beb1ff1595
After forking, Each file descriptor in the child refers to the same open file description as the parent. So when calling open() before fork(), the child can access the device file without checking by exclusive access in device_open(). It may cause race conditions in device_ioctl(). Because of that, it is unnecessary to check the multiple access in device_open(). It just needs check in device_ioctl(), since read(), write(), seek() system call are atomic [1][2]. Related discussion: - https://github.com/sysprog21/lkmpg/issues/148 [1] https://lore.kernel.org/lkml/53022DB1.4070805@gmail.com/ [2] https://www.kernel.org/doc/html/latest/filesystems/files.html Close #148 |
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| .ci | ||
| .github/workflows | ||
| assets | ||
| examples | ||
| lib | ||
| scripts | ||
| .gitignore | ||
| .mailmap | ||
| contrib.tex | ||
| GPL-2 | ||
| html.cfg | ||
| LICENSE | ||
| lkmpg.tex | ||
| Makefile | ||
| README.md | ||
The Linux Kernel Module Programming Guide
This project keeps the Linux Kernel Module Programming Guide up to date, with working examples for recent 5.x kernel versions.
The guide has been around since 2001 and most copies of it on the web only describe old 2.6.x kernels.
The book can be freely accessed via https://sysprog21.github.io/lkmpg/ or latest PDF file.
The original guide may be found at Linux Documentation Project.
You may check other freely available programming books listed by The Free Ebook Foundation or Linux online books collected by The Online Books Page.
Getting Started
Summary
- Get the latest source code from the GitHub page.
- Install the prerequisites.
- Generate PDF and/or HTML documents.
Step 1: Get the latest source code
Make sure you can run git with an Internet connection.
$ git clone https://github.com/sysprog21/lkmpg.git && cd lkmpg
Step 2: Install the prerequisites
To generate the book from source, TeXLive (MacTeX) is required.
For Ubuntu Linux, macOS, and other Unix-like systems, run the following command(s):
# Debian / Ubuntu
$ sudo apt install make texlive-full
# Arch / Manjaro
$ sudo pacman -S make texlive-most texlive-bin
# macOS
$ brew install --cask mactex
$ sudo tlmgr update --self
Note that latexmk is required to generated PDF, and it probably has been installed on your OS already. If not, please follow the installation guide.
Alternatively, using Docker is recommended, as it guarantees the same dependencies with our GitHub Actions workflow.
After install docker engine on your machine, pull the docker image twtug/lkmpg and run in isolated containers.
# pull docker image and run it as container
$ docker pull twtug/lkmpg
$ docker run --rm -it -v $(pwd):/workdir twtug/lkmpg
nerdctl is a Docker-compatible command line tool for containerd, and you can replace the above docker commands with nerdctl counterparts.
Step 3: Generate PDF and/or HTML documents
Now we could build document with following commands:
$ make all # Generate PDF document
$ make html # Convert TeX to HTML
$ make clean # Delete generated files
License
The Linux Kernel Module Programming Guide is a free book; you may reproduce and/or modify it under the terms of the Open Software License.
Use of this work is governed by a copyleft license that can be found in the LICENSE file.
The complementary sample code is licensed under GNU GPL version 2, as same as Linux kernel.