On 04/10, Oleg Nesterov wrote: > > On 04/10, Oleg Nesterov wrote: > > > > On 04/10, Steven Rostedt wrote: > > > > > > Hendrik, we are debating about removing > > > cc3b13c11c567c69a6356be98d0c03ff11541d5c as it stops > > > call_usermodehelper tasks from tracing their syscalls. > > > > > > If Hendrik has no problems with this, neither do I. > > > > OK. > > > > cc3b13c11c567 mentions ret_from_fork, today copy_thread(PF_KTHREAD) uses > > ret_from_kernel_thread on 32bit, and still ret_from_fork on 64 bit but > > in the last case it checks PF_KTHREAD... I am wondering why they both > > (ret_from_kernel_thread and "1: " label in ret_from_fork) can't simply > > call do_exit() at the end? > > probably because we need to change all architectures...
Heh. And because "call *%rbx" can actually return if this kernel thread execs ;) But in this case we want TIF_SYSCALL_TRACING, so > > And, since they do not, every kernel_thread's function (fn argument of > > kernel_thread) must call do_exit itself? > > Hmm yes. See fb45550d76bb5 "make sure that kernel_thread() callbacks call > do_exit() themselves". > > > Looks a bit strange, I guess I missed something obvious. > > And I forgot to mention, given that the kernel_thread() callback should > call do_exit() itself, then this part of cc3b13c11c567c69a63 > > one case when a kernel thread can reach the > usual syscall exit tracing path: when we create a kernel thread, the > child comes to ret_from_fork > > is no longer relevant? A PF_KTHREAD child should never return from the > callback and thus it should never do "jmp syscall_exit" ? this is still true, I guess. 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/
