From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [KVM PATCH v7 2/3] kvm: add support for irqfd via eventfd-notification interface Date: Thu, 14 May 2009 15:20:38 +0300 Message-ID: <4A0C0C96.6050600@redhat.com> References: <20090512181134.26131.10023.stgit@dev.haskins.net> <20090512182655.26131.53824.stgit@dev.haskins.net> <4A0BE8CA.7080801@redhat.com> <4A0C060D.2060107@novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, viro@ZenIV.linux.org.uk, linux-kernel@vger.kernel.org, davidel@xmailserver.org To: Gregory Haskins Return-path: Received: from mx2.redhat.com ([66.187.237.31]:55684 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752800AbZENMUj (ORCPT ); Thu, 14 May 2009 08:20:39 -0400 In-Reply-To: <4A0C060D.2060107@novell.com> Sender: kvm-owner@vger.kernel.org List-ID: Gregory Haskins wrote: >> Please fget() the new fd and compare the filps; fds aren't meaningful >> in the kernel. You can also drop _irqfd::fd. >> > > I like this as a second option... > > >> It may also be useful to compare the gsi, this allows a >> "make-before-break" switchover: >> > > ...but I like this best. Good idea. > I thought of comparing both. >> - guest reroutes irq to a different gsi >> - associate irqfd with new gsi >> - disassociate irqfd from old gsi >> >> >>> + >>> + irqfd_release(irqfd); >>> + mutex_unlock(&kvm->lock); >>> + return 0; >>> >>> >> Don't return, userspace may have multiple associations? >> > > Parse error. Can you elaborate? > > You break out of the look when you match your irqfd. But there may be multiple matches. Granted, it doesn't make much sense to hook the same fd to the same gsi multiple times (it may make sense to hook multiple fds to a single gsi, or maybe a single fd to multiple gsis), but it pays to have a consistent do-what-I-said-even-if-it-doesn't-make-sense interface. -- error compiling committee.c: too many arguments to function