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Subject: Re: [patch] spinlocks: remove 'volatile'
From: Arjan van de Ven <arjan@infradead.org>
To: trajce nedev <trajcenedev@hotmail.com>
Cc: chase.venters@clientec.com, torvalds@osdl.org, acahalan@gmail.com,
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Date: Sat, 08 Jul 2006 08:58:44 +0200
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> 
> __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.