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Date:   Mon, 22 May 2023 15:13:46 +0200
From:   Simon Horman <simon.horman@corigine.com>
To:     Arseniy Krasnov <AVKrasnov@sberdevices.ru>
Cc:     Stefan Hajnoczi <stefanha@redhat.com>,
        Stefano Garzarella <sgarzare@redhat.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Jason Wang <jasowang@redhat.com>,
        Bobby Eshleman <bobby.eshleman@bytedance.com>,
        kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        kernel@sberdevices.ru, oxffffaa@gmail.com
Subject: Re: [RFC PATCH v3 04/17] vsock/virtio: non-linear skb handling for
 tap
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References: <20230522073950.3574171-1-AVKrasnov@sberdevices.ru>
 <20230522073950.3574171-5-AVKrasnov@sberdevices.ru>
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On Mon, May 22, 2023 at 10:39:37AM +0300, Arseniy Krasnov wrote:
> For tap device new skb is created and data from the current skb is
> copied to it. This adds copying data from non-linear skb to new
> the skb.
> 
> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
> ---
>  net/vmw_vsock/virtio_transport_common.c | 31 ++++++++++++++++++++++---
>  1 file changed, 28 insertions(+), 3 deletions(-)
> 
> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
> index 16effa8d55d2..9854f48a0544 100644
> --- a/net/vmw_vsock/virtio_transport_common.c
> +++ b/net/vmw_vsock/virtio_transport_common.c
> @@ -106,6 +106,27 @@ virtio_transport_alloc_skb(struct virtio_vsock_pkt_info *info,
>  	return NULL;
>  }
>  
> +static void virtio_transport_copy_nonlinear_skb(struct sk_buff *skb,
> +						void *dst,
> +						size_t len)
> +{
> +	struct iov_iter iov_iter = { 0 };
> +	struct iovec iovec;
> +	size_t to_copy;
> +
> +	iovec.iov_base = dst;

Hi Arseniy,

Sparse seems unhappy about this.
Though, TBH, I'm unsure what should be done about it.

.../virtio_transport_common.c:117:24: warning: incorrect type in assignment (different address spaces)
.../virtio_transport_common.c:117:24:    expected void [noderef] __user *iov_base
.../virtio_transport_common.c:117:24:    got void *dst


...