From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45315) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1agAdb-0001dw-FC for qemu-devel@nongnu.org; Wed, 16 Mar 2016 08:33:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1agAdX-0002hi-Eg for qemu-devel@nongnu.org; Wed, 16 Mar 2016 08:33:19 -0400 References: <1458123018-18651-1-git-send-email-famz@redhat.com> <56E9355A.5070700@redhat.com> <56E93A22.1080102@de.ibm.com> <56E93ECE.10103@redhat.com> <20160316123213.3dcf0abc.cornelia.huck@de.ibm.com> <56E94806.7060505@redhat.com> <20160316125623.38ab4c7e.cornelia.huck@de.ibm.com> <56E94AA9.8000803@redhat.com> <20160316132212.674f766f.cornelia.huck@de.ibm.com> From: Paolo Bonzini Message-ID: <56E9527B.9010001@redhat.com> Date: Wed, 16 Mar 2016 13:32:59 +0100 MIME-Version: 1.0 In-Reply-To: <20160316132212.674f766f.cornelia.huck@de.ibm.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Cornelia Huck Cc: Kevin Wolf , Fam Zheng , qemu-block@nongnu.org, "Michael S. Tsirkin" , qemu-devel@nongnu.org, Christian Borntraeger , tubo@linux.vnet.ibm.com, Stefan Hajnoczi On 16/03/2016 13:22, Cornelia Huck wrote: >> > Yeah, it doesn't help that the functions are underdocumented (as in = the >> > "assign" parameter above). > My understanding is: >=20 > - 'assign': set up a new notifier (true) or disable it (false) > - 'set_handler': use our handler (true) or have it handled elsewhere > (false) Right. So if we're setting up a new notifier in virtio_queue_aio_set_host_notifier_handler, virtio_pci_stop_ioeventfd sho= uld > > > I don't think the ->set_host_notifiers() api really allows for this= . > >=20 > > I think it does, assign is the last argument to k->set_host_notifier(= ). >=20 > This depends on whether we want 'assign' to clean up any old notifiers > before setting up new ones. I think we want different behaviour for > dataplane and vhost. I think dataplane and vhost are the same. The question is whether ioeventfd=3Doff,vhost=3Don or ioeventfd=3Doff,dataplane=3Don are valid combinations; I think they aren'= t. If they aren't, it should be okay to remove the virtio_queue_host_notifier_read call in virtio_queue_set_host_notifier_fd_handler and virtio_queue_aio_set_host_notifier_handler. That's because a handler for the notifier will always be set _somewhere_. It could be the usual ioeventfd handler, the vhost handler or the dataplane handler, but one will be there. Paolo