Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964818AbWHWKVt (ORCPT ); Wed, 23 Aug 2006 06:21:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964817AbWHWKVt (ORCPT ); Wed, 23 Aug 2006 06:21:49 -0400 Received: from relay.2ka.mipt.ru ([194.85.82.65]:10655 "EHLO 2ka.mipt.ru") by vger.kernel.org with ESMTP id S964815AbWHWKVs (ORCPT ); Wed, 23 Aug 2006 06:21:48 -0400 Date: Wed, 23 Aug 2006 14:20:37 +0400 From: Evgeniy Polyakov To: Jari Sundell Cc: David Miller , kuznet@ms2.inr.ac.ru, nmiell@comcast.net, linux-kernel@vger.kernel.org, drepper@redhat.com, akpm@osdl.org, netdev@vger.kernel.org, zach.brown@oracle.com, hch@infradead.org Subject: Re: [take12 0/3] kevent: Generic event handling mechanism. Message-ID: <20060823102037.GA23664@2ka.mipt.ru> References: <20060822231129.GA18296@ms2.inr.ac.ru> <20060822.173200.126578369.davem@davemloft.net> <20060823065659.GC24787@2ka.mipt.ru> <20060823083859.GA8936@2ka.mipt.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=koi8-r Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.9i X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-1.7.5 (2ka.mipt.ru [0.0.0.0]); Wed, 23 Aug 2006 14:20:42 +0400 (MSD) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1593 Lines: 48 On Wed, Aug 23, 2006 at 11:49:22AM +0200, Jari Sundell (sundell.software@gmail.com) wrote: > >> Only void * I'm seeing belongs to the user, (udata) perhaps you are > >> talking of something different? > > > >Yes, exactly about it. > > > >I put union { > > u32 a[2]; > > void *b; > >} > >epcially to eliminate that problem. > > It's just random data of a known maximum size appended to the struct, > I'm sure you can find a clean way to handle it. If you mangle the > first variable name in your union, you'll end up with something that > should be usable instead of udata. If there will be usual pointer, size of the whole structure will be different in kernel and userspace. > >And I'm not that sure aboit stuff like uptr_t or how they call pointers > >in userspace and kernelspace. > > Well, I can't find any use of pointers in your struct ukevent, nor in > any of the kqueue events in my man page. So if this is a deficit it > applies to both, I guess? No, it will change sizes of the structure in kernelspace and userspace, so they just can not communicate. > >ukevent is aligned to 8 bytes already (it's size selected to be 40 bytes), > >so it should not be a problem. > > > >> Eric > > Even if it is so, wouldn't it be better to be explicit about it? Ok, I will add a comment about it. > Rakshasa -- Evgeniy Polyakov - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/