From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from hurricane.elijah.cs.cmu.edu ([128.2.209.191]:60246 "EHLO hurricane.elijah.cs.cmu.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727397AbeIEV4U (ORCPT ); Wed, 5 Sep 2018 17:56:20 -0400 Date: Wed, 5 Sep 2018 12:54:47 -0400 From: Jan Harkes To: David Howells Cc: linux-api@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 05/11] UAPI: coda: Don't use internal kernel structs in UAPI Message-ID: <20180905165447.gnjcc2xbgaem3ue3@cs.cmu.edu> References: <153616286704.23468.584491117180383924.stgit@warthog.procyon.org.uk> <153616291029.23468.16421004714304578585.stgit@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <153616291029.23468.16421004714304578585.stgit@warthog.procyon.org.uk> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Wed, Sep 05, 2018 at 04:55:10PM +0100, David Howells wrote: > The size and layout of internal kernel structures may not be relied upon > outside of the kernel and may even change in a containerised environment if > a container image is frozen and shifted to another machine. > > Excise these from Coda's upc_req struct. Argh, that won't work. I still have to look at where this structure is used exactly, but... Either this structure is used by the messages that the kernel sends to userspace, in which case we don't want the kernel to pack the larger structure that includes a list_head and a wait_queue_head_t in the message while userspace reads as if it was a smaller structure without those. But my gut feeling is that this is not part of the upcall request messages and never gets to userspace and as such shouldn't be in uapi to begin with. Jan