virtio, vhost fixes for 3.19

This fixes a couple of bugs triggered by hot-unplug
 of virtio devices, as well as a regression in vhost-net.
 
 Cc: Rusty Russell <rusty@rustcorp.com.au>
 Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

pull virtio/vhost fixes from Michael Tsirkin:
 "This fixes a couple of bugs triggered by hot-unplug of virtio devices,
  as well as a regression in vhost-net"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  vhost/net: length miscalculation
  virtio_pci: document why we defer kfree
  virtio_pci: defer kfree until release callback
  virtio_pci: device-specific release callback
  virtio: make del_vqs idempotent

drivers/vhost/net.c

@@ -538,7 +538,7 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
 		++headcount;
 		seg += in;
 	}
-	heads[headcount - 1].len = cpu_to_vhost32(vq, len - datalen);
+	heads[headcount - 1].len = cpu_to_vhost32(vq, len + datalen);
 	*iovcount = seg;
 	if (unlikely(log))
 		*log_num = nlogs;

drivers/virtio/virtio_pci_common.c

@@ -282,6 +282,7 @@ void vp_del_vqs(struct virtio_device *vdev)
 
 	vp_free_vectors(vdev);
 	kfree(vp_dev->vqs);
+	vp_dev->vqs = NULL;
 }
 
 static int vp_try_to_find_vqs(struct virtio_device *vdev, unsigned nvqs,
@@ -421,15 +422,6 @@ int vp_set_vq_affinity(struct virtqueue *vq, int cpu)
 	return 0;
 }
 
-void virtio_pci_release_dev(struct device *_d)
-{
-	/*
-	 * No need for a release method as we allocate/free
-	 * all devices together with the pci devices.
-	 * Provide an empty one to avoid getting a warning from core.
-	 */
-}
-
 #ifdef CONFIG_PM_SLEEP
 static int virtio_pci_freeze(struct device *dev)
 {

drivers/virtio/virtio_pci_common.h

@@ -126,7 +126,6 @@ const char *vp_bus_name(struct virtio_device *vdev);
  * - ignore the affinity request if we're using INTX
  */
 int vp_set_vq_affinity(struct virtqueue *vq, int cpu);
-void virtio_pci_release_dev(struct device *);
 
 int virtio_pci_legacy_probe(struct pci_dev *pci_dev,
 			    const struct pci_device_id *id);

drivers/virtio/virtio_pci_legacy.c

@@ -211,6 +211,17 @@ static const struct virtio_config_ops virtio_pci_config_ops = {
 	.set_vq_affinity = vp_set_vq_affinity,
 };
 
+static void virtio_pci_release_dev(struct device *_d)
+{
+	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);
+}
+
 /* the PCI probing function */
 int virtio_pci_legacy_probe(struct pci_dev *pci_dev,
 			    const struct pci_device_id *id)
@@ -302,5 +313,4 @@ void virtio_pci_legacy_remove(struct pci_dev *pci_dev)
 	pci_iounmap(pci_dev, vp_dev->ioaddr);
 	pci_release_regions(pci_dev);
 	pci_disable_device(pci_dev);
-	kfree(vp_dev);
 }