linux-kernel - [PATCH RFC bpf-next 42/52] net, xdp: shortcut skb->dev in bpf_prog_run_generic

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Date:   Tue, 28 Jun 2022 21:48:02 +0200
From:   Alexander Lobakin <alexandr.lobakin@...el.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>
Cc:     Alexander Lobakin <alexandr.lobakin@...el.com>,
        Larysa Zaremba <larysa.zaremba@...el.com>,
        Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        Björn Töpel <bjorn@...nel.org>,
        Magnus Karlsson <magnus.karlsson@...el.com>,
        Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        Toke Hoiland-Jorgensen <toke@...hat.com>,
        Lorenzo Bianconi <lorenzo@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>,
        John Fastabend <john.fastabend@...il.com>,
        Yajun Deng <yajun.deng@...ux.dev>,
        Willem de Bruijn <willemb@...gle.com>, bpf@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        xdp-hints@...-project.net
Subject: [PATCH RFC bpf-next 42/52] net, xdp: shortcut skb->dev in bpf_prog_run_generic_xdp()

It's being used 3 times and more to come. Fetch it onto the stack
to reduce jumping back and forth.

Signed-off-by: Alexander Lobakin <alexandr.lobakin@...el.com>
---
 net/bpf/dev.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/bpf/dev.c b/net/bpf/dev.c
index cc43f73929f3..350ebdc783a0 100644
--- a/net/bpf/dev.c
+++ b/net/bpf/dev.c
@@ -31,6 +31,7 @@ u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp,
 			     struct bpf_prog *xdp_prog)
 {
 	void *orig_data, *orig_data_end, *hard_start;
+	struct net_device *dev = skb->dev;
 	struct netdev_rx_queue *rxqueue;
 	bool orig_bcast, orig_host;
 	u32 mac_len, frame_sz;
@@ -57,7 +58,7 @@ u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp,
 	orig_data_end = xdp->data_end;
 	orig_data = xdp->data;
 	eth = (struct ethhdr *)xdp->data;
-	orig_host = ether_addr_equal_64bits(eth->h_dest, skb->dev->dev_addr);
+	orig_host = ether_addr_equal_64bits(eth->h_dest, dev->dev_addr);
 	orig_bcast = is_multicast_ether_addr_64bits(eth->h_dest);
 	orig_eth_type = eth->h_proto;
 
@@ -86,11 +87,11 @@ u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp,
 	eth = (struct ethhdr *)xdp->data;
 	if ((orig_eth_type != eth->h_proto) ||
 	    (orig_host != ether_addr_equal_64bits(eth->h_dest,
-						  skb->dev->dev_addr)) ||
+						  dev->dev_addr)) ||
 	    (orig_bcast != is_multicast_ether_addr_64bits(eth->h_dest))) {
 		__skb_push(skb, ETH_HLEN);
 		skb->pkt_type = PACKET_HOST;
-		skb->protocol = eth_type_trans(skb, skb->dev);
+		skb->protocol = eth_type_trans(skb, dev);
 	}
 
 	/* Redirect/Tx gives L2 packet, code that will reuse skb must __skb_pull
-- 
2.36.1