From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56924) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1evwXL-0005JE-U2 for qemu-devel@nongnu.org; Tue, 13 Mar 2018 22:53:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1evwXL-0000wK-1r for qemu-devel@nongnu.org; Tue, 13 Mar 2018 22:53:07 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:43410 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1evwXK-0000wC-Sr for qemu-devel@nongnu.org; Tue, 13 Mar 2018 22:53:06 -0400 Date: Wed, 14 Mar 2018 04:53:05 +0200 From: "Michael S. Tsirkin" Message-ID: <20180314045130-mutt-send-email-mst@kernel.org> References: <1520426065-40265-1-git-send-email-wei.w.wang@intel.com> <1520426065-40265-4-git-send-email-wei.w.wang@intel.com> <20180313183558-mutt-send-email-mst@kernel.org> <5AA88C35.90300@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5AA88C35.90300@intel.com> Subject: Re: [Qemu-devel] [virtio-dev] Re: [PATCH v4 3/4] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Wei Wang Cc: qemu-devel@nongnu.org, virtio-dev@lists.oasis-open.org, quintela@redhat.com, dgilbert@redhat.com, pbonzini@redhat.com, liliang.opensource@gmail.com, yang.zhang.wz@gmail.com, quan.xu0@gmail.com, nilal@redhat.com, riel@redhat.com On Wed, Mar 14, 2018 at 10:43:01AM +0800, Wei Wang wrote: > On 03/14/2018 12:49 AM, Michael S. Tsirkin wrote: > > On Wed, Mar 07, 2018 at 08:34:24PM +0800, Wei Wang wrote: > > > > > Signed-off-by: Wei Wang > > > Signed-off-by: Liang Li > > > CC: Michael S. Tsirkin > > > CC: Dr. David Alan Gilbert > > > CC: Juan Quintela > > I find it suspicious that neither unrealize nor reset > > functions have been touched at all. > > Are you sure you have thought through scenarious like > > hot-unplug or disabling the device by guest? > > OK. I think we can call balloon_free_page_stop in unrealize and reset. > > > > +static void *virtio_balloon_poll_free_page_hints(void *opaque) > > +{ > > + VirtQueueElement *elem; > > + VirtIOBalloon *dev = opaque; > > + VirtQueue *vq = dev->free_page_vq; > > + uint32_t id; > > + size_t size; > > What makes it safe to poke at this device from multiple threads? > > I think that it would be safer to do it from e.g. BH. > > > > Actually the free_page_optimization thread is the only user of free_page_vq, > and there is only one optimization thread each time. Would this be safe > enough? > > Best, > Wei Aren't there other fields there? Also things like reset affect all VQs. -- MST