6/23/26 20:26, Michael S. Tsirkin wrote:
> 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?
Yes, this case is currently for io_uring only, because io_uring doesn't set
SOCK_ZEROCOPY to perform zerocopy transmission.
>
>
> Maybe the right call, but saying "does not change logic" seems wrong.
Agree, I need to update commit message again :)
Thanks
>
>
>> + } 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
