=1000 count=1 DEVICE=$(losetup --show -f testfile.img) diff --git a/samples/bpf/tracex7_user.c b/samples/bpf/tracex7_user.c index fdcd6580dd736a..8be7ce18d3ba05 100644 --- a/samples/bpf/tracex7_user.c +++ b/samples/bpf/tracex7_user.c @@ -14,6 +14,11 @@ int main(int argc, char **argv) int ret = 0; FILE *f; + if (!argv[1]) { + fprintf(stderr, "ERROR: Run with the btrfs device argument!n"); + return 0; + } + snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]); $ git diff
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 133 Write a commit message After modifying the source code, create a commit with detailed message $ git commit -s
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 134 Write a commit message Having a trouble with writing commit message? Check previous commit log. $ git log -- samples/bpf/tracex7_user.c commit 2bf3e2ef425bc2a164f10b554b7db6a8b4090ef4 samples: bpf: include bpf/bpf.h instead of local libbpf.h There are two files in the tree called libbpf.h which is becoming problematic. Most samples don't actually need the local libbpf.h they simply include it to get to bpf/bpf.h. Include bpf/bpf.h directly instead. . . . commit 965de87e54b803223bff703ea6b2a76c056695ae Author: Josef Bacik <jbacik@fb.com> Date: Mon Dec 11 11:36:49 2017 -0500 samples/bpf: add a test for bpf_override_return < change file name >
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 135 Write a commit message samples: bpf: Fix tracex7 error raised on the missing argument The current behavior of 'tracex7' doesn't consist with other bpf samples tracex{1..6}. Other samples do not require any argument to run with, but tracex7 should be run with btrfs device argument. (it should be executed with test_override_return.sh) Currently, tracex7 doesn't have any description about how to run this program and raises an unexpected error. And this result might be confusing since users might not have a hunch about how to run this program. . . . In order to fix this error, this commit adds logic to report a message and exit when running this program with a missing argument. Additionally in test_override_return.sh, there is a problem with multiple directory(tmpmnt) creation. So in this commit adds a line with removing the directory with every execution. Signed-off-by: Juhee Kang <claudiajkang@gmail.com> Write commit message in detail.
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 136 Write a commit message samples: bpf: Fix tracex7 error raised on the missing argument The current behavior of 'tracex7' doesn't consist with other bpf samples tracex{1..6}. Other samples do not require any argument to run with, but tracex7 should be run with btrfs device argument. (it should be executed with test_override_return.sh) Currently, tracex7 doesn't have any description about how to run this program and raises an unexpected error. And this result might be confusing since users might not have a hunch about how to run this program. // Current behavior # ./tracex7 sh: 1: Syntax error: word unexpected (expecting ")") // Fixed behavior # ./tracex7 ERROR: Run with the btrfs device argument! In order to fix this error, this commit adds logic to report a message and exit when running this program with a missing argument. Additionally in test_override_return.sh, there is a problem with multiple directory(tmpmnt) creation. So in this commit adds a line with removing the directory with every execution. Signed-off-by: Juhee Kang <claudiajkang@gmail.com> Commit description - elaborate detail - 72 characters per line If necessary, describe how to reproduce (for detailed explanation) Commit Tag - Add Signed-off-by Tag Commit Header - less than 50 characters
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 137 Other Commit Tags 1) Signed-off-by understood the licensing policy, agree to submit commit 2) Acked-by maintainer reviewed the patch and decided to approve the patch 3) Reviewed-by Reviewer or another developer reviewed the code for the patch 4) Tested-by Reviewer or other developer tested for changes to the patch 5) Reported-by / Suggested-by Tags left to indicate who found the bug or suggested the feature 6) Fixes Tags that track bugs(commit) that this patch fixes mlxsw: spectrum: use netif_is_macsec() instead of open code === Commit Body === Signed-off-by: Juhee Kang <claudiajkang@gmail.com> Commit Tag Detail samples: bpf: Fix tracex7 error raised on the missing argument === Commit Body === Acked-by: Yonghong Song <yhs@fb.com> amt: Use BIT macros instead of open codes === Commit Body === Reviewed-by: Taehee Yoo <ap420073@gmail.com> Tested-by: Taehee Yoo <ap420073@gmail.com> net: hsr: fix hsr build error when lockdep is not enabled === Commit Body === Reported-by: Eric Dumazet <eric.dumazet@gmail.com> bpf_glue: include errno.h === Commit Body === Fixes: ac4e0913beb1 (“bpf: Export bpf syscall wrapper”)
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 138 Configure Environment: prepare to send patch send patches with git-email # apt-get install git-email $ git config --global sendemail.smtpencryption tls $ git config --global sendemail.smtpserver <mailserver> $ git config --global sendemail.smtpuser <email> $ git config --global sendemail.smtpserverport 587 $ git config --global sendemail.smtppass <password> Configure smtp account with git config ex) gmail smtp
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 139 Create patch and check format $ git format-patch -1 --subject-prefix=“PATCH, bpf-next“ total: 0 errors, 0 warnings, 0 checks, 17 lines checked 0001-*.patch has no obvious style problems and is ready for submission.
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 140 Create patch and check format $ git format-patch -1 --subject-prefix=“PATCH, bpf-next“ <Add kernel tree to mail prefix> total: 0 errors, 0 warnings, 0 checks, 17 lines checked 0001-*.patch has no obvious style problems and is ready for submission. <commit count>
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 141 Create patch and check format $ git format-patch -1 --subject-prefix=“PATCH, bpf-next“ 0001-samples-bpf-Fix-tracex7-error-raised-on-the-missing-.patch total: 0 errors, 0 warnings, 0 checks, 17 lines checked 0001-*.patch has no obvious style problems and is ready for submission. <Add kernel tree to mail prefix> <commit count>
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 142 Create patch and check format $ git format-patch -1 --subject-prefix=“PATCH, bpf-next“ 0001-samples-bpf-Fix-tracex7-error-raised-on-the-missing-.patch $ apt-get install codespell python-ply python-git $ ./scripts/checkpatch.pl --strict --codespell 0001-*.patch total: 0 errors, 0 warnings, 0 checks, 17 lines checked 0001-*.patch has no obvious style problems and is ready for submission. <created patch file here>
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 143 Create patch and check format $ git format-patch -1 --subject-prefix=“PATCH, bpf-next“ 0001-samples-bpf-Fix-tracex7-error-raised-on-the-missing-.patch $ apt-get install codespell python-ply python-git $ ./scripts/checkpatch.pl --strict --codespell 0001-*.patch total: 0 errors, 0 warnings, 0 checks, 17 lines checked 0001-*.patch has no obvious style problems and is ready for submission. < Good to go! >
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 144 Find patch mail recipients and send $ ./scripts/get_maintainer.pl –-no-multiline -–no-rolestats 0001-*.patch Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, Andrii Nakryiko <andrii@kernel.org>, netdev@vger.kernel.org, bpf@vger.kernel.org $ git send-email --to=“maintainer mail” --to=“mailing list mail” 0001-*.patch Send this email? ([y]es|[n]o|[q]uit|[a]ll): [...] Result: OK <created patch file here> Find maintainers &mailing lists
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 145 Find patch mail recipients and send $ ./scripts/get_maintainer.pl –-no-multiline -–no-rolestats 0001-*.patch Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, Andrii Nakryiko <andrii@kernel.org>, netdev@vger.kernel.org, bpf@vger.kernel.org $ git send-email --to=“maintainer mail” --to=“mailing list mail” 0001-*.patch Send this email? ([y]es|[n]o|[q]uit|[a]ll): [...] Result: OK Find maintainers &mailing lists
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 146 Find patch mail recipients and send $ ./scripts/get_maintainer.pl –-no-multiline -–no-rolestats 0001-*.patch Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, Andrii Nakryiko <andrii@kernel.org>, netdev@vger.kernel.org, bpf@vger.kernel.org $ git send-email --to=“maintainer mail” --to=“mailing list mail” 0001-*.patch Send this email? ([y]es|[n]o|[q]uit|[a]ll): Y [...] Result: OK Send mail
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 147 Make sure mail has been sent You can check the patch through Gmail
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 148 Make sure mail has been sent https://patchwork.kernel.org/project/netdevbpf/list You can check the patch through Patchwork as well (Patchwork : Discussions and development of subsystem View patches.)
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 149 Check for review From: Andrii Nakryiko <andrii.nakryiko@gmail.com> To: Juhee Kang <claudiajkang@gmail.com> Cc: Daniel Borkmann <daniel@iogearbox.net>, Alexei Starovoitov <ast@kernel.org>, Andrii Nakryiko <andrii@kernel.org>, Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org> Subject: Re: [bpf-next 1/2] samples: bpf: Fix tracex7 error raised on the missing argument On Sat, Jul 24, 2021 at 8:21 AM Juhee Kang <claudiajkang@gmail.com> wrote: [...] > diff --git a/samples/bpf/test_override_return.sh b/samples/bpf/test_override_return.sh > index e68b9ee6814b..6480b55502c7 100755 > --- a/samples/bpf/test_override_return.sh > +++ b/samples/bpf/test_override_return.sh > @@ -1,5 +1,6 @@ > #!/bin/bash > > +rm -rf tmpmnt Do we need -rf or -r would do? [...] > -- > 2.27.0
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 150 Reply to review From: Juhee Kang <claudiajkang@gmail.com> To: Andrii Nakryiko <andrii.nakryiko@gmail.com> Cc: Daniel Borkmann <daniel@iogearbox.net>, Alexei Starovoitov <ast@kernel.org>, Andrii Nakryiko <andrii@kernel.org>, Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org> Subject: Re: [bpf-next 1/2] samples: bpf: Fix tracex7 error raised on the missing argument On Tue, Jul 27, 2021 at 5:08 AM Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote: > On Sat, Jul 24, 2021 at 8:21 AM Juhee Kang <claudiajkang@gmail.com> wrote: [...] > > +rm -rf tmpmnt > Do we need -rf or -r would do? It works properly using only -r. Thanks for pointing it out! I will stick to this method. I will send the next version as soon as possible. [...] > > 2.27.0
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 151 Modify Code and create second Patch $ git format-patch -1 –v2 --subject-prefix=“PATCH, bpf-next“ v2-0001-samples-bpf-Fix-tracex7-error-raised-on-the-missing-.patch $ ./scripts/checkpatch.pl --strict --codespell v2-0001-*.patch total: 0 errors, 0 warnings, 0 checks, 17 lines checked v2-0001-*.patch has no obvious style problems and is ready for submission. < Specify version of the patch >
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 152 Find patch mail recipients and send $ ./scripts/get_maintainer.pl –-no-multiline -–no-rolestats v2-0001-*.patch Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, Andrii Nakryiko <andrii@kernel.org>, netdev@vger.kernel.org, bpf@vger.kernel.org $ git send-email --to=“maintainer mail” --to=“mailing list mail” v2-0001-*.patch Send this email? ([y]es|[n]o|[q]uit|[a]ll): Y [...] Result: OK Send mail
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 153 Patch accept From: patchwork-bot+netdevbpf <patchwork-bot+netdevbpf@kernel.org> To: Juhee Kang <claudiajkang@gmail.com> Subject: Re: [bpf-next v2 1/2] samples: bpf: Fix tracex7 error raised on the missing argument Hello: This series was applied to bpf/bpf-next.git (refs/heads/master): On Tue, 27 Jul 2021 04:10:55 +0000 you wrote: > The current behavior of 'tracex7' doesn't consist with other bpf samples > tracex{1..6}. Other samples do not require any argument to run with, but > tracex7 should be run with btrfs device argument. (it should be executed > with test_override_return.sh) > [...] Here is the summary with links: - [bpf-next,v2,1/2] samples: bpf: Fix tracex7 error raised on the missing argument https://git.kernel.org/bpf/bpf-next/c/7d07006f0592 - [bpf-next,v2,2/2] samples: bpf: Add the omitted xdp samples to .gitignore https://git.kernel.org/bpf/bpf-next/c/05e9b4f60d31 You are awesome, thank you! You can also check it through Gmail
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 154 Patch accept https://patchwork.kernel.org/project/netdevbpf/list If the patch is reflected, the state about the patch in patchwork changes to accept.
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack This was a quick guide to Linux kernel contribution 155
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 156 Need help with kernel patching? Participate in the kernel-related Contribution program
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Hope you've overcome the barriers to kernel contribution! 158
UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Q&A

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Breaking Down the Entry Barriers on Linux Kernel Networking Stack

  • 1. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Breaking Down the Entry Barriers on Linux Kernel Networking Stack Juhee Kang(claudiajkang@gmail.com)
  • 2. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 2 Speaker Juhee Kang Open-Source Part Frontier Developer Project: Linux Kernel Networking Stack, Kubernetes i18n Interest: Cloud, Network, Backend, etc... Special Lecture at Universities - Open-Source Software Development Mechanism.
  • 3. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Linux Kernel Networking Stack 1 Step by Step Kernel Contribution 3 3 INDEX Kernel Ecosystem 2
  • 4. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 4 Let’s think about it Linux Kernel Contribution?
  • 5. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 5 Linux Kernel Contribution? How do I start?
  • 6. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 6 Contribution like other open-sources? Maybe, contribute through GitHub? (like any other open source)
  • 7. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 7 Open-Source Contribution: managed with GitHub File an Issue Create a Branch Make a commit PR (Pull Request) Fetch latest remote repo (pull) merge review clone Original repository forked repository
  • 8. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 8 Is Kernel Contribution done in the same way?
  • 9. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 9 Is Kernel Contribution done in the same way? In torvalds/linux Kernel GitHub repository,
  • 10. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 10 Is Kernel Contribution done in the same way? Pull Request exists just as other open-source.
  • 11. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 11 Is Kernel Contribution done in the same way? Pull Request 존재 확인 As KernelPRBot replied,
  • 12. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 12 Is Kernel Contribution done in the same way? Linux Kernel development doesn't happen on GitHub. Read-Only mirror purpose
  • 13. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 13 Is Kernel Contribution done in the same way? detailed guide for kernel contribution
  • 14. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 14 Kernel Contribution? - Linux Kernel (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git) Instead of using GitHub, Linux kernel uses its own git service.
  • 15. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Send Patch mail review 15 Kernel Contribution process? clone Fetch latest remote repo (pull) merge Create a local branch Make a commit Make a Patch linux.git
  • 16. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Send Patch mail review 16 Kernel Contribution process? clone Fetch latest remote repo (pull) merge Create a local branch Make a commit Make a Patch linux.git
  • 17. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 17 Kernel Contribution Where to get source code? How to configure build env? What is a patch? Committing by email? Countless barriers before we even started...
  • 18. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack In this scenario, suppose we fix a bug. 18 Goal of this session $ cd samples/bpf $ make -j $ ./tracex7 sh: 1: Syntax error: word unexpected (expecting ")")
  • 19. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 19 Goal of this session Step through the Linux kernel contribution to break down contribution barriers.
  • 20. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 1 Linux Kernel Networking Stack 20
  • 21. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 21 Linux Kernel Networking Stack Packet Ethernet Frame Preamble Ethernet Frame Inter Frame Gap MAC. Destination MAC. Source Type PAYLOAD (IP/IPv6/ARP…) CRC 8 Bytes 6 Bytes 6 Bytes 2 Bytes 46-1500 Bytes 4 Bytes 12 Bytes 8 64 12
  • 22. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 22 Linux Kernel Networking Stack Packet Ethernet Frame NIC Network Hardware
  • 23. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 23 Linux Kernel Networking Stack Packet Ethernet Frame NIC Network Hardware ???
  • 24. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 24 Linux Kernel Networking Stack Packet Ethernet Frame NIC Network Hardware ??? Userspace Program Userspace Software
  • 25. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 25 Linux Kernel Networking Stack Packet Ethernet Frame NIC Network Hardware Kernel Linux Kernel Network Stack Userspace Program Userspace Software
  • 26. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 26 Linux Kernel Networking Stack Packet Receiving Packet Sending Packet Forwarding Packet Filtering Packet Mangling Packet Tunneling Routing NAT TCP HSR UDP AMT
  • 27. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 27 Basic Packet Path Packet Receiving Packet Sending Packet Forwarding Packet Filtering Packet Mangling Packet Tunneling Routing NAT TCP HSR UDP AMT
  • 28. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Basic Packet Rx/Tx Path 28
  • 29. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack ① Receiving Path ② Forwarding Path ③ Sending Path 🖥️ 🖥️ 🖥️ 29 Packet Path
  • 30. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 30 Packet Receiving Path Packet Kernel Linux Kernel Network Stack Userspace Program Userspace Software NIC Network Hardware
  • 31. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 31 Packet Receiving Path 🖥️ Host A 192.168.0.1 RX Application Transport (L4) Network (L3) Data Link (L2) NIC Driver Packet NIC Hardware Network Interface Card receives the packet
  • 32. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 32 Packet Receiving Path 🖥️ Host A 192.168.0.1 RX Application Transport (L4) Network (L3) Data Link (L2) NIC Hardware Packet NIC Driver Rx/Tx Queue From Device Driver, pops the packet from the NIC hardware Queue (RX)
  • 33. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 33 Packet Receiving Path 🖥️ Host A 192.168.0.1 RX Application Transport (L4) Network (L3) NIC Driver NIC Hardware Packet Data Link (L2) Rx/Tx Queue 📄 struct sk_buff Create a sk_buff structure with this packet.
  • 34. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 34 Packet Receiving Path 🖥️ Host A 192.168.0.1 RX Application Transport (L4) Data Link (L2) NIC Driver NIC Hardware Packet Network (L3) Rx/Tx Queue 📄 struct sk_buff IP ARP Protocol Handler ICMP Determines which protocol the packet is,
  • 35. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 35 Packet Receiving Path 🖥️ Host A 192.168.0.1 RX Application Network (L3) Data Link (L2) NIC Driver NIC Hardware Packet Transport (L4) Rx/Tx Queue 📄 struct sk_buff IP ARP UDP TCP Protocol Handler ICMP QUIC Call the appropriate handler function for the protocol
  • 36. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 36 Packet Receiving Path 🖥️ Host A 192.168.0.1 RX Transport (L4) Network (L3) Data Link (L2) NIC Driver NIC Hardware Packet Application Rx/Tx Queue 📄 struct sk_buff IP ARP UDP TCP Protocol Handler ICMP QUIC Hand over processed packet to user applications
  • 37. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 37 Linux Kernel Networking Packet Path
  • 38. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 38 Packet Receiving Path Packet Kernel Linux Kernel Network Stack Userspace Program Userspace Software NIC Network Hardware
  • 39. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 39 Packet Receiving Path After Network Interface Card receives the packet, Device Driver pops the packet from the NIC hardware Queue (RX)
  • 40. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 40 Packet Receiving Path Create a sk_buff structure with this packet
  • 41. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 41 Packet Receiving Path Determine which protocol the packet is and call the appropriate handler function for the protocol
  • 42. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 42 Packet Receiving Path Lookup the ROUTING table to identify where the packet is headed
  • 43. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 43 Packet Receiving Path Lookup the ROUTING table to identify where the packet is headed $ route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 _gateway 0.0.0.0 UG 101 0 0 eth0 192.168.0.0 0.0.0.0 255.255.255.0 U 101 0 0 eth0 192.168.0.1 192.168.0.2 255.255.255.255 UGH 0 0 0 veth21 192.168.0.4 192.168.0.3 255.255.255.255 UGH 0 0 0 veth23 _gateway 0.0.0.0 255.255.255.255 UH 101 0 0 eth0
  • 44. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 44 Packet Receiving Path Preprocess the packet before calling L4 function
  • 45. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 45 Packet Receiving Path Hand over processed packet to upper layer
  • 46. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 46 Packet Receiving Path
  • 47. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Packet Kernel Linux Kernel Network Stack Packet NIC Network Hardware 47 Packet Forwarding Path NIC Network Hardware
  • 48. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 48 Packet Forwarding Path Lookup the ROUTING table to identify where the packet is headed
  • 49. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 49 Packet Forwarding Path Lookup the ROUTING table to identify where the packet is headed $ route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 _gateway 0.0.0.0 UG 101 0 0 eth0 192.168.0.0 0.0.0.0 255.255.255.0 U 101 0 0 eth0 192.168.0.1 192.168.0.2 255.255.255.255 UGH 0 0 0 veth21 192.168.0.4 192.168.0.3 255.255.255.255 UGH 0 0 0 veth23 _gateway 0.0.0.0 255.255.255.255 UH 101 0 0 eth0
  • 50. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 50 Packet Forwarding Path If forwarding is required, send to corresponding interface
  • 51. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 51 Packet Forwarding Path Determine the MAC address of the destination to send
  • 52. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 52 Packet Forwarding Path Send the packet to device driver function
  • 53. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 53 Packet Forwarding Path Transmit packet through the network interface
  • 54. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 54 Packet Forwarding Path
  • 55. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Userspace Program Userspace Software Kernel Linux Kernel Network Stack Packet 📦 NIC Network Hardware 55 Packet Sending Path
  • 56. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 56 Packet Sending Path Packet handed over from upper layer
  • 57. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 57 Packet Sending Path Check the ROUTING table to see which interface to send packet
  • 58. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 58 Packet Sending Path Preprocess the packet for the transmission (ex. fragmentation)
  • 59. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 59 Packet Sending Path Determine the MAC address of the destination to send
  • 60. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 60 Packet Sending Path Send the packet to device driver function
  • 61. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 61 Packet Sending Path Transmit packet through the network interface
  • 62. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack DEVICE DRIVER UPPER LAYER Ingress PROTO HANDLER ROUTING FORWARDING OUTPUT INPUT NEIGH ROUTING Egress L4~ L3 L2 62 Packet Sending Path
  • 63. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack ① Receiving Path ② Forwarding Path ③ Sending Path 🖥️ 🖥️ 🖥️ 63 Packet Path
  • 64. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 64 Linux Kernel Networking Stack Packet Receiving Packet Sending Packet Forwarding Packet Filtering Packet Mangling Packet Tunneling Routing NAT TCP HSR UDP AMT
  • 65. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 65 Packet Processing Packet Receiving Packet Sending Packet Forwarding Packet Filtering Packet Mangling Packet Tunneling Routing NAT TCP HSR UDP AMT
  • 66. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 66 Network Protocol Packet Receiving Packet Sending Packet Forwarding Packet Filtering Packet Mangling Packet Tunneling Routing NAT TCP HSR UDP AMT
  • 67. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 2 Kernel Ecosystem 67
  • 68. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 68 Linux Kernel The core of the Linux Operating System Interface that connects computer hardware to processes Linux Kernel mascot Tux
  • 69. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 69 Linux Kernel Development The largest open-source project involving developers worldwide https://www.semanticscholar.org/paper/Perpetual-development%3A-A-model-of-the-Linux-kernel- Feitelson/eb7cf446e983e98c1400c8181949f038caf0c8a8/figure/1 Development is done in units called Patch
  • 70. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack v5.15 v5.16 v5.16-rc1 v5.16-rc2 … v5.16-rc7 Stable (v5.15) LTS Release new kernel released in every 10-11 weeks (2 months), stable kernel released once a week Kernel Release 70 Stable (v5.16) LTS Release Mainline Kernel Release Candidate (RC) Stable Long-term
  • 71. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack v5.15 v5.16 Kernel Release - 1. Mainline Kernel 71 - released every 9 to 10 weeks - New features introduced, major bug fix patches Mainline Kernel
  • 72. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack - Switch to stable mode after mainline kernel release - Bug fixes & mainline kernel backporting Stable (v5.15) Kernel Release - 2. Stable 72 Stable (v5.16) Stable v5.15 v5.16
  • 73. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack LTS Release Kernel Release - 3. LTS Release 73 LTS Release v5.15 v5.16 - provides a critical bug fix among the stable release versions LTS Release
  • 74. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack v5.15 v5.16 v5.16-rc1 v5.16-rc2 … v5.16-rc7 Kernel Release - 4. Release Candidate (RC) 74 Release Candidate (RC) Commit - "pre-release" of Mainline kernel - For testing new features - This release must be compiled from source - Usually, released up to rc7
  • 75. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 75 Linux Kernel Release Cycle v5.15 v5.16 5.15 mainline kernel version release
  • 76. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 76 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) 5.15 mainline kernel version release 5.15 Stable release
  • 77. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 77 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release 5.15 mainline kernel version release 5.15 Stable release 5.15 LTS release
  • 78. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 78 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release 5.15 mainline kernel version release 5.15 Stable release 5.15 LTS release
  • 79. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 79 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release v5.16-rc1 5.15 mainline kernel version release v5.16-rc1 5.15 Stable release 5.15 LTS release
  • 80. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 80 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release v5.16-rc1 5.15 mainline kernel version release v5.16-rc1 v5.16-rc2 v5.16-rc2 5.15 Stable release 5.15 LTS release
  • 81. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 81 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release v5.16-rc1 5.15 mainline kernel version release v5.16-rc1 v5.16-rc2 … v5.16-rc2 . . . 5.15 Stable release 5.15 LTS release
  • 82. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 82 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release v5.16-rc1 5.15 mainline kernel version release v5.16-rc1 v5.16-rc2 … v5.16-rc2 . . . 5.15 Stable release 5.15 LTS release v5.16-rc6
  • 83. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 83 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release v5.16-rc1 5.15 mainline kernel version release v5.16-rc1 v5.16-rc2 … v5.16-rc7 v5.16-rc2 . . . v5.16-rc7 5.15 Stable release 5.15 LTS release v5.16-rc6
  • 84. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 84 Linux Kernel Release Cycle http://vger.kernel.org/~davem/net-next.html
  • 85. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Merge window 85 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release v5.16-rc1 5.15 mainline kernel version release v5.16-rc1 v5.16-rc2 … v5.16-rc7 v5.16-rc2 . . . v5.16-rc7 Merge window 5.15 Stable release 5.15 LTS release v5.16-rc6
  • 86. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Merge window 86 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release v5.16-rc1 5.15 mainline kernel version release v5.16-rc1 v5.16-rc2 … v5.16-rc7 v5.16-rc2 . . . v5.16-rc7 Merge window v5.16-rc6 * Merge window (2 weeks) - Linux Torvalds receives a pull of code from the maintainer of subsystem and adds it together - New version of the kernel is released after merge window - After period ends, the kernel is developed every two weeks. Naming convention: <mainline kernel version name>-rc-<rc version name>
  • 87. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Merge window 87 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release v5.16-rc1 5.15 mainline kernel version release v5.16-rc1 v5.16-rc2 … v5.16-rc7 v5.16-rc2 . . . v5.16-rc7 Merge window 5.16 mainline kernel version release 5.15 Stable release 5.15 LTS release v5.16-rc6
  • 88. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 88 Linux Kernel Release Cycle http://vger.kernel.org/~davem/net-next.html
  • 89. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Merge window 89 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release v5.16-rc1 5.15 mainline kernel version release v5.16-rc1 v5.16-rc2 … v5.16-rc7 v5.16-rc2 . . . v5.16-rc7 Merge window 5.16 mainline kernel version release Stable (v5.16) 5.15 Stable release 5.15 LTS release 5.16 Stable release v5.16-rc6
  • 90. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Merge window 90 Linux Kernel Release Cycle v5.15 v5.16 Stable (v5.15) LTS Release v5.16-rc1 5.15 mainline kernel version release v5.16-rc1 v5.16-rc2 … v5.16-rc7 v5.16-rc2 . . . v5.16-rc7 Merge window 5.16 mainline kernel version release Stable (v5.16) LTS Release 5.15 Stable release 5.15 LTS release 5.16 Stable release 5.16 LTS release v5.16-rc6
  • 91. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 91 Linux Kernel Subsystem Inside the kernel there are numerous subsystems, http://www.MakeLinux.net/kernel/diagram 5.16 mainline kernel version release
  • 92. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 92 Linux Kernel Subsystem Inside the kernel there are numerous subsystems, Features developed by each subsystem are combined to be released as the mainline kernel http://www.MakeLinux.net/kernel/diagram 5.16 mainline kernel version release
  • 93. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 93 Linux Kernel Subsystem Subsystems are developed in each directory of the source code. http://www.MakeLinux.net/kernel/diagram linux $ tree -d -L 1 . ├── arch ├── block ├── certs ├── crypto ├── Documentation ├── drivers ├── fs ├── include ├── init ├── ipc ├── kernel ├── lib ├── LICENSES ├── mm ├── net ├── samples ├── scripts ├── security ├── sound ├── tools ├── usr └── virt
  • 94. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 94 Linux Kernel Subsystem Network subsystem are developed in net directory of the source code. http://www.MakeLinux.net/kernel/diagram linux $ tree -d -L 1 . ├── arch ├── block => block device subsystem ├── certs ├── crypto ├── Documentation ├── drivers => driver subsystem ├── fs => file system subsystem ├── include ├── init ├── ipc => IPC subsystem ├── kernel ├── lib ├── LICENSES ├── mm => memory management subsystem ├── net => network subsystem ├── samples ├── scripts ├── security ├── sound ├── tools ├── usr └── virt
  • 95. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 95 Kernel Tree https://git.kernel.org/ kernel code is managed by several major subsystem git repositories, which is called the Kernel Tree
  • 96. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 96 Kernel Tree Mainline Kernel tree - Managed by Linus Torvalds - Mainline kernel tree & RC release source code * https://www.devcurmudgeon.com/images/mainline-lts-ltsi-genivi-20131025.pdf#page=18
  • 97. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 97 Kernel Tree Mainline Kernel tree - Managed by Linus Torvalds - Mainline kernel tree & RC release source code Stable Kernel tree - Managed by Greg Kroah-Hartman - stable release branches source code * https://www.devcurmudgeon.com/images/mainline-lts-ltsi-genivi-20131025.pdf#page=18
  • 98. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 98 Kernel Tree * https://www.devcurmudgeon.com/images/mainline-lts-ltsi-genivi-20131025.pdf#page=18 Mainline Kernel tree - Managed by Linus Torvalds - Mainline kernel tree & RC release source code Stable Kernel tree - Managed by Greg Kroah-Hartman - stable release branches source code linux-next tree - Managed by Stephen Rothwell - Subsystem changes are periodically reflected - Integrated testing of the code is conducted - After testing, pull request is performed with mainline kernel tree
  • 99. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 99 Linux Kernel Tree Hierarchy Developer Developer net-next Developer Developer driver-core Developer Developer cgroup linux Major subsystems have independent tree
  • 100. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 100 Linux Kernel Tree Hierarchy Developer Developer Maintainer Developer Developer Maintainer Developer Developer Maintainer Torvalds Each subsystem tree is managed by "Maintainer" netdev/net-next.git torvalds/linux.git gregkh/driver-core.git tj/cgroup.git
  • 101. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 101 Linux Kernel Tree Hierarchy These maintainers manage the tree for each subsystem, and there are two trees in each subsystem Developer Developer Maintainer Torvalds netdev/net-next.git Mainline Kernel Tree Developer Developer Maintainer Greg netdev/net.git Stable Kernel Tree Networking Subsystem
  • 102. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 102 Networking Subsystem Tree Developer Developer Maintainer Developer Developer Maintainer Developer Developer Maintainer Greg netdev/net.git git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git stable/linux.git netdev/net.git : netdev Stable Tree Allow only release version of bug fix patch
  • 103. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 103 Networking Subsystem Tree Developer Developer Maintainer Developer Developer Maintainer Developer Developer Maintainer Torvalds netdev/net-next.git torvalds/linux.git git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git netdev/net-next.git : netdev Mainline Tree Feature Enhancement, Bug-Fix tree
  • 104. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 104 Subsystem Tree $ cat MAINTAINERS | grep -A 30 'NETWORKING [GENERAL]' NETWORKING [GENERAL] M: "David S. Miller" <davem@davemloft.net> M: Eric Dumazet <edumazet@google.com> M: Jakub Kicinski <kuba@kernel.org> M: Paolo Abeni <pabeni@redhat.com> L: netdev@vger.kernel.org S: Maintained Q: https://patchwork.kernel.org/project/netdevbpf/list/ B: mailto:netdev@vger.kernel.org T: git git://git.kernel.org/.../netdev/net.git T: git git://git.kernel.org/.../netdev/net-next.git F: Documentation/networking/ F: Documentation/process/maintainer-netdev.rst F: include/linux/in.h F: include/linux/net.h F: include/linux/netdevice.h F: include/net/ F: include/uapi/linux/in.h F: include/uapi/linux/net.h F: include/uapi/linux/net_namespace.h F: include/uapi/linux/netdevice.h F: lib/net_utils.c F: lib/random32.c F: net/ F: tools/testing/selftests/net/ Developer Developer Maintainer Developer Developer Maintainer Developer Developer Maintainer Torvalds netdev/net.git
  • 105. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 105 Mailing List Each subsystem has a mailing list, where contributors submit and discuss patches. $ cat MAINTAINERS | grep -A 30 'NETWORKING [GENERAL]' NETWORKING [GENERAL] M: "David S. Miller" <davem@davemloft.net> M: Eric Dumazet <edumazet@google.com> M: Jakub Kicinski <kuba@kernel.org> M: Paolo Abeni <pabeni@redhat.com> L: netdev@vger.kernel.org S: Maintained http://vger.kernel.org/vger-lists.html
  • 106. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 106 Patch Contributing units in the kernel
  • 107. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 107 Patch From 0199215216978b612d4e8be11e878b87bc643033 Mon Sep 17 00:00:00 2001 From: Juhee Kang <claudiajkang@gmail.com> Date: Sun, 10 Oct 2021 13:03:29 +0900 Subject: [PATCH, net-next] mlxsw: spectrum: use netif_is_macsec() instead of open code Open code which is dev->priv_flags & IFF_MACSEC has already defined as netif_is_macsec(). So use netif_is_macsec() instead of open code. This patch doesn't change logic. Signed-off-by: Juhee Kang <claudiajkang@gmail.com> --- include/linux/netdevice.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 15f4a658e436..0723c1314ea2 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -5237,7 +5237,7 @@ static inline void netif_keep_dst(struct net_device *dev) static inline bool netif_reduces_vlan_mtu(struct net_device *dev) { /* TODO: reserve and use an additional IFF bit, if we get more users */ - return dev->priv_flags & IFF_MACSEC; + return netif_is_macsec(dev); } extern struct pernet_operations __net_initdata loopback_net_ops; -- 2.34.1 $ git format-patch -1 --subject-prefix="PATCH, net-next" Contributing units in the kernel Developers make a patch of development
  • 108. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Contributing units in the kernel Developers make a patch of development and submit it to the mailing list by email 108 Patch $ git format-patch -1 --subject-prefix="PATCH, net-next" $ git send-patch --cc “Network Maintainer <example@email.com>“ --to “Network Mailing List <list@email.com>” *.patch
  • 109. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 109 Kernel Development Process Developer L: netdev patch 📧 📜 [PATCH net-next] mlxsw: spectrum: use netif_is_macsec() instead of open code Open code which is dev->priv_flags & IFF_MACSEC has already defined as netif_is_macsec(). So use netif_is_macsec() instead of open code. This patch doesn't change logic. Signed-off-by: Juhee Kang <claudiajkang@gmail.com> Contributor create patches $ git format-patch -1 --subject-prefix="PATCH, net-next"
  • 110. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 110 Kernel Development Process Developer L: netdev 📧 📜 [PATCH net-next] mlxsw: spectrum: use netif_is_macsec() instead of open code Open code which is dev->priv_flags & IFF_MACSEC has already defined as netif_is_macsec(). So use netif_is_macsec() instead of open code. This patch doesn't change logic. Signed-off-by: Juhee Kang <claudiajkang@gmail.com> Contributor sends patches to the mailing list. $ git send-patch --cc “Network Maintainer <example@email.com>“ --to “Network Mailing List <list@email.com>” *.patch
  • 111. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 111 Kernel Development Process Developer L: netdev patch 📧 📜 From mailing list, review and discussion is conducted. [PATCH net-next] mlxsw: spectrum: use netif_is_macsec() instead of open code Open code which is dev->priv_flags & IFF_MACSEC has already defined as netif_is_macsec(). So use netif_is_macsec() instead of open code. This patch doesn't change logic. Signed-off-by: Juhee Kang <claudiajkang@gmail.com>
  • 112. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 112 Kernel Development Process Developer L: netdev patch 📧 📜 Once the patch has been accepted, an email will be sent informing that it was reflected in the subsystem [PATCH net-next] mlxsw: spectrum: use netif_is_macsec() instead of open code Open code which is dev->priv_flags & IFF_MACSEC has already defined as netif_is_macsec(). So use netif_is_macsec() instead of open code. This patch doesn't change logic. Signed-off-by: Juhee Kang <claudiajkang@gmail.com> Maintainer 📧 Re: [PATCH net-next] mlxsw: spectrum: use netif_is_macsec() instead of open ode Hello: This series was applied to netdev/net-next.git (master) by David S. Miller <davem@davemloft.net>:
  • 113. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 113 Kernel Development Process Developer Maintainer Torvalds netdev/net-next.git Patch is reflected in net-next git tree 📧 📜
  • 114. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 114 Kernel Development Process Developer Developer Maintainer Torvalds netdev/net-next.git 📧 📜 📜 📜 Maintainer will Send Pull Request to Parent Tree torvalds/linux.git
  • 115. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 115 Kernel Development Process Developer Developer Maintainer Developer Developer Maintainer Developer Developer Maintainer Torvalds netdev/net-next.git Pull Requests are sent from various subsystems to the parent tree 📧 📜 📜 📜 📧 📜 📜 📜 gregkh/driver-core.git tj/cgroup.git torvalds/linux.git
  • 116. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 116 Kernel Development Process Developer Developer Maintainer Developer Developer Maintainer Developer Developer Maintainer Torvalds netdev/net-next.git Code combined to release as new version of kernel 📧 📜 📜 📜 📧 📜 📜 📜 gregkh/driver-core.git tj/cgroup.git torvalds/linux.git Mainline Kernel Release Candidate (RC)
  • 117. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack ① Documentation ② Bug-Fix ③ Feature Enhancement ④ etc.. 117 Linux Kernel Contribution
  • 118. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 118 1. Documentation Improve the documentation - add undocumented or elaborate details
  • 119. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 119 2. Bug Fix Fixing Bugs - fix code to work as expected
  • 120. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Adding a new feature - for improved usability 120 3. Feature Enhancement
  • 121. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Enhance feature - performance improvement 121 3. Feature Enhancement
  • 122. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Now let's do Contributions to Linux Kernel 122
  • 123. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 3 Step by Step Kernel Contribution 123
  • 124. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack In this scenario, suppose we fix a bug. 124 Kernel Patch in Action
  • 125. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 125 Discover a Bug An error occurred while running the kernel test script. $ cd samples/bpf $ make -j $ ./tracex7 sh: 1: Syntax error: word unexpected (expecting ")")
  • 126. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 126 Configure Environment: kernel development Fedora Debian OpenSUSE Ubuntu Prepare Linux in VM
  • 127. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 127 Configure Environment: kernel development # apt-get install build-essential vim git cscope libncurses-dev libssl-dev bison flex bison # systemctl enable serial-getty@ttyS0.service # systemctl start serial-getty@ttyS0.service # systemctl daemon-reload # vim /etc/default/grub # update-grub2 Install development packages on Linux VM
  • 128. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 128 Configure Environment: kernel development Configure Linux for a debugging # apt-get install build-essential vim git cscope libncurses-dev libssl-dev bison flex bison # systemctl enable serial-getty@ttyS0.service # systemctl start serial-getty@ttyS0.service # systemctl daemon-reload # vim /etc/default/grub # update-grub2
  • 129. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 129 Configure Environment: get kernel source $ git clone https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git $ cd net-next $ git checkout -f main
  • 130. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 130 Reproduce Bug: find the cause $ cd samples/bpf $ make -j $ ./tracex7 sh: 1: Syntax error: word unexpected (expecting ")") Maybe Kernel test script has a Bug. An error occurred while running the kernel test script.
  • 131. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 131 Reproduce Bug: find the cause An error occurred while running the kernel test script. $ cd samples/bpf $ make -j $ ./tracex7 sh: 1: Syntax error: word unexpected (expecting ")") # vim tracex7_user.c Problem caused by failure to check argument at runtime
  • 132. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 132 Fix source code: resolve problem diff --git a/samples/bpf/test_override_return.sh b/samples/bpf/test_override_return.sh index e68b9ee6814b8b..35db26f736b9d9 100755 --- a/samples/bpf/test_override_return.sh +++ b/samples/bpf/test_override_return.sh @@ -1,5 +1,6 @@ #!/bin/bash +rm -r tmpmnt rm -f testfile.img dd if=/dev/zero of=testfile.img bs=1M seek=1000 count=1 DEVICE=$(losetup --show -f testfile.img) diff --git a/samples/bpf/tracex7_user.c b/samples/bpf/tracex7_user.c index fdcd6580dd736a..8be7ce18d3ba05 100644 --- a/samples/bpf/tracex7_user.c +++ b/samples/bpf/tracex7_user.c @@ -14,6 +14,11 @@ int main(int argc, char **argv) int ret = 0; FILE *f; + if (!argv[1]) { + fprintf(stderr, "ERROR: Run with the btrfs device argument!n"); + return 0; + } + snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]); $ git diff
  • 133. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 133 Write a commit message After modifying the source code, create a commit with detailed message $ git commit -s
  • 134. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 134 Write a commit message Having a trouble with writing commit message? Check previous commit log. $ git log -- samples/bpf/tracex7_user.c commit 2bf3e2ef425bc2a164f10b554b7db6a8b4090ef4 samples: bpf: include bpf/bpf.h instead of local libbpf.h There are two files in the tree called libbpf.h which is becoming problematic. Most samples don't actually need the local libbpf.h they simply include it to get to bpf/bpf.h. Include bpf/bpf.h directly instead. . . . commit 965de87e54b803223bff703ea6b2a76c056695ae Author: Josef Bacik <jbacik@fb.com> Date: Mon Dec 11 11:36:49 2017 -0500 samples/bpf: add a test for bpf_override_return < change file name >
  • 135. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 135 Write a commit message samples: bpf: Fix tracex7 error raised on the missing argument The current behavior of 'tracex7' doesn't consist with other bpf samples tracex{1..6}. Other samples do not require any argument to run with, but tracex7 should be run with btrfs device argument. (it should be executed with test_override_return.sh) Currently, tracex7 doesn't have any description about how to run this program and raises an unexpected error. And this result might be confusing since users might not have a hunch about how to run this program. . . . In order to fix this error, this commit adds logic to report a message and exit when running this program with a missing argument. Additionally in test_override_return.sh, there is a problem with multiple directory(tmpmnt) creation. So in this commit adds a line with removing the directory with every execution. Signed-off-by: Juhee Kang <claudiajkang@gmail.com> Write commit message in detail.
  • 136. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 136 Write a commit message samples: bpf: Fix tracex7 error raised on the missing argument The current behavior of 'tracex7' doesn't consist with other bpf samples tracex{1..6}. Other samples do not require any argument to run with, but tracex7 should be run with btrfs device argument. (it should be executed with test_override_return.sh) Currently, tracex7 doesn't have any description about how to run this program and raises an unexpected error. And this result might be confusing since users might not have a hunch about how to run this program. // Current behavior # ./tracex7 sh: 1: Syntax error: word unexpected (expecting ")") // Fixed behavior # ./tracex7 ERROR: Run with the btrfs device argument! In order to fix this error, this commit adds logic to report a message and exit when running this program with a missing argument. Additionally in test_override_return.sh, there is a problem with multiple directory(tmpmnt) creation. So in this commit adds a line with removing the directory with every execution. Signed-off-by: Juhee Kang <claudiajkang@gmail.com> Commit description - elaborate detail - 72 characters per line If necessary, describe how to reproduce (for detailed explanation) Commit Tag - Add Signed-off-by Tag Commit Header - less than 50 characters
  • 137. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 137 Other Commit Tags 1) Signed-off-by understood the licensing policy, agree to submit commit 2) Acked-by maintainer reviewed the patch and decided to approve the patch 3) Reviewed-by Reviewer or another developer reviewed the code for the patch 4) Tested-by Reviewer or other developer tested for changes to the patch 5) Reported-by / Suggested-by Tags left to indicate who found the bug or suggested the feature 6) Fixes Tags that track bugs(commit) that this patch fixes mlxsw: spectrum: use netif_is_macsec() instead of open code === Commit Body === Signed-off-by: Juhee Kang <claudiajkang@gmail.com> Commit Tag Detail samples: bpf: Fix tracex7 error raised on the missing argument === Commit Body === Acked-by: Yonghong Song <yhs@fb.com> amt: Use BIT macros instead of open codes === Commit Body === Reviewed-by: Taehee Yoo <ap420073@gmail.com> Tested-by: Taehee Yoo <ap420073@gmail.com> net: hsr: fix hsr build error when lockdep is not enabled === Commit Body === Reported-by: Eric Dumazet <eric.dumazet@gmail.com> bpf_glue: include errno.h === Commit Body === Fixes: ac4e0913beb1 (“bpf: Export bpf syscall wrapper”)
  • 138. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 138 Configure Environment: prepare to send patch send patches with git-email # apt-get install git-email $ git config --global sendemail.smtpencryption tls $ git config --global sendemail.smtpserver <mailserver> $ git config --global sendemail.smtpuser <email> $ git config --global sendemail.smtpserverport 587 $ git config --global sendemail.smtppass <password> Configure smtp account with git config ex) gmail smtp
  • 139. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 139 Create patch and check format $ git format-patch -1 --subject-prefix=“PATCH, bpf-next“ total: 0 errors, 0 warnings, 0 checks, 17 lines checked 0001-*.patch has no obvious style problems and is ready for submission.
  • 140. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 140 Create patch and check format $ git format-patch -1 --subject-prefix=“PATCH, bpf-next“ <Add kernel tree to mail prefix> total: 0 errors, 0 warnings, 0 checks, 17 lines checked 0001-*.patch has no obvious style problems and is ready for submission. <commit count>
  • 141. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 141 Create patch and check format $ git format-patch -1 --subject-prefix=“PATCH, bpf-next“ 0001-samples-bpf-Fix-tracex7-error-raised-on-the-missing-.patch total: 0 errors, 0 warnings, 0 checks, 17 lines checked 0001-*.patch has no obvious style problems and is ready for submission. <Add kernel tree to mail prefix> <commit count>
  • 142. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 142 Create patch and check format $ git format-patch -1 --subject-prefix=“PATCH, bpf-next“ 0001-samples-bpf-Fix-tracex7-error-raised-on-the-missing-.patch $ apt-get install codespell python-ply python-git $ ./scripts/checkpatch.pl --strict --codespell 0001-*.patch total: 0 errors, 0 warnings, 0 checks, 17 lines checked 0001-*.patch has no obvious style problems and is ready for submission. <created patch file here>
  • 143. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 143 Create patch and check format $ git format-patch -1 --subject-prefix=“PATCH, bpf-next“ 0001-samples-bpf-Fix-tracex7-error-raised-on-the-missing-.patch $ apt-get install codespell python-ply python-git $ ./scripts/checkpatch.pl --strict --codespell 0001-*.patch total: 0 errors, 0 warnings, 0 checks, 17 lines checked 0001-*.patch has no obvious style problems and is ready for submission. < Good to go! >
  • 144. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 144 Find patch mail recipients and send $ ./scripts/get_maintainer.pl –-no-multiline -–no-rolestats 0001-*.patch Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, Andrii Nakryiko <andrii@kernel.org>, netdev@vger.kernel.org, bpf@vger.kernel.org $ git send-email --to=“maintainer mail” --to=“mailing list mail” 0001-*.patch Send this email? ([y]es|[n]o|[q]uit|[a]ll): [...] Result: OK <created patch file here> Find maintainers &mailing lists
  • 145. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 145 Find patch mail recipients and send $ ./scripts/get_maintainer.pl –-no-multiline -–no-rolestats 0001-*.patch Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, Andrii Nakryiko <andrii@kernel.org>, netdev@vger.kernel.org, bpf@vger.kernel.org $ git send-email --to=“maintainer mail” --to=“mailing list mail” 0001-*.patch Send this email? ([y]es|[n]o|[q]uit|[a]ll): [...] Result: OK Find maintainers &mailing lists
  • 146. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 146 Find patch mail recipients and send $ ./scripts/get_maintainer.pl –-no-multiline -–no-rolestats 0001-*.patch Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, Andrii Nakryiko <andrii@kernel.org>, netdev@vger.kernel.org, bpf@vger.kernel.org $ git send-email --to=“maintainer mail” --to=“mailing list mail” 0001-*.patch Send this email? ([y]es|[n]o|[q]uit|[a]ll): Y [...] Result: OK Send mail
  • 147. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 147 Make sure mail has been sent You can check the patch through Gmail
  • 148. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 148 Make sure mail has been sent https://patchwork.kernel.org/project/netdevbpf/list You can check the patch through Patchwork as well (Patchwork : Discussions and development of subsystem View patches.)
  • 149. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 149 Check for review From: Andrii Nakryiko <andrii.nakryiko@gmail.com> To: Juhee Kang <claudiajkang@gmail.com> Cc: Daniel Borkmann <daniel@iogearbox.net>, Alexei Starovoitov <ast@kernel.org>, Andrii Nakryiko <andrii@kernel.org>, Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org> Subject: Re: [bpf-next 1/2] samples: bpf: Fix tracex7 error raised on the missing argument On Sat, Jul 24, 2021 at 8:21 AM Juhee Kang <claudiajkang@gmail.com> wrote: [...] > diff --git a/samples/bpf/test_override_return.sh b/samples/bpf/test_override_return.sh > index e68b9ee6814b..6480b55502c7 100755 > --- a/samples/bpf/test_override_return.sh > +++ b/samples/bpf/test_override_return.sh > @@ -1,5 +1,6 @@ > #!/bin/bash > > +rm -rf tmpmnt Do we need -rf or -r would do? [...] > -- > 2.27.0
  • 150. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 150 Reply to review From: Juhee Kang <claudiajkang@gmail.com> To: Andrii Nakryiko <andrii.nakryiko@gmail.com> Cc: Daniel Borkmann <daniel@iogearbox.net>, Alexei Starovoitov <ast@kernel.org>, Andrii Nakryiko <andrii@kernel.org>, Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org> Subject: Re: [bpf-next 1/2] samples: bpf: Fix tracex7 error raised on the missing argument On Tue, Jul 27, 2021 at 5:08 AM Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote: > On Sat, Jul 24, 2021 at 8:21 AM Juhee Kang <claudiajkang@gmail.com> wrote: [...] > > +rm -rf tmpmnt > Do we need -rf or -r would do? It works properly using only -r. Thanks for pointing it out! I will stick to this method. I will send the next version as soon as possible. [...] > > 2.27.0
  • 151. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 151 Modify Code and create second Patch $ git format-patch -1 –v2 --subject-prefix=“PATCH, bpf-next“ v2-0001-samples-bpf-Fix-tracex7-error-raised-on-the-missing-.patch $ ./scripts/checkpatch.pl --strict --codespell v2-0001-*.patch total: 0 errors, 0 warnings, 0 checks, 17 lines checked v2-0001-*.patch has no obvious style problems and is ready for submission. < Specify version of the patch >
  • 152. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 152 Find patch mail recipients and send $ ./scripts/get_maintainer.pl –-no-multiline -–no-rolestats v2-0001-*.patch Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, Andrii Nakryiko <andrii@kernel.org>, netdev@vger.kernel.org, bpf@vger.kernel.org $ git send-email --to=“maintainer mail” --to=“mailing list mail” v2-0001-*.patch Send this email? ([y]es|[n]o|[q]uit|[a]ll): Y [...] Result: OK Send mail
  • 153. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 153 Patch accept From: patchwork-bot+netdevbpf <patchwork-bot+netdevbpf@kernel.org> To: Juhee Kang <claudiajkang@gmail.com> Subject: Re: [bpf-next v2 1/2] samples: bpf: Fix tracex7 error raised on the missing argument Hello: This series was applied to bpf/bpf-next.git (refs/heads/master): On Tue, 27 Jul 2021 04:10:55 +0000 you wrote: > The current behavior of 'tracex7' doesn't consist with other bpf samples > tracex{1..6}. Other samples do not require any argument to run with, but > tracex7 should be run with btrfs device argument. (it should be executed > with test_override_return.sh) > [...] Here is the summary with links: - [bpf-next,v2,1/2] samples: bpf: Fix tracex7 error raised on the missing argument https://git.kernel.org/bpf/bpf-next/c/7d07006f0592 - [bpf-next,v2,2/2] samples: bpf: Add the omitted xdp samples to .gitignore https://git.kernel.org/bpf/bpf-next/c/05e9b4f60d31 You are awesome, thank you! You can also check it through Gmail
  • 154. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 154 Patch accept https://patchwork.kernel.org/project/netdevbpf/list If the patch is reflected, the state about the patch in patchwork changes to accept.
  • 155. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack This was a quick guide to Linux kernel contribution 155
  • 156. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack 156 Need help with kernel patching? Participate in the kernel-related Contribution program
  • 157. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Hope you've overcome the barriers to kernel contribution! 158
  • 158. UbuCon Asia 2022 | Breaking Down the Entry Barriers on Linux Kernel Networking Stack Q&A