Zack's Kernel News
Zack's Kernel News
The month Zack Brown reports on wonky typecasting.
Wonky Typecasting
Tinkering with strange forces, Steven Rostedt felt that a particular struct in the kernel should be tucked away into a private file, and the parts of the kernel using that struct should only be given a pointer to it. However, some (but not all) compilers started to complain about those in-kernel users trying to dereference the pointer (i.e., to see what it pointed to, which Steven had rendered hidden and inaccessible).
However, it was a little more complicated than that. The code that dereferenced the pointer wasn't targeting this specific pointer; it would simply dereference any pointer that was handed to it. But in this case, the struct's pointer was a secret hidden struct and was thus different from the types of pointers that code was usually handed, so … boom.
To fix this, Steven went through a big pile of kernel code and changed a lot of pointer declarations so that the dereferencing code wouldn't complain anymore. He didn't change it to be more accurate; he just changed it so the dereferencing process itself wouldn't care what was at the end of its request.
[...]
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
News
-
Kali Linux Waxes Nostalgic with BackTrack Mode
For those who've used Kali Linux since its inception, the changes with the new release are sure to put a smile on your face.
-
Gnome 50 Smooths Out NVIDIA GPU Issues
Gamers rejoice, your favorite pastime just got better with Gnome 50 and NVIDIA GPUs.
-
System76 Retools Thelio Desktop
The new Thelio Mira has landed with improved performance, repairability, and front-facing ports alongside a high-quality tempered glass facade.
-
Some Linux Distros Skirt Age Verification Laws
After California introduced an age verification law recently, open source operating system developers have had to get creative with how they deal with it.
-
UN Creates Open Source Portal
In a quest to strengthen open source collaboration, the United Nations Office of Information and Communications Technology has created a new portal.
-
Latest Linux Kernel RC Contains Changes Galore
Linux kernel 7.0-rc3 includes more changes than have been made in a single release in recent history.
-
Nitrux 6.0 Now Ready to Rock Your World
The latest iteration of the Debian-based distribution includes all kinds of newness.
-
Linux Foundation Reports that Open Source Delivers Better ROI
In a report that may surprise no one in the Linux community, the Linux Foundation found that businesses are finding a 5X return on investment with open source software.
-
Keep Android Open
Google has announced that, soon, anyone looking to develop Android apps will have to first register centrally with Google.
-
Kernel 7.0 Now in Testing
Linus Torvalds has announced the first Release Candidate (RC) for the 7.x kernel is available for those who want to test it.