How to send a signal from inside the kernel?

[John-Mark Gurney]

Aziz KEZZOU wrote this message on Thu, Mar 17, 2005 at 12:34 -0500:
> Hi all,
> I would like to send a signal (e.g SIGUSR1) to a user process from
> inside the kernel (kld module).
> Can any one tell me how to do it ?
> I tried the following code inspired from sys/kern/kern_sig.c :
> ==============================================================
> #include <sys/types.h> 
> #include <sys/signal.h>
> 
> int process_pid;
> struct kill_args {
> 	int	pid;
> 	int	signum;
> };
> 
> void send_SIGUSR1() {
>   struct kill_args uap;
>   uap.pid = process_pid;
>   uap.signum = SIGUSR1;  
>   kill((struct thread *)0, &uap);
> }
> ===============================================================
> 
> but that causes a page fault in kernel mode (ie. Kernel panic :-)
> 
> Any help is appreciated, thanks.

Take a look at psignal(9)...  You'll need to look up the struct proc
for psignal with pfind(9)...   and then PROC_UNLOCK the struct proc
after you've used psignal...

so:
struct proc *p;

p = pfind(pid);
if (p != NULL) {
	psignal(p, SIGUSR1);
	PROC_UNLOCK(p);
}

I haven't tried the code above, but that should do what you want...

-- 
  John-Mark Gurney				Voice: +1 415 225 5579

     "All that I will do, has been done, All that I have, has not."