Subject: Re: [PATCH net] virtio_net: use control_buf for coalesce params

From: "Michael S. Tsirkin" <[email-masked]>
Date: Tue, 6 Jun 2023 04:29:58 -0400

On Mon, Jun 05, 2023 at 12:59:25PM -0700, Brett Creeley wrote:
> Commit 699b045a8e43 ("net: virtio_net: notifications coalescing
> support") added coalescing command support for virtio_net. However,
> the coalesce commands are using buffers on the stack, which is causing
> the device to see DMA errors. There should also be a complaint from
> check_for_stack() in debug_dma_map_xyz(). Fix this by adding and using
> coalesce params from the control_buf struct, which aligns with other
> commands.
> 
> Fixes: 699b045a8e43 ("net: virtio_net: notifications coalescing support")
> Reviewed-by: Shannon Nelson <[email-masked]>
> Signed-off-by: Allen Hubbe <[email-masked]>
> Signed-off-by: Brett Creeley <[email-masked]>

Acked-by: Michael S. Tsirkin <[email-masked]>

stable material too.

> ---
>  drivers/net/virtio_net.c | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 56ca1d270304..486b5849033d 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -205,6 +205,8 @@ struct control_buf {
>  	__virtio16 vid;
>  	__virtio64 offloads;
>  	struct virtio_net_ctrl_rss rss;
> +	struct virtio_net_ctrl_coal_tx coal_tx;
> +	struct virtio_net_ctrl_coal_rx coal_rx;
>  };
>  
>  struct virtnet_info {
> @@ -2934,12 +2936,10 @@ static int virtnet_send_notf_coal_cmds(struct virtnet_info *vi,
>  				       struct ethtool_coalesce *ec)
>  {
>  	struct scatterlist sgs_tx, sgs_rx;
> -	struct virtio_net_ctrl_coal_tx coal_tx;
> -	struct virtio_net_ctrl_coal_rx coal_rx;
>  
> -	coal_tx.tx_usecs = cpu_to_le32(ec->tx_coalesce_usecs);
> -	coal_tx.tx_max_packets = cpu_to_le32(ec->tx_max_coalesced_frames);
> -	sg_init_one(&sgs_tx, &coal_tx, sizeof(coal_tx));
> +	vi->ctrl->coal_tx.tx_usecs = cpu_to_le32(ec->tx_coalesce_usecs);
> +	vi->ctrl->coal_tx.tx_max_packets = cpu_to_le32(ec->tx_max_coalesced_frames);
> +	sg_init_one(&sgs_tx, &vi->ctrl->coal_tx, sizeof(vi->ctrl->coal_tx));
>  
>  	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL,
>  				  VIRTIO_NET_CTRL_NOTF_COAL_TX_SET,
> @@ -2950,9 +2950,9 @@ static int virtnet_send_notf_coal_cmds(struct virtnet_info *vi,
>  	vi->tx_usecs = ec->tx_coalesce_usecs;
>  	vi->tx_max_packets = ec->tx_max_coalesced_frames;
>  
> -	coal_rx.rx_usecs = cpu_to_le32(ec->rx_coalesce_usecs);
> -	coal_rx.rx_max_packets = cpu_to_le32(ec->rx_max_coalesced_frames);
> -	sg_init_one(&sgs_rx, &coal_rx, sizeof(coal_rx));
> +	vi->ctrl->coal_rx.rx_usecs = cpu_to_le32(ec->rx_coalesce_usecs);
> +	vi->ctrl->coal_rx.rx_max_packets = cpu_to_le32(ec->rx_max_coalesced_frames);
> +	sg_init_one(&sgs_rx, &vi->ctrl->coal_rx, sizeof(vi->ctrl->coal_rx));
>  
>  	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL,
>  				  VIRTIO_NET_CTRL_NOTF_COAL_RX_SET,
> -- 
> 2.17.1