Re: [dpdk-dev] [PATCH BUG 335 3/3] net/virtio: fix compilation error with 0 headroom

[Olivier Matz <olivier.matz@6wind.com>]

Hi,

On Thu, Jul 25, 2019 at 04:36:45PM +0530, Hemant Agrawal wrote:
> When using RTE_PKTMBUF_HEADROOM as 0, virito ethdev driver throws
> compilation error
> virtio_ethdev.c:1851:2: note: in expansion of macro ‘RTE_BUILD_BUG_ON’
> RTE_BUILD_BUG_ON(RTE_PKTMBUF_HEADROOM
> 	< sizeof(struct virtio_net_hdr_mrg_rxbuf));
> 
> This patch change it into run-time check.
> Reported as: https://bugs.dpdk.org/show_bug.cgi?id=335
> 
> Fixes: 198ab33677c9 ("net/virtio: move device initialization in a function")

I think the proper commit is:
Fixes: dec08c28c0b3 ("virtio: check packet headroom at compile time")

It looks this patch more or less reverts this old commit.
+CC Stephen


> Cc: stable@dpdk.org
> Cc: Olivier Matz <olivier.matz@6wind.com>
> 
> Signed-off-by: Hemant Agrawal <hemant.agrawal@nxp.com>
> ---
>  drivers/net/virtio/virtio_ethdev.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
> index 62c827443..3e2e8bd2a 100644
> --- a/drivers/net/virtio/virtio_ethdev.c
> +++ b/drivers/net/virtio/virtio_ethdev.c
> @@ -1848,7 +1848,14 @@ eth_virtio_dev_init(struct rte_eth_dev *eth_dev)
>  	struct virtio_hw *hw = eth_dev->data->dev_private;
>  	int ret;
>  
> -	RTE_BUILD_BUG_ON(RTE_PKTMBUF_HEADROOM < sizeof(struct virtio_net_hdr_mrg_rxbuf));
> +	if (sizeof(struct virtio_net_hdr_mrg_rxbuf) > RTE_PKTMBUF_HEADROOM) {
> +		PMD_INIT_LOG(ERR,
> +			"Not sufficient headroom required = %d, avail = %d",
> +			(int)sizeof(struct virtio_net_hdr_mrg_rxbuf),
> +			RTE_PKTMBUF_HEADROOM);
> +
> +		return -1;
> +	}
>  
>  	eth_dev->dev_ops = &virtio_eth_dev_ops;
>  
> -- 
> 2.17.1
>