Stefano Garzarella
2021-Feb-23 14:15 UTC
[RFC PATCH v5 11/19] virtio/vsock: dequeue callback for SOCK_SEQPACKET
On Thu, Feb 18, 2021 at 08:39:37AM +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. If during copy SEQ_BEGIN >was found(and not all data was copied), copying is restarted by reset >user's iov iterator(previous unfinished data is dropped). > >Signed-off-by: Arseny Krasnov <arseny.krasnov at kaspersky.com> >--- > include/linux/virtio_vsock.h | 10 +++ > include/uapi/linux/virtio_vsock.h | 16 ++++ > net/vmw_vsock/virtio_transport_common.c | 114 ++++++++++++++++++++++++ > 3 files changed, 140 insertions(+)This patch LGTM, maybe we only need to change 'msg_cnt' as we discussed on virtio-comment, but let's see if there are any other comments.> >diff --git a/include/linux/virtio_vsock.h >b/include/linux/virtio_vsock.h >index dc636b727179..003d06ae4a85 100644 >--- a/include/linux/virtio_vsock.h >+++ b/include/linux/virtio_vsock.h >@@ -36,6 +36,11 @@ struct virtio_vsock_sock { > u32 rx_bytes; > u32 buf_alloc; > struct list_head rx_queue; >+ >+ /* For SOCK_SEQPACKET */ >+ u32 user_read_seq_len; >+ u32 user_read_copied; >+ u32 curr_rx_msg_cnt; > }; > > struct virtio_vsock_pkt { >@@ -80,6 +85,11 @@ virtio_transport_dgram_dequeue(struct vsock_sock *vsk, > struct msghdr *msg, > size_t len, int flags); > >+int >+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/include/uapi/linux/virtio_vsock.h b/include/uapi/linux/virtio_vsock.h >index 1d57ed3d84d2..cf9c165e5cca 100644 >--- a/include/uapi/linux/virtio_vsock.h >+++ b/include/uapi/linux/virtio_vsock.h >@@ -63,8 +63,14 @@ struct virtio_vsock_hdr { > __le32 fwd_cnt; > } __attribute__((packed)); > >+struct virtio_vsock_seq_hdr { >+ __le32 msg_cnt; >+ __le32 msg_len; >+} __attribute__((packed)); >+ > enum virtio_vsock_type { > VIRTIO_VSOCK_TYPE_STREAM = 1, >+ VIRTIO_VSOCK_TYPE_SEQPACKET = 2, > }; > > enum virtio_vsock_op { >@@ -83,6 +89,11 @@ enum virtio_vsock_op { > VIRTIO_VSOCK_OP_CREDIT_UPDATE = 6, > /* Request the peer to send the credit info to us */ > VIRTIO_VSOCK_OP_CREDIT_REQUEST = 7, >+ >+ /* Record begin for SOCK_SEQPACKET */ >+ VIRTIO_VSOCK_OP_SEQ_BEGIN = 8, >+ /* Record end for SOCK_SEQPACKET */ >+ VIRTIO_VSOCK_OP_SEQ_END = 9, > }; > > /* VIRTIO_VSOCK_OP_SHUTDOWN flags values */ >@@ -91,4 +102,9 @@ enum virtio_vsock_shutdown { > VIRTIO_VSOCK_SHUTDOWN_SEND = 2, > }; > >+/* VIRTIO_VSOCK_OP_RW flags values */ >+enum virtio_vsock_rw { >+ VIRTIO_VSOCK_RW_EOR = 1, >+}; >+ > #endif /* _UAPI_LINUX_VIRTIO_VSOCK_H */ >diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c >index 833104b71a1c..d8ec2dfa2315 100644 >--- a/net/vmw_vsock/virtio_transport_common.c >+++ b/net/vmw_vsock/virtio_transport_common.c >@@ -393,6 +393,108 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk, > return err; > } > >+static inline void virtio_transport_remove_pkt(struct virtio_vsock_pkt *pkt) >+{ >+ list_del(&pkt->list); >+ virtio_transport_free_pkt(pkt); >+} >+ >+static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk, >+ struct msghdr *msg, >+ 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) { >+ pkt = list_first_entry(&vvs->rx_queue, struct virtio_vsock_pkt, list); >+ >+ switch (le16_to_cpu(pkt->hdr.op)) { >+ case VIRTIO_VSOCK_OP_SEQ_BEGIN: { >+ /* Unexpected 'SEQ_BEGIN' during record copy: >+ * Leave receive loop, 'EAGAIN' will restart it from >+ * outer receive loop, packet is still in queue and >+ * counters are cleared. So in next loop enter, >+ * 'SEQ_BEGIN' will be dequeued first. User's iov >+ * iterator will be reset in outer loop. Also >+ * send credit update, because some bytes could be >+ * copied. User will never see unfinished record. >+ */ >+ err = -EAGAIN; >+ break; >+ } >+ case VIRTIO_VSOCK_OP_SEQ_END: { >+ struct virtio_vsock_seq_hdr *seq_hdr; >+ >+ seq_hdr = (struct virtio_vsock_seq_hdr *)pkt->buf; >+ /* First check that whole record is received. */ >+ >+ if (vvs->user_read_copied != vvs->user_read_seq_len || >+ (le32_to_cpu(seq_hdr->msg_cnt) - vvs->curr_rx_msg_cnt) != 1) { >+ /* Tail of current record and head of next missed, >+ * so this EOR is from next record. Restart receive. >+ * Current record will be dropped, next headless will >+ * be dropped on next attempt to get record length. >+ */ >+ err = -EAGAIN; >+ } else { >+ /* Success. */ >+ *msg_ready = true; >+ } >+ >+ break; >+ } >+ case VIRTIO_VSOCK_OP_RW: { >+ size_t bytes_to_copy; >+ size_t pkt_len; >+ >+ pkt_len = (size_t)le32_to_cpu(pkt->hdr.len); >+ bytes_to_copy = min(user_buf_len, pkt_len); >+ >+ /* 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)) { >+ spin_lock_bh(&vvs->rx_lock); >+ err = -EINVAL; >+ break; >+ } >+ >+ spin_lock_bh(&vvs->rx_lock); >+ user_buf_len -= bytes_to_copy; >+ vvs->user_read_copied += pkt_len; >+ >+ if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_RW_EOR) >+ msg->msg_flags |= MSG_EOR; >+ break; >+ } >+ default: >+ ; >+ } >+ >+ /* For unexpected 'SEQ_BEGIN', keep such packet in queue, >+ * but drop any other type of packet. >+ */ >+ if (le16_to_cpu(pkt->hdr.op) != VIRTIO_VSOCK_OP_SEQ_BEGIN) { >+ virtio_transport_dec_rx_pkt(vvs, pkt); >+ virtio_transport_remove_pkt(pkt); >+ } >+ } >+ >+ spin_unlock_bh(&vvs->rx_lock); >+ >+ virtio_transport_send_credit_update(vsk); >+ >+ return err; >+} >+ > ssize_t > virtio_transport_stream_dequeue(struct vsock_sock *vsk, > struct msghdr *msg, >@@ -405,6 +507,18 @@ virtio_transport_stream_dequeue(struct vsock_sock *vsk, > } > EXPORT_SYMBOL_GPL(virtio_transport_stream_dequeue); > >+int >+virtio_transport_seqpacket_dequeue(struct vsock_sock *vsk, >+ struct msghdr *msg, >+ int flags, bool *msg_ready) >+{ >+ if (flags & MSG_PEEK) >+ return -EOPNOTSUPP; >+ >+ return virtio_transport_seqpacket_do_dequeue(vsk, msg, msg_ready); >+} >+EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_dequeue); >+ > int > virtio_transport_dgram_dequeue(struct vsock_sock *vsk, > struct msghdr *msg, >-- >2.25.1 >