Re: [PATCH 1/2] fix kill_proc_info() vs CLONE_THREAD race

[Oleg Nesterov <oleg@tv-sign.ru>]

"Paul E. McKenney" wrote:
> 
> > After that we don't need tasklist_lock to iterate over the thread
> > list, and we can simplify things, see for example do_sigaction()
> > or sys_times().
> 
> The above proposal would require that we hold siglock during the
> traversal, correct?

Yes, of course.

>                     Is that reasonable for non-signal-related traversals?
> Or were you thinking of making this change only for signal code?

Yes, I think it may be useful for non-signal-related traversals.

Currently we need tasklist_lock in order to use next_thread().
I beleive, we can migrate to rcu_read_lock+spinlock(sighand)
in most cases.

Well, next_thread() itself is safe already, but it can return
already zapped threads.

Oleg.
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