virtio/vsock: don't use skbuff state to account credit

'skb->len' can vary when we partially read the data, this complicates the
calculation of credit to be updated in 'virtio_transport_inc_rx_pkt()/
virtio_transport_dec_rx_pkt()'.

Also in 'virtio_transport_dec_rx_pkt()' we were miscalculating the
credit since 'skb->len' was redundant.

For these reasons, let's replace the use of skbuff state to calculate new
'rx_bytes'/'fwd_cnt' values with explicit value as input argument. This
makes code more simple, because it is not needed to change skbuff state
before each call to update 'rx_bytes'/'fwd_cnt'.

Fixes: 71dc9ec9ac7d ("virtio/vsock: replace virtio_vsock_pkt with sk_buff")
Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Acked-by: Bobby Eshleman <bobby.eshleman@bytedance.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index a1581c77cf84a81bb5503d57039e49b5b970ce85..618680fd9906feb9a6c7a177cc0ef8ed3871b030 100644 (file)
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -241,21 +241,18 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
 }
 
 static bool virtio_transport_inc_rx_pkt(struct virtio_vsock_sock *vvs,
-                                       struct sk_buff *skb)
+                                       u32 len)
 {
-       if (vvs->rx_bytes + skb->len > vvs->buf_alloc)
+       if (vvs->rx_bytes + len > vvs->buf_alloc)
                return false;
 
-       vvs->rx_bytes += skb->len;
+       vvs->rx_bytes += len;
        return true;
 }
 
 static void virtio_transport_dec_rx_pkt(struct virtio_vsock_sock *vvs,
-                                       struct sk_buff *skb)
+                                       u32 len)
 {
-       int len;
-
-       len = skb_headroom(skb) - sizeof(struct virtio_vsock_hdr) - skb->len;
        vvs->rx_bytes -= len;
        vvs->fwd_cnt += len;
 }
@@ -388,7 +385,9 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,
                skb_pull(skb, bytes);
 
                if (skb->len == 0) {
-                       virtio_transport_dec_rx_pkt(vvs, skb);
+                       u32 pkt_len = le32_to_cpu(virtio_vsock_hdr(skb)->len);
+
+                       virtio_transport_dec_rx_pkt(vvs, pkt_len);
                        consume_skb(skb);
                } else {
                        __skb_queue_head(&vvs->rx_queue, skb);
@@ -437,17 +436,17 @@ static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
 
        while (!msg_ready) {
                struct virtio_vsock_hdr *hdr;
+               size_t pkt_len;
 
                skb = __skb_dequeue(&vvs->rx_queue);
                if (!skb)
                        break;
                hdr = virtio_vsock_hdr(skb);
+               pkt_len = (size_t)le32_to_cpu(hdr->len);
 
                if (dequeued_len >= 0) {
-                       size_t pkt_len;
                        size_t bytes_to_copy;
 
-                       pkt_len = (size_t)le32_to_cpu(hdr->len);
                        bytes_to_copy = min(user_buf_len, pkt_len);
 
                        if (bytes_to_copy) {
@@ -484,7 +483,7 @@ static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
                                msg->msg_flags |= MSG_EOR;
                }
 
-               virtio_transport_dec_rx_pkt(vvs, skb);
+               virtio_transport_dec_rx_pkt(vvs, pkt_len);
                kfree_skb(skb);
        }
 
@@ -1040,7 +1039,7 @@ virtio_transport_recv_enqueue(struct vsock_sock *vsk,
 
        spin_lock_bh(&vvs->rx_lock);
 
-       can_enqueue = virtio_transport_inc_rx_pkt(vvs, skb);
+       can_enqueue = virtio_transport_inc_rx_pkt(vvs, len);
        if (!can_enqueue) {
                free_pkt = true;
                goto out;