From mboxrd@z Thu Jan 1 00:00:00 1970 From: Octavian Purdila Subject: Re: [net-next PATCH v4 1/3] sysctl: refactor integer handling proc code Date: Wed, 17 Feb 2010 23:09:14 +0200 Message-ID: <201002172009.14191.opurdila@ixiacom.com> References: <1266271241-6293-1-git-send-email-opurdila@ixiacom.com> <201002161600.54975.opurdila@ixiacom.com> <4B7C19F1.9090106@redhat.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: David Miller , Linux Kernel Network Developers , Linux Kernel Developers , "Eric W. Biederman" To: Cong Wang Return-path: In-Reply-To: <4B7C19F1.9090106@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Wednesday 17 February 2010 15:31:45 you wrote: > >>> > >>> What about the EFAULT check, is that really required? > >> > >> I think so, it means to keep the errno to user-space when it is EFAULT, > >> right? This seems reasonable. > > > > The problem I see is that this way we don't actually acknowledge some of > > the set values, e.g. say that we have buffer="1 2 3" and length = 100. > > Although we do accept values 1, 2 and 3 we don't acknowledge that to the > > user (as we would do for, say "1 2 3 4a"), but return -EFAULT. > > > > I think it would be better to skip this check. That means that the user > > will get the ack for the 1, 2 and 3 values and next time it continues the > > write it will get -EFAULT. > > > > This will of course change the userspace ABI, albeit in a minor way, and > > it is not clear to me if doing this is allowed (even if this new approach > > would be the correct one). > > I think the right behavior is accept "1 2 3" and return the number of > bytes that we accept. > OK, it seems nobody is complaining about this corner case ABI change. I will remove the EFAULT check then. This will also help with making the code clearer, I hope.