Re: [PATCH net-next V2 3/3] tap: XDP support
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From: Daniel Borkmann <daniel@iogearbox.net>
Date: 2017-08-14 08:44:03
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On 08/11/2017 01:41 PM, Jason Wang wrote:
This patch tries to implement XDP for tun. The implementation was split into two parts:
[...]
quoted hunk ↗ jump to hunk
@@ -1402,6 +1521,22 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, skb_reset_network_header(skb); skb_probe_transport_header(skb, 0); + if (generic_xdp) { + struct bpf_prog *xdp_prog; + int ret; + + rcu_read_lock(); + xdp_prog = rcu_dereference(tun->xdp_prog);
The name generic_xdp is a bit confusing in this context given this is 'native' XDP, perhaps above if (generic_xdp) should have a comment explaining semantics for tun and how it relates to actual generic xdp that sits at dev->xdp_prog, and gets run from netif_rx_ni(). Or just name the bool xdp_handle_gso with a comment that we let the generic XDP infrastructure deal with non-linear skbs instead of having to re-implement the do_xdp_generic() internals, plus a statement that the actual generic XDP comes a bit later in the path. That would at least make it more obvious to read, imho.
quoted hunk ↗ jump to hunk
+ if (xdp_prog) { + ret = do_xdp_generic(xdp_prog, skb); + if (ret != XDP_PASS) { + rcu_read_unlock(); + return total_len; + } + } + rcu_read_unlock(); + } + rxhash = __skb_get_hash_symmetric(skb); #ifndef CONFIG_4KSTACKS tun_rx_batched(tun, tfile, skb, more);