net: mscc: ocelot: install MAC addresses in .ndo_set_rx_mode from process context

Currently ocelot_set_rx_mode calls ocelot_mact_learn directly, which has
a very nice ocelot_mact_wait_for_completion at the end. Introduced in
commit 639c1b2625af ("net: mscc: ocelot: Register poll timeout should be
wall time not attempts"), this function uses readx_poll_timeout which
triggers a lot of lockdep warnings and is also dangerous to use from
atomic context, potentially leading to lockups and panics.

Steen Hegelund added a poll timeout of 100 ms for checking the MAC
table, a duration which is clearly absurd to poll in atomic context.
So we need to defer the MAC table access to process context, which we do
via a dynamically allocated workqueue which contains all there is to
know about the MAC table operation it has to do.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20201212191612.222019-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/net/ethernet/mscc/ocelot.c b/drivers/net/ethernet/mscc/ocelot.c
index abea8dd2b0cb..0b9992bd6626 100644
--- a/drivers/net/ethernet/mscc/ocelot.c
+++ b/drivers/net/ethernet/mscc/ocelot.c
@@ -1513,6 +1513,12 @@ int ocelot_init(struct ocelot *ocelot)
 	if (!ocelot->stats_queue)
 		return -ENOMEM;
 
+	ocelot->owq = alloc_ordered_workqueue("ocelot-owq", 0);
+	if (!ocelot->owq) {
+		destroy_workqueue(ocelot->stats_queue);
+		return -ENOMEM;
+	}
+
 	INIT_LIST_HEAD(&ocelot->multicast);
 	INIT_LIST_HEAD(&ocelot->pgids);
 	ocelot_mact_init(ocelot);
@@ -1619,6 +1625,7 @@ void ocelot_deinit(struct ocelot *ocelot)
 {
 	cancel_delayed_work(&ocelot->stats_work);
 	destroy_workqueue(ocelot->stats_queue);
+	destroy_workqueue(ocelot->owq);
 	mutex_destroy(&ocelot->stats_lock);
 }
 EXPORT_SYMBOL(ocelot_deinit);