Messages in this thread | | | Date | Wed, 18 Dec 2019 16:08:32 +0800 | From | chenqiwu <> | Subject | Re: [PATCH v2] kernel/exit: do panic earlier to get coredump if global init task exit |
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On Tue, Dec 17, 2019 at 04:23:33PM +0100, Oleg Nesterov wrote: > On 12/17, chenqiwu wrote: > > > > But in fact, I think atomic_read() > > can avoid the racy even if both threads exit in parallel, since it is > > an atomic operation forever. > > Hmm, not sure I understand. atomic_read() is just READ_ONCE(), it can't be > re-ordered but that is all. > > How can it avoid the race if it is called before atomic_dec_and_test() ? > > Again, suppose that we have 2 exiting threads and signal->live == 2. With > your patch each thread does atomic_read() before atomic_dec_and_test(), > both threads can observe atomic_read(signal->live) == 2 simply because > the counter was not decremented yet. > > Oleg. >
Yeah, I agree your idea. Now, if there are no further questions, I will resend this as a proper patch for v3.
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