[PATCH net v3 2/2] net: sparx5: fix sleep in atomic context in MAC table access

sparx5_set_rx_mode() runs with netif_addr_lock_bh held and iterates
dev->mc via __dev_mc_sync(), which per address calls sparx5_mc_sync() /
sparx5_mc_unsync() -> sparx5_mact_learn() / sparx5_mact_forget().  These
take sparx5->lock, a mutex, and then poll the MAC access command
register with readx_poll_timeout(). A mutex may block, which is not
allowed from atomic context.

Convert the driver to the new .ndo_set_rx_mode_async callback introduced
in commit 3554b4345d85 ("net: introduce ndo_set_rx_mode_async and
netdev_rx_mode_work"). The async callback is invoked from process
context, so the mutex and sleeping completion poll can remain.

Observed with CONFIG_PROVE_LOCKING, CONFIG_DEBUG_SPINLOCK,
CONFIG_DEBUG_MUTEXES and CONFIG_DEBUG_ATOMIC_SLEEP enabled:

  BUG: sleeping function called from invalid context at kernel/locking/mutex.c:591
  in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 217, name: ip
  preempt_count: 201, expected: 0
  Call trace:
   __might_resched+0x144/0x248
   __might_sleep+0x48/0x7c
   __mutex_lock+0x74/0x850
   mutex_lock_nested+0x24/0x30
   sparx5_mact_learn+0x78/0x100
   sparx5_mc_sync+0x40/0x54
   __hw_addr_sync_dev+0xc4/0x170
   sparx5_set_rx_mode+0x4c/0x58
   __dev_set_rx_mode+0x64/0xa4
   __dev_open+0x1ec/0x26c

Fixes: d6fce5141929 ("net: sparx5: add switching support")
Signed-off-by: Daniel Machon <daniel.machon@microchip.com>
---
 drivers/net/ethernet/microchip/sparx5/sparx5_netdev.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/microchip/sparx5/sparx5_netdev.c b/drivers/net/ethernet/microchip/sparx5/sparx5_netdev.c
index 1d34af78166a..4dedf5d92641 100644
--- a/drivers/net/ethernet/microchip/sparx5/sparx5_netdev.c
+++ b/drivers/net/ethernet/microchip/sparx5/sparx5_netdev.c

@@ -162,13 +162,18 @@ static int sparx5_port_stop(struct net_device *ndev)
 	return 0;
 }
 
-static void sparx5_set_rx_mode(struct net_device *dev)
+static int sparx5_set_rx_mode(struct net_device *dev,
+			      struct netdev_hw_addr_list *uc,
+			      struct netdev_hw_addr_list *mc)
 {
 	struct sparx5_port *port = netdev_priv(dev);
 	struct sparx5 *sparx5 = port->sparx5;
 
 	if (!test_bit(port->portno, sparx5->bridge_mask))
-		__dev_mc_sync(dev, sparx5_mc_sync, sparx5_mc_unsync);
+		return __hw_addr_sync_dev(mc, dev, sparx5_mc_sync,
+					  sparx5_mc_unsync);
+
+	return 0;
 }
 
 static int sparx5_port_get_phys_port_name(struct net_device *dev,

@@ -249,7 +254,7 @@ static const struct net_device_ops sparx5_port_netdev_ops = {
 	.ndo_open               = sparx5_port_open,
 	.ndo_stop               = sparx5_port_stop,
 	.ndo_start_xmit         = sparx5_port_xmit_impl,
-	.ndo_set_rx_mode        = sparx5_set_rx_mode,
+	.ndo_set_rx_mode_async  = sparx5_set_rx_mode,
 	.ndo_get_phys_port_name = sparx5_port_get_phys_port_name,
 	.ndo_set_mac_address    = sparx5_set_mac_address,
 	.ndo_validate_addr      = eth_validate_addr,

-- 
2.34.1