[PATCH v3 net 7/7] net: mvneta: Fix race condition during stopping
From: Gregory CLEMENT <hidden>
Date: 2016-02-04 21:10:35
Also in:
lkml, netdev
Subsystem:
marvell mvneta ethernet driver, networking drivers, the rest · Maintainers:
Marcin Wojtas, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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: Gregory CLEMENT <redacted> --- drivers/net/ethernet/marvell/mvneta.c | 36 +++++++++++++++++++++++++++-------- 1 file changed, 28 insertions(+), 8 deletions(-)
diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index b12a745a0e4c..b0ae69f84493 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c@@ -374,6 +374,7 @@ struct mvneta_port { * ensuring that the configuration remains coherent. */ spinlock_t lock; + bool is_stopped; /* Core clock */ struct clk *clk;
@@ -2855,16 +2856,14 @@ static void mvneta_percpu_disable(void *arg) 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) { 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 * 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++; } - spin_unlock(&pp->lock); }; static int mvneta_percpu_notifier(struct notifier_block *nfb,
@@ -2922,6 +2920,14 @@ static int mvneta_percpu_notifier(struct notifier_block *nfb, switch (action) { case CPU_ONLINE: 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); /* 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_PSC_SYNC_CHANGE); netif_tx_start_all_queues(pp->dev); + spin_unlock(&pp->lock); break; case CPU_DOWN_PREPARE: case CPU_DOWN_PREPARE_FROZEN:
@@ -2983,7 +2990,9 @@ static int mvneta_percpu_notifier(struct notifier_block *nfb, case CPU_DEAD: case CPU_DEAD_FROZEN: /* Check if a new CPU must be elected now this on is down */ + spin_lock(&pp->lock); mvneta_percpu_elect(pp); + spin_unlock(&pp->lock); /* Unmask all ethernet port interrupts */ on_each_cpu(mvneta_percpu_unmask_interrupt, pp, true); 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); - + pp->is_stopped = false; /* Register a CPU notifier to handle the case where our CPU * might be taken offline. */
@@ -3060,9 +3069,18 @@ 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 + */ + spin_lock(&pp->lock); + pp->is_stopped = true; 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);
@@ -3333,7 +3351,9 @@ static int mvneta_config_rss(struct mvneta_port *pp) mvreg_write(pp, MVNETA_PORT_CONFIG, val); /* Update the elected CPU matching the new rxq_def */ + spin_lock(&pp->lock); mvneta_percpu_elect(pp); + spin_unlock(&pp->lock); /* We have to synchronise on the napi of each CPU */ for_each_online_cpu(cpu) {
--
2.5.0