Book Image

Linux Kernel Programming Part 2 - Char Device Drivers and Kernel Synchronization

By : Kaiwan N. Billimoria
Book Image

Linux Kernel Programming Part 2 - Char Device Drivers and Kernel Synchronization

By: Kaiwan N. Billimoria

Overview of this book

Linux Kernel Programming Part 2 - Char Device Drivers and Kernel Synchronization is an ideal companion guide to the Linux Kernel Programming book. This book provides a comprehensive introduction for those new to Linux device driver development and will have you up and running with writing misc class character device driver code (on the 5.4 LTS Linux kernel) in next to no time. You'll begin by learning how to write a simple and complete misc class character driver before interfacing your driver with user-mode processes via procfs, sysfs, debugfs, netlink sockets, and ioctl. You'll then find out how to work with hardware I/O memory. The book covers working with hardware interrupts in depth and helps you understand interrupt request (IRQ) allocation, threaded IRQ handlers, tasklets, and softirqs. You'll also explore the practical usage of useful kernel mechanisms, setting up delays, timers, kernel threads, and workqueues. Finally, you'll discover how to deal with the complexity of kernel synchronization with locking technologies (mutexes, spinlocks, and atomic/refcount operators), including more advanced topics such as cache effects, a primer on lock-free techniques, deadlock avoidance (with lockdep), and kernel lock debugging techniques. By the end of this Linux kernel book, you'll have learned the fundamentals of writing Linux character device driver code for real-world projects and products.
Table of Contents (11 chapters)
1
Section 1: Character Device Driver Basics
3
User-Kernel Communication Pathways
5
Handling Hardware Interrupts
6
Working with Kernel Timers, Threads, and Workqueues
7
Section 2: Delving Deeper

Measuring interrupts with [e]BPF

In the companion guide Linux Kernel Programming - Chapter 1, Kernel Workspace Setup, in the Modern tracing and performance analysis with [e]BPF section, we pointed out how the modern approach to tracing, performance measurement, and analysis on (recent 4.x) Linux is [e]BPF, the enhanced Berkeley Packet Filter (just called BPF as well). Among the plethora of tools it stocks (https://github.com/iovisor/bcc#tools), two suit our immediate purpose of tracing, measuring, and analyzing interrupts (both hardirqs and softirqs). (The tools are named toolname-bpfcc on Ubuntu, where toolname is the name of the tool in question, such as hardirqs-bpfcc and softirqs-bpfcc). These tools dynamically trace interrupts (at the time of writing, they're not based on kernel tracepoints yet). You will require root access to run these [e]BPF tools.

Important: You can install the BCC tools for your regular host...