Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755645Ab1EDUYe (ORCPT ); Wed, 4 May 2011 16:24:34 -0400 Received: from lennier.cc.vt.edu ([198.82.162.213]:41196 "EHLO lennier.cc.vt.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754354Ab1EDUYd (ORCPT ); Wed, 4 May 2011 16:24:33 -0400 X-Mailer: exmh version 2.7.2 01/07/2005 with nmh-1.3-dev To: Christoph Lameter Cc: Linus Torvalds , Pekka Enberg , Thomas Gleixner , Tejun Heo , Ingo Molnar , Jens Axboe , Andrew Morton , werner , "H. Peter Anvin" , Linux Kernel Mailing List Subject: Re: [block IO crash] Re: 2.6.39-rc5-git2 boot crashs In-Reply-To: Your message of "Wed, 04 May 2011 15:04:39 CDT." From: Valdis.Kletnieks@vt.edu References: <20110504101932.GA3392@elte.hu> <20110504112746.GE8007@htj.dyndns.org> <20110504132022.GA17294@htj.dyndns.org> <20110504142532.GC17294@htj.dyndns.org> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1304540499_7352P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Date: Wed, 04 May 2011 16:21:39 -0400 Message-ID: <19422.1304540499@localhost> X-Mirapoint-Received-SPF: 198.82.161.152 auth3.smtp.vt.edu Valdis.Kletnieks@vt.edu 2 pass X-Mirapoint-IP-Reputation: reputation=neutral-1, source=Fixed, refid=n/a, actions=MAILHURDLE SPF TAG X-Junkmail-Status: score=35/50, host=dagger.cc.vt.edu X-Junkmail-Signature-Raw: score=suspect(0), refid=str=0001.0A020205.4DC1B555.00BB,ss=2,fgs=0, ip=0.0.0.0, so=2010-07-22 22:03:31, dmn=2009-09-10 00:05:08, mode=single engine X-Junkmail-IWF: false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1195 Lines: 36 --==_Exmh_1304540499_7352P Content-Type: text/plain; charset=us-ascii On Wed, 04 May 2011 15:04:39 CDT, Christoph Lameter said: > On Wed, 4 May 2011, Linus Torvalds wrote: > > But cmpxchg DOES NOT MAKE SENSE without atomicity guarantees. > > This is not a real cmpxchg after all. Its not atomic in the sense of > other functions. Its only "percpu atomic" if you want it that way. This is > *not* a full cmpxchg_double(). Calling it a cmpxchg when it doesn't have the primary distinguishing property of a hardware cmpxchg is just loading a bullet in the chamber and inviting kernel hackers to point it at their feet... --==_Exmh_1304540499_7352P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Exmh version 2.5 07/13/2001 iD8DBQFNwbVTcC3lWbTT17ARApiAAJ40IG5yrhZyPQ9C81jXlg4XY+d66ACeNtSU s/Z1D+Pl/+k+sgXrrcWDKSs= =G38D -----END PGP SIGNATURE----- --==_Exmh_1304540499_7352P-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/