netdev - [PATCH net-next 2/2] net: gro: no longer use skb_vlan_tag

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Date:   Wed,  9 Nov 2022 09:57:59 +0000
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii@...nel.org>
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        eric.dumazet@...il.com, Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 2/2] net: gro: no longer use skb_vlan_tag_present()

We can remove a conditional test in gro_list_prepare()
by comparing vlan_all fields of the two skbs.

Notes:

While comparing the vlan_proto is not strictly needed,
because part of the following compare_ether_header() call,
using 32bit word is actually faster than using 16bit values.

napi_reuse_skb() makes sure to clear skb->vlan_all,
as it already calls __vlan_hwaccel_clear_tag()

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/core/gro.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/net/core/gro.c b/net/core/gro.c
index bc9451743307bc380cca96ae6995aa0a3b83d185..4a6925569bf313a0a8e1b22174470c2af3f9dae3 100644
--- a/net/core/gro.c
+++ b/net/core/gro.c
@@ -370,9 +370,7 @@ static void gro_list_prepare(const struct list_head *head,
 		}
 
 		diffs = (unsigned long)p->dev ^ (unsigned long)skb->dev;
-		diffs |= skb_vlan_tag_present(p) ^ skb_vlan_tag_present(skb);
-		if (skb_vlan_tag_present(p))
-			diffs |= skb_vlan_tag_get(p) ^ skb_vlan_tag_get(skb);
+		diffs |= p->vlan_all ^ skb->vlan_all;
 		diffs |= skb_metadata_differs(p, skb);
 		if (maclen == ETH_HLEN)
 			diffs |= compare_ether_header(skb_mac_header(p),
-- 
2.38.1.431.g37b22c650d-goog