Linux Kernel coding style

Question

I am new in the kernel-programming, so I would like to find out what coding style is more acceptable. For example, in case of the error handling which of the following is better?

This one:

/* some stuff */
if(error) {
    /* error handling */
    return -(errorcode);
}
/* normal actions */

or this one:

/* some stuff */
if(!error) {
    /* normal actions */
} else {
    /* error handling */
    return -(errorcode);
}

Where can I find any document, that regards to kernel coding standard?

And to elaborate on ouah's Most Excellent reply: your first snippet is "preferred" over the second. But the main point is to use K & R style (vs. .Net or Java or - heaven forbid - MS "Hungarian" coding styles) ;) — paulsm4
– paulsm4, Commented Oct 7, 2012 at 19:53
And add space after "if" :) lxr.linux.no/#linux+v3.6.1/Documentation/CodingStyle#L179 , When it comes to coding style in general I have used that document as base for all coding in C - not only kernel-coding and found it invaluable. — Morpfh
– Morpfh, Commented Oct 7, 2012 at 20:09

ouah · Accepted Answer · 2021-02-14 00:15:57Z

32

Linux kernel has a coding style guide:

https://www.kernel.org/doc/Documentation/process/coding-style.rst

Nicer Formatted Version

Regarding your example, I personally prefer the first style. With the second style you will quickly violate this Linux kernel style rule (kernel style has 8-character indentation):

if you need more than 3 levels of indentation, you're screwed anyway, and should fix your program.

Writing code from top to bottom (as opposed to horizontally) is sometimes referred as duffing. I can suggest you this excellent reading on the subject:

Reading Code From Top to Bottom

edited Feb 14, 2021 at 0:15

answered Oct 7, 2012 at 19:50

ouah

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2 Comments

Lionia Vasilev Over a year ago

Thank you for the reference to the Reading Code From Top to Bottom article. It is indeed an excellent one.

mja Over a year ago

HTML link: kernel.org/doc/html/v4.10/process/coding-style.html

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