netdev - [PATCH net-next 1/4] bridge: Allow enslaving DSA master network devices

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Message-Id: <20200429161952.17769-2-olteanv@gmail.com>
Date:   Wed, 29 Apr 2020 19:19:49 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     andrew@...n.ch, f.fainelli@...il.com, vivien.didelot@...il.com,
        davem@...emloft.net
Cc:     jiri@...nulli.us, idosch@...sch.org, kuba@...nel.org,
        netdev@...r.kernel.org, leoyang.li@....com,
        nikolay@...ulusnetworks.com
Subject: [PATCH net-next 1/4] bridge: Allow enslaving DSA master network devices

From: Florian Fainelli <f.fainelli@...il.com>

Commit 8db0a2ee2c63 ("net: bridge: reject DSA-enabled master netdevices
as bridge members") added a special check in br_if.c in order to check
for a DSA master network device with a tagging protocol configured. This
was done because back then, such devices, once enslaved in a bridge
would become inoperative and would not pass DSA tagged traffic anymore
due to br_handle_frame returning RX_HANDLER_CONSUMED.

But right now we have valid use cases which do require bridging of DSA
masters. One such example is when the DSA master ports are DSA switch
ports themselves (in a disjoint tree setup). This should be completely
equivalent, functionally speaking, from having multiple DSA switches
hanging off of the ports of a switchdev driver. So we should allow the
enslaving of DSA tagged master network devices.

Make br_handle_frame() return RX_HANDLER_PASS in order to call into the
DSA specific tagging protocol handlers, and lift the restriction from
br_add_if.

Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
---
 net/bridge/br_if.c    | 4 +---
 net/bridge/br_input.c | 4 +++-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index ca685c0cdf95..e0fbdb855664 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -18,7 +18,6 @@
 #include <linux/rtnetlink.h>
 #include <linux/if_ether.h>
 #include <linux/slab.h>
-#include <net/dsa.h>
 #include <net/sock.h>
 #include <linux/if_vlan.h>
 #include <net/switchdev.h>
@@ -571,8 +570,7 @@ int br_add_if(struct net_bridge *br, struct net_device *dev,
 	 */
 	if ((dev->flags & IFF_LOOPBACK) ||
 	    dev->type != ARPHRD_ETHER || dev->addr_len != ETH_ALEN ||
-	    !is_valid_ether_addr(dev->dev_addr) ||
-	    netdev_uses_dsa(dev))
+	    !is_valid_ether_addr(dev->dev_addr))
 		return -EINVAL;

 	/* No bridging of bridges */
diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index d5c34f36f0f4..396bc0c18cb5 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -17,6 +17,7 @@
 #endif
 #include <linux/neighbour.h>
 #include <net/arp.h>
+#include <net/dsa.h>
 #include <linux/export.h>
 #include <linux/rculist.h>
 #include "br_private.h"
@@ -263,7 +264,8 @@ rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
 	struct sk_buff *skb = *pskb;
 	const unsigned char *dest = eth_hdr(skb)->h_dest;

-	if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
+	if (unlikely(skb->pkt_type == PACKET_LOOPBACK) ||
+	    netdev_uses_dsa(skb->dev))
 		return RX_HANDLER_PASS;

 	if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
-- 
2.17.1