From mboxrd@z Thu Jan  1 00:00:00 1970
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Mon, 28 Sep 2009 22:54:09 +0000
Subject: RE: [git pull] ia64 changes
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To: linux-ia64@vger.kernel.org



On Mon, 28 Sep 2009, Luck, Tony wrote:
> 
> 	ticket = ia64_fetchadd(1, p, acq);
> 
> 	if (!(((ticket >> TICKET_SHIFT) ^ ticket) & ((1L << TICKET_BITS) - 1)))
> 		return;

I think the above is wrong.

Doesn't 'fetchadd' return the _old_ value? 

If so, the "fastcase" above will not trigger in the normal case, so you'll 
always fall down to the slowcase:

> 	do {
> 		cpu_relax();
> 		serve = ACCESS_ONCE(*p);
> 	} while (((serve >> TICKET_SHIFT) ^ ticket) & ((1 << TICKET_BITS) - 1));

Or did I miss something?

		Linus