On 26.06.2023 19:28, Stefano Garzarella wrote:
> On Sun, Jun 18, 2023 at 09:24:49AM +0300, Arseniy Krasnov wrote:
>> This adds support of MSG_PEEK flag for SOCK_SEQPACKET type of socket.
>> Difference with SOCK_STREAM is that this callback returns either length
>> of the message or error.
>>
>> Signed-off-by: Arseniy Krasnov <AVKrasnov@xxxxxxxxxxxxxx>
>> ---
>> net/vmw_vsock/virtio_transport_common.c | 63 +++++++++++++++++++++++--
>> 1 file changed, 60 insertions(+), 3 deletions(-)
>>
>> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
>> index 2ee40574c339..352d042b130b 100644
>> --- a/net/vmw_vsock/virtio_transport_common.c
>> +++ b/net/vmw_vsock/virtio_transport_common.c
>> @@ -460,6 +460,63 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,
>> return err;
>> }
>>
>> +static ssize_t
>> +virtio_transport_seqpacket_do_peek(struct vsock_sock *vsk,
>> + struct msghdr *msg)
>> +{
>> + struct virtio_vsock_sock *vvs = vsk->trans;
>> + struct sk_buff *skb;
>> + size_t total, len;
>> +
>> + spin_lock_bh(&vvs->rx_lock);
>> +
>> + if (!vvs->msg_count) {
>> + spin_unlock_bh(&vvs->rx_lock);
>> + return 0;
>> + }
>> +
>> + total = 0;
>> + len = msg_data_left(msg);
>> +
>> + skb_queue_walk(&vvs->rx_queue, skb) {
>> + struct virtio_vsock_hdr *hdr;
>> +
>> + if (total < len) {
>> + size_t bytes;
>> + int err;
>> +
>> + bytes = len - total;
>> + if (bytes > skb->len)
>> + bytes = skb->len;
>> +
>> + 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.
>> + */
>> + err = memcpy_to_msg(msg, skb->data, bytes);
>> + if (err)
>> + return err;
>> +
>> + spin_lock_bh(&vvs->rx_lock);
>> + }
>> +
>> + total += skb->len;
>> + hdr = virtio_vsock_hdr(skb);
>> +
>> + if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOM) {
>> + if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOR)
>> + msg->msg_flags |= MSG_EOR;
>> +
>> + break;
>> + }
>> + }
>> +
>> + spin_unlock_bh(&vvs->rx_lock);
>> +
>> + return total;
>
> Should we return the minimum between total and len?
I guess no, because seqpacket dequeue callback always returns length of message,
then, in af_vsock.c we return either number of bytes read or length of message
depending on MSG_TRUNC flags.
Thanks, Arseniy
>
> Thanks,
> Stefano
>
>> +}
>> +
>> static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
>> struct msghdr *msg,
>> int flags)
>> @@ -554,9 +611,9 @@ virtio_transport_seqpacket_dequeue(struct vsock_sock *vsk,
>> int flags)
>> {
>> if (flags & MSG_PEEK)
>> - return -EOPNOTSUPP;
>> -
>> - return virtio_transport_seqpacket_do_dequeue(vsk, msg, flags);
>> + return virtio_transport_seqpacket_do_peek(vsk, msg);
>> + else
>> + return virtio_transport_seqpacket_do_dequeue(vsk, msg, flags);
>> }
>> EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_dequeue);
>>
>> --
>> 2.25.1
>>
>
