Commit 8017c279 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Thomas Gleixner
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net/virtio-net: Convert to hotplug state machine 



Install the callbacks via the state machine.

The driver supports multiple instances and therefore the new
cpuhp_state_add_instance_nocalls() infrastrucure is used. The driver
currently uses get_online_cpus() to avoid missing a CPU hotplug event while
invoking virtnet_set_affinity(). This could be avoided by using
cpuhp_state_add_instance() variant which holds the hotplug lock and invokes
callback during registration. This is more or less a 1:1 conversion of the
current code.

Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: netdev@vger.kernel.org
Cc: Will Deacon <will.deacon@arm.com>
Cc: virtualization@lists.linux-foundation.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/1471024183-12666-7-git-send-email-bigeasy@linutronix.de


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 8df03872

drivers/net/virtio_net.c

+86 −24
Original line number Diff line number Diff line
@@ -138,8 +138,9 @@ struct virtnet_info { 
	/* Does the affinity hint is set for virtqueues? */

	bool affinity_hint_set;



	/* CPU hot plug notifier */

	struct notifier_block nb;

	/* CPU hotplug instances for online & dead */

	struct hlist_node node;

	struct hlist_node node_dead;



	/* Control VQ buffers: protected by the rtnl lock */

	struct virtio_net_ctrl_hdr ctrl_hdr;
@@ -1237,25 +1238,53 @@ static void virtnet_set_affinity(struct virtnet_info *vi) 
	vi->affinity_hint_set = true;

}



static int virtnet_cpu_callback(struct notifier_block *nfb,

			        unsigned long action, void *hcpu)

static int virtnet_cpu_online(unsigned int cpu, struct hlist_node *node)

{

	struct virtnet_info *vi = container_of(nfb, struct virtnet_info, nb);

	struct virtnet_info *vi = hlist_entry_safe(node, struct virtnet_info,

						   node);

	virtnet_set_affinity(vi);

	return 0;

}



	switch(action & ~CPU_TASKS_FROZEN) {

	case CPU_ONLINE:

	case CPU_DOWN_FAILED:

	case CPU_DEAD:

static int virtnet_cpu_dead(unsigned int cpu, struct hlist_node *node)

{

	struct virtnet_info *vi = hlist_entry_safe(node, struct virtnet_info,

						   node_dead);

	virtnet_set_affinity(vi);

		break;

	case CPU_DOWN_PREPARE:

		virtnet_clean_affinity(vi, (long)hcpu);

		break;

	default:

		break;

	return 0;

}



static int virtnet_cpu_down_prep(unsigned int cpu, struct hlist_node *node)

{

	struct virtnet_info *vi = hlist_entry_safe(node, struct virtnet_info,

						   node);



	virtnet_clean_affinity(vi, cpu);

	return 0;

}



static enum cpuhp_state virtionet_online;



static int virtnet_cpu_notif_add(struct virtnet_info *vi)

{

	int ret;



	ret = cpuhp_state_add_instance_nocalls(virtionet_online, &vi->node);

	if (ret)

		return ret;

	ret = cpuhp_state_add_instance_nocalls(CPUHP_VIRT_NET_DEAD,

					       &vi->node_dead);

	if (!ret)

		return ret;

	cpuhp_state_remove_instance_nocalls(virtionet_online, &vi->node);

	return ret;

}



	return NOTIFY_OK;

static void virtnet_cpu_notif_remove(struct virtnet_info *vi)

{

	cpuhp_state_remove_instance_nocalls(virtionet_online, &vi->node);

	cpuhp_state_remove_instance_nocalls(CPUHP_VIRT_NET_DEAD,

					    &vi->node_dead);

}



static void virtnet_get_ringparam(struct net_device *dev,
@@ -1879,8 +1908,7 @@ static int virtnet_probe(struct virtio_device *vdev) 


	virtio_device_ready(vdev);



	vi->nb.notifier_call = &virtnet_cpu_callback;

	err = register_hotcpu_notifier(&vi->nb);

	err = virtnet_cpu_notif_add(vi);

	if (err) {

		pr_debug("virtio_net: registering cpu notifier failed\n");

		goto free_unregister_netdev;
@@ -1934,7 +1962,7 @@ static void virtnet_remove(struct virtio_device *vdev) 
{

	struct virtnet_info *vi = vdev->priv;



	unregister_hotcpu_notifier(&vi->nb);

	virtnet_cpu_notif_remove(vi);



	/* Make sure no work handler is accessing the device. */

	flush_work(&vi->config_work);
@@ -1953,7 +1981,7 @@ static int virtnet_freeze(struct virtio_device *vdev) 
	struct virtnet_info *vi = vdev->priv;

	int i;



	unregister_hotcpu_notifier(&vi->nb);

	virtnet_cpu_notif_remove(vi);



	/* Make sure no work handler is accessing the device */

	flush_work(&vi->config_work);
@@ -1997,7 +2025,7 @@ static int virtnet_restore(struct virtio_device *vdev) 
	virtnet_set_queues(vi, vi->curr_queue_pairs);

	rtnl_unlock();



	err = register_hotcpu_notifier(&vi->nb);

	err = virtnet_cpu_notif_add(vi);

	if (err)

		return err;
@@ -2039,7 +2067,41 @@ static struct virtio_driver virtio_net_driver = { 
#endif

};



module_virtio_driver(virtio_net_driver);

static __init int virtio_net_driver_init(void)

{

	int ret;



	ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, "AP_VIRT_NET_ONLINE",

				      virtnet_cpu_online,

				      virtnet_cpu_down_prep);

	if (ret < 0)

		goto out;

	virtionet_online = ret;

	ret = cpuhp_setup_state_multi(CPUHP_VIRT_NET_DEAD, "VIRT_NET_DEAD",

				      NULL, virtnet_cpu_dead);

	if (ret)

		goto err_dead;



        ret = register_virtio_driver(&virtio_net_driver);

	if (ret)

		goto err_virtio;

	return 0;

err_virtio:

	cpuhp_remove_multi_state(CPUHP_VIRT_NET_DEAD);

err_dead:

	cpuhp_remove_multi_state(virtionet_online);

out:

	return ret;

}

module_init(virtio_net_driver_init);



static __exit void virtio_net_driver_exit(void)

{

	cpuhp_remove_multi_state(CPUHP_VIRT_NET_DEAD);

	cpuhp_remove_multi_state(virtionet_online);

	unregister_virtio_driver(&virtio_net_driver);

}

module_exit(virtio_net_driver_exit);



MODULE_DEVICE_TABLE(virtio, id_table);

MODULE_DESCRIPTION("Virtio network driver");

include/linux/cpuhotplug.h

+1 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ enum cpuhp_state { 
	CPUHP_PERF_SUPERH,

	CPUHP_X86_HPET_DEAD,

	CPUHP_X86_APB_DEAD,

	CPUHP_VIRT_NET_DEAD,

	CPUHP_WORKQUEUE_PREP,

	CPUHP_POWER_NUMA_PREPARE,

	CPUHP_HRTIMERS_PREPARE,

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