Messages in this thread | | | Date | Wed, 26 Aug 2009 15:53:35 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH 08/12] add trace events for each syscall entry/exit |
| |
On Wed, Aug 26, 2009 at 09:48:48AM -0400, Steven Rostedt wrote: > > On Wed, 26 Aug 2009, Frederic Weisbecker wrote: > > > > > > That won't always work as pointed out in the other example: > > > - Process doing sys_init_module then scheduled away > > > - User enables syscall tracing -> TIF_SYSCALL_FTRACE gets set > > > - init function of the module gets called and is doing kernel_thread() > > > (old API) -> kernel thread inherits TIF_SYSCALL_FTRACE. > > > > > > I don't think that's what you want. You might want to clear the flag for > > > new processes during fork (only for kernel threads I would guess). > > > > > > At least the current patch leaves a hole. > > > > > > Ah, there are callsites that use kernel_thread() directly? > > Does it means that t->mm could be non NULL for such resulting > > kernel threads, in that case it would be hard to hook on > > do_fork() to check that. > > All kernel threads have a NULL t->mm. Since do_fork is called by kthreadd > and not by kthread_create, the caller of do_fork will also have a > t->mm = NULL. > > -- Steve >
Yeah, that's the case with kthread_create() creation fashion, but what if you create a kernel thread using the low level kernel_thread() directly (ie: without relaying on kthreadd queue)?
Especially in Heiko example, it seems to be a duplication of user task.
I wonder what obvious think I'm missing here...
| |