Re: [PATCH 4/8] x86/spinlock: Leftover conversion ACCESS_ONCE->READ_ONCE

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Am 15.01.2015 um 21:01 schrieb Oleg Nesterov:
> 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?

OK, I will change that one as well.


--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [KVM ARM]     [KVM ia64]     [KVM ppc]     [Virtualization Tools]     [Spice Development]     [Libvirt]     [Libvirt Users]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite Questions]     [Linux Kernel]     [Linux SCSI]     [XFree86]
  Powered by Linux