[PATCH 2/4] [RFC] virtio: Introduce new API to get free space
From: Krishna Kumar <hidden>
Date: 2011-05-04 14:03:26
Also in:
kvm
Introduce virtqueue_get_capacity() to help bail out of transmit path early. Also remove notification when we run out of space (I am not sure if this should be under a feature bit). Signed-off-by: Krishna Kumar <redacted> --- drivers/virtio/virtio_ring.c | 13 ++++++++----- include/linux/virtio.h | 5 +++++ 2 files changed, 13 insertions(+), 5 deletions(-) diff -ruNp org/include/linux/virtio.h new/include/linux/virtio.h
--- org/include/linux/virtio.h 2011-05-04 18:57:06.000000000 +0530
+++ new/include/linux/virtio.h 2011-05-04 18:57:09.000000000 +0530@@ -27,6 +27,9 @@ struct virtqueue { /** * operations for virtqueue + * virtqueue_get_capacity: Get vq capacity + * vq: the struct virtqueue we're talking about. + * Returns remaining capacity of queue * virtqueue_add_buf: expose buffer to other end * vq: the struct virtqueue we're talking about. * sg: the description of the buffer(s).
@@ -62,6 +65,8 @@ struct virtqueue { * All operations can be called in any context. */ +int virtqueue_get_capacity(struct virtqueue *vq); + int virtqueue_add_buf_gfp(struct virtqueue *vq, struct scatterlist sg[], unsigned int out_num,
diff -ruNp org/drivers/virtio/virtio_ring.c new/drivers/virtio/virtio_ring.c
--- org/drivers/virtio/virtio_ring.c 2011-05-04 18:57:06.000000000 +0530
+++ new/drivers/virtio/virtio_ring.c 2011-05-04 18:57:09.000000000 +0530@@ -156,6 +156,14 @@ static int vring_add_indirect(struct vri return head; } +int virtqueue_get_capacity(struct virtqueue *_vq) +{ + struct vring_virtqueue *vq = to_vvq(_vq); + + return vq->num_free; +} +EXPORT_SYMBOL_GPL(virtqueue_get_capacity); + int virtqueue_add_buf_gfp(struct virtqueue *_vq, struct scatterlist sg[], unsigned int out,
@@ -185,11 +193,6 @@ int virtqueue_add_buf_gfp(struct virtque if (vq->num_free < out + in) { pr_debug("Can't add buf len %i - avail = %i\n", out + in, vq->num_free); - /* FIXME: for historical reasons, we force a notify here if - * there are outgoing parts to the buffer. Presumably the - * host should service the ring ASAP. */ - if (out) - vq->notify(&vq->vq); END_USE(vq); return -ENOSPC; }