Re: [RFC PATCH v2 2/4] virtio/vsock: support MSG_PEEK for SOCK_SEQPACKET
From: Stefano Garzarella <sgarzare@redhat.com>
Date: 2023-07-25 15:40:44
Also in:
kvm, lkml, virtualization
On Wed, Jul 19, 2023 at 10:27:06PM +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 <redacted> --- net/vmw_vsock/virtio_transport_common.c | 63 +++++++++++++++++++++++-- 1 file changed, 60 insertions(+), 3 deletions(-)
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
quoted hunk ↗ jump to hunk
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; +} + 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