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Message-ID: <1412608214-31944-5-git-send-email-mst@redhat.com>
Date: Mon, 6 Oct 2014 18:10:55 +0300
From: "Michael S. Tsirkin" <mst@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: kvm@...r.kernel.org, Rusty Russell <rusty@...tcorp.com.au>,
virtualization@...ts.linux-foundation.org,
Heinz Graalfs <graalfs@...ux.vnet.ibm.com>
Subject: [PATCH v2 04/15] 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: Michael S. Tsirkin <mst@...hat.com>
---
include/linux/virtio.h | 6 ++++++
drivers/virtio/virtio.c | 57 +++++++++++++++++++++++++++++++++++++++++--------
2 files changed, 54 insertions(+), 9 deletions(-)
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 8df7ba8..5636b11 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -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_changed: 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_changed;
+ spinlock_t config_lock;
struct device dev;
struct virtio_device_id id;
const struct virtio_config_ops *config;
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index 657f817..6214744 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -117,6 +117,42 @@ 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_changed = 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;
+ __virtio_config_changed(dev);
+ dev->config_changed = false;
+ spin_unlock_irq(&dev->config_lock);
+}
+
static int virtio_dev_probe(struct device *_d)
{
int err, i;
@@ -153,6 +189,8 @@ 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 +201,8 @@ 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 +251,10 @@ 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_changed = 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 +283,13 @@ 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)
@@ -296,6 +333,8 @@ int virtio_device_restore(struct virtio_device *dev)
add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
}
+ virtio_config_enable(dev);
+
return 0;
}
EXPORT_SYMBOL_GPL(virtio_device_restore);
--
MST
--
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