On Thu, Mar 09, 2023 at 11:26:00PM +0300, Arseniy Krasnov wrote:
'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 <[email protected]>
---
net/vmw_vsock/virtio_transport_common.c | 23 +++++++++++------------
1 file changed, 11 insertions(+), 12 deletions(-)

Reviewed-by: Stefano Garzarella <[email protected]>


diff --git a/net/vmw_vsock/virtio_transport_common.c 
b/net/vmw_vsock/virtio_transport_common.c
index a1581c77cf84..618680fd9906 100644
--- 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;
--
2.25.1


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