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Commit 22b7050a authored by Michael S. Tsirkin's avatar Michael S. Tsirkin Committed by Rusty Russell
Browse files

virtio: defer config changed notifications 



Defer config changed notifications that arrive during
probe/scan/freeze/restore.

This will allow drivers to set DRIVER_OK earlier, without worrying about
racing with config change interrupts.

This change will also benefit old hypervisors (before 2009)
that send interrupts without checking DRIVER_OK: previously,
the callback could race with driver-specific initialization.

This will also help simplify drivers.

Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (cosmetic changes)
parent c6716bae

drivers/virtio/virtio.c

+49 −9
Original line number Diff line number Diff line
@@ -117,6 +117,43 @@ void virtio_check_driver_offered_feature(const struct virtio_device *vdev, 
}

EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);



static void __virtio_config_changed(struct virtio_device *dev)

{

	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);



	if (!dev->config_enabled)

		dev->config_change_pending = true;

	else if (drv && drv->config_changed)

		drv->config_changed(dev);

}



void virtio_config_changed(struct virtio_device *dev)

{

	unsigned long flags;



	spin_lock_irqsave(&dev->config_lock, flags);

	__virtio_config_changed(dev);

	spin_unlock_irqrestore(&dev->config_lock, flags);

}

EXPORT_SYMBOL_GPL(virtio_config_changed);



static void virtio_config_disable(struct virtio_device *dev)

{

	spin_lock_irq(&dev->config_lock);

	dev->config_enabled = false;

	spin_unlock_irq(&dev->config_lock);

}



static void virtio_config_enable(struct virtio_device *dev)

{

	spin_lock_irq(&dev->config_lock);

	dev->config_enabled = true;

	if (dev->config_change_pending)

		__virtio_config_changed(dev);

	dev->config_change_pending = false;

	spin_unlock_irq(&dev->config_lock);

}



static int virtio_dev_probe(struct device *_d)

{

	int err, i;
@@ -153,6 +190,8 @@ static int virtio_dev_probe(struct device *_d) 
		add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);

		if (drv->scan)

			drv->scan(dev);



		virtio_config_enable(dev);

	}



	return err;
@@ -163,6 +202,8 @@ static int virtio_dev_remove(struct device *_d) 
	struct virtio_device *dev = dev_to_virtio(_d);

	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);



	virtio_config_disable(dev);



	drv->remove(dev);



	/* Driver should have reset device. */
@@ -211,6 +252,10 @@ int register_virtio_device(struct virtio_device *dev) 
	dev->index = err;

	dev_set_name(&dev->dev, "virtio%u", dev->index);



	spin_lock_init(&dev->config_lock);

	dev->config_enabled = false;

	dev->config_change_pending = false;



	/* We always start by resetting the device, in case a previous

	 * driver messed it up.  This also tests that code path a little. */

	dev->config->reset(dev);
@@ -239,20 +284,13 @@ void unregister_virtio_device(struct virtio_device *dev) 
}

EXPORT_SYMBOL_GPL(unregister_virtio_device);



void virtio_config_changed(struct virtio_device *dev)

{

	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);



	if (drv && drv->config_changed)

		drv->config_changed(dev);

}

EXPORT_SYMBOL_GPL(virtio_config_changed);



#ifdef CONFIG_PM_SLEEP

int virtio_device_freeze(struct virtio_device *dev)

{

	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);



	virtio_config_disable(dev);



	dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;



	if (drv && drv->freeze)
@@ -297,6 +335,8 @@ 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_config_enable(dev);



	return 0;

}

EXPORT_SYMBOL_GPL(virtio_device_restore);

include/linux/virtio.h

+6 −0
Original line number Diff line number Diff line
@@ -79,6 +79,9 @@ bool virtqueue_is_broken(struct virtqueue *vq); 
 * virtio_device - representation of a device using virtio

 * @index: unique position on the virtio bus

 * @failed: saved value for CONFIG_S_FAILED bit (for restore)

 * @config_enabled: configuration change reporting enabled

 * @config_change_pending: configuration change reported while disabled

 * @config_lock: protects configuration change reporting

 * @dev: underlying device.

 * @id: the device type identification (used to match it with a driver).

 * @config: the configuration ops for this device.
@@ -90,6 +93,9 @@ bool virtqueue_is_broken(struct virtqueue *vq); 
struct virtio_device {

	int index;

	bool failed;

	bool config_enabled;

	bool config_change_pending;

	spinlock_t config_lock;

	struct device dev;

	struct virtio_device_id id;

	const struct virtio_config_ops *config;