From owner-svn-src-stable-7@FreeBSD.ORG Mon Dec 1 22:03:05 2008 Return-Path: Delivered-To: svn-src-stable-7@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 894341065680; Mon, 1 Dec 2008 22:03:05 +0000 (UTC) (envelope-from wb@freebie.xs4all.nl) Received: from smtp-vbr9.xs4all.nl (smtp-vbr9.xs4all.nl [194.109.24.29]) by mx1.freebsd.org (Postfix) with ESMTP id E31D98FC14; Mon, 1 Dec 2008 22:03:04 +0000 (UTC) (envelope-from wb@freebie.xs4all.nl) Received: from freebie.xs4all.nl (freebie.xs4all.nl [82.95.250.254]) by smtp-vbr9.xs4all.nl (8.13.8/8.13.8) with ESMTP id mB1Lga0e099897; Mon, 1 Dec 2008 22:42:37 +0100 (CET) (envelope-from wb@freebie.xs4all.nl) Received: from freebie.xs4all.nl (localhost [127.0.0.1]) by freebie.xs4all.nl (8.14.2/8.14.2) with ESMTP id mB1LdsYC016527; Mon, 1 Dec 2008 22:39:54 +0100 (CET) (envelope-from wb@freebie.xs4all.nl) Received: (from wb@localhost) by freebie.xs4all.nl (8.14.2/8.14.2/Submit) id mB1LdnSf016526; Mon, 1 Dec 2008 22:39:49 +0100 (CET) (envelope-from wb) Date: Mon, 1 Dec 2008 22:39:49 +0100 From: Wilko Bulte To: Marcel Moolenaar Message-ID: <20081201213948.GI15094@freebie.xs4all.nl> References: <200812011740.mB1Hev1f032334@svn.freebsd.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200812011740.mB1Hev1f032334@svn.freebsd.org> User-Agent: Mutt/1.5.18 (2008-05-17) X-Virus-Scanned: by XS4ALL Virus Scanner Cc: svn-src-stable@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org, svn-src-stable-7@FreeBSD.org Subject: Re: svn commit: r185526 - in stable/7/sys: . ia64/include X-BeenThere: svn-src-stable-7@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: SVN commit messages for only the 7-stable src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 01 Dec 2008 22:03:05 -0000 Quoting Marcel Moolenaar, who wrote on Mon, Dec 01, 2008 at 05:40:57PM +0000 .. > Author: marcel > Date: Mon Dec 1 17:40:57 2008 > New Revision: 185526 > URL: http://svn.freebsd.org/changeset/base/185526 > > Log: > MFC rev 179382: > Work-around a compiler optimization bug, that broke libthr. Massive > inlining resulted in constant propagation to the extend that cmpval > was known to the compiler to be URWLOCK_WRITE_OWNER (= 0x80000000U). > Unfortunately, instead of zero-extending the unsigned constant, it > was sign-extended. As such, the cmpxchg instruction was comparing > 0x0000000080000000LU to 0xffffffff80000000LU and obviously didn't > perform the exchange. > But, since the value returned by cmpxhg equalled cmpval (when zero- > extended), the _thr_rtld_lock_release() function thought the exchange > did happen and as such returned as if having released the lock. This > was not the case. Subsequent locking requests found rw_state non-zero > and the thread in question entered the kernel and block indefinitely. > *WOW*... Wilko