net: mvneta: Fix spinlock usage

In the previous patch, the spinlock was not initialized. While it didn't
cause any trouble yet it could be a problem to use it uninitialized.

The most annoying part was the critical section protected by the spinlock
in mvneta_stop(). Some of the functions could sleep as pointed when
activated CONFIG_DEBUG_ATOMIC_SLEEP. Actually, in mvneta_stop() we only
need to protect the is_stopped flagged, indeed the code of the notifier
for CPU online is protected by the same spinlock, so when we get the
lock, the notifer work is done.

Reported-by: Patrick Uiterwijk <patrick@puiterwijk.org>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index be92668faf3e473454f5f7f155d523ff25f6da2d..665eac2c2469689f9382c81d5762a782d7136d42 100644 (file)
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -3480,17 +3480,17 @@ static int mvneta_stop(struct net_device *dev)
        struct mvneta_port *pp = netdev_priv(dev);
 
        /* Inform that we are stopping so we don't want to setup the
-        * driver for new CPUs in the notifiers
+        * driver for new CPUs in the notifiers. The code of the
+        * notifier for CPU online is protected by the same spinlock,
+        * so when we get the lock, the notifer work is done.
         */
        spin_lock(&pp->lock);
        pp->is_stopped = true;
+       spin_unlock(&pp->lock);
+
        mvneta_stop_dev(pp);
        mvneta_mdio_remove(pp);
        unregister_cpu_notifier(&pp->cpu_notifier);
-       /* Now that the notifier are unregistered, we can release le
-        * lock
-        */
-       spin_unlock(&pp->lock);
        on_each_cpu(mvneta_percpu_disable, pp, true);
        free_percpu_irq(dev->irq, pp->ports);
        mvneta_cleanup_rxqs(pp);
@@ -4023,6 +4023,7 @@ static int mvneta_probe(struct platform_device *pdev)
        dev->ethtool_ops = &mvneta_eth_tool_ops;
 
        pp = netdev_priv(dev);
+       spin_lock_init(&pp->lock);
        pp->phy_node = phy_node;
        pp->phy_interface = phy_mode;