Messages in this thread | | | Date | Thu, 10 Apr 2014 20:14:17 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH RESEND 2/2] tracing: syscall_regfunc() should not skip kernel threads |
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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...
> 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" ?
Or I am totally confused?
Oleg.
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