From 5b22d3669f2fa6e762c5302fc4b6051a92b81617 Mon Sep 17 00:00:00 2001 From: Vladimir Oltean Date: Thu, 22 Jul 2021 18:55:39 +0300 Subject: [PATCH] net: dsa: track the number of switches in a tree In preparation of supporting data plane forwarding on behalf of a software bridge, some drivers might need to view bridges as virtual switches behind the CPU port in a cross-chip topology. Give them some help and let them know how many physical switches there are in the tree, so that they can count the virtual switches starting from that number on. Note that the first dsa_switch_ops method where this information is reliably available is .setup(). This is because of how DSA works: in a tree with 3 switches, each calling dsa_register_switch(), the first 2 will advance until dsa_tree_setup() -> dsa_tree_setup_routing_table() and exit with error code 0 because the topology is not complete. Since probing is parallel at this point, one switch does not know about the existence of the other. Then the third switch comes, and for it, dsa_tree_setup_routing_table() returns complete = true. This switch goes ahead and calls dsa_tree_setup_switches() for everybody else, calling their .setup() methods too. This acts as the synchronization point. Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller --- include/net/dsa.h | 3 +++ net/dsa/dsa2.c | 3 +++ 2 files changed, 6 insertions(+) diff --git a/include/net/dsa.h b/include/net/dsa.h index 9e55938..929bcae 100644 --- a/include/net/dsa.h +++ b/include/net/dsa.h @@ -159,6 +159,9 @@ struct dsa_switch_tree { */ struct net_device **lags; unsigned int lags_len; + + /* Track the largest switch index within a tree */ + unsigned int last_switch; }; #define dsa_lags_foreach_id(_id, _dst) \ diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c index 185629f..de5e93b 100644 --- a/net/dsa/dsa2.c +++ b/net/dsa/dsa2.c @@ -1265,6 +1265,9 @@ static int dsa_switch_parse_member_of(struct dsa_switch *ds, return -EEXIST; } + if (ds->dst->last_switch < ds->index) + ds->dst->last_switch = ds->index; + return 0; } -- 2.7.4