[net PATCH v5 5/6] virtio_net: refactor freeze/restore logic into virtnet reset logic

[John Fastabend <john.fastabend@gmail.com>]

For XDP we will need to reset the queues to allow for buffer headroom
to be configured. In order to do this we need to essentially run the
freeze()/restore() code path. Unfortunately the locking requirements
between the freeze/restore and reset paths are different however so
we can not simply reuse the code.

This patch refactors the code path and adds a reset helper routine.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
---
 drivers/net/virtio_net.c |   75 ++++++++++++++++++++++++++++------------------
 drivers/virtio/virtio.c  |   42 ++++++++++++++------------
 include/linux/virtio.h   |    4 ++
 3 files changed, 73 insertions(+), 48 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 922ca66..62dbf4b 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1684,6 +1684,49 @@ static void virtnet_init_settings(struct net_device *dev)
 	.set_settings = virtnet_set_settings,
 };
 
+static void virtnet_freeze_down(struct virtio_device *vdev)
+{
+	struct virtnet_info *vi = vdev->priv;
+	int i;
+
+	/* Make sure no work handler is accessing the device */
+	flush_work(&vi->config_work);
+
+	netif_device_detach(vi->dev);
+	cancel_delayed_work_sync(&vi->refill);
+
+	if (netif_running(vi->dev)) {
+		for (i = 0; i < vi->max_queue_pairs; i++)
+			napi_disable(&vi->rq[i].napi);
+	}
+}
+
+static int init_vqs(struct virtnet_info *vi);
+
+static int virtnet_restore_up(struct virtio_device *vdev)
+{
+	struct virtnet_info *vi = vdev->priv;
+	int err, i;
+
+	err = init_vqs(vi);
+	if (err)
+		return err;
+
+	virtio_device_ready(vdev);
+
+	if (netif_running(vi->dev)) {
+		for (i = 0; i < vi->curr_queue_pairs; i++)
+			if (!try_fill_recv(vi, &vi->rq[i], GFP_KERNEL))
+				schedule_delayed_work(&vi->refill, 0);
+
+		for (i = 0; i < vi->max_queue_pairs; i++)
+			virtnet_napi_enable(&vi->rq[i]);
+	}
+
+	netif_device_attach(vi->dev);
+	return err;
+}
+
 static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog)
 {
 	unsigned long int max_sz = PAGE_SIZE - sizeof(struct padded_vnet_hdr);
@@ -2374,21 +2417,9 @@ static void virtnet_remove(struct virtio_device *vdev)
 static int virtnet_freeze(struct virtio_device *vdev)
 {
 	struct virtnet_info *vi = vdev->priv;
-	int i;
 
 	virtnet_cpu_notif_remove(vi);
-
-	/* Make sure no work handler is accessing the device */
-	flush_work(&vi->config_work);
-
-	netif_device_detach(vi->dev);
-	cancel_delayed_work_sync(&vi->refill);
-
-	if (netif_running(vi->dev)) {
-		for (i = 0; i < vi->max_queue_pairs; i++)
-			napi_disable(&vi->rq[i].napi);
-	}
-
+	virtnet_freeze_down(vdev);
 	remove_vq_common(vi);
 
 	return 0;
@@ -2397,25 +2428,11 @@ static int virtnet_freeze(struct virtio_device *vdev)
 static int virtnet_restore(struct virtio_device *vdev)
 {
 	struct virtnet_info *vi = vdev->priv;
-	int err, i;
+	int err;
 
-	err = init_vqs(vi);
+	err = virtnet_restore_up(vdev);
 	if (err)
 		return err;
-
-	virtio_device_ready(vdev);
-
-	if (netif_running(vi->dev)) {
-		for (i = 0; i < vi->curr_queue_pairs; i++)
-			if (!try_fill_recv(vi, &vi->rq[i], GFP_KERNEL))
-				schedule_delayed_work(&vi->refill, 0);
-
-		for (i = 0; i < vi->max_queue_pairs; i++)
-			virtnet_napi_enable(&vi->rq[i]);
-	}
-
-	netif_device_attach(vi->dev);
-
 	virtnet_set_queues(vi, vi->curr_queue_pairs);
 
 	err = virtnet_cpu_notif_add(vi);
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index 7062bb0..400d70b 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -100,11 +100,6 @@ static int virtio_uevent(struct device *_dv, struct kobj_uevent_env *env)
 			      dev->id.device, dev->id.vendor);
 }
 
-static void add_status(struct virtio_device *dev, unsigned status)
-{
-	dev->config->set_status(dev, dev->config->get_status(dev) | status);
-}
-
 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
 					 unsigned int fbit)
 {
@@ -145,14 +140,15 @@ void virtio_config_changed(struct virtio_device *dev)
 }
 EXPORT_SYMBOL_GPL(virtio_config_changed);
 
-static void virtio_config_disable(struct virtio_device *dev)
+void virtio_config_disable(struct virtio_device *dev)
 {
 	spin_lock_irq(&dev->config_lock);
 	dev->config_enabled = false;
 	spin_unlock_irq(&dev->config_lock);
 }
+EXPORT_SYMBOL_GPL(virtio_config_disable);
 
-static void virtio_config_enable(struct virtio_device *dev)
+void virtio_config_enable(struct virtio_device *dev)
 {
 	spin_lock_irq(&dev->config_lock);
 	dev->config_enabled = true;
@@ -161,8 +157,15 @@ static void virtio_config_enable(struct virtio_device *dev)
 	dev->config_change_pending = false;
 	spin_unlock_irq(&dev->config_lock);
 }
+EXPORT_SYMBOL_GPL(virtio_config_enable);
+
+void virtio_add_status(struct virtio_device *dev, unsigned int status)
+{
+	dev->config->set_status(dev, dev->config->get_status(dev) | status);
+}
+EXPORT_SYMBOL_GPL(virtio_add_status);
 
-static int virtio_finalize_features(struct virtio_device *dev)
+int virtio_finalize_features(struct virtio_device *dev)
 {
 	int ret = dev->config->finalize_features(dev);
 	unsigned status;
@@ -173,7 +176,7 @@ static int virtio_finalize_features(struct virtio_device *dev)
 	if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1))
 		return 0;
 
-	add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK);
+	virtio_add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK);
 	status = dev->config->get_status(dev);
 	if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) {
 		dev_err(&dev->dev, "virtio: device refuses features: %x\n",
@@ -182,6 +185,7 @@ static int virtio_finalize_features(struct virtio_device *dev)
 	}
 	return 0;
 }
+EXPORT_SYMBOL_GPL(virtio_finalize_features);
 
 static int virtio_dev_probe(struct device *_d)
 {
@@ -193,7 +197,7 @@ static int virtio_dev_probe(struct device *_d)
 	u64 driver_features_legacy;
 
 	/* We have a driver! */
-	add_status(dev, VIRTIO_CONFIG_S_DRIVER);
+	virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 
 	/* Figure out what features the device supports. */
 	device_features = dev->config->get_features(dev);
@@ -247,7 +251,7 @@ static int virtio_dev_probe(struct device *_d)
 
 	return 0;
 err:
-	add_status(dev, VIRTIO_CONFIG_S_FAILED);
+	virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 	return err;
 
 }
@@ -265,7 +269,7 @@ static int virtio_dev_remove(struct device *_d)
 	WARN_ON_ONCE(dev->config->get_status(dev));
 
 	/* Acknowledge the device's existence again. */
-	add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
+	virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 	return 0;
 }
 
@@ -316,7 +320,7 @@ int register_virtio_device(struct virtio_device *dev)
 	dev->config->reset(dev);
 
 	/* Acknowledge that we've seen the device. */
-	add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
+	virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 
 	INIT_LIST_HEAD(&dev->vqs);
 
@@ -325,7 +329,7 @@ int register_virtio_device(struct virtio_device *dev)
 	err = device_register(&dev->dev);
 out:
 	if (err)
-		add_status(dev, VIRTIO_CONFIG_S_FAILED);
+		virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 	return err;
 }
 EXPORT_SYMBOL_GPL(register_virtio_device);
@@ -365,18 +369,18 @@ int virtio_device_restore(struct virtio_device *dev)
 	dev->config->reset(dev);
 
 	/* Acknowledge that we've seen the device. */
-	add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
+	virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 
 	/* Maybe driver failed before freeze.
 	 * Restore the failed status, for debugging. */
 	if (dev->failed)
-		add_status(dev, VIRTIO_CONFIG_S_FAILED);
+		virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 
 	if (!drv)
 		return 0;
 
 	/* We have a driver! */
-	add_status(dev, VIRTIO_CONFIG_S_DRIVER);
+	virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 
 	ret = virtio_finalize_features(dev);
 	if (ret)
@@ -389,14 +393,14 @@ int virtio_device_restore(struct virtio_device *dev)
 	}
 
 	/* Finally, tell the device we're all set */
-	add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
+	virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
 
 	virtio_config_enable(dev);
 
 	return 0;
 
 err:
-	add_status(dev, VIRTIO_CONFIG_S_FAILED);
+	virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(virtio_device_restore);
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index d5eb547..04b0d3f 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -132,12 +132,16 @@ static inline struct virtio_device *dev_to_virtio(struct device *_dev)
 	return container_of(_dev, struct virtio_device, dev);
 }
 
+void virtio_add_status(struct virtio_device *dev, unsigned int status);
 int register_virtio_device(struct virtio_device *dev);
 void unregister_virtio_device(struct virtio_device *dev);
 
 void virtio_break_device(struct virtio_device *dev);
 
 void virtio_config_changed(struct virtio_device *dev);
+void virtio_config_disable(struct virtio_device *dev);
+void virtio_config_enable(struct virtio_device *dev);
+int virtio_finalize_features(struct virtio_device *dev);
 #ifdef CONFIG_PM_SLEEP
 int virtio_device_freeze(struct virtio_device *dev);
 int virtio_device_restore(struct virtio_device *dev);