On Tue, Jun 23, 2026 at 06:38:19PM +0300, Arseniy Krasnov wrote:
> Logically it was based on TCP implementation, so to make further support
> easier, rewrite it in the TCP way (like in 'tcp_sendmsg_locked()'). This
> patch only rewrites flag handling (e.g. it doesn't change logic).
>
> Signed-off-by: Arseniy Krasnov <[email protected]>
It seems to change logic though:
> ---
> Changelog v1->v2:
> * Rebase on last 'net-next'. Don't need 'skb_zcopy_set()' now - it was
> already added.
> Changelog v2->v3:
> * Update commit message.
> * Remove one empty line.
>
> net/vmw_vsock/virtio_transport_common.c | 47 ++++++++++++-------------
> 1 file changed, 22 insertions(+), 25 deletions(-)
>
> diff --git a/net/vmw_vsock/virtio_transport_common.c
> b/net/vmw_vsock/virtio_transport_common.c
> index 09475007165b..41c2a0b82a8e 100644
> --- a/net/vmw_vsock/virtio_transport_common.c
> +++ b/net/vmw_vsock/virtio_transport_common.c
> @@ -328,38 +328,35 @@ static int virtio_transport_send_pkt_info(struct
> vsock_sock *vsk,
> if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW)
> return pkt_len;
>
> - if (info->msg) {
> - /* If zerocopy is not enabled by 'setsockopt()', we behave as
> - * there is no MSG_ZEROCOPY flag set.
> + if (info->msg && (info->msg->msg_flags & MSG_ZEROCOPY)) {
> + /* If 'info->msg' is not NULL, this is only VIRTIO_VSOCK_OP_RW.
> + * 'MSG_ZEROCOPY' flag handling here is based on the same flag
> + * handling from 'tcp_sendmsg_locked()'.
> */
> - if (!sock_flag(sk_vsock(vsk), SOCK_ZEROCOPY))
> - info->msg->msg_flags &= ~MSG_ZEROCOPY;
So previously without SOCK_ZEROCOPY, MSG_ZEROCOPY was always ignored...
> + if (info->msg->msg_ubuf) {
> + uarg = info->msg->msg_ubuf;
> + can_zcopy = virtio_transport_can_zcopy(t_ops, info,
> pkt_len);
now it's not in this case?
Maybe the right call, but saying "does not change logic" seems wrong.
> + } else if (sock_flag(sk_vsock(vsk), SOCK_ZEROCOPY)) {
> + uarg = msg_zerocopy_realloc(sk_vsock(vsk), pkt_len,
> + NULL, false);
> + if (!uarg) {
> + virtio_transport_put_credit(vvs, pkt_len);
> + return -ENOMEM;
> + }
>
> - if (info->msg->msg_flags & MSG_ZEROCOPY)
> can_zcopy = virtio_transport_can_zcopy(t_ops, info,
> pkt_len);
> + if (!can_zcopy)
> + uarg_to_msgzc(uarg)->zerocopy = 0;
>
> + have_uref = true;
> + }
> +
> + /* 'can_zcopy' means that this transmission will be
> + * in zerocopy way (e.g. using 'frags' array).
> + */
> if (can_zcopy)
> max_skb_len = min_t(u32, VIRTIO_VSOCK_MAX_PKT_BUF_SIZE,
> (MAX_SKB_FRAGS * PAGE_SIZE));
> -
> - if (info->msg->msg_flags & MSG_ZEROCOPY &&
> - info->op == VIRTIO_VSOCK_OP_RW) {
> - uarg = info->msg->msg_ubuf;
> -
> - if (!uarg) {
> - uarg = msg_zerocopy_realloc(sk_vsock(vsk),
> - pkt_len, NULL,
> false);
> - if (!uarg) {
> - virtio_transport_put_credit(vvs,
> pkt_len);
> - return -ENOMEM;
> - }
> -
> - if (!can_zcopy)
> - uarg_to_msgzc(uarg)->zerocopy = 0;
> -
> - have_uref = true;
> - }
> - }
> }
>
> rest_len = pkt_len;
> --
> 2.25.1
