From e83d56537859849f2223b90749e554831b1f3c27 Mon Sep 17 00:00:00 2001 From: Vladimir Oltean Date: Wed, 2 Feb 2022 01:03:21 +0100 Subject: [PATCH] net: dsa: replay master state events in dsa_tree_{setup,teardown}_master In order for switch driver to be able to make simple and reliable use of the master tracking operations, they must also be notified of the initial state of the DSA master, not just of the changes. This is because they might enable certain features only during the time when they know that the DSA master is up and running. Therefore, this change explicitly checks the state of the DSA master under the same rtnl_mutex as we were holding during the dsa_master_setup() and dsa_master_teardown() call. The idea being that if the DSA master became operational in between the moment in which it became a DSA master (dsa_master_setup set dev->dsa_ptr) and the moment when we checked for the master being up, there is a chance that we would emit a ->master_state_change() call with no actual state change. We need to avoid that by serializing the concurrent netdevice event with us. If the netdevice event started before, we force it to finish before we begin, because we take rtnl_lock before making netdev_uses_dsa() return true. So we also handle that early event and do nothing on it. Similarly, if the dev_open() attempt is concurrent with us, it will attempt to take the rtnl_mutex, but we're holding it. We'll see that the master flag IFF_UP isn't set, then when we release the rtnl_mutex we'll process the NETDEV_UP notifier. Signed-off-by: Vladimir Oltean Signed-off-by: Ansuel Smith Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller --- net/dsa/dsa2.c | 28 ++++++++++++++++++++++++---- 1 file changed, 24 insertions(+), 4 deletions(-) diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c index ff998c0ede027..909b045c9b118 100644 --- a/net/dsa/dsa2.c +++ b/net/dsa/dsa2.c @@ -15,6 +15,7 @@ #include #include #include +#include #include "dsa_priv.h" @@ -1064,9 +1065,18 @@ static int dsa_tree_setup_master(struct dsa_switch_tree *dst) list_for_each_entry(dp, &dst->ports, list) { if (dsa_port_is_cpu(dp)) { - err = dsa_master_setup(dp->master, dp); + struct net_device *master = dp->master; + bool admin_up = (master->flags & IFF_UP) && + !qdisc_tx_is_noop(master); + + err = dsa_master_setup(master, dp); if (err) return err; + + /* Replay master state event */ + dsa_tree_master_admin_state_change(dst, master, admin_up); + dsa_tree_master_oper_state_change(dst, master, + netif_oper_up(master)); } } @@ -1081,9 +1091,19 @@ static void dsa_tree_teardown_master(struct dsa_switch_tree *dst) rtnl_lock(); - list_for_each_entry(dp, &dst->ports, list) - if (dsa_port_is_cpu(dp)) - dsa_master_teardown(dp->master); + list_for_each_entry(dp, &dst->ports, list) { + if (dsa_port_is_cpu(dp)) { + struct net_device *master = dp->master; + + /* Synthesizing an "admin down" state is sufficient for + * the switches to get a notification if the master is + * currently up and running. + */ + dsa_tree_master_admin_state_change(dst, master, false); + + dsa_master_teardown(master); + } + } rtnl_unlock(); } -- 2.39.5