Re: [patch] spinlocks: remove 'volatile'

Arjan van de Ven
2006-07-08T06:58:52Z

>
> __forceinline void Lock(volatile LONG *hPtr)
> {
> int iValue;
>
> for (;;) {
> iValue = _InterlockedExchange((LPLONG)hPtr, 1);
> if (iValue == 0)
> return;
> while (*hPtr);
> }
> }
>
> Please show me how I can write this to spinlock without using volatile.

this code is broken, at the very minimum that while (*hPtr); needs to be
"while (*hPtr) cpu_relax();" for hardware reasons.
At which point you can drop the volatile entirely without any change.