Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753258Ab3F0Kso (ORCPT ); Thu, 27 Jun 2013 06:48:44 -0400 Received: from mail-pa0-f47.google.com ([209.85.220.47]:33306 "EHLO mail-pa0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752400Ab3F0Ksl (ORCPT ); Thu, 27 Jun 2013 06:48:41 -0400 Message-ID: <51CC1881.5060500@ozlabs.ru> Date: Thu, 27 Jun 2013 20:48:33 +1000 From: Alexey Kardashevskiy User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130514 Thunderbird/17.0.6 MIME-Version: 1.0 To: Benjamin Herrenschmidt CC: Stephen Rothwell , linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, Alexander Graf , kvm-ppc@vger.kernel.org, linux-kernel@vger.kernel.org, Alex Williamson , Paul Mackerras , "Paul E . McKenney" , David Gibson Subject: Re: [PATCH 3/8] vfio: add external user support References: <1372309356-28320-1-git-send-email-aik@ozlabs.ru> <1372309356-28320-4-git-send-email-aik@ozlabs.ru> <20130627165929.3828c261c957845a549ad95b@canb.auug.org.au> <1372326166.18612.42.camel@pasglop> In-Reply-To: <1372326166.18612.42.camel@pasglop> Content-Type: text/plain; charset=KOI8-R Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1188 Lines: 31 On 06/27/2013 07:42 PM, Benjamin Herrenschmidt wrote: > On Thu, 2013-06-27 at 16:59 +1000, Stephen Rothwell wrote: >>> +/* Allows an external user (for example, KVM) to unlock an IOMMU >> group */ >>> +static void vfio_group_del_external_user(struct file *filep) >>> +{ >>> + struct vfio_group *group = filep->private_data; >>> + >>> + BUG_ON(filep->f_op != &vfio_group_fops); >> >> We usually reserve BUG_ON for situations where there is no way to >> continue running or continuing will corrupt the running kernel. Maybe >> WARN_ON() and return? > > Not even that. This is a user space provided "fd", we shouldn't oops the > kernel because we passed a wrong argument, just return -EINVAL or > something like that (add a return code). I'll change to WARN_ON but... This is going to be called on KVM exit on a file pointer previously verified for correctness. If it is a wrong file*, then something went terribly wrong. -- Alexey -- 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/