[PATCH net-next v4 1/2] vsock/virtio: refactor virtio_transport_send_pkt_work

Luigi Leonardi via B4 Relay
2024-07-30T19:47:35Z

From: Marco Pinna <marco.pinn95@gmail.com>

Preliminary patch to introduce an optimization to the
enqueue system.

All the code used to enqueue a packet into the virtqueue
is removed from virtio_transport_send_pkt_work()
and moved to the new virtio_transport_send_skb() function.

Co-developed-by: Luigi Leonardi <luigi.leonardi@outlook.com>
Signed-off-by: Luigi Leonardi <luigi.leonardi@outlook.com>
Signed-off-by: Marco Pinna <marco.pinn95@gmail.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
---
net/vmw_vsock/virtio_transport.c | 105 ++++++++++++++++++++++-----------------
1 file changed, 59 insertions(+), 46 deletions(-)

diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index 64a07acfef12..f641e906f351 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -94,6 +94,63 @@ static u32 virtio_transport_get_local_cid(void)
return ret;
}

+/* Caller need to hold vsock->tx_lock on vq */
+static int virtio_transport_send_skb(struct sk_buff *skb, struct virtqueue *vq,
+ struct virtio_vsock *vsock)
+{
+ int ret, in_sg = 0, out_sg = 0;
+ struct scatterlist **sgs;
+
+ sgs = vsock->out_sgs;
+ sg_init_one(sgs[out_sg], virtio_vsock_hdr(skb),
+ sizeof(*virtio_vsock_hdr(skb)));
+ out_sg++;
+
+ if (!skb_is_nonlinear(skb)) {
+ if (skb->len > 0) {
+ sg_init_one(sgs[out_sg], skb->data, skb->len);
+ out_sg++;
+ }
+ } else {
+ struct skb_shared_info *si;
+ int i;
+
+ /* If skb is nonlinear, then its buffer must contain
+ * only header and nothing more. Data is stored in
+ * the fragged part.
+ */
+ WARN_ON_ONCE(skb_headroom(skb) != sizeof(*virtio_vsock_hdr(skb)));
+
+ si = skb_shinfo(skb);
+
+ for (i = 0; i < si->nr_frags; i++) {
+ skb_frag_t *skb_frag = &si->frags[i];
+ void *va;
+
+ /* We will use 'page_to_virt()' for the userspace page
+ * here, because virtio or dma-mapping layers will call
+ * 'virt_to_phys()' later to fill the buffer descriptor.
+ * We don't touch memory at "virtual" address of this page.
+ */
+ va = page_to_virt(skb_frag_page(skb_frag));
+ sg_init_one(sgs[out_sg],
+ va + skb_frag_off(skb_frag),
+ skb_frag_size(skb_frag));
+ out_sg++;
+ }
+ }
+
+ ret = virtqueue_add_sgs(vq, sgs, out_sg, in_sg, skb, GFP_KERNEL);
+ /* Usually this means that there is no more space available in
+ * the vq
+ */
+ if (ret < 0)
+ return ret;
+
+ virtio_transport_deliver_tap_pkt(skb);
+ return 0;
+}
+
static void
virtio_transport_send_pkt_work(struct work_struct *work)
{
@@ -111,66 +168,22 @@ virtio_transport_send_pkt_work(struct work_struct *work)
vq = vsock->vqs[VSOCK_VQ_TX];

for (;;) {
- int ret, in_sg = 0, out_sg = 0;
- struct scatterlist **sgs;
struct sk_buff *skb;
bool reply;
+ int ret;

skb = virtio_vsock_skb_dequeue(&vsock->send_pkt_queue);
if (!skb)
break;

reply = virtio_vsock_skb_reply(skb);
- sgs = vsock->out_sgs;
- sg_init_one(sgs[out_sg], virtio_vsock_hdr(skb),
- sizeof(*virtio_vsock_hdr(skb)));
- out_sg++;
-
- if (!skb_is_nonlinear(skb)) {
- if (skb->len > 0) {
- sg_init_one(sgs[out_sg], skb->data, skb->len);
- out_sg++;
- }
- } else {
- struct skb_shared_info *si;
- int i;
-
- /* If skb is nonlinear, then its buffer must contain
- * only header and nothing more. Data is stored in
- * the fragged part.
- */
- WARN_ON_ONCE(skb_headroom(skb) != sizeof(*virtio_vsock_hdr(skb)));
-
- si = skb_shinfo(skb);

- for (i = 0; i < si->nr_frags; i++) {
- skb_frag_t *skb_frag = &si->frags[i];
- void *va;
-
- /* We will use 'page_to_virt()' for the userspace page
- * here, because virtio or dma-mapping layers will call
- * 'virt_to_phys()' later to fill the buffer descriptor.
- * We don't touch memory at "virtual" address of this page.
- */
- va = page_to_virt(skb_frag_page(skb_frag));
- sg_init_one(sgs[out_sg],
- va + skb_frag_off(skb_frag),
- skb_frag_size(skb_frag));
- out_sg++;
- }
- }
-
- ret = virtqueue_add_sgs(vq, sgs, out_sg, in_sg, skb, GFP_KERNEL);
- /* Usually this means that there is no more space available in
- * the vq
- */
+ ret = virtio_transport_send_skb(skb, vq, vsock);
if (ret < 0) {
virtio_vsock_skb_queue_head(&vsock->send_pkt_queue, skb);
break;
}

- virtio_transport_deliver_tap_pkt(skb);
-
if (reply) {
struct virtqueue *rx_vq = vsock->vqs[VSOCK_VQ_RX];
int val;

--
2.45.2