Re: [PATCH net-next v3 4/4] vsock/virtio: MSG_ZEROCOPY flag support
From: Arseniy Krasnov
Date: Tue Jul 25 2023 - 09:35:47 EST
On 25.07.2023 16:23, Michael S. Tsirkin wrote:
> On Tue, Jul 25, 2023 at 04:10:40PM +0300, Arseniy Krasnov wrote:
>>
>>
>> On 25.07.2023 14:59, Michael S. Tsirkin wrote:
>>> On Tue, Jul 25, 2023 at 11:39:22AM +0300, Arseniy Krasnov wrote:
>>>>
>>>>
>>>> On 25.07.2023 11:25, Michael S. Tsirkin wrote:
>>>>> On Fri, Jul 21, 2023 at 12:42:45AM +0300, Arseniy Krasnov wrote:
>>>>>> This adds handling of MSG_ZEROCOPY flag on transmission path: if this
>>>>>> flag is set and zerocopy transmission is possible (enabled in socket
>>>>>> options and transport allows zerocopy), then non-linear skb will be
>>>>>> created and filled with the pages of user's buffer. Pages of user's
>>>>>> buffer are locked in memory by 'get_user_pages()'. Second thing that
>>>>>> this patch does is replace type of skb owning: instead of calling
>>>>>> 'skb_set_owner_sk_safe()' it calls 'skb_set_owner_w()'. Reason of this
>>>>>> change is that '__zerocopy_sg_from_iter()' increments 'sk_wmem_alloc'
>>>>>> of socket, so to decrease this field correctly proper skb destructor is
>>>>>> needed: 'sock_wfree()'. This destructor is set by 'skb_set_owner_w()'.
>>>>>>
>>>>>> Signed-off-by: Arseniy Krasnov <AVKrasnov@xxxxxxxxxxxxxx>
>>>>>> ---
>>>>>> Changelog:
>>>>>> v5(big patchset) -> v1:
>>>>>> * Refactorings of 'if' conditions.
>>>>>> * Remove extra blank line.
>>>>>> * Remove 'frag_off' field unneeded init.
>>>>>> * Add function 'virtio_transport_fill_skb()' which fills both linear
>>>>>> and non-linear skb with provided data.
>>>>>> v1 -> v2:
>>>>>> * Use original order of last four arguments in 'virtio_transport_alloc_skb()'.
>>>>>> v2 -> v3:
>>>>>> * Add new transport callback: 'msgzerocopy_check_iov'. It checks that
>>>>>> provided 'iov_iter' with data could be sent in a zerocopy mode.
>>>>>> If this callback is not set in transport - transport allows to send
>>>>>> any 'iov_iter' in zerocopy mode. Otherwise - if callback returns 'true'
>>>>>> then zerocopy is allowed. Reason of this callback is that in case of
>>>>>> G2H transmission we insert whole skb to the tx virtio queue and such
>>>>>> skb must fit to the size of the virtio queue to be sent in a single
>>>>>> iteration (may be tx logic in 'virtio_transport.c' could be reworked
>>>>>> as in vhost to support partial send of current skb). This callback
>>>>>> will be enabled only for G2H path. For details pls see comment
>>>>>> 'Check that tx queue...' below.
>>>>>>
>>>>>> include/net/af_vsock.h | 3 +
>>>>>> net/vmw_vsock/virtio_transport.c | 39 ++++
>>>>>> net/vmw_vsock/virtio_transport_common.c | 257 ++++++++++++++++++------
>>>>>> 3 files changed, 241 insertions(+), 58 deletions(-)
>>>>>>
>>>>>> diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
>>>>>> index 0e7504a42925..a6b346eeeb8e 100644
>>>>>> --- a/include/net/af_vsock.h
>>>>>> +++ b/include/net/af_vsock.h
>>>>>> @@ -177,6 +177,9 @@ struct vsock_transport {
>>>>>>
>>>>>> /* Read a single skb */
>>>>>> int (*read_skb)(struct vsock_sock *, skb_read_actor_t);
>>>>>> +
>>>>>> + /* Zero-copy. */
>>>>>> + bool (*msgzerocopy_check_iov)(const struct iov_iter *);
>>>>>> };
>>>>>>
>>>>>> /**** CORE ****/
>>>>>> diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
>>>>>> index 7bbcc8093e51..23cb8ed638c4 100644
>>>>>> --- a/net/vmw_vsock/virtio_transport.c
>>>>>> +++ b/net/vmw_vsock/virtio_transport.c
>>>>>> @@ -442,6 +442,43 @@ static void virtio_vsock_rx_done(struct virtqueue *vq)
>>>>>> queue_work(virtio_vsock_workqueue, &vsock->rx_work);
>>>>>> }
>>>>>>
>>>>>> +static bool virtio_transport_msgzerocopy_check_iov(const struct iov_iter *iov)
>>>>>> +{
>>>>>> + struct virtio_vsock *vsock;
>>>>>> + bool res = false;
>>>>>> +
>>>>>> + rcu_read_lock();
>>>>>> +
>>>>>> + vsock = rcu_dereference(the_virtio_vsock);
>>>>>> + if (vsock) {
>>>>>> + struct virtqueue *vq;
>>>>>> + int iov_pages;
>>>>>> +
>>>>>> + vq = vsock->vqs[VSOCK_VQ_TX];
>>>>>> +
>>>>>> + iov_pages = round_up(iov->count, PAGE_SIZE) / PAGE_SIZE;
>>>>>> +
>>>>>> + /* Check that tx queue is large enough to keep whole
>>>>>> + * data to send. This is needed, because when there is
>>>>>> + * not enough free space in the queue, current skb to
>>>>>> + * send will be reinserted to the head of tx list of
>>>>>> + * the socket to retry transmission later, so if skb
>>>>>> + * is bigger than whole queue, it will be reinserted
>>>>>> + * again and again, thus blocking other skbs to be sent.
>>>>>> + * Each page of the user provided buffer will be added
>>>>>> + * as a single buffer to the tx virtqueue, so compare
>>>>>> + * number of pages against maximum capacity of the queue.
>>>>>> + * +1 means buffer for the packet header.
>>>>>> + */
>>>>>> + if (iov_pages + 1 <= vq->num_max)
>>>>>> + res = true;
>>>>>
>>>>>
>>>>> Yes but can't there already be buffers in the queue?
>>>>> Then you can't stick num_max there.
>>>>
>>>> I think, that it is not critical, because vhost part always tries to process all
>>>> incoming buffers (yes, 'vhost_exceeds_weight()' breaks at some moment, but it will
>>>> reschedule tx kick ('vhost_vsock_handle_tx_kick()') work again), so current "too
>>>> big" skb will wait until there will be enough space in queue and as it is requeued
>>>> to the head of tx list it will be inserted to tx queue first.
>>>>
>>>> But anyway, I agree that comparing to 'num_free' may be more effective to the whole
>>>> system performance...
>>>>
>>>> Thanks, Arseniy
>>>
>>> Oh I see. It makes sense then - instead of copying just so we can
>>> stick it in the queue, wait a bit and send later.
>>> Also - for stream transports can't the message be split
>>> and sent chunk by chunk? Better than copying ...
>>
>> Technically yes, also we can split message for non-stream sockets (as vhost
>> does when it copies data to rx buffers of the guest),
>
> Won't breaking up messages break applications though?
No, for seqpacket we have special marker + port in each message, so we
can restore original message at the receiver and pass it to the socket.
Thanks, Arseniy
>
>
>> but it requires to rework
>> current implementation by adding buffers one by one to the tx queue. I think
>> it was not implemented here because until MSG_ZEROCOPY all skbs requires one
>> (if it is control message) or two (with payload) buffers, so there is no big
>> sense in processing max two buffers in "one-by-one" mode - we can just wait
>> for space.
>>
>> May be, I can add this logic for non-linear skb's here:
>>
>> if (skb->len > vq->max_num)
>> add buffers "one-by-one", incrementing internal offset in skb,
>> if (new skb insertion fails)
>> requeue skb, wait for space.
>>
>> In TX done callback I'll call consume skb only when above mentioned internal
>> offset == skb->len. I think this approach allows to get rid of new 'check_iov'
>> callback from this patch.
>>
>>
>> Stefano, what do You think?
>>
>> Thanks, Arseniy
>>
>>>
>>>
>>>>>
>>>>>
>>>>>> + }
>>>>>> +
>>>>>> + rcu_read_unlock();
>>>>>> +
>>>>>> + return res;
>>>>>> +}
>>>>>> +
>>>>>> static bool virtio_transport_seqpacket_allow(u32 remote_cid);
>>>>>>
>>>>>> static struct virtio_transport virtio_transport = {
>>>>>> @@ -475,6 +512,8 @@ static struct virtio_transport virtio_transport = {
>>>>>> .seqpacket_allow = virtio_transport_seqpacket_allow,
>>>>>> .seqpacket_has_data = virtio_transport_seqpacket_has_data,
>>>>>>
>>>>>> + .msgzerocopy_check_iov = virtio_transport_msgzerocopy_check_iov,
>>>>>> +
>>>>>> .notify_poll_in = virtio_transport_notify_poll_in,
>>>>>> .notify_poll_out = virtio_transport_notify_poll_out,
>>>>>> .notify_recv_init = virtio_transport_notify_recv_init,
>>>>>> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
>>>>>> index 26a4d10da205..e4e3d541aff4 100644
>>>>>> --- a/net/vmw_vsock/virtio_transport_common.c
>>>>>> +++ b/net/vmw_vsock/virtio_transport_common.c
>>>>>> @@ -37,73 +37,122 @@ virtio_transport_get_ops(struct vsock_sock *vsk)
>>>>>> return container_of(t, struct virtio_transport, transport);
>>>>>> }
>>>>>>
>>>>>> -/* Returns a new packet on success, otherwise returns NULL.
>>>>>> - *
>>>>>> - * If NULL is returned, errp is set to a negative errno.
>>>>>> - */
>>>>>> -static struct sk_buff *
>>>>>> -virtio_transport_alloc_skb(struct virtio_vsock_pkt_info *info,
>>>>>> - size_t len,
>>>>>> - u32 src_cid,
>>>>>> - u32 src_port,
>>>>>> - u32 dst_cid,
>>>>>> - u32 dst_port)
>>>>>> -{
>>>>>> - const size_t skb_len = VIRTIO_VSOCK_SKB_HEADROOM + len;
>>>>>> - struct virtio_vsock_hdr *hdr;
>>>>>> - struct sk_buff *skb;
>>>>>> - void *payload;
>>>>>> - int err;
>>>>>> +static bool virtio_transport_can_zcopy(struct virtio_vsock_pkt_info *info,
>>>>>> + size_t max_to_send)
>>>>>> +{
>>>>>> + const struct vsock_transport *t;
>>>>>> + struct iov_iter *iov_iter;
>>>>>>
>>>>>> - skb = virtio_vsock_alloc_skb(skb_len, GFP_KERNEL);
>>>>>> - if (!skb)
>>>>>> - return NULL;
>>>>>> + if (!info->msg)
>>>>>> + return false;
>>>>>>
>>>>>> - hdr = virtio_vsock_hdr(skb);
>>>>>> - hdr->type = cpu_to_le16(info->type);
>>>>>> - hdr->op = cpu_to_le16(info->op);
>>>>>> - hdr->src_cid = cpu_to_le64(src_cid);
>>>>>> - hdr->dst_cid = cpu_to_le64(dst_cid);
>>>>>> - hdr->src_port = cpu_to_le32(src_port);
>>>>>> - hdr->dst_port = cpu_to_le32(dst_port);
>>>>>> - hdr->flags = cpu_to_le32(info->flags);
>>>>>> - hdr->len = cpu_to_le32(len);
>>>>>> + iov_iter = &info->msg->msg_iter;
>>>>>>
>>>>>> - if (info->msg && len > 0) {
>>>>>> - payload = skb_put(skb, len);
>>>>>> - err = memcpy_from_msg(payload, info->msg, len);
>>>>>> - if (err)
>>>>>> - goto out;
>>>>>> + t = vsock_core_get_transport(info->vsk);
>>>>>>
>>>>>> - if (msg_data_left(info->msg) == 0 &&
>>>>>> - info->type == VIRTIO_VSOCK_TYPE_SEQPACKET) {
>>>>>> - hdr->flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
>>>>>> + if (t->msgzerocopy_check_iov &&
>>>>>> + !t->msgzerocopy_check_iov(iov_iter))
>>>>>> + return false;
>>>>>>
>>>>>> - if (info->msg->msg_flags & MSG_EOR)
>>>>>> - hdr->flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
>>>>>> - }
>>>>>> + /* Data is simple buffer. */
>>>>>> + if (iter_is_ubuf(iov_iter))
>>>>>> + return true;
>>>>>> +
>>>>>> + if (!iter_is_iovec(iov_iter))
>>>>>> + return false;
>>>>>> +
>>>>>> + if (iov_iter->iov_offset)
>>>>>> + return false;
>>>>>> +
>>>>>> + /* We can't send whole iov. */
>>>>>> + if (iov_iter->count > max_to_send)
>>>>>> + return false;
>>>>>> +
>>>>>> + return true;
>>>>>> +}
>>>>>> +
>>>>>> +static int virtio_transport_init_zcopy_skb(struct vsock_sock *vsk,
>>>>>> + struct sk_buff *skb,
>>>>>> + struct msghdr *msg,
>>>>>> + bool zerocopy)
>>>>>> +{
>>>>>> + struct ubuf_info *uarg;
>>>>>> +
>>>>>> + if (msg->msg_ubuf) {
>>>>>> + uarg = msg->msg_ubuf;
>>>>>> + net_zcopy_get(uarg);
>>>>>> + } else {
>>>>>> + struct iov_iter *iter = &msg->msg_iter;
>>>>>> + struct ubuf_info_msgzc *uarg_zc;
>>>>>> + int len;
>>>>>> +
>>>>>> + /* Only ITER_IOVEC or ITER_UBUF are allowed and
>>>>>> + * checked before.
>>>>>> + */
>>>>>> + if (iter_is_iovec(iter))
>>>>>> + len = iov_length(iter->__iov, iter->nr_segs);
>>>>>> + else
>>>>>> + len = iter->count;
>>>>>> +
>>>>>> + uarg = msg_zerocopy_realloc(sk_vsock(vsk),
>>>>>> + len,
>>>>>> + NULL);
>>>>>> + if (!uarg)
>>>>>> + return -1;
>>>>>> +
>>>>>> + uarg_zc = uarg_to_msgzc(uarg);
>>>>>> + uarg_zc->zerocopy = zerocopy ? 1 : 0;
>>>>>> }
>>>>>>
>>>>>> - if (info->reply)
>>>>>> - virtio_vsock_skb_set_reply(skb);
>>>>>> + skb_zcopy_init(skb, uarg);
>>>>>>
>>>>>> - trace_virtio_transport_alloc_pkt(src_cid, src_port,
>>>>>> - dst_cid, dst_port,
>>>>>> - len,
>>>>>> - info->type,
>>>>>> - info->op,
>>>>>> - info->flags);
>>>>>> + return 0;
>>>>>> +}
>>>>>>
>>>>>> - if (info->vsk && !skb_set_owner_sk_safe(skb, sk_vsock(info->vsk))) {
>>>>>> - WARN_ONCE(1, "failed to allocate skb on vsock socket with sk_refcnt == 0\n");
>>>>>> - goto out;
>>>>>> +static int virtio_transport_fill_skb(struct sk_buff *skb,
>>>>>> + struct virtio_vsock_pkt_info *info,
>>>>>> + size_t len,
>>>>>> + bool zcopy)
>>>>>> +{
>>>>>> + if (zcopy) {
>>>>>> + return __zerocopy_sg_from_iter(info->msg, NULL, skb,
>>>>>> + &info->msg->msg_iter,
>>>>>> + len);
>>>>>> + } else {
>>>>>> + void *payload;
>>>>>> + int err;
>>>>>> +
>>>>>> + payload = skb_put(skb, len);
>>>>>> + err = memcpy_from_msg(payload, info->msg, len);
>>>>>> + if (err)
>>>>>> + return -1;
>>>>>> +
>>>>>> + if (msg_data_left(info->msg))
>>>>>> + return 0;
>>>>>> +
>>>>>> + return 0;
>>>>>> }
>>>>>> +}
>>>>>>
>>>>>> - return skb;
>>>>>> +static void virtio_transport_init_hdr(struct sk_buff *skb,
>>>>>> + struct virtio_vsock_pkt_info *info,
>>>>>> + u32 src_cid,
>>>>>> + u32 src_port,
>>>>>> + u32 dst_cid,
>>>>>> + u32 dst_port,
>>>>>> + size_t len)
>>>>>> +{
>>>>>> + struct virtio_vsock_hdr *hdr;
>>>>>>
>>>>>> -out:
>>>>>> - kfree_skb(skb);
>>>>>> - return NULL;
>>>>>> + hdr = virtio_vsock_hdr(skb);
>>>>>> + hdr->type = cpu_to_le16(info->type);
>>>>>> + hdr->op = cpu_to_le16(info->op);
>>>>>> + hdr->src_cid = cpu_to_le64(src_cid);
>>>>>> + hdr->dst_cid = cpu_to_le64(dst_cid);
>>>>>> + hdr->src_port = cpu_to_le32(src_port);
>>>>>> + hdr->dst_port = cpu_to_le32(dst_port);
>>>>>> + hdr->flags = cpu_to_le32(info->flags);
>>>>>> + hdr->len = cpu_to_le32(len);
>>>>>> }
>>>>>>
>>>>>> static void virtio_transport_copy_nonlinear_skb(const struct sk_buff *skb,
>>>>>> @@ -214,6 +263,70 @@ static u16 virtio_transport_get_type(struct sock *sk)
>>>>>> return VIRTIO_VSOCK_TYPE_SEQPACKET;
>>>>>> }
>>>>>>
>>>>>> +static struct sk_buff *virtio_transport_alloc_skb(struct vsock_sock *vsk,
>>>>>> + struct virtio_vsock_pkt_info *info,
>>>>>> + size_t payload_len,
>>>>>> + bool zcopy,
>>>>>> + u32 src_cid,
>>>>>> + u32 src_port,
>>>>>> + u32 dst_cid,
>>>>>> + u32 dst_port)
>>>>>> +{
>>>>>> + struct sk_buff *skb;
>>>>>> + size_t skb_len;
>>>>>> +
>>>>>> + skb_len = VIRTIO_VSOCK_SKB_HEADROOM;
>>>>>> +
>>>>>> + if (!zcopy)
>>>>>> + skb_len += payload_len;
>>>>>> +
>>>>>> + skb = virtio_vsock_alloc_skb(skb_len, GFP_KERNEL);
>>>>>> + if (!skb)
>>>>>> + return NULL;
>>>>>> +
>>>>>> + virtio_transport_init_hdr(skb, info, src_cid, src_port,
>>>>>> + dst_cid, dst_port,
>>>>>> + payload_len);
>>>>>> +
>>>>>> + /* Set owner here, because '__zerocopy_sg_from_iter()' uses
>>>>>> + * owner of skb without check to update 'sk_wmem_alloc'.
>>>>>> + */
>>>>>> + if (vsk)
>>>>>> + skb_set_owner_w(skb, sk_vsock(vsk));
>>>>>> +
>>>>>> + if (info->msg && payload_len > 0) {
>>>>>> + int err;
>>>>>> +
>>>>>> + err = virtio_transport_fill_skb(skb, info, payload_len, zcopy);
>>>>>> + if (err)
>>>>>> + goto out;
>>>>>> +
>>>>>> + if (info->type == VIRTIO_VSOCK_TYPE_SEQPACKET) {
>>>>>> + struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
>>>>>> +
>>>>>> + hdr->flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
>>>>>> +
>>>>>> + if (info->msg->msg_flags & MSG_EOR)
>>>>>> + hdr->flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
>>>>>> + }
>>>>>> + }
>>>>>> +
>>>>>> + if (info->reply)
>>>>>> + virtio_vsock_skb_set_reply(skb);
>>>>>> +
>>>>>> + trace_virtio_transport_alloc_pkt(src_cid, src_port,
>>>>>> + dst_cid, dst_port,
>>>>>> + payload_len,
>>>>>> + info->type,
>>>>>> + info->op,
>>>>>> + info->flags);
>>>>>> +
>>>>>> + return skb;
>>>>>> +out:
>>>>>> + kfree_skb(skb);
>>>>>> + return NULL;
>>>>>> +}
>>>>>> +
>>>>>> /* This function can only be used on connecting/connected sockets,
>>>>>> * since a socket assigned to a transport is required.
>>>>>> *
>>>>>> @@ -222,10 +335,12 @@ static u16 virtio_transport_get_type(struct sock *sk)
>>>>>> static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
>>>>>> struct virtio_vsock_pkt_info *info)
>>>>>> {
>>>>>> + u32 max_skb_len = VIRTIO_VSOCK_MAX_PKT_BUF_SIZE;
>>>>>> u32 src_cid, src_port, dst_cid, dst_port;
>>>>>> const struct virtio_transport *t_ops;
>>>>>> struct virtio_vsock_sock *vvs;
>>>>>> u32 pkt_len = info->pkt_len;
>>>>>> + bool can_zcopy = false;
>>>>>> u32 rest_len;
>>>>>> int ret;
>>>>>>
>>>>>> @@ -254,15 +369,30 @@ 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 (!sock_flag(sk_vsock(vsk), SOCK_ZEROCOPY))
>>>>>> + info->msg->msg_flags &= ~MSG_ZEROCOPY;
>>>>>> +
>>>>>> + if (info->msg->msg_flags & MSG_ZEROCOPY)
>>>>>> + can_zcopy = virtio_transport_can_zcopy(info, pkt_len);
>>>>>> +
>>>>>> + if (can_zcopy)
>>>>>> + max_skb_len = min_t(u32, VIRTIO_VSOCK_MAX_PKT_BUF_SIZE,
>>>>>> + (MAX_SKB_FRAGS * PAGE_SIZE));
>>>>>> + }
>>>>>> +
>>>>>> rest_len = pkt_len;
>>>>>>
>>>>>> do {
>>>>>> struct sk_buff *skb;
>>>>>> size_t skb_len;
>>>>>>
>>>>>> - skb_len = min_t(u32, VIRTIO_VSOCK_MAX_PKT_BUF_SIZE, rest_len);
>>>>>> + skb_len = min(max_skb_len, rest_len);
>>>>>>
>>>>>> - skb = virtio_transport_alloc_skb(info, skb_len,
>>>>>> + skb = virtio_transport_alloc_skb(vsk, info, skb_len, can_zcopy,
>>>>>> src_cid, src_port,
>>>>>> dst_cid, dst_port);
>>>>>> if (!skb) {
>>>>>> @@ -270,6 +400,17 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
>>>>>> break;
>>>>>> }
>>>>>>
>>>>>> + /* This is last skb to send this portion of data. */
>>>>>> + if (info->msg && info->msg->msg_flags & MSG_ZEROCOPY &&
>>>>>> + skb_len == rest_len && info->op == VIRTIO_VSOCK_OP_RW) {
>>>>>> + if (virtio_transport_init_zcopy_skb(vsk, skb,
>>>>>> + info->msg,
>>>>>> + can_zcopy)) {
>>>>>> + ret = -ENOMEM;
>>>>>> + break;
>>>>>> + }
>>>>>> + }
>>>>>> +
>>>>>> virtio_transport_inc_tx_pkt(vvs, skb);
>>>>>>
>>>>>> ret = t_ops->send_pkt(skb);
>>>>>> @@ -934,7 +1075,7 @@ static int virtio_transport_reset_no_sock(const struct virtio_transport *t,
>>>>>> if (!t)
>>>>>> return -ENOTCONN;
>>>>>>
>>>>>> - reply = virtio_transport_alloc_skb(&info, 0,
>>>>>> + reply = virtio_transport_alloc_skb(NULL, &info, 0, false,
>>>>>> le64_to_cpu(hdr->dst_cid),
>>>>>> le32_to_cpu(hdr->dst_port),
>>>>>> le64_to_cpu(hdr->src_cid),
>>>>>> --
>>>>>> 2.25.1
>>>>>
>>>
>