vsock/virtio: Move length check to callers of virtio_vsock_skb_rx_put()

virtio_vsock_skb_rx_put() only calls skb_put() if the length in the
packet header is not zero even though skb_put() handles this case
gracefully.

Remove the functionally redundant check from virtio_vsock_skb_rx_put()
and, on the assumption that this is a worthwhile optimisation for
handling credit messages, augment the existing length checks in
virtio_transport_rx_work() to elide the call for zero-length payloads.
Since the callers all have the length, extend virtio_vsock_skb_rx_put()
to take it as an additional parameter rather than fish it back out of
the packet header.

Note that the vhost code already has similar logic in
vhost_vsock_alloc_skb().

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Will Deacon <will@kernel.org>
Message-Id: <20250717090116.11987-4-will@kernel.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 66a0f060770ef228e3205d96154c00857526faca..4c4a642945ebbdbd8886afc6b7855f5a90a591fc 100644 (file)
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -375,7 +375,7 @@ vhost_vsock_alloc_skb(struct vhost_virtqueue *vq,
                return NULL;
        }
 
-       virtio_vsock_skb_rx_put(skb);
+       virtio_vsock_skb_rx_put(skb, payload_len);
 
        nbytes = copy_from_iter(skb->data, payload_len, &iov_iter);
        if (nbytes != payload_len) {

diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index 36fb3edfa403d9bc244a2784893482f71f66a54b..97465f378ade46c6854ebebee3c9482847f2bfed 100644 (file)
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -47,14 +47,9 @@ static inline void virtio_vsock_skb_clear_tap_delivered(struct sk_buff *skb)
        VIRTIO_VSOCK_SKB_CB(skb)->tap_delivered = false;
 }
 
-static inline void virtio_vsock_skb_rx_put(struct sk_buff *skb)
+static inline void virtio_vsock_skb_rx_put(struct sk_buff *skb, u32 len)
 {
-       u32 len;
-
-       len = le32_to_cpu(virtio_vsock_hdr(skb)->len);
-
-       if (len > 0)
-               skb_put(skb, len);
+       skb_put(skb, len);
 }
 
 static inline struct sk_buff *virtio_vsock_alloc_skb(unsigned int size, gfp_t mask)

diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index eb08a393413d456a5e82b9a98f12be8c553aebd1..0166919f87056c487248551d9858bdd87fb2b9c7 100644 (file)
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -656,7 +656,9 @@ static void virtio_transport_rx_work(struct work_struct *work)
                                continue;
                        }
 
-                       virtio_vsock_skb_rx_put(skb);
+                       if (payload_len)
+                               virtio_vsock_skb_rx_put(skb, payload_len);
+
                        virtio_transport_deliver_tap_pkt(skb);
                        virtio_transport_recv_pkt(&virtio_transport, skb);
                }