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Message-ID: <8014f898ca6b768d7be626b83c617a1e84adfeb9.1307029009.git.mst@redhat.com>
Date: Thu, 2 Jun 2011 18:42:59 +0300
From: "Michael S. Tsirkin" <mst@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: Rusty Russell <rusty@...tcorp.com.au>,
Carsten Otte <cotte@...ibm.com>,
Christian Borntraeger <borntraeger@...ibm.com>,
linux390@...ibm.com, Martin Schwidefsky <schwidefsky@...ibm.com>,
Heiko Carstens <heiko.carstens@...ibm.com>,
Shirley Ma <xma@...ibm.com>, lguest@...ts.ozlabs.org,
linux-kernel@...r.kernel.org,
virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
linux-s390@...r.kernel.org, kvm@...r.kernel.org,
Krishna Kumar <krkumar2@...ibm.com>,
Tom Lendacky <tahm@...ux.vnet.ibm.com>, steved@...ibm.com,
habanero@...ux.vnet.ibm.com
Subject: [PATCHv2 RFC 1/4] virtio_ring: add capacity check API
Add API to check ring capacity. Because of the option
to use indirect buffers, this returns the worst
case, not the normal case capacity.
Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
---
drivers/virtio/virtio_ring.c | 8 ++++++++
include/linux/virtio.h | 5 +++++
2 files changed, 13 insertions(+), 0 deletions(-)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 68b9136..23422f1 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -344,6 +344,14 @@ void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len)
}
EXPORT_SYMBOL_GPL(virtqueue_get_buf);
+int virtqueue_min_capacity(struct virtqueue *_vq)
+{
+ struct vring_virtqueue *vq = to_vvq(_vq);
+
+ return vq->num_free;
+}
+EXPORT_SYMBOL_GPL(virtqueue_min_capacity);
+
void virtqueue_disable_cb(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 7108857..209220d 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -42,6 +42,9 @@ struct virtqueue {
* vq: the struct virtqueue we're talking about.
* len: the length written into the buffer
* Returns NULL or the "data" token handed to add_buf.
+ * virtqueue_min_capacity: get the current capacity of the queue
+ * vq: the struct virtqueue we're talking about.
+ * Returns the current worst case capacity of the queue.
* virtqueue_disable_cb: disable callbacks
* vq: the struct virtqueue we're talking about.
* Note that this is not necessarily synchronous, hence unreliable and only
@@ -89,6 +92,8 @@ void virtqueue_kick(struct virtqueue *vq);
void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len);
+int virtqueue_min_capacity(struct virtqueue *vq);
+
void virtqueue_disable_cb(struct virtqueue *vq);
bool virtqueue_enable_cb(struct virtqueue *vq);
--
1.7.5.53.gc233e
--
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