implicit declaration of function when compiling kernel module

Asked Dec 13 '15 at 18:12

Active Dec 13 '15 at 18:12

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I am new to working in kernel space, so I hope someone can help me with the issue I am having.

I have seen a lot of questions related to implicit declaration of function for userspace c/c++ programs, but I think the issue I am having may be approached differently in kernel space.

The code I am working on is to test out signaling a user application from the driver, which I have working, but the issue was I could not use the function send_sig_info declared in linux/signal.h until I had declared it in the header of my own driver source. I figured if I had included to correct header to access the function call declared there, it should work.

So without the declaration of send_sig_info in my own header:

error: implicit declaration of function ‘send_sig_info’

And then adding to my header file:

static int send_sig_info(int sig, struct siginfo *info, struct task_struct *p);

would allow my code to compile just fine.

Does anyone have an idea why this is?

Thanks.

asked Dec 13 '15 at 18:12

user2884074

In the current kernel(4.3) the function is declared in `linux/sched.h` (Presizely at lxr.free-electrons.com/source/include/linux/sched.h#L2483). Which kernel version you use? – Tsyvarev Dec 13 '15 at 22:20
I should have mentioned I am using kernel 3.10. – user2884074 Dec 14 '15 at 17:15
For your kernel the function is declared in the same file as in 4.3. You can easly check that with that site. – Tsyvarev Dec 14 '15 at 20:04
@user2884074 Did you find a solution to the problem? – S.S. Anne Aug 26 '19 at 01:10
It's moved to `linux/sched/signal.h` since 4.11 and 4.20 has changed `siginfo` to `kernel_siginfo`. – Louis Go Nov 19 '20 at 01:06

implicit declaration of function when compiling kernel module

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