Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755286AbYLMCJV (ORCPT ); Fri, 12 Dec 2008 21:09:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753465AbYLMCI7 (ORCPT ); Fri, 12 Dec 2008 21:08:59 -0500 Received: from nlpi025.sbcis.sbc.com ([207.115.36.54]:41921 "EHLO nlpi025.prodigy.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753417AbYLMCI6 (ORCPT ); Fri, 12 Dec 2008 21:08:58 -0500 Date: Fri, 12 Dec 2008 20:07:56 -0600 (CST) From: Christoph Lameter X-X-Sender: cl@quilx.com To: Eric Dumazet cc: "Paul E. McKenney" , Nick Piggin , Andrew Morton , Ingo Molnar , Christoph Hellwig , David Miller , "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, "kernel-testers@vger.kernel.org >> Kernel Testers List" , Mike Galbraith , Peter Zijlstra , Linux Netdev List , linux-fsdevel@vger.kernel.org, Al Viro Subject: Re: [PATCH v3 6/7] fs: struct file move from call_rcu() to SLAB_DESTROY_BY_RCU In-Reply-To: <494295C6.2020906@cosmosbay.com> Message-ID: References: <493100B0.6090104@cosmosbay.com> <494196DD.5070600@cosmosbay.com> <200707241113.46834.nickpiggin@yahoo.com.au> <4941EC65.5040903@cosmosbay.com> <494295C6.2020906@cosmosbay.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Spam-Score: -2.6 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1583 Lines: 40 On Fri, 12 Dec 2008, Eric Dumazet wrote: > > a truly allocated file. At this point the file is > > a truly allocated file but not anymore ours. Its a valid file. Does ownership matter here? > Reading again this mail I realise we call put_filp(file), while this should > be fput(file) or put_filp(file), we dont know. > > Damned, this patch is wrong as is. > > Christoph, Paul, do you see the problem ? Yes. > In fget()/fget_light() we dont know if the other thread (the one who re-allocated the file, > and tried to close it while we got a reference on file) had to call put_filp() or fput() > to release its own reference. So we call atomic_long_dec_and_test() and cannot > take the appropriate action (calling the full __fput() version or the small one, > that some systems use to 'close' an not really opened file. The difference is mainly that fput() does full processing whereas put_filp() is used when we know that the file was not fully operational. If the checks in __fput are able to handle the put_filp() situation by not releasing resources that were not allocated then we should be fine. > I believe put_filp() is only called on slowpath (error cases). Looks like it. It seems to assume that no dentry is associated. > Should we just zap it and always call fput() ? Only if fput() can handle partially setup files. -- 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/