From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH 1/2] virtio: Add detach unused buffer from vring Date: Sun, 20 Dec 2009 13:24:05 +0200 Message-ID: <20091220112405.GA11168@redhat.com> References: <1261122090.4148.24.camel@localhost.localdomain> <1261122230.4148.26.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Rusty Russell , Avi Kivity , netdev@vger.kernel.org, kvm@vger.kernel.org To: Shirley Ma Return-path: Received: from mx1.redhat.com ([209.132.183.28]:62730 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751442AbZLTL1G (ORCPT ); Sun, 20 Dec 2009 06:27:06 -0500 Content-Disposition: inline In-Reply-To: <1261122230.4148.26.camel@localhost.localdomain> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Dec 17, 2009 at 11:43:50PM -0800, Shirley Ma wrote: > There's currently no way for a virtio driver to ask for unused > buffers, so it has to keep a list itself to reclaim them at shutdown. > This is redundant, since virtio_ring stores that information. So > add a new hook to do this: virtio_net will be the first user. > > Signed-off-by: Shirley Ma Acked-by: Michael S. Tsirkin > --- > drivers/virtio/virtio_ring.c | 25 +++++++++++++++++++++++++ > include/linux/virtio.h | 4 ++++ > 2 files changed, 29 insertions(+), 0 deletions(-) > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index fbd2ecd..71929ee 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -334,6 +334,30 @@ static bool vring_enable_cb(struct virtqueue *_vq) > return true; > } > > +static void *vring_detach_unused_buf(struct virtqueue *_vq) > +{ > + struct vring_virtqueue *vq = to_vvq(_vq); > + unsigned int i; > + void *buf; > + > + START_USE(vq); > + > + for (i = 0; i < vq->vring.num; i++) { > + if (!vq->data[i]) > + continue; > + /* detach_buf clears data, so grab it now. */ > + buf = vq->data[i]; > + detach_buf(vq, i); > + END_USE(vq); > + return buf; > + } > + /* That should have freed everything. */ > + BUG_ON(vq->num_free != vq->vring.num); > + > + END_USE(vq); > + return NULL; > +} > + > irqreturn_t vring_interrupt(int irq, void *_vq) > { > struct vring_virtqueue *vq = to_vvq(_vq); > @@ -360,6 +384,7 @@ static struct virtqueue_ops vring_vq_ops = { > .kick = vring_kick, > .disable_cb = vring_disable_cb, > .enable_cb = vring_enable_cb, > + .detach_unused_buf = vring_detach_unused_buf, > }; > > struct virtqueue *vring_new_virtqueue(unsigned int num, > diff --git a/include/linux/virtio.h b/include/linux/virtio.h > index 057a2e0..f508c65 100644 > --- a/include/linux/virtio.h > +++ b/include/linux/virtio.h > @@ -51,6 +51,9 @@ struct virtqueue { > * This re-enables callbacks; it returns "false" if there are pending > * buffers in the queue, to detect a possible race between the driver > * checking for more work, and enabling callbacks. > + * @detach_unused_buf: detach first unused buffer > + * vq: the struct virtqueue we're talking about. > + * Returns NULL or the "data" token handed to add_buf > * > * Locking rules are straightforward: the driver is responsible for > * locking. No two operations may be invoked simultaneously, with the exception > @@ -71,6 +74,7 @@ struct virtqueue_ops { > > void (*disable_cb)(struct virtqueue *vq); > bool (*enable_cb)(struct virtqueue *vq); > + void *(*detach_unused_buf)(struct virtqueue *vq); > }; > > /** >