Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH 1/2] lkdtm: use atomic_t to replace count_lock | Date | Thu, 2 Feb 2012 13:44:19 +0000 |
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On Thursday 02 February 2012, Cong Wang wrote: > > In order to have an atomic here, you have to use a loop around > > atomic_cmpxchg, like > > > > > > int old, new; > > old = atomic_read(&count); > > do { > > new = old ? old - 1 : cpoint_count; > > old = cmpxchg(&count, old, new); > > } while (old != new); > > > > I suppose you could also just keep the spinlock and move lkdtm_do_action() > > outside of it? > > If we still need spinlock, I think we don't need to bother atomic_t at all.
Yes, it's one or the other: If you use the cmpxchg loop, you don't need a spinlock and vice versa.
Arnd
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