From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCHv2] kvm: remove in_range and switch to rwsem for iobus Date: Mon, 29 Jun 2009 11:37:00 +0300 Message-ID: <4A487D2C.2020007@redhat.com> References: <20090628193425.GA14204@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: Gregory Haskins , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, mtosatti@redhat.com, paulmck@linux.vnet.ibm.com, markmc@redhat.com To: "Michael S. Tsirkin" Return-path: Received: from mx2.redhat.com ([66.187.237.31]:44606 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752542AbZF2Ifa (ORCPT ); Mon, 29 Jun 2009 04:35:30 -0400 In-Reply-To: <20090628193425.GA14204@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 06/28/2009 10:34 PM, Michael S. Tsirkin wrote: > This changes bus accesses to use high-level kvm_io_bus_read/kvm_io_bus_write > functions, which utilize read/write semaphore intead of mutex. in_range now > becomes unused so it is removed from device ops in favor of read/write > callbacks performing range checks internally. > > This allows aliasing (mostly for in-kernel virtio), as well as better error > handling by making it possible to pass errors up to userspace. And it's enough > to look at the diffstat to see that it's a better API anyway. > > While we are at it, document locking rules for kvm_io_device_ops. > > Note: since the use of the new bus_lock is localized to a small number of > places, it will be easy to switch to srcu in the future if we so desire. > Looks good. But please split into a locking change patch and an API change patch (in whatever order makes more sense). I think you can reuse slots_lock instead of adding a new lock. IIRC slots_lock is already taken for read everywhere, so you only need to take it for write when registering things. -- error compiling committee.c: too many arguments to function