From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: Strange latency spikes/TX network stalls on Sun Fire
 X4150(x86) and e1000e
Date: Wed, 30 May 2012 13:59:11 +0200
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Cc: Hiroaki SHIMODA <shimoda.hiroaki@gmail.com>,
	Tom Herbert <therbert@google.com>,
	Denys Fedoryshchenko <denys@visp.net.lb>,
	netdev@vger.kernel.org, e1000-devel@lists.sourceforge.net,
	jeffrey.t.kirsher@intel.com, jesse.brandeburg@intel.com,
	davem@davemloft.net
To: Joe Perches <joe@perches.com>
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On Wed, 2012-05-30 at 04:20 -0700, Joe Perches wrote:
> On Wed, 2012-05-30 at 13:08 +0200, Eric Dumazet wrote:
> > Maybe we should change all POSDIFF(), not selected ones.
> > #define POSDIFF(A, B) ((int)((A) - (B)) > 0 ? (A) - (B) : 0)
> 
> maybe use an eval once statement expression macro
> ({
> 	typeof (A) _a = (A);
> 	typeof (B) _b = (B);
> 	((int)(_a - _b) > 0 ? _a - _b : 0;
> })
> 
> 

Well, many choices are possible, including

#define POSDIFF(A, B) max_t(int, (A) - (B), 0);