From owner-freebsd-current@FreeBSD.ORG Thu Aug 6 14:39:56 2009 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 2F89E106566B; Thu, 6 Aug 2009 14:39:56 +0000 (UTC) (envelope-from rmacklem@uoguelph.ca) Received: from esa-jnhn.mail.uoguelph.ca (esa-jnhn.mail.uoguelph.ca [131.104.91.44]) by mx1.freebsd.org (Postfix) with ESMTP id 45A7C8FC24; Thu, 6 Aug 2009 14:39:55 +0000 (UTC) X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: ApoEAB+IekqDaFvJ/2dsb2JhbADRKoQYBYFM X-IronPort-AV: E=Sophos;i="4.43,333,1246852800"; d="scan'208";a="43577207" Received: from ganges.cs.uoguelph.ca ([131.104.91.201]) by esa-jnhn-pri.mail.uoguelph.ca with ESMTP; 06 Aug 2009 10:39:54 -0400 Received: from localhost (localhost.localdomain [127.0.0.1]) by ganges.cs.uoguelph.ca (Postfix) with ESMTP id 5390CFB80C4; Thu, 6 Aug 2009 10:39:54 -0400 (EDT) X-Virus-Scanned: amavisd-new at ganges.cs.uoguelph.ca Received: from ganges.cs.uoguelph.ca ([127.0.0.1]) by localhost (ganges.cs.uoguelph.ca [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id l9FVv-yK0m6E; Thu, 6 Aug 2009 10:39:53 -0400 (EDT) Received: from muncher.cs.uoguelph.ca (muncher.cs.uoguelph.ca [131.104.91.102]) by ganges.cs.uoguelph.ca (Postfix) with ESMTP id 5946DFB80C2; Thu, 6 Aug 2009 10:39:53 -0400 (EDT) Received: from localhost (rmacklem@localhost) by muncher.cs.uoguelph.ca (8.11.7p3+Sun/8.11.6) with ESMTP id n76Ehfh26136; Thu, 6 Aug 2009 10:43:41 -0400 (EDT) X-Authentication-Warning: muncher.cs.uoguelph.ca: rmacklem owned process doing -bs Date: Thu, 6 Aug 2009 10:43:41 -0400 (EDT) From: Rick Macklem X-X-Sender: rmacklem@muncher.cs.uoguelph.ca To: Robert Watson In-Reply-To: Message-ID: References: <20090804225806.GA54680@hub.freebsd.org> <20090805054115.O93661@maildrop.int.zabbadoz.net> <20090805063417.GA10969@doormat.home> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: jeff@FreeBSD.org, "Bjoern A. Zeeb" , freebsd-current@FreeBSD.org, kib@FreeBSD.org, Navdeep Parhar , Navdeep Parhar , Larry Rosenman , lstewart@FreeBSD.org Subject: Re: reproducible panic in netisr X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 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: Thu, 06 Aug 2009 14:39:56 -0000 On Thu, 6 Aug 2009, Robert Watson wrote: > other places where we have very strong alignment requirements on i386/amd64, > such as the td_ucred pointer that we check for change on system calls/traps > to see if we need to refresh the thread's credential from the process > credential. > Does this imply that the nfs/krpc hack of: oldcred = td->td_ucred; td->td_ucred = "some other cred ptr" ... td->td_ucred = oldcred; could be dangerous? Maybe it should be converted to code that replaces the contents instead of replacing the *cred? (Variants of the above live in a bunch of places in the krpc, nlm and nfs code, due to the fact that the socket functions use td->td_ucred in various places.) rick