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Message-Id: <1471024183-12666-7-git-send-email-bigeasy@linutronix.de>
Date: Fri, 12 Aug 2016 19:49:43 +0200
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: linux-kernel@...r.kernel.org
Cc: rt@...utronix.de, Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Will Deacon <will.deacon@....com>,
Mark Rutland <mark.rutland@....com>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
"Michael S. Tsirkin" <mst@...hat.com>,
virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org
Subject: [PATCH 6/6] 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
conversation of the current code.
Cc: "Michael S. Tsirkin" <mst@...hat.com>
Cc: virtualization@...ts.linux-foundation.org
Cc: netdev@...r.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
drivers/net/virtio_net.c | 110 +++++++++++++++++++++++++++++++++++----------
include/linux/cpuhotplug.h | 1 +
2 files changed, 87 insertions(+), 24 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 1b5f531eeb25..e9be88cd76c1 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -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:
- virtnet_set_affinity(vi);
- break;
- case CPU_DOWN_PREPARE:
- virtnet_clean_affinity(vi, (long)hcpu);
- break;
- default:
- break;
- }
+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);
+ return 0;
+}
- return NOTIFY_OK;
+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;
+}
+
+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_state_nocalls(CPUHP_VIRT_NET_DEAD);
+err_dead:
+ cpuhp_remove_state_nocalls(virtionet_online);
+out:
+ return ret;
+}
+module_init(virtio_net_driver_init);
+
+static __exit void virtio_net_driver_exit(void)
+{
+ cpuhp_remove_state_nocalls(CPUHP_VIRT_NET_DEAD);
+ cpuhp_remove_state_nocalls(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");
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 81cc20789a3e..5c657c836de6 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -20,6 +20,7 @@ enum cpuhp_state {
CPUHP_PROFILE_PREPARE,
CPUHP_X2APIC_PREPARE,
CPUHP_SMPCFD_PREPARE,
+ CPUHP_VIRT_NET_DEAD,
CPUHP_RCUTREE_PREP,
CPUHP_NOTIFY_PREPARE,
CPUHP_TIMERS_DEAD,
--
2.8.1
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