netdev - [PATCH v2 net-next 2/7] vlan: Introduce helper functions to check if skb is tagged

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Date:	Fri, 27 Mar 2015 14:31:11 +0900
From:	Toshiaki Makita <makita.toshiaki@....ntt.co.jp>
To:	"David S . Miller" <davem@...emloft.net>,
	Patrick McHardy <kaber@...sh.net>,
	Ariel Elior <ariel.elior@...gic.com>,
	Amir Vadai <amirv@...lanox.com>,
	Shahed Shaikh <shahed.shaikh@...gic.com>,
	Dept-GELinuxNICDev@...gic.com, Jay Vosburgh <j.vosburgh@...il.com>,
	Veaceslav Falico <vfalico@...il.com>,
	Andy Gospodarek <gospo@...ulusnetworks.com>,
	Jiri Pirko <jiri@...nulli.us>,
	Linux NICS <linux.nics@...el.com>
Cc:	Toshiaki Makita <makita.toshiaki@....ntt.co.jp>,
	Vlad Yasevich <vyasevic@...hat.com>,
	Eric Dumazet <eric.dumazet@...il.com>, netdev@...r.kernel.org,
	e1000-devel@...ts.sourceforge.net
Subject: [PATCH v2 net-next 2/7] vlan: Introduce helper functions to check if skb is tagged

Separate the two checks for single vlan and multiple vlans in
netif_skb_features().  This allows us to move the check for multiple
vlans to another function later.

Signed-off-by: Toshiaki Makita <makita.toshiaki@....ntt.co.jp>
---
 include/linux/if_vlan.h | 45 +++++++++++++++++++++++++++++++++++++++++++++
 net/core/dev.c          | 24 ++++++++----------------
 2 files changed, 53 insertions(+), 16 deletions(-)

diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
index b11b28a..4265d44 100644
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h
@@ -561,4 +561,49 @@ static inline void vlan_set_encap_proto(struct sk_buff *skb,
 		skb->protocol = htons(ETH_P_802_2);
 }
 
+/**
+ * skb_vlan_tagged - check if skb is vlan tagged.
+ * @skb: skbuff to query
+ *
+ * Returns true if the skb is tagged, regardless of whether it is hardware
+ * accelerated or not.
+ */
+static inline bool skb_vlan_tagged(const struct sk_buff *skb)
+{
+	if (!skb_vlan_tag_present(skb) &&
+	    likely(skb->protocol != htons(ETH_P_8021Q) &&
+		   skb->protocol != htons(ETH_P_8021AD)))
+		return false;
+
+	return true;
+}
+
+/**
+ * skb_vlan_tagged_multi - check if skb is vlan tagged with multiple headers.
+ * @skb: skbuff to query
+ *
+ * Returns true if the skb is tagged with multiple vlan headers, regardless
+ * of whether it is hardware accelerated or not.
+ */
+static inline bool skb_vlan_tagged_multi(const struct sk_buff *skb)
+{
+	__be16 protocol = skb->protocol;
+
+	if (!skb_vlan_tag_present(skb)) {
+		struct vlan_ethhdr *veh;
+
+		if (likely(protocol != htons(ETH_P_8021Q) &&
+			   protocol != htons(ETH_P_8021AD)))
+			return false;
+
+		veh = (struct vlan_ethhdr *)skb->data;
+		protocol = veh->h_vlan_encapsulated_proto;
+	}
+
+	if (protocol != htons(ETH_P_8021Q) && protocol != htons(ETH_P_8021AD))
+		return false;
+
+	return true;
+}
+
 #endif /* !(_LINUX_IF_VLAN_H_) */
diff --git a/net/core/dev.c b/net/core/dev.c
index a0408d4..04bffcd 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2567,7 +2567,6 @@ netdev_features_t netif_skb_features(struct sk_buff *skb)
 	struct net_device *dev = skb->dev;
 	netdev_features_t features = dev->features;
 	u16 gso_segs = skb_shinfo(skb)->gso_segs;
-	__be16 protocol = skb->protocol;
 
 	if (gso_segs > dev->gso_max_segs || gso_segs < dev->gso_min_segs)
 		features &= ~NETIF_F_GSO_MASK;
@@ -2579,22 +2578,15 @@ netdev_features_t netif_skb_features(struct sk_buff *skb)
 	if (skb->encapsulation)
 		features &= dev->hw_enc_features;
 
-	if (!skb_vlan_tag_present(skb)) {
-		if (unlikely(protocol == htons(ETH_P_8021Q) ||
-			     protocol == htons(ETH_P_8021AD))) {
-			struct vlan_ethhdr *veh = (struct vlan_ethhdr *)skb->data;
-			protocol = veh->h_vlan_encapsulated_proto;
-		} else {
-			goto finalize;
-		}
-	}
-
-	features = netdev_intersect_features(features,
-					     dev->vlan_features |
-					     NETIF_F_HW_VLAN_CTAG_TX |
-					     NETIF_F_HW_VLAN_STAG_TX);
+	if (skb_vlan_tagged(skb))
+		features = netdev_intersect_features(features,
+						     dev->vlan_features |
+						     NETIF_F_HW_VLAN_CTAG_TX |
+						     NETIF_F_HW_VLAN_STAG_TX);
+	else
+		goto finalize;
 
-	if (protocol == htons(ETH_P_8021Q) || protocol == htons(ETH_P_8021AD))
+	if (skb_vlan_tagged_multi(skb))
 		features = netdev_intersect_features(features,
 						     NETIF_F_SG |
 						     NETIF_F_HIGHDMA |
-- 
1.8.1.2


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