| Date | Sat, 13 Nov 2010 18:17:32 +0800 | From | Américo Wang <> | Subject | Re: [PATCH 06/20] x86/ticketlock: make __ticket_spin_trylock common |
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On Wed, Nov 03, 2010 at 10:59:47AM -0400, Jeremy Fitzhardinge wrote:
>+ union { >+ struct __raw_tickets tickets; >+ __ticketpair_t slock; >+ } tmp, new; >+ int ret; >+ >+ tmp.tickets = ACCESS_ONCE(lock->tickets); >+ if (tmp.tickets.head != tmp.tickets.tail) >+ return 0; >+ >+ new.slock = tmp.slock + (1 << TICKET_SHIFT); >+ >+ ret = cmpxchg(&lock->ticketpair, tmp.slock, new.slock) == tmp.slock; >+ barrier(); /* just make nothing creeps before lock is claimed */
This one should be smp_wmb(), right? No CONFIG_X86_OOSTORE protected.
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