Re: [PATCH 1/2] virtio: Add detach unused buffer from vring
On (Thu) Dec 17 2009 [23:43:50], 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 x...@us.ibm.com Acked-By: Amit Shah amit.s...@redhat.com Amit -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 1/2] virtio: Add detach unused buffer from vring
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 x...@us.ibm.com
Acked-by: Michael S. Tsirkin m...@redhat.com
---
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);
};
/**
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[PATCH 1/2] virtio: Add detach unused buffer from vring
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 x...@us.ibm.com
---
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);
};
/**
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