[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 4/8] x86/spinlock: Leftover conversion ACCESS_ONCE->READ_ONCE
On 01/15, Christian Borntraeger wrote: > > Am 15.01.2015 um 20:38 schrieb Oleg Nesterov: > > On 01/15, Christian Borntraeger wrote: > >> > >> --- a/arch/x86/include/asm/spinlock.h > >> +++ b/arch/x86/include/asm/spinlock.h > >> @@ -186,7 +186,7 @@ static inline void > >> arch_spin_unlock_wait(arch_spinlock_t *lock) > >> __ticket_t head = ACCESS_ONCE(lock->tickets.head); > >> > >> for (;;) { > >> - struct __raw_tickets tmp = ACCESS_ONCE(lock->tickets); > >> + struct __raw_tickets tmp = READ_ONCE(lock->tickets); > > > > Agreed, but what about another ACCESS_ONCE() above? > > > > Oleg. > > tickets.head is a scalar type, so ACCESS_ONCE does work fine with gcc 4.6/4.7. > My goal was to convert all accesses on non-scalar types I understand, but READ_ONCE(lock->tickets.head) looks better anyway and arch_spin_lock() already use READ_ONCE() for this. So why we should keep the last ACCESS_ONCE() in spinlock.h ? Just to make another cosmetic cleanup which touches the same function later? Oleg. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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