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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Matteo Croce <mcroce@redhat.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.14 26/33] mvpp2: refactor MTU change code
Date:   Thu,  8 Aug 2019 21:05:33 +0200
Message-Id: <20190808190454.926578477@linuxfoundation.org>
In-Reply-To: <20190808190453.582417307@linuxfoundation.org>
References: <20190808190453.582417307@linuxfoundation.org>
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From: Matteo Croce <mcroce@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 <mcroce@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/marvell/mvpp2.c |   41 +++++++++++------------------------
 1 file changed, 13 insertions(+), 28 deletions(-)

--- a/drivers/net/ethernet/marvell/mvpp2.c
+++ b/drivers/net/ethernet/marvell/mvpp2.c
@@ -6952,6 +6952,7 @@ log_error:
 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)) {
@@ -6960,40 +6961,24 @@ 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;
 }