summaryrefslogtreecommitdiff
path: root/drivers/vhost
diff options
context:
space:
mode:
authorArseniy Krasnov <avkrasnov@salutedevices.com>2023-09-16 16:09:15 +0300
committerPaolo Abeni <pabeni@redhat.com>2023-09-21 13:34:00 +0300
commit0df7cd3c13e44d01f9f28e29cbce74e2931b00fe (patch)
treed0df79ec4196c2913d43cb741903d7039b4df1f6 /drivers/vhost
parentb3af9c0e89ca721dfed95401c88c8c6e8067b558 (diff)
downloadlinux-0df7cd3c13e44d01f9f28e29cbce74e2931b00fe.tar.xz
vsock/virtio/vhost: read data from non-linear skb
This is preparation patch for MSG_ZEROCOPY support. It adds handling of non-linear skbs by replacing direct calls of 'memcpy_to_msg()' with 'skb_copy_datagram_iter()'. Main advantage of the second one is that it can handle paged part of the skb by using 'kmap()' on each page, but if there are no pages in the skb, it behaves like simple copying to iov iterator. This patch also adds new field to the control block of skb - this value shows current offset in the skb to read next portion of data (it doesn't matter linear it or not). Idea behind this field is that 'skb_copy_datagram_iter()' handles both types of skb internally - it just needs an offset from which to copy data from the given skb. This offset is incremented on each read from skb. This approach allows to simplify handling of both linear and non-linear skbs, because for linear skb we need to call 'skb_pull()' after reading data from it, while in non-linear case we need to update 'data_len'. Signed-off-by: Arseniy Krasnov <avkrasnov@salutedevices.com> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Diffstat (limited to 'drivers/vhost')
-rw-r--r--drivers/vhost/vsock.c14
1 files changed, 9 insertions, 5 deletions
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 817d377a3f36..83711aad855c 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -114,6 +114,7 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
struct sk_buff *skb;
unsigned out, in;
size_t nbytes;
+ u32 offset;
int head;
skb = virtio_vsock_skb_dequeue(&vsock->send_pkt_queue);
@@ -156,7 +157,8 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
}
iov_iter_init(&iov_iter, ITER_DEST, &vq->iov[out], in, iov_len);
- payload_len = skb->len;
+ offset = VIRTIO_VSOCK_SKB_CB(skb)->offset;
+ payload_len = skb->len - offset;
hdr = virtio_vsock_hdr(skb);
/* If the packet is greater than the space available in the
@@ -197,8 +199,10 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
break;
}
- nbytes = copy_to_iter(skb->data, payload_len, &iov_iter);
- if (nbytes != payload_len) {
+ if (skb_copy_datagram_iter(skb,
+ offset,
+ &iov_iter,
+ payload_len)) {
kfree_skb(skb);
vq_err(vq, "Faulted on copying pkt buf\n");
break;
@@ -212,13 +216,13 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
vhost_add_used(vq, head, sizeof(*hdr) + payload_len);
added = true;
- skb_pull(skb, payload_len);
+ VIRTIO_VSOCK_SKB_CB(skb)->offset += payload_len;
total_len += payload_len;
/* If we didn't send all the payload we can requeue the packet
* to send it with the next available buffer.
*/
- if (skb->len > 0) {
+ if (VIRTIO_VSOCK_SKB_CB(skb)->offset < skb->len) {
hdr->flags |= cpu_to_le32(flags_to_restore);
/* We are queueing the same skb to handle