Subject: Re: [net-next, PATCH 3/3, v2] net: netsec: add XDP support

From: Ilias Apalodimas <[email-masked]>
Date: Sun, 30 Jun 2019 19:32:14 +0300

On Sun, Jun 30, 2019 at 07:25:53PM +0300, Ivan Khoronzhuk wrote:
> On Sat, Jun 29, 2019 at 08:23:25AM +0300, Ilias Apalodimas wrote:
> >The interface only supports 1 Tx queue so locking is introduced on
> >the Tx queue if XDP is enabled to make sure .ndo_start_xmit and
> >.ndo_xdp_xmit won't corrupt Tx ring
> >
> >- Performance (SMMU off)
> >
> >Benchmark   XDP_SKB     XDP_DRV
> >xdp1        291kpps     344kpps
> >rxdrop      282kpps     342kpps
> >
> >- Performance (SMMU on)
> >Benchmark   XDP_SKB     XDP_DRV
> >xdp1        167kpps     324kpps
> >rxdrop      164kpps     323kpps
> >
> >Signed-off-by: Ilias Apalodimas <[email-masked]>
> >---
> >drivers/net/ethernet/socionext/netsec.c | 361 ++++++++++++++++++++++--
> >1 file changed, 334 insertions(+), 27 deletions(-)
> >
> 
> [...]
> 
> >+
> >+static int netsec_xdp_setup(struct netsec_priv *priv, struct bpf_prog *prog,
> >+			    struct netlink_ext_ack *extack)
> >+{
> >+	struct net_device *dev = priv->ndev;
> >+	struct bpf_prog *old_prog;
> >+
> >+	/* For now just support only the usual MTU sized frames */
> >+	if (prog && dev->mtu > 1500) {
> >+		NL_SET_ERR_MSG_MOD(extack, "Jumbo frames not supported on XDP");
> >+		return -EOPNOTSUPP;
> >+	}
> >+
> >+	if (netif_running(dev))
> >+		netsec_netdev_stop(dev);
> And why to stop the interface. XDP allows to update prog in runtime.
> 
Adding the support is not limited to  adding a prog only in this driver.
It also rebuilts the queues which changes the dma mapping of buffers.
Since i don't want to map BIDIRECTIONAL buffers if XDP is not in place,
i am resetting the device and forcing the buffer re-allocation

Thanks
/Ilias