RE: [Intel-wired-lan] [PATCH net-next v4 1/2] e1000e: add basic XDP support

[Loktionov, Aleksandr]

> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces@xxxxxxxxxx> On Behalf
> Of Matteo Croce
> Sent: Monday, March 23, 2026 7:28 PM
> To: Nguyen, Anthony L <anthony.l.nguyen@xxxxxxxxx>; Kitszel,
> Przemyslaw <przemyslaw.kitszel@xxxxxxxxx>; Andrew Lunn
> <andrew+netdev@xxxxxxx>; David S. Miller <davem@xxxxxxxxxxxxx>; Eric
> Dumazet <edumazet@xxxxxxxxxx>; Jakub Kicinski <kuba@xxxxxxxxxx>; Paolo
> Abeni <pabeni@xxxxxxxxxx>; Alexei Starovoitov <ast@xxxxxxxxxx>; Daniel
> Borkmann <daniel@xxxxxxxxxxxxx>; Jesper Dangaard Brouer
> <hawk@xxxxxxxxxx>; John Fastabend <john.fastabend@xxxxxxxxx>; Mohsin
> Bashir <mohsin.bashr@xxxxxxxxx>
> Cc: netdev@xxxxxxxxxxxxxxx; bpf@xxxxxxxxxxxxxxx; intel-wired-
> lan@xxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: [Intel-wired-lan] [PATCH net-next v4 1/2] e1000e: add basic
> XDP support
> 
> Add XDP support to the e1000e driver covering the actions defined by
> NETDEV_XDP_ACT_BASIC: XDP_DROP, XDP_PASS, XDP_TX and XDP_ABORTED.
> 
> Infrastructure:

...

> +/**
> + * e1000_xdp_setup - add/remove an XDP program
> + * @netdev: network interface device structure
> + * @bpf: XDP program setup structure
> + **/
> +static int e1000_xdp_setup(struct net_device *netdev, struct
> netdev_bpf
> +*bpf) {
> +	struct e1000_adapter *adapter = netdev_priv(netdev);
> +	struct bpf_prog *prog = bpf->prog, *old_prog;
> +	bool running = netif_running(netdev);
> +	bool need_reset;
> +
> +	/* XDP is incompatible with jumbo frames */
> +	if (prog && netdev->mtu > ETH_DATA_LEN) {
> +		NL_SET_ERR_MSG_MOD(bpf->extack,
> +				   "XDP is not supported with jumbo
> frames");
> +		return -EINVAL;
> +	}
> +
> +	/* Validate frame fits in a single page with XDP headroom */
> +	if (prog && netdev->mtu + VLAN_ETH_HLEN + ETH_FCS_LEN +
> +	    XDP_PACKET_HEADROOM > PAGE_SIZE) {
> +		NL_SET_ERR_MSG_MOD(bpf->extack,
> +				   "Frame size too large for XDP");
> +		return -EINVAL;
> +	}
> +
> +	old_prog = xchg(&adapter->xdp_prog, prog);
> +	need_reset = (!!prog != !!old_prog);
> +
> +	/* Transition between XDP and non-XDP requires ring
> reconfiguration */
> +	if (need_reset && running)
> +		e1000e_close(netdev);
> +
> +	if (old_prog)
> +		bpf_prog_put(old_prog);
> +
> +	if (!need_reset)
> +		return 0;
> +
> +	if (running) {
> +		int err = e1000e_open(netdev);
> +
> +		if (err) {
> +			/* Remove the XDP program since interface is down
> */
> +			xchg(&adapter->xdp_prog, NULL);
> +			if (prog)
> +				bpf_prog_put(prog);
I'm afraid the reference is owned by the BPF infrastructure, and you will drop refcount to 0.

> +			return err;
> +		}
> +	}
> +
> +	return 0;
> +}

...

>  	kfree(adapter->tx_ring);
>  	kfree(adapter->rx_ring);
> 
> --
> 2.53.0