linux-kernel - [PATCH net-next 4/9] net: dsa: don't keep track of admin/oper state on LAG DSA masters

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Date:   Tue, 30 Aug 2022 22:59:27 +0300
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     netdev@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vladimir Oltean <olteanv@...il.com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        UNGLinuxDriver@...rochip.com,
        Colin Foster <colin.foster@...advantage.com>,
        Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <razor@...ckwall.org>,
        Tobias Waldekranz <tobias@...dekranz.com>,
        Marek Behún <kabel@...nel.org>,
        Ansuel Smith <ansuelsmth@...il.com>,
        DENG Qingfang <dqfext@...il.com>,
        Alvin Šipraga <alsi@...g-olufsen.dk>,
        Linus Walleij <linus.walleij@...aro.org>,
        Luiz Angelo Daros de Luca <luizluca@...il.com>,
        Felix Fietkau <nbd@....name>, John Crispin <john@...ozen.org>,
        Sean Wang <sean.wang@...iatek.com>
Subject: [PATCH net-next 4/9] net: dsa: don't keep track of admin/oper state on LAG DSA masters

We store information about the DSA master's state in
cpu_dp->master_admin_up and cpu_dp->master_oper_up, and this assumes a
bijective association between a CPU port and a DSA master.

However, when we have CPU ports in a LAG (and DSA masters in a LAG too),
the way in which we set up things is that the physical DSA masters still
have dev->dsa_ptr pointing to our cpu_dp, but the bonding/team device
itself also has its dev->dsa_ptr pointing towards one of the CPU port
structures (the first one).

So logically speaking, that first cpu_dp can't keep track of both the
physical master's admin/oper state, and of the bonding master's state.

This isn't even needed; the reason why we keep track of the DSA master's
state is to know when it is available for Ethernet-based register access.
For that use case, we don't even need LAG; we just need to decide upon
one of the physical DSA masters (if there is more than 1 available) and
use that.

This change suppresses dsa_tree_master_{admin,oper}_state_change() calls
on LAG DSA masters (which will be supported in a future change), to
allow the tracking of just physical DSA masters.

Link: https://lore.kernel.org/netdev/628cc94d.1c69fb81.15b0d.422d@mx.google.com/
Suggested-by: Christian Marangi <ansuelsmth@...il.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
---
 net/dsa/dsa2.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index 42422ddea59b..7024e2120de1 100644
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c
@@ -1326,6 +1326,12 @@ void dsa_tree_master_admin_state_change(struct dsa_switch_tree *dst,
 	struct dsa_port *cpu_dp = master->dsa_ptr;
 	bool notify = false;

+	/* Don't keep track of admin state on LAG DSA masters,
+	 * but rather just of physical DSA masters
+	 */
+	if (netif_is_lag_master(master))
+		return;
+
 	if ((dsa_port_master_is_operational(cpu_dp)) !=
 	    (up && cpu_dp->master_oper_up))
 		notify = true;
@@ -1343,6 +1349,12 @@ void dsa_tree_master_oper_state_change(struct dsa_switch_tree *dst,
 	struct dsa_port *cpu_dp = master->dsa_ptr;
 	bool notify = false;

+	/* Don't keep track of oper state on LAG DSA masters,
+	 * but rather just of physical DSA masters
+	 */
+	if (netif_is_lag_master(master))
+		return;
+
 	if ((dsa_port_master_is_operational(cpu_dp)) !=
 	    (cpu_dp->master_admin_up && up))
 		notify = true;
-- 
2.34.1