Emmanuel Dreyfus wrote:

>Hi
>
>Linux's exit_group system call is meant to exit a whole group of processes. 
>In order to emulate it correctly, I must be able to cause a process to exit
>from another process. 
>
>How could this be done correctly? I tried sending SIGKILL to the members
>of the program group, but that does not work very well, as it fires an
>unwanted SIGCHLD to the parent. 
>
>Calling sys_exit(l, v, retval) within the context of a lwp different than
>l does not work. What alternative do I have?
>
>  
>
I'd just set the "sig" argument that is passed by linux_sys_clone to 
fork1() to 0, iff CLONE_THREAD is set. That way, when a clone/"thread" 
exits (really a process), it will not send the parent a signal.  
Glancing at the Linux kernel, it seems like the desired emulated behavior.

So then, the SIGKILL approach will work, if we ignore the case of 
processes waiting in the kernel. I bet there are tons of places in the 
kernel where the code doesn't expect to exit from a ltsleep() by a 
forced exit, so a change in semantics there would require a lot of code 
changes.

- Frank