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    SubjectRe: [PATCH 06/20] x86/ticketlock: make __ticket_spin_trylock common
    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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