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authorShirley Ma <mashirle@us.ibm.com>2010-01-18 14:45:23 +0100
committerRusty Russell <rusty@rustcorp.com.au>2010-02-24 04:52:27 +0100
commitc021eac4148c16bf53baa0dd14e8ebee6f39dab5 (patch)
tree558db2ede74488606614d6e7e277f9914e38fbc1
parentvirtio_blk: add block topology support (diff)
downloadlinux-c021eac4148c16bf53baa0dd14e8ebee6f39dab5.tar.xz
linux-c021eac4148c16bf53baa0dd14e8ebee6f39dab5.zip
virtio: Add ability to detach unused buffers from vrings
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. Signed-off-by: Shirley Ma <xma@us.ibm.com> Signed-off-by: Amit Shah <amit.shah@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
-rw-r--r--drivers/virtio/virtio_ring.c25
-rw-r--r--include/linux/virtio.h4
2 files changed, 29 insertions, 0 deletions
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 827f7e042610..782b7292a3d8 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -351,6 +351,30 @@ 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);
@@ -377,6 +401,7 @@ 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 057a2e010758..f508c651e53d 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);
};
/**