Compilation error expected

Question

I came across the following declaration in the device driver programming:

static int __init sum_init(void)

I have seen static int sum_init(void). Why does the above declaration not give compilation errors?

Take a look here: http://stackoverflow.com/questions/8832114/what-does-init-mean-in-this-linux-kernel-code and here http://www.tldp.org/LDP/lkmpg/2.4/html/x281.htm — MByD, Nov 24 '13 at 16:18

mcleod_ideafix · Answer 1 · 2013-11-24T17:00:14.440

2

Because probably __init is some sort of #define that is assigned to anything that won't cause a compilation error.

#define __init

Or...

#define __init __section(.init.text) __cold notrace

edited Nov 24 '13 at 17:00

answered Nov 24 '13 at 16:20

mcleod_ideafix

That is usually not correct ( in context of linux device drivers) – MByD Nov 24 '13 at 16:21
Clarified :) I didn't realize the poster is speaking about Linux drivers. Anyway, __init is just a macro that could expand to nothing, or to something that makes no harm. The confussion seems to be that the poster is not familiarized with GCC extensions to function declarations. – mcleod_ideafix Nov 24 '13 at 16:26

score -1 · Answer 2 · answered Nov 24 '13 at 16:20

-1

Its just like saying:

static int __init sum_init()

{
    return 0;
}

It doesn't return any value so no errors were occurred.

answered Nov 24 '13 at 16:20

RocketArrows1

1

But your function does return a value: 0, and indeed it has to, as it's declared to return an int. – mcleod_ideafix Nov 24 '13 at 16:21
No it's not. (And I think you miss the actual question, maybe because it wasn't so clear to begin with) – MByD Nov 24 '13 at 16:38

2 Answers2