Messages in this thread | | | Date | Wed, 26 Aug 2009 09:48:48 -0400 (EDT) | From | Steven Rostedt <> | Subject | Re: [PATCH 08/12] add trace events for each syscall entry/exit |
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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
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