From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763882AbXGSH1Y (ORCPT ); Thu, 19 Jul 2007 03:27:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754158AbXGSH1S (ORCPT ); Thu, 19 Jul 2007 03:27:18 -0400 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:54789 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751046AbXGSH1R (ORCPT ); Thu, 19 Jul 2007 03:27:17 -0400 Date: Thu, 19 Jul 2007 00:27:16 -0700 (PDT) Message-Id: <20070719.002716.30181989.davem@davemloft.net> To: akpm@linux-foundation.org Cc: airlied@linux.ie, linux-kernel@vger.kernel.org Subject: Re: cmpxchg is not available to generic code From: David Miller In-Reply-To: <20070719000549.1e57b5b2.akpm@linux-foundation.org> References: <20070719000549.1e57b5b2.akpm@linux-foundation.org> X-Mailer: Mew version 5.1.52 on Emacs 21.4 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: Andrew Morton Date: Thu, 19 Jul 2007 00:05:49 -0700 > What's that code doing anyway? driver-private locking primitives? It's an atomic lock shared with userspace. Whatever implementation is used to do the lock on that object must be identical in the userspace DRM bits. Unlike futex, the lock operation on the user side isn't optional. So if the platform can't do a true cmpxchg it generally cannot support DRM.