[Xen-devel] Re: [PATCH 06/20] x86/ticketlock: make __ticket_spin_trylock common

[AmÃrico Wang <xiyou.wangcong@xxxxxxxxx>]

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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