On 04/08, Eric W. Biederman wrote: > Oleg Nesterov <[EMAIL PROTECTED]> writes: > > > For review only. > > > > To implement for-in-kerenl-use-only CLONE_ flags, we need to filter out them > > in sys_clone(). > > Nack > > The current clone_flags field is for user space consumption and we > have proposed users for all or almost all of the remaining bits.
OK. > If we are going to have kernel only flags please use an additional > argument to do_fork and copy_process. Yes, we can do this. But we have a number of architectures which use sys_clone() to implement kernel_thread(). It would be nice to have an architecture neutral kernel_thread() implementation as you proposed. We should change all of them if we want to add a new parameter to do_fork(). Perhaps it is better to add reparent_kthread() (next patch) to kthread() and forget about CLONE_KERNEL_THREAD. Anyway, re-parenting to swapper breaks pstree, it doesn't show kernel threads. And if ->parent == /sbin/init, we can't remove us from ->children (unless we forbid sub-thread-of-init exec). So the only safe change is set ->exit_state = -1. > Your current scheme also has the bad side that if user space supplied > a kernel flag it is hard to detect it and return -EINVAL. Which > limits future expansion. Silently dropping clone flags is a real > pain, if you are trying to detect if a new flag has been implemented. Yes. But that is what we are doing now. copy_process() just ignores unknown flags. Oleg. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
