Merge branch 'net-dsa-Improve-dsa_untag_bridge_pvid'

Florian Fainelli says:

====================
net: dsa: Improve dsa_untag_bridge_pvid()

This patch series is based on the recent discussions with Vladimir:

https://lore.kernel.org/netdev/20201001030623.343535-1-f.fainelli@gmail.com/

the simplest way forward was to call dsa_untag_bridge_pvid() after
eth_type_trans() has been set which guarantees that skb->protocol is set
to a correct value and this allows us to utilize
__vlan_find_dev_deep_rcu() properly without playing or using the bridge
master as a net_device reference.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/b53/b53_common.c

@@ -2603,6 +2603,7 @@ struct b53_device *b53_switch_alloc(struct device *base,
 	dev->ops = ops;
 	ds->ops = &b53_switch_ops;
 	ds->configure_vlan_while_not_filtering = true;
+	ds->untag_bridge_pvid = true;
 	dev->vlan_enabled = ds->configure_vlan_while_not_filtering;
 	mutex_init(&dev->reg_mutex);
 	mutex_init(&dev->stats_mutex);

include/net/dsa.h

@@ -308,6 +308,14 @@ struct dsa_switch {
 	 */
 	bool			configure_vlan_while_not_filtering;
 
+	/* If the switch driver always programs the CPU port as egress tagged
+	 * despite the VLAN configuration indicating otherwise, then setting
+	 * @untag_bridge_pvid will force the DSA receive path to pop the bridge's
+	 * default_pvid VLAN tagged frames to offer a consistent behavior
+	 * between a vlan_filtering=0 and vlan_filtering=1 bridge device.
+	 */
+	bool			untag_bridge_pvid;
+
 	/* In case vlan_filtering_is_global is set, the VLAN awareness state
 	 * should be retrieved from here and not from the per-port settings.
 	 */

net/dsa/dsa.c

@@ -225,6 +225,15 @@ static int dsa_switch_rcv(struct sk_buff *skb, struct net_device *dev,
 	skb->pkt_type = PACKET_HOST;
 	skb->protocol = eth_type_trans(skb, skb->dev);
 
+	if (unlikely(cpu_dp->ds->untag_bridge_pvid)) {
+		nskb = dsa_untag_bridge_pvid(skb);
+		if (!nskb) {
+			kfree_skb(skb);
+			return 0;
+		}
+		skb = nskb;
+	}
+
 	s = this_cpu_ptr(p->stats64);
 	u64_stats_update_begin(&s->syncp);
 	s->rx_packets++;

net/dsa/dsa_priv.h

@@ -201,11 +201,9 @@ dsa_slave_to_master(const struct net_device *dev)
 static inline struct sk_buff *dsa_untag_bridge_pvid(struct sk_buff *skb)
 {
 	struct dsa_port *dp = dsa_slave_to_port(skb->dev);
-	struct vlan_ethhdr *hdr = vlan_eth_hdr(skb);
 	struct net_device *br = dp->bridge_dev;
 	struct net_device *dev = skb->dev;
 	struct net_device *upper_dev;
-	struct list_head *iter;
 	u16 vid, pvid, proto;
 	int err;
 
@@ -217,7 +215,7 @@ static inline struct sk_buff *dsa_untag_bridge_pvid(struct sk_buff *skb)
 		return skb;
 
 	/* Move VLAN tag from data to hwaccel */
-	if (!skb_vlan_tag_present(skb) && hdr->h_vlan_proto == htons(proto)) {
+	if (!skb_vlan_tag_present(skb) && skb->protocol == htons(proto)) {
 		skb = skb_vlan_untag(skb);
 		if (!skb)
 			return NULL;
@@ -247,13 +245,9 @@ static inline struct sk_buff *dsa_untag_bridge_pvid(struct sk_buff *skb)
 	 * supports because vlan_filtering is 0. In that case, we should
 	 * definitely keep the tag, to make sure it keeps working.
 	 */
-	netdev_for_each_upper_dev_rcu(dev, upper_dev, iter) {
-		if (!is_vlan_dev(upper_dev))
-			continue;
-
-		if (vid == vlan_dev_vlan_id(upper_dev))
+	upper_dev = __vlan_find_dev_deep_rcu(br, htons(proto), vid);
+	if (upper_dev)
 		return skb;
-	}
 
 	__vlan_hwaccel_clear_tag(skb);
 

net/dsa/tag_brcm.c

@@ -152,11 +152,6 @@ static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb,
 	/* Remove Broadcom tag and update checksum */
 	skb_pull_rcsum(skb, BRCM_TAG_LEN);
 
-	/* Set the MAC header to where it should point for
-	 * dsa_untag_bridge_pvid() to parse the correct VLAN header.
-	 */
-	skb_set_mac_header(skb, -ETH_HLEN);
-
 	skb->offload_fwd_mark = 1;
 
 	return skb;
@@ -187,7 +182,7 @@ static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
 		nskb->data - ETH_HLEN - BRCM_TAG_LEN,
 		2 * ETH_ALEN);
 
-	return dsa_untag_bridge_pvid(nskb);
+	return nskb;
 }
 
 static const struct dsa_device_ops brcm_netdev_ops = {
@@ -214,14 +209,8 @@ static struct sk_buff *brcm_tag_rcv_prepend(struct sk_buff *skb,
 					    struct net_device *dev,
 					    struct packet_type *pt)
 {
-	struct sk_buff *nskb;
-
 	/* tag is prepended to the packet */
-	nskb = brcm_tag_rcv_ll(skb, dev, pt, ETH_HLEN);
-	if (!nskb)
-		return nskb;
-
-	return dsa_untag_bridge_pvid(nskb);
+	return brcm_tag_rcv_ll(skb, dev, pt, ETH_HLEN);
 }
 
 static const struct dsa_device_ops brcm_prepend_netdev_ops = {