[PATCH 4.19 20/45] mvpp2: refactor MTU change code

[Greg Kroah-Hartman]

From: Matteo Croce <mcr...@redhat.com>

[ Upstream commit 230bd958c2c846ee292aa38bc6b006296c24ca01 ]

The MTU change code can call napi_disable() with the device already down,
leading to a deadlock. Also, lot of code is duplicated unnecessarily.

Rework mvpp2_change_mtu() to avoid the deadlock and remove duplicated code.

Fixes: 3f518509dedc ("ethernet: Add new driver for Marvell Armada 375 network 
unit")
Signed-off-by: Matteo Croce <mcr...@redhat.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c |   41 +++++++-----------------
 1 file changed, 13 insertions(+), 28 deletions(-)

--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
@@ -3501,6 +3501,7 @@ static int mvpp2_set_mac_address(struct
 static int mvpp2_change_mtu(struct net_device *dev, int mtu)
 {
        struct mvpp2_port *port = netdev_priv(dev);
+       bool running = netif_running(dev);
        int err;
 
        if (!IS_ALIGNED(MVPP2_RX_PKT_SIZE(mtu), 8)) {
@@ -3509,40 +3510,24 @@ static int mvpp2_change_mtu(struct net_d
                mtu = ALIGN(MVPP2_RX_PKT_SIZE(mtu), 8);
        }
 
-       if (!netif_running(dev)) {
-               err = mvpp2_bm_update_mtu(dev, mtu);
-               if (!err) {
-                       port->pkt_size =  MVPP2_RX_PKT_SIZE(mtu);
-                       return 0;
-               }
+       if (running)
+               mvpp2_stop_dev(port);
 
+       err = mvpp2_bm_update_mtu(dev, mtu);
+       if (err) {
+               netdev_err(dev, "failed to change MTU\n");
                /* Reconfigure BM to the original MTU */
-               err = mvpp2_bm_update_mtu(dev, dev->mtu);
-               if (err)
-                       goto log_error;
+               mvpp2_bm_update_mtu(dev, dev->mtu);
+       } else {
+               port->pkt_size =  MVPP2_RX_PKT_SIZE(mtu);
        }
 
-       mvpp2_stop_dev(port);
-
-       err = mvpp2_bm_update_mtu(dev, mtu);
-       if (!err) {
-               port->pkt_size =  MVPP2_RX_PKT_SIZE(mtu);
-               goto out_start;
+       if (running) {
+               mvpp2_start_dev(port);
+               mvpp2_egress_enable(port);
+               mvpp2_ingress_enable(port);
        }
 
-       /* Reconfigure BM to the original MTU */
-       err = mvpp2_bm_update_mtu(dev, dev->mtu);
-       if (err)
-               goto log_error;
-
-out_start:
-       mvpp2_start_dev(port);
-       mvpp2_egress_enable(port);
-       mvpp2_ingress_enable(port);
-
-       return 0;
-log_error:
-       netdev_err(dev, "failed to change MTU\n");
        return err;
 }