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128 lines
4.0 KiB
128 lines
4.0 KiB
From: Gregory CLEMENT <gregory.clement@free-electrons.com>
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Date: Thu, 4 Feb 2016 22:09:29 +0100
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Subject: [PATCH] net: mvneta: Fix race condition during stopping
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When stopping the port, the CPU notifier are still there whereas the
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mvneta_stop_dev function calls mvneta_percpu_disable() on each CPUs.
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It was possible to have a new CPU coming at this point which could be
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racy.
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This patch adds a flag preventing executing the code notifier for a new
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CPU when the port is stopping. It also uses the spinlock introduces
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previously. To avoid the deadlock, the lock has been moved outside the
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mvneta_percpu_elect function.
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Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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--- a/drivers/net/ethernet/marvell/mvneta.c
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+++ b/drivers/net/ethernet/marvell/mvneta.c
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@@ -374,6 +374,7 @@ struct mvneta_port {
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* ensuring that the configuration remains coherent.
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*/
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spinlock_t lock;
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+ bool is_stopped;
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/* Core clock */
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struct clk *clk;
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@@ -2857,16 +2858,14 @@ static void mvneta_percpu_disable(void *
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disable_percpu_irq(pp->dev->irq);
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}
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+/* Electing a CPU must be done in an atomic way: it should be done
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+ * after or before the removal/insertion of a CPU and this function is
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+ * not reentrant.
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+ */
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static void mvneta_percpu_elect(struct mvneta_port *pp)
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{
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int elected_cpu = 0, max_cpu, cpu, i = 0;
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- /* Electing a CPU must be done in an atomic way: it should be
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- * done after or before the removal/insertion of a CPU and
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- * this function is not reentrant.
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- */
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- spin_lock(&pp->lock);
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-
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/* Use the cpu associated to the rxq when it is online, in all
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* the other cases, use the cpu 0 which can't be offline.
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*/
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@@ -2910,7 +2909,6 @@ static void mvneta_percpu_elect(struct m
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i++;
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}
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- spin_unlock(&pp->lock);
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};
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static int mvneta_percpu_notifier(struct notifier_block *nfb,
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@@ -2924,6 +2922,14 @@ static int mvneta_percpu_notifier(struct
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switch (action) {
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case CPU_ONLINE:
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case CPU_ONLINE_FROZEN:
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+ spin_lock(&pp->lock);
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+ /* Configuring the driver for a new CPU while the
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+ * driver is stopping is racy, so just avoid it.
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+ */
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+ if (pp->is_stopped) {
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+ spin_unlock(&pp->lock);
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+ break;
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+ }
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netif_tx_stop_all_queues(pp->dev);
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/* We have to synchronise on tha napi of each CPU
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@@ -2961,6 +2967,7 @@ static int mvneta_percpu_notifier(struct
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MVNETA_CAUSE_LINK_CHANGE |
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MVNETA_CAUSE_PSC_SYNC_CHANGE);
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netif_tx_start_all_queues(pp->dev);
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+ spin_unlock(&pp->lock);
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break;
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case CPU_DOWN_PREPARE:
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case CPU_DOWN_PREPARE_FROZEN:
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@@ -2985,7 +2992,9 @@ static int mvneta_percpu_notifier(struct
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case CPU_DEAD:
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case CPU_DEAD_FROZEN:
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/* Check if a new CPU must be elected now this on is down */
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+ spin_lock(&pp->lock);
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mvneta_percpu_elect(pp);
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+ spin_unlock(&pp->lock);
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/* Unmask all ethernet port interrupts */
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on_each_cpu(mvneta_percpu_unmask_interrupt, pp, true);
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mvreg_write(pp, MVNETA_INTR_MISC_MASK,
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@@ -3037,7 +3046,7 @@ static int mvneta_open(struct net_device
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*/
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on_each_cpu(mvneta_percpu_enable, pp, true);
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-
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+ pp->is_stopped = false;
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/* Register a CPU notifier to handle the case where our CPU
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* might be taken offline.
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*/
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@@ -3070,9 +3079,18 @@ static int mvneta_stop(struct net_device
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{
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struct mvneta_port *pp = netdev_priv(dev);
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+ /* Inform that we are stopping so we don't want to setup the
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+ * driver for new CPUs in the notifiers
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+ */
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+ spin_lock(&pp->lock);
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+ pp->is_stopped = true;
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mvneta_stop_dev(pp);
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mvneta_mdio_remove(pp);
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unregister_cpu_notifier(&pp->cpu_notifier);
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+ /* Now that the notifier are unregistered, we can release le
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+ * lock
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+ */
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+ spin_unlock(&pp->lock);
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on_each_cpu(mvneta_percpu_disable, pp, true);
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free_percpu_irq(dev->irq, pp->ports);
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mvneta_cleanup_rxqs(pp);
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@@ -3343,7 +3361,9 @@ static int mvneta_config_rss(struct mvn
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mvreg_write(pp, MVNETA_PORT_CONFIG, val);
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/* Update the elected CPU matching the new rxq_def */
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+ spin_lock(&pp->lock);
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mvneta_percpu_elect(pp);
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+ spin_unlock(&pp->lock);
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/* We have to synchronise on the napi of each CPU */
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for_each_online_cpu(cpu) {
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