Understanding container_of macro in the Linux kernel When you begin with the kernel, and you start to look around and read the code, you will eventually come across this magical preprocessor construct. What does it do? Well, precisely what its name indicates. It takes three arguments – a pointer , type of the container, and the name of the member the pointer refers to. The macro will then expand to a new address pointing to the container which accommodates the respective member. It is indeed a particularly clever macro, but how the hell can this possibly work? Let me illustrate… The first diagram illustrates the principle of the container_of(ptr, type, member) macro for who might find the above description too clumsy. I llustration of how the containter_of macro works. Bellow is the actual implementation of the macro from Linux Kernel: #define container_of(ptr, type, member) ({ \ const typeof( ((type *)0)->member ) *__mptr = (
This blog is intended to help understand internals about linux environment. It stack together very basic and important contents, to help naive kernel users.