From owner-freebsd-current@FreeBSD.ORG Wed Dec 18 19:43:29 2013 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 5265047F; Wed, 18 Dec 2013 19:43:29 +0000 (UTC) Received: from mail-qe0-x236.google.com (mail-qe0-x236.google.com [IPv6:2607:f8b0:400d:c02::236]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id DF1A91DB6; Wed, 18 Dec 2013 19:43:28 +0000 (UTC) Received: by mail-qe0-f54.google.com with SMTP id cy11so117700qeb.27 for ; Wed, 18 Dec 2013 11:43:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:content-type; bh=S/ZH3Yl9SiCBHTDZJxwjKINFz8dqbIovdXUqewOfhZI=; b=fecChnAMfUCzgzKEmBVg6I1dlgMLiYmdJvikTG3wmb7c8urKMqjv1A0BFDnSaHHW8J zYf1PjnVF8xRIK+RrBfAh4jS7TVV6DuYvijeZQ+eLFOPBoG0Qetos2BfxSVztik9BJk+ qubulsI+R4V8E1P5kpKFJamD6nNFgxUDwRNfovxrZYxpvrSqDm26hiDoiI+/06p5yP8y p3RwHYSl9V24/UdDlhtYKFDH7uNgPgyq+iwYDPqKkl+MlTajKBbna3Od43KSAkSMgreZ 06b0W/00bJiIXRoyjvFZHDVGNWMOeHyfqng4mR/Nf7yEX+/7tXMAxI30fM/Et0/DE8Nh Ehng== MIME-Version: 1.0 X-Received: by 10.224.89.73 with SMTP id d9mr57618647qam.5.1387395808086; Wed, 18 Dec 2013 11:43:28 -0800 (PST) Sender: adrian.chadd@gmail.com Received: by 10.224.53.200 with HTTP; Wed, 18 Dec 2013 11:43:28 -0800 (PST) In-Reply-To: <52B17777.6060703@FreeBSD.org> References: <527F95BE.7080908@gmx.com> <527FC05D.8080703@gmx.com> <5283E123.5000305@FreeBSD.org> <20131114113846.4dcb2037@kalimero.tijl.coosemans.org> <52858067.2060200@gmx.com> <52AEAD7A.1040205@gmx.com> <52B0C004.9010702@FreeBSD.org> <52B14384.5060102@gmx.com> <52B17777.6060703@FreeBSD.org> Date: Wed, 18 Dec 2013 11:43:28 -0800 X-Google-Sender-Auth: zxYWPGdobLzwN8A0mwxaYjRkcW8 Message-ID: Subject: Re: new Xorg (KMS, etc.) for Radeon 9600 From: Adrian Chadd To: =?ISO-8859-1?Q?Jean=2DS=E9bastien_P=E9dron?= Content-Type: text/plain; charset=ISO-8859-1 Cc: dt71@gmx.com, "freebsd-current@freebsd.org" , Robert Noland X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 18 Dec 2013 19:43:29 -0000 [snip] So the standard trop of UNLOCK/WORK/RELOCK is pretty dangerous. There's no state re-validation going on when you re-acquire that lock. So, although it meets the lock requirements, it may not be 'correct'. It's scattered throughout the code base (wifi drivers aren't an exception here either, sigh.) Just something to keep in mind when you validate the 'correctness' of this kind of lock hack. -adrian