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Commit 120cfa50 authored by Gregory CLEMENT's avatar Gregory CLEMENT Committed by David S. Miller
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net: mvneta: Fix race condition during stopping 



When stopping the port, the CPU notifier are still there whereas the
mvneta_stop_dev function calls mvneta_percpu_disable() on each CPUs.
It was possible to have a new CPU coming at this point which could be
racy.

This patch adds a flag preventing executing the code notifier for a new
CPU when the port is stopping. It also uses the spinlock introduces
previously. To avoid the deadlock, the lock has been moved outside the
mvneta_percpu_elect function.

Signed-off-by: default avatarGregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5888511e

drivers/net/ethernet/marvell/mvneta.c

+28 −8
Original line number Original line Diff line number Diff line
@@ -374,6 +374,7 @@ struct mvneta_port { 
	 * ensuring that the configuration remains coherent.

	 * ensuring that the configuration remains coherent.

	 */

	 */

	spinlock_t lock;

	spinlock_t lock;

	bool is_stopped;





	/* Core clock */

	/* Core clock */

	struct clk *clk;

	struct clk *clk;
@@ -2855,16 +2856,14 @@ static void mvneta_percpu_disable(void *arg) 
	disable_percpu_irq(pp->dev->irq);

	disable_percpu_irq(pp->dev->irq);

}

}





/* Electing a CPU must be done in an atomic way: it should be done

 * after or before the removal/insertion of a CPU and this function is

 * not reentrant.

 */

static void mvneta_percpu_elect(struct mvneta_port *pp)

static void mvneta_percpu_elect(struct mvneta_port *pp)

{

{

	int elected_cpu = 0, max_cpu, cpu, i = 0;

	int elected_cpu = 0, max_cpu, cpu, i = 0;





	/* Electing a CPU must be done in an atomic way: it should be

	 * done after or before the removal/insertion of a CPU and

	 * this function is not reentrant.

	 */

	spin_lock(&pp->lock);



	/* Use the cpu associated to the rxq when it is online, in all

	/* Use the cpu associated to the rxq when it is online, in all

	 * the other cases, use the cpu 0 which can't be offline.

	 * the other cases, use the cpu 0 which can't be offline.

	 */

	 */
@@ -2908,7 +2907,6 @@ static void mvneta_percpu_elect(struct mvneta_port *pp) 
		i++;

		i++;





	}

	}

	spin_unlock(&pp->lock);

};

};





static int mvneta_percpu_notifier(struct notifier_block *nfb,

static int mvneta_percpu_notifier(struct notifier_block *nfb,
@@ -2922,6 +2920,14 @@ static int mvneta_percpu_notifier(struct notifier_block *nfb, 
	switch (action) {

	switch (action) {

	case CPU_ONLINE:

	case CPU_ONLINE:

	case CPU_ONLINE_FROZEN:

	case CPU_ONLINE_FROZEN:

		spin_lock(&pp->lock);

		/* Configuring the driver for a new CPU while the

		 * driver is stopping is racy, so just avoid it.

		 */

		if (pp->is_stopped) {

			spin_unlock(&pp->lock);

			break;

		}

		netif_tx_stop_all_queues(pp->dev);

		netif_tx_stop_all_queues(pp->dev);





		/* We have to synchronise on tha napi of each CPU

		/* We have to synchronise on tha napi of each CPU
@@ -2959,6 +2965,7 @@ static int mvneta_percpu_notifier(struct notifier_block *nfb, 
			MVNETA_CAUSE_LINK_CHANGE |

			MVNETA_CAUSE_LINK_CHANGE |

			MVNETA_CAUSE_PSC_SYNC_CHANGE);

			MVNETA_CAUSE_PSC_SYNC_CHANGE);

		netif_tx_start_all_queues(pp->dev);

		netif_tx_start_all_queues(pp->dev);

		spin_unlock(&pp->lock);

		break;

		break;

	case CPU_DOWN_PREPARE:

	case CPU_DOWN_PREPARE:

	case CPU_DOWN_PREPARE_FROZEN:

	case CPU_DOWN_PREPARE_FROZEN:
@@ -2983,7 +2990,9 @@ static int mvneta_percpu_notifier(struct notifier_block *nfb, 
	case CPU_DEAD:

	case CPU_DEAD:

	case CPU_DEAD_FROZEN:

	case CPU_DEAD_FROZEN:

		/* Check if a new CPU must be elected now this on is down */

		/* Check if a new CPU must be elected now this on is down */

		spin_lock(&pp->lock);

		mvneta_percpu_elect(pp);

		mvneta_percpu_elect(pp);

		spin_unlock(&pp->lock);

		/* Unmask all ethernet port interrupts */

		/* Unmask all ethernet port interrupts */

		on_each_cpu(mvneta_percpu_unmask_interrupt, pp, true);

		on_each_cpu(mvneta_percpu_unmask_interrupt, pp, true);

		mvreg_write(pp, MVNETA_INTR_MISC_MASK,

		mvreg_write(pp, MVNETA_INTR_MISC_MASK,
@@ -3027,7 +3036,7 @@ static int mvneta_open(struct net_device *dev) 
	 */

	 */

	on_each_cpu(mvneta_percpu_enable, pp, true);

	on_each_cpu(mvneta_percpu_enable, pp, true);







	pp->is_stopped = false;

	/* Register a CPU notifier to handle the case where our CPU

	/* Register a CPU notifier to handle the case where our CPU

	 * might be taken offline.

	 * might be taken offline.

	 */

	 */
@@ -3060,9 +3069,18 @@ static int mvneta_stop(struct net_device *dev) 
{

{

	struct mvneta_port *pp = netdev_priv(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

	 */

	spin_lock(&pp->lock);

	pp->is_stopped = true;

	mvneta_stop_dev(pp);

	mvneta_stop_dev(pp);

	mvneta_mdio_remove(pp);

	mvneta_mdio_remove(pp);

	unregister_cpu_notifier(&pp->cpu_notifier);

	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);

	on_each_cpu(mvneta_percpu_disable, pp, true);

	free_percpu_irq(dev->irq, pp->ports);

	free_percpu_irq(dev->irq, pp->ports);

	mvneta_cleanup_rxqs(pp);

	mvneta_cleanup_rxqs(pp);
@@ -3333,7 +3351,9 @@ static int mvneta_config_rss(struct mvneta_port *pp) 
	mvreg_write(pp, MVNETA_PORT_CONFIG, val);

	mvreg_write(pp, MVNETA_PORT_CONFIG, val);





	/* Update the elected CPU matching the new rxq_def */

	/* Update the elected CPU matching the new rxq_def */

	spin_lock(&pp->lock);

	mvneta_percpu_elect(pp);

	mvneta_percpu_elect(pp);

	spin_unlock(&pp->lock);





	/* We have to synchronise on the napi of each CPU */

	/* We have to synchronise on the napi of each CPU */

	for_each_online_cpu(cpu) {

	for_each_online_cpu(cpu) {