virtio: set device index in common code.

Anthony Liguori points out that three different transports use the virtio code,
but each one keeps its own counter to set the virtio_device's index field.  In
theory (though not in current practice) this means that names could be
duplicated, and that risk grows as more transports are created.

So we move the selection of the unique virtio_device.index into the common code
in virtio.c, which has the side-benefit of removing duplicate code.

The only complexity is that lguest and S/390 use the index to uniquely identify
the device in case of catastrophic failure before register_virtio_device() is
called: now we use the offset within the descriptor page as a unique identifier
for the printks.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Carsten Otte <cotte@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Chris Lalancette <clalance@redhat.com>
Cc: Anthony Liguori <anthony@codemonkey.ws>

1 files changed, 6 insertions, 12 deletions

diff --git a/drivers/s390/kvm/kvm_virtio.c b/drivers/s390/kvm/kvm_virtio.c
index 9f55ce6f3c78..5ab34340919b 100644
--- a/drivers/s390/kvm/kvm_virtio.c
+++ b/drivers/s390/kvm/kvm_virtio.c
@@ -31,11 +31,6 @@
  */
 static void *kvm_devices;
 
-/*
- * Unique numbering for kvm devices.
- */
-static unsigned int dev_index;
-
 struct kvm_device {
         struct virtio_device vdev;
         struct kvm_device_desc *desc;
@@ -250,26 +245,25 @@ static struct device kvm_root = {
  * adds a new device and register it with virtio
  * appropriate drivers are loaded by the device model
  */
-static void add_kvm_device(struct kvm_device_desc *d)
+static void add_kvm_device(struct kvm_device_desc *d, unsigned int offset)
 {
         struct kvm_device *kdev;
 
         kdev = kzalloc(sizeof(*kdev), GFP_KERNEL);
         if (!kdev) {
-                printk(KERN_EMERG "Cannot allocate kvm dev %u\n",
-                       dev_index++);
+                printk(KERN_EMERG "Cannot allocate kvm dev %u type %u\n",
+                       offset, d->type);
                 return;
         }
 
         kdev->vdev.dev.parent = &kvm_root;
-        kdev->vdev.index = dev_index++;
         kdev->vdev.id.device = d->type;
         kdev->vdev.config = &kvm_vq_configspace_ops;
         kdev->desc = d;
 
         if (register_virtio_device(&kdev->vdev) != 0) {
-                printk(KERN_ERR "Failed to register kvm device %u\n",
-                       kdev->vdev.index);
+                printk(KERN_ERR "Failed to register kvm device %u type %u\n",
+                       offset, d->type);
                 kfree(kdev);
         }
 }
@@ -289,7 +283,7 @@ static void scan_devices(void)
                 if (d->type == 0)
                         break;
 
-                add_kvm_device(d);
+                add_kvm_device(d, i);
         }
 }