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Subject[tip:smp/hotplug] net/mvneta: Convert to hotplug state machine
Commit-ID:  84a3f4db039e7c4bfe8ae9bebdebdf2a4e09bf86
Gitweb: http://git.kernel.org/tip/84a3f4db039e7c4bfe8ae9bebdebdf2a4e09bf86
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
AuthorDate: Thu, 18 Aug 2016 14:57:23 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Tue, 6 Sep 2016 18:30:22 +0200

net/mvneta: Convert to hotplug state machine

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: netdev@vger.kernel.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160818125731.27256-9-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
drivers/net/ethernet/marvell/mvneta.c | 232 +++++++++++++++++++++-------------
include/linux/cpuhotplug.h | 1 +
2 files changed, 144 insertions(+), 89 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index d41c28d..b745487 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -382,7 +382,8 @@ struct mvneta_port {
struct mvneta_rx_queue *rxqs;
struct mvneta_tx_queue *txqs;
struct net_device *dev;
- struct notifier_block cpu_notifier;
+ struct hlist_node node_online;
+ struct hlist_node node_dead;
int rxq_def;
/* Protect the access to the percpu interrupt registers,
* ensuring that the configuration remains coherent.
@@ -574,6 +575,7 @@ struct mvneta_rx_queue {
int next_desc_to_proc;
};

+static enum cpuhp_state online_hpstate;
/* The hardware supports eight (8) rx queues, but we are only allowing
* the first one to be used. Therefore, let's just allocate one queue.
*/
@@ -3311,101 +3313,104 @@ static void mvneta_percpu_elect(struct mvneta_port *pp)
}
};

-static int mvneta_percpu_notifier(struct notifier_block *nfb,
- unsigned long action, void *hcpu)
+static int mvneta_cpu_online(unsigned int cpu, struct hlist_node *node)
{
- struct mvneta_port *pp = container_of(nfb, struct mvneta_port,
- cpu_notifier);
- int cpu = (unsigned long)hcpu, other_cpu;
+ int other_cpu;
+ struct mvneta_port *pp = hlist_entry_safe(node, struct mvneta_port,
+ node_online);
struct mvneta_pcpu_port *port = per_cpu_ptr(pp->ports, cpu);

- switch (action) {
- case CPU_ONLINE:
- case CPU_ONLINE_FROZEN:
- case CPU_DOWN_FAILED:
- case CPU_DOWN_FAILED_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
- * except the one just being waked up
- */
- for_each_online_cpu(other_cpu) {
- if (other_cpu != cpu) {
- struct mvneta_pcpu_port *other_port =
- per_cpu_ptr(pp->ports, other_cpu);
+ 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);
+ return 0;
+ }
+ netif_tx_stop_all_queues(pp->dev);

- napi_synchronize(&other_port->napi);
- }
+ /*
+ * We have to synchronise on tha napi of each CPU except the one
+ * just being woken up
+ */
+ for_each_online_cpu(other_cpu) {
+ if (other_cpu != cpu) {
+ struct mvneta_pcpu_port *other_port =
+ per_cpu_ptr(pp->ports, other_cpu);
+
+ napi_synchronize(&other_port->napi);
}
+ }

- /* Mask all ethernet port interrupts */
- on_each_cpu(mvneta_percpu_mask_interrupt, pp, true);
- napi_enable(&port->napi);
+ /* Mask all ethernet port interrupts */
+ on_each_cpu(mvneta_percpu_mask_interrupt, pp, true);
+ napi_enable(&port->napi);

+ /*
+ * Enable per-CPU interrupts on the CPU that is
+ * brought up.
+ */
+ mvneta_percpu_enable(pp);

- /* Enable per-CPU interrupts on the CPU that is
- * brought up.
- */
- mvneta_percpu_enable(pp);
+ /*
+ * Enable per-CPU interrupt on the one CPU we care
+ * about.
+ */
+ mvneta_percpu_elect(pp);

- /* Enable per-CPU interrupt on the one CPU we care
- * about.
- */
- mvneta_percpu_elect(pp);
-
- /* Unmask all ethernet port interrupts */
- on_each_cpu(mvneta_percpu_unmask_interrupt, pp, true);
- mvreg_write(pp, MVNETA_INTR_MISC_MASK,
- MVNETA_CAUSE_PHY_STATUS_CHANGE |
- 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:
- netif_tx_stop_all_queues(pp->dev);
- /* Thanks to this lock we are sure that any pending
- * cpu election is done
- */
- spin_lock(&pp->lock);
- /* Mask all ethernet port interrupts */
- on_each_cpu(mvneta_percpu_mask_interrupt, pp, true);
- 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,
+ MVNETA_CAUSE_PHY_STATUS_CHANGE |
+ MVNETA_CAUSE_LINK_CHANGE |
+ MVNETA_CAUSE_PSC_SYNC_CHANGE);
+ netif_tx_start_all_queues(pp->dev);
+ spin_unlock(&pp->lock);
+ return 0;
+}

- napi_synchronize(&port->napi);
- napi_disable(&port->napi);
- /* Disable per-CPU interrupts on the CPU that is
- * brought down.
- */
- mvneta_percpu_disable(pp);
+static int mvneta_cpu_down_prepare(unsigned int cpu, struct hlist_node *node)
+{
+ struct mvneta_port *pp = hlist_entry_safe(node, struct mvneta_port,
+ node_online);
+ struct mvneta_pcpu_port *port = per_cpu_ptr(pp->ports, cpu);

- break;
- 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,
- MVNETA_CAUSE_PHY_STATUS_CHANGE |
- MVNETA_CAUSE_LINK_CHANGE |
- MVNETA_CAUSE_PSC_SYNC_CHANGE);
- netif_tx_start_all_queues(pp->dev);
- break;
- }
+ /*
+ * Thanks to this lock we are sure that any pending cpu election is
+ * done.
+ */
+ spin_lock(&pp->lock);
+ /* Mask all ethernet port interrupts */
+ on_each_cpu(mvneta_percpu_mask_interrupt, pp, true);
+ spin_unlock(&pp->lock);

- return NOTIFY_OK;
+ napi_synchronize(&port->napi);
+ napi_disable(&port->napi);
+ /* Disable per-CPU interrupts on the CPU that is brought down. */
+ mvneta_percpu_disable(pp);
+ return 0;
+}
+
+static int mvneta_cpu_dead(unsigned int cpu, struct hlist_node *node)
+{
+ struct mvneta_port *pp = hlist_entry_safe(node, struct mvneta_port,
+ node_dead);
+
+ /* 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,
+ MVNETA_CAUSE_PHY_STATUS_CHANGE |
+ MVNETA_CAUSE_LINK_CHANGE |
+ MVNETA_CAUSE_PSC_SYNC_CHANGE);
+ netif_tx_start_all_queues(pp->dev);
+ return 0;
}

static int mvneta_open(struct net_device *dev)
@@ -3442,7 +3447,15 @@ static int mvneta_open(struct net_device *dev)
/* Register a CPU notifier to handle the case where our CPU
* might be taken offline.
*/
- register_cpu_notifier(&pp->cpu_notifier);
+ ret = cpuhp_state_add_instance_nocalls(online_hpstate,
+ &pp->node_online);
+ if (ret)
+ goto err_free_irq;
+
+ ret = cpuhp_state_add_instance_nocalls(CPUHP_NET_MVNETA_DEAD,
+ &pp->node_dead);
+ if (ret)
+ goto err_free_online_hp;

/* In default link is down */
netif_carrier_off(pp->dev);
@@ -3450,15 +3463,19 @@ static int mvneta_open(struct net_device *dev)
ret = mvneta_mdio_probe(pp);
if (ret < 0) {
netdev_err(dev, "cannot probe MDIO bus\n");
- goto err_free_irq;
+ goto err_free_dead_hp;
}

mvneta_start_dev(pp);

return 0;

+err_free_dead_hp:
+ cpuhp_state_remove_instance_nocalls(CPUHP_NET_MVNETA_DEAD,
+ &pp->node_dead);
+err_free_online_hp:
+ cpuhp_state_remove_instance_nocalls(online_hpstate, &pp->node_online);
err_free_irq:
- unregister_cpu_notifier(&pp->cpu_notifier);
on_each_cpu(mvneta_percpu_disable, pp, true);
free_percpu_irq(pp->dev->irq, pp->ports);
err_cleanup_txqs:
@@ -3484,7 +3501,10 @@ static int mvneta_stop(struct net_device *dev)

mvneta_stop_dev(pp);
mvneta_mdio_remove(pp);
- unregister_cpu_notifier(&pp->cpu_notifier);
+
+ cpuhp_state_remove_instance_nocalls(online_hpstate, &pp->node_online);
+ cpuhp_state_remove_instance_nocalls(CPUHP_NET_MVNETA_DEAD,
+ &pp->node_dead);
on_each_cpu(mvneta_percpu_disable, pp, true);
free_percpu_irq(dev->irq, pp->ports);
mvneta_cleanup_rxqs(pp);
@@ -4024,7 +4044,6 @@ static int mvneta_probe(struct platform_device *pdev)
err = of_property_read_string(dn, "managed", &managed);
pp->use_inband_status = (err == 0 &&
strcmp(managed, "in-band-status") == 0);
- pp->cpu_notifier.notifier_call = mvneta_percpu_notifier;

pp->rxq_def = rxq_def;

@@ -4227,7 +4246,42 @@ static struct platform_driver mvneta_driver = {
},
};

-module_platform_driver(mvneta_driver);
+static int __init mvneta_driver_init(void)
+{
+ int ret;
+
+ ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, "net/mvmeta:online",
+ mvneta_cpu_online,
+ mvneta_cpu_down_prepare);
+ if (ret < 0)
+ goto out;
+ online_hpstate = ret;
+ ret = cpuhp_setup_state_multi(CPUHP_NET_MVNETA_DEAD, "net/mvneta:dead",
+ NULL, mvneta_cpu_dead);
+ if (ret)
+ goto err_dead;
+
+ ret = platform_driver_register(&mvneta_driver);
+ if (ret)
+ goto err;
+ return 0;
+
+err:
+ cpuhp_remove_multi_state(CPUHP_NET_MVNETA_DEAD);
+err_dead:
+ cpuhp_remove_multi_state(online_hpstate);
+out:
+ return ret;
+}
+module_init(mvneta_driver_init);
+
+static void __exit mvneta_driver_exit(void)
+{
+ platform_driver_unregister(&mvneta_driver);
+ cpuhp_remove_multi_state(CPUHP_NET_MVNETA_DEAD);
+ cpuhp_remove_multi_state(online_hpstate);
+}
+module_exit(mvneta_driver_exit);

MODULE_DESCRIPTION("Marvell NETA Ethernet Driver - www.marvell.com");
MODULE_AUTHOR("Rami Rosen <rosenr@marvell.com>, Thomas Petazzoni <thomas.petazzoni@free-electrons.com>");
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index a421407..332b39c 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -18,6 +18,7 @@ enum cpuhp_state {
CPUHP_SLUB_DEAD,
CPUHP_MM_WRITEBACK_DEAD,
CPUHP_SOFTIRQ_DEAD,
+ CPUHP_NET_MVNETA_DEAD,
CPUHP_WORKQUEUE_PREP,
CPUHP_POWER_NUMA_PREPARE,
CPUHP_HRTIMERS_PREPARE,
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