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
-
Framework Laptop 13 Pro Competes with the Best
Framework has released what might be considered the MacBook of Linux devices.
-
The Latest CachyOS Features Supercharged Kernel
The latest release of CachyOS brings with it an enhanced version of the latest Linux kernel.
-
Kernel 7.0 Is a Bit More Rusty
Linux kernel 7.0 has been released for general availability, with Rust finally getting its due.
-
France Says "Au Revoir" to Microsoft
In a move that should surprise no one, France announced plans to reduce its reliance on US technology, and Microsoft Windows is the first to get the boot.
-
CIQ Releases Compatibility Catalog for Rocky Linux
The company behind Rocky Linux is making an open catalog available to developers, hobbyists, and other contributors, so they can verify and publish compatibility with the CIQ lineup.
-
KDE Gets Some Resuscitation
KDE is bringing back two themes that vanished a few years ago, putting a bit more air under its wings.
-
Ubuntu 26.04 Beta Arrives with Some Surprises
Ubuntu 26.04 is almost here, but the beta version has been released, and it might surprise some people.
-
Ubuntu MATE Dev Leaving After 12 years
Martin Wimpress, the maintainer of Ubuntu MATE, is now searching for his successor. Are you the next in line?
-
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.