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authorArseniy Krasnov <avkrasnov@salutedevices.com>2023-09-16 16:09:15 +0300
committerPaolo Abeni <pabeni@redhat.com>2023-09-21 12:34:00 +0200
commit0df7cd3c13e44d01f9f28e29cbce74e2931b00fe (patch)
treed0df79ec4196c2913d43cb741903d7039b4df1f6 /net
parentb3af9c0e89ca721dfed95401c88c8c6e8067b558 (diff)
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 'net')
-rw-r--r--net/vmw_vsock/virtio_transport_common.c32
1 files changed, 19 insertions, 13 deletions
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index 352d042b130b..3e08d52a9355 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -364,9 +364,10 @@ virtio_transport_stream_do_peek(struct vsock_sock *vsk,
spin_unlock_bh(&vvs->rx_lock);
/* sk_lock is held by caller so no one else can dequeue.
- * Unlock rx_lock since memcpy_to_msg() may sleep.
+ * Unlock rx_lock since skb_copy_datagram_iter() may sleep.
*/
- err = memcpy_to_msg(msg, skb->data, bytes);
+ err = skb_copy_datagram_iter(skb, VIRTIO_VSOCK_SKB_CB(skb)->offset,
+ &msg->msg_iter, bytes);
if (err)
goto out;
@@ -410,25 +411,27 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,
while (total < len && !skb_queue_empty(&vvs->rx_queue)) {
skb = skb_peek(&vvs->rx_queue);
- bytes = len - total;
- if (bytes > skb->len)
- bytes = skb->len;
+ bytes = min_t(size_t, len - total,
+ skb->len - VIRTIO_VSOCK_SKB_CB(skb)->offset);
/* sk_lock is held by caller so no one else can dequeue.
- * Unlock rx_lock since memcpy_to_msg() may sleep.
+ * Unlock rx_lock since skb_copy_datagram_iter() may sleep.
*/
spin_unlock_bh(&vvs->rx_lock);
- err = memcpy_to_msg(msg, skb->data, bytes);
+ err = skb_copy_datagram_iter(skb,
+ VIRTIO_VSOCK_SKB_CB(skb)->offset,
+ &msg->msg_iter, bytes);
if (err)
goto out;
spin_lock_bh(&vvs->rx_lock);
total += bytes;
- skb_pull(skb, bytes);
- if (skb->len == 0) {
+ VIRTIO_VSOCK_SKB_CB(skb)->offset += bytes;
+
+ if (skb->len == VIRTIO_VSOCK_SKB_CB(skb)->offset) {
u32 pkt_len = le32_to_cpu(virtio_vsock_hdr(skb)->len);
virtio_transport_dec_rx_pkt(vvs, pkt_len);
@@ -492,9 +495,10 @@ virtio_transport_seqpacket_do_peek(struct vsock_sock *vsk,
spin_unlock_bh(&vvs->rx_lock);
/* sk_lock is held by caller so no one else can dequeue.
- * Unlock rx_lock since memcpy_to_msg() may sleep.
+ * Unlock rx_lock since skb_copy_datagram_iter() may sleep.
*/
- err = memcpy_to_msg(msg, skb->data, bytes);
+ err = skb_copy_datagram_iter(skb, VIRTIO_VSOCK_SKB_CB(skb)->offset,
+ &msg->msg_iter, bytes);
if (err)
return err;
@@ -553,11 +557,13 @@ static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
int err;
/* sk_lock is held by caller so no one else can dequeue.
- * Unlock rx_lock since memcpy_to_msg() may sleep.
+ * Unlock rx_lock since skb_copy_datagram_iter() may sleep.
*/
spin_unlock_bh(&vvs->rx_lock);
- err = memcpy_to_msg(msg, skb->data, bytes_to_copy);
+ err = skb_copy_datagram_iter(skb, 0,
+ &msg->msg_iter,
+ bytes_to_copy);
if (err) {
/* Copy of message failed. Rest of
* fragments will be freed without copy.