net: dsa: hold rtnl_mutex when calling dsa_master_{setup,teardown}

DSA needs to simulate master tracking events when a binding is first
with a DSA master established and torn down, in order to give drivers
the simplifying guarantee that ->master_state_change calls are made
only when the master's readiness state to pass traffic changes.
master_state_change() provide a operational bool that DSA driver can use
to understand if DSA master is operational or not.
To avoid races, we need to block the reception of
NETDEV_UP/NETDEV_CHANGE/NETDEV_GOING_DOWN events in the netdev notifier
chain while we are changing the master's dev->dsa_ptr (this changes what
netdev_uses_dsa(dev) reports).

The dsa_master_setup() and dsa_master_teardown() functions optionally
require the rtnl_mutex to be held, if the tagger needs the master to be
promiscuous, these functions call dev_set_promiscuity(). Move the
rtnl_lock() from that function and make it top-level.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index a0d84f9f864fe48e2e601418f158d6dd5c6b80b8..52fb1958b53586eb84ae06773331ba04c5fce77e 100644 (file)
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c
@@ -1038,6 +1038,8 @@ static int dsa_tree_setup_master(struct dsa_switch_tree *dst)
        struct dsa_port *dp;
        int err;
 
+       rtnl_lock();
+
        list_for_each_entry(dp, &dst->ports, list) {
                if (dsa_port_is_cpu(dp)) {
                        err = dsa_master_setup(dp->master, dp);
@@ -1046,6 +1048,8 @@ static int dsa_tree_setup_master(struct dsa_switch_tree *dst)
                }
        }
 
+       rtnl_unlock();
+
        return 0;
 }
 
@@ -1053,9 +1057,13 @@ static void dsa_tree_teardown_master(struct dsa_switch_tree *dst)
 {
        struct dsa_port *dp;
 
+       rtnl_lock();
+
        list_for_each_entry(dp, &dst->ports, list)
                if (dsa_port_is_cpu(dp))
                        dsa_master_teardown(dp->master);
+
+       rtnl_unlock();
 }
 
 static int dsa_tree_setup_lags(struct dsa_switch_tree *dst)

diff --git a/net/dsa/master.c b/net/dsa/master.c
index f4efb244f91d1610160124c68e21f88f551ea733..2199104ca7dfa15f943b24bb3dd52c4e181d33eb 100644 (file)
--- a/net/dsa/master.c
+++ b/net/dsa/master.c
@@ -267,9 +267,9 @@ static void dsa_master_set_promiscuity(struct net_device *dev, int inc)
        if (!ops->promisc_on_master)
                return;
 
-       rtnl_lock();
+       ASSERT_RTNL();
+
        dev_set_promiscuity(dev, inc);
-       rtnl_unlock();
 }
 
 static ssize_t tagging_show(struct device *d, struct device_attribute *attr,