Stefano Garzarella
2021-May-13 11:58 UTC
[RFC PATCH v9 11/19] virtio/vsock: dequeue callback for SOCK_SEQPACKET
On Sat, May 08, 2021 at 07:35:20PM +0300, Arseny Krasnov wrote:>This adds transport callback and it's logic for SEQPACKET dequeue. >Callback fetches RW packets from rx queue of socket until whole record >is copied(if user's buffer is full, user is not woken up). This is done >to not stall sender, because if we wake up user and it leaves syscall, >nobody will send credit update for rest of record, and sender will wait >for next enter of read syscall at receiver's side. So if user buffer is >full, we just send credit update and drop data. > >Signed-off-by: Arseny Krasnov <arseny.krasnov at kaspersky.com> >--- > v8 -> v9: > 1) Check for RW packet type is removed from loop(all packet now > considered RW). > 2) Locking in loop is fixed. > 3) cpu_to_le32()/le32_to_cpu() now used. > 4) MSG_TRUNC handling removed from transport. > > include/linux/virtio_vsock.h | 5 ++ > net/vmw_vsock/virtio_transport_common.c | 64 +++++++++++++++++++++++++ > 2 files changed, 69 insertions(+) > >diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h >index dc636b727179..02acf6e9ae04 100644 >--- a/include/linux/virtio_vsock.h >+++ b/include/linux/virtio_vsock.h >@@ -80,6 +80,11 @@ virtio_transport_dgram_dequeue(struct vsock_sock *vsk, > struct msghdr *msg, > size_t len, int flags); > >+ssize_t >+virtio_transport_seqpacket_dequeue(struct vsock_sock *vsk, >+ struct msghdr *msg, >+ int flags, >+ bool *msg_ready); > s64 virtio_transport_stream_has_data(struct vsock_sock *vsk); > s64 virtio_transport_stream_has_space(struct vsock_sock *vsk); > >diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c >index ad0d34d41444..f649a21dd23b 100644 >--- a/net/vmw_vsock/virtio_transport_common.c >+++ b/net/vmw_vsock/virtio_transport_common.c >@@ -393,6 +393,58 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk, > return err; > } > >+static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk, >+ struct msghdr *msg, >+ int flags, >+ bool *msg_ready) >+{ >+ struct virtio_vsock_sock *vvs = vsk->trans; >+ struct virtio_vsock_pkt *pkt; >+ int err = 0; >+ size_t user_buf_len = msg->msg_iter.count; >+ >+ *msg_ready = false; >+ spin_lock_bh(&vvs->rx_lock); >+ >+ while (!*msg_ready && !list_empty(&vvs->rx_queue) && err >= 0) { >+ size_t bytes_to_copy; >+ size_t pkt_len; >+ >+ pkt = list_first_entry(&vvs->rx_queue, struct virtio_vsock_pkt, list); >+ pkt_len = (size_t)le32_to_cpu(pkt->hdr.len); >+ bytes_to_copy = min(user_buf_len, pkt_len); >+ >+ if (bytes_to_copy) { >+ /* sk_lock is held by caller so no one else can dequeue. >+ * Unlock rx_lock since memcpy_to_msg() may sleep. >+ */ >+ spin_unlock_bh(&vvs->rx_lock); >+ >+ if (memcpy_to_msg(msg, pkt->buf, bytes_to_copy)) >{ >+ err = -EINVAL; >+ } else { >+ err += pkt_len;If `bytes_to_copy == 0` we are not increasing the real length. Anyway is a bit confusing increase a variable called `err`, I think is better to have another variable to store this information that we return if there aren't errors.