virtio_pci: document why we defer kfree

[pandora-kernel.git] / drivers / virtio / virtio_pci.c

diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index 79a31e5..13f6cd8 100644 (file)
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -169,11 +169,29 @@ static void vp_set_status(struct virtio_device *vdev, u8 status)
        iowrite8(status, vp_dev->ioaddr + VIRTIO_PCI_STATUS);
 }
 
+/* wait for pending irq handlers */
+static void vp_synchronize_vectors(struct virtio_device *vdev)
+{
+       struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+       int i;
+
+       if (vp_dev->intx_enabled)
+               synchronize_irq(vp_dev->pci_dev->irq);
+
+       for (i = 0; i < vp_dev->msix_vectors; ++i)
+               synchronize_irq(vp_dev->msix_entries[i].vector);
+}
+
 static void vp_reset(struct virtio_device *vdev)
 {
        struct virtio_pci_device *vp_dev = to_vp_device(vdev);
        /* 0 status means a reset. */
        iowrite8(0, vp_dev->ioaddr + VIRTIO_PCI_STATUS);
+       /* Flush out the status write, and flush in device writes,
+        * including MSi-X interrupts, if any. */
+       ioread8(vp_dev->ioaddr + VIRTIO_PCI_STATUS);
+       /* Flush pending VQ/configuration callbacks. */
+       vp_synchronize_vectors(vdev);
 }
 
 /* the notify function used when creating a virt queue */
@@ -594,10 +612,12 @@ static struct virtio_config_ops virtio_pci_config_ops = {
 
 static void virtio_pci_release_dev(struct device *_d)
 {
-       struct virtio_device *dev = container_of(_d, struct virtio_device,
-                                                dev);
-       struct virtio_pci_device *vp_dev = to_vp_device(dev);
+       struct virtio_device *vdev = dev_to_virtio(_d);
+       struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 
+       /* As struct device is a kobject, it's not safe to
+        * free the memory (including the reference counter itself)
+        * until it's release callback. */
        kfree(vp_dev);
 }