From c146f9bc195a9dc3ad7fd000a14540e7c9df952d Mon Sep 17 00:00:00 2001 From: Vladimir Oltean Date: Thu, 6 Jan 2022 01:11:15 +0200 Subject: [PATCH 4/6] 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 Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller --- net/dsa/dsa2.c | 8 ++++++++ net/dsa/master.c | 4 ++-- 2 files changed, 10 insertions(+), 2 deletions(-) --- a/net/dsa/dsa2.c +++ b/net/dsa/dsa2.c @@ -1034,6 +1034,8 @@ static int dsa_tree_setup_master(struct 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); @@ -1042,6 +1044,8 @@ static int dsa_tree_setup_master(struct } } + rtnl_unlock(); + return 0; } @@ -1049,9 +1053,13 @@ static void dsa_tree_teardown_master(str { 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) --- a/net/dsa/master.c +++ b/net/dsa/master.c @@ -266,9 +266,9 @@ static void dsa_master_set_promiscuity(s 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,