From owner-freebsd-stable@FreeBSD.ORG Tue Jun 2 12:43:02 2009 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 02D7810656A6; Tue, 2 Jun 2009 12:43:02 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from cyrus.watson.org (cyrus.watson.org [65.122.17.42]) by mx1.freebsd.org (Postfix) with ESMTP id 6F93D8FC30; Tue, 2 Jun 2009 12:43:01 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from bigwig.baldwin.cx (66.111.2.69.static.nyinternet.net [66.111.2.69]) by cyrus.watson.org (Postfix) with ESMTPSA id 2220646B52; Tue, 2 Jun 2009 08:43:01 -0400 (EDT) Received: from jhbbsd.hudson-trading.com (unknown [209.249.190.8]) by bigwig.baldwin.cx (Postfix) with ESMTPA id 27E698A02B; Tue, 2 Jun 2009 08:43:00 -0400 (EDT) From: John Baldwin To: freebsd-stable@freebsd.org Date: Tue, 2 Jun 2009 08:42:41 -0400 User-Agent: KMail/1.9.7 References: <20090601161903.GA40377@stack.nl> <4A24457C.6060100@FreeBSD.org> In-Reply-To: <4A24457C.6060100@FreeBSD.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200906020842.42330.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.0.1 (bigwig.baldwin.cx); Tue, 02 Jun 2009 08:43:00 -0400 (EDT) X-Virus-Scanned: clamav-milter 0.95 at bigwig.baldwin.cx X-Virus-Status: Clean X-Spam-Status: No, score=-2.5 required=4.2 tests=AWL,BAYES_00,RDNS_NONE autolearn=no version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on bigwig.baldwin.cx Cc: Vlad Galu , Bruce Simpson , Jilles Tjoelker Subject: Re: Unnamed POSIX shared semaphores X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 02 Jun 2009 12:43:03 -0000 On Monday 01 June 2009 5:17:48 pm Bruce Simpson wrote: > Jilles Tjoelker wrote: > > If process-shared semaphores really work, then the above structure is > > not a pathological case. Effectively, sem_t is carved in stone. So > > process-private semaphores should continue to have most of their stuff > > in a separately allocated structure, to preserve flexibility. > > > > There was an inadvertent race in FreeBSD's POSIX semaphores which I > fixed in HEAD and STABLE about 6 weeks before 7.2 was released. > > I believe process-shared POSIX semaphores now work -- the Python > 'multiprocessing' regression test now runs to completion with no errors > on both HEAD and STABLE. The semaphores in recent 7 and 8 are definitely not process-shared (at least not intentionally). They may work across a fork accidentally, but you can't store it in an mmap() region and share it with an arbitrary process. -- John Baldwin