netdev - [PATCH net-next 01/10] net: dsa: remove workarounds for changing master promisc/allmulti only while up

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Date:   Wed,  2 Mar 2022 21:14:08 +0200
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     netdev@...r.kernel.org
Cc:     Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        Ido Schimmel <idosch@...dia.com>,
        Tobias Waldekranz <tobias@...dekranz.com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        UNGLinuxDriver@...rochip.com
Subject: [PATCH net-next 01/10] net: dsa: remove workarounds for changing master promisc/allmulti only while up

Lennert Buytenhek explains in commit df02c6ff2e39 ("dsa: fix master
interface allmulti/promisc handling"), dated Nov 2008, that changing the
promiscuity of interfaces that are down (here the master) is broken.

This fact regarding promisc/allmulti has changed since commit
b6c40d68ff64 ("net: only invoke dev->change_rx_flags when device is UP")
by Vlad Yasevich, dated Nov 2013.

Therefore, DSA now has unnecessary complexity to handle master state
transitions from down to up. In fact, syncing the unicast and multicast
addresses can happen completely asynchronously to the administrative
state changes.

This change reduces that complexity by effectively fully reverting
commit df02c6ff2e39 ("dsa: fix master interface allmulti/promisc
handling").

Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
---
 net/dsa/slave.c | 45 ++++++++-------------------------------------
 1 file changed, 8 insertions(+), 37 deletions(-)

diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index 089616206b11..52d1316368c9 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -81,29 +81,12 @@ static int dsa_slave_open(struct net_device *dev)
 			goto out;
 	}
 
-	if (dev->flags & IFF_ALLMULTI) {
-		err = dev_set_allmulti(master, 1);
-		if (err < 0)
-			goto del_unicast;
-	}
-	if (dev->flags & IFF_PROMISC) {
-		err = dev_set_promiscuity(master, 1);
-		if (err < 0)
-			goto clear_allmulti;
-	}
-
 	err = dsa_port_enable_rt(dp, dev->phydev);
 	if (err)
-		goto clear_promisc;
+		goto del_unicast;
 
 	return 0;
 
-clear_promisc:
-	if (dev->flags & IFF_PROMISC)
-		dev_set_promiscuity(master, -1);
-clear_allmulti:
-	if (dev->flags & IFF_ALLMULTI)
-		dev_set_allmulti(master, -1);
 del_unicast:
 	if (!ether_addr_equal(dev->dev_addr, master->dev_addr))
 		dev_uc_del(master, dev->dev_addr);
@@ -118,13 +101,6 @@ static int dsa_slave_close(struct net_device *dev)
 
 	dsa_port_disable_rt(dp);
 
-	dev_mc_unsync(master, dev);
-	dev_uc_unsync(master, dev);
-	if (dev->flags & IFF_ALLMULTI)
-		dev_set_allmulti(master, -1);
-	if (dev->flags & IFF_PROMISC)
-		dev_set_promiscuity(master, -1);
-
 	if (!ether_addr_equal(dev->dev_addr, master->dev_addr))
 		dev_uc_del(master, dev->dev_addr);
 
@@ -134,14 +110,13 @@ static int dsa_slave_close(struct net_device *dev)
 static void dsa_slave_change_rx_flags(struct net_device *dev, int change)
 {
 	struct net_device *master = dsa_slave_to_master(dev);
-	if (dev->flags & IFF_UP) {
-		if (change & IFF_ALLMULTI)
-			dev_set_allmulti(master,
-					 dev->flags & IFF_ALLMULTI ? 1 : -1);
-		if (change & IFF_PROMISC)
-			dev_set_promiscuity(master,
-					    dev->flags & IFF_PROMISC ? 1 : -1);
-	}
+
+	if (change & IFF_ALLMULTI)
+		dev_set_allmulti(master,
+				 dev->flags & IFF_ALLMULTI ? 1 : -1);
+	if (change & IFF_PROMISC)
+		dev_set_promiscuity(master,
+				    dev->flags & IFF_PROMISC ? 1 : -1);
 }
 
 static void dsa_slave_set_rx_mode(struct net_device *dev)
@@ -161,9 +136,6 @@ static int dsa_slave_set_mac_address(struct net_device *dev, void *a)
 	if (!is_valid_ether_addr(addr->sa_data))
 		return -EADDRNOTAVAIL;
 
-	if (!(dev->flags & IFF_UP))
-		goto out;
-
 	if (!ether_addr_equal(addr->sa_data, master->dev_addr)) {
 		err = dev_uc_add(master, addr->sa_data);
 		if (err < 0)
@@ -173,7 +145,6 @@ static int dsa_slave_set_mac_address(struct net_device *dev, void *a)
 	if (!ether_addr_equal(dev->dev_addr, master->dev_addr))
 		dev_uc_del(master, dev->dev_addr);
 
-out:
 	eth_hw_addr_set(dev, addr->sa_data);
 
 	return 0;
-- 
2.25.1