From owner-freebsd-current Thu Jul 18 13:20: 8 2002 Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 757A737B401 for ; Thu, 18 Jul 2002 13:20:01 -0700 (PDT) Received: from mail.speakeasy.net (mail16.speakeasy.net [216.254.0.216]) by mx1.FreeBSD.org (Postfix) with ESMTP id AE86243E4A for ; Thu, 18 Jul 2002 13:20:00 -0700 (PDT) (envelope-from jhb@FreeBSD.org) Received: (qmail 15908 invoked from network); 18 Jul 2002 20:19:57 -0000 Received: from unknown (HELO server.baldwin.cx) ([216.27.160.63]) (envelope-sender ) by mail16.speakeasy.net (qmail-ldap-1.03) with DES-CBC3-SHA encrypted SMTP for ; 18 Jul 2002 20:19:57 -0000 Received: from laptop.baldwin.cx (gw1.twc.weather.com [216.133.140.1]) by server.baldwin.cx (8.11.6/8.11.6) with ESMTP id g6IKJl062734; Thu, 18 Jul 2002 16:19:47 -0400 (EDT) (envelope-from jhb@FreeBSD.org) Message-ID: X-Mailer: XFMail 1.5.2 on FreeBSD X-Priority: 3 (Normal) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit MIME-Version: 1.0 In-Reply-To: <200207181909.g6IJ9hTq019460@apollo.backplane.com> Date: Thu, 18 Jul 2002 16:19:51 -0400 (EDT) From: John Baldwin To: Matthew Dillon Subject: Re: Questions about kern_descrip.c Cc: current@FreeBSD.ORG, Alfred Perlstein Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On 18-Jul-2002 Matthew Dillon wrote: > >: >:* Matthew Dillon [020718 11:40] wrote: >:> >:> fdalloc() does not reserve the descriptor number it >:> returns, it simply finds a free slot and says 'this >:> index is a free slot'. Even in the latest -current, >:> fdalloc() releases the fdp lock when it goes to >:> MALLOC so the race appears to still be present. >: >:This is true. I think one way to fix this is to preallocate >:the 'struct file' you're going to put into the array and have >:fdalloc() insert the created file instead of just finding a >:slot. Problem is that it's a bunch of grunt work to do this. >: >:-- >:-Alfred Perlstein [alfred@freebsd.org] >:'Instead of asking why a piece of software is using "1970s technology," > > If you do this be careful in regards to open() and close() which > might place the descriptor in a transitory state. You don't want > another thread picking the descriptor up while it is in that > state. If you really wanted to do this you could just use '(struct file *)1' or some other evil, but I really don't think it's necessary. -- John Baldwin <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message