lguest: update commentry

Every so often, after code shuffles, I need to go through and unbitrot
the Lguest Journey (see drivers/lguest/README).  Since we now use RCU in
a simple form in one place I took the opportunity to expand that explanation.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
index cc000e79c3d1..1401c1ace1ec 100644
--- a/drivers/lguest/lguest_device.c
+++ b/drivers/lguest/lguest_device.c
@@ -236,7 +236,7 @@ static void lg_notify(struct virtqueue *vq)
 extern void lguest_setup_irq(unsigned int irq);
 
 /*
- * This routine finds the first virtqueue described in the configuration of
+ * This routine finds the Nth virtqueue described in the configuration of
  * this device and sets it up.
  *
  * This is kind of an ugly duckling.  It'd be nicer to have a standard
@@ -244,9 +244,6 @@ extern void lguest_setup_irq(unsigned int irq);
  * everyone wants to do it differently.  The KVM coders want the Guest to
  * allocate its own pages and tell the Host where they are, but for lguest it's
  * simpler for the Host to simply tell us where the pages are.
- *
- * So we provide drivers with a "find the Nth virtqueue and set it up"
- * function.
  */
 static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
                                     unsigned index,
@@ -422,7 +419,11 @@ static void add_lguest_device(struct lguest_device_desc *d,
 
         /* This devices' parent is the lguest/ dir. */
         ldev->vdev.dev.parent = lguest_root;
-        /* We have a unique device index thanks to the dev_index counter. */
+        /*
+         * The device type comes straight from the descriptor.  There's also a
+         * device vendor field in the virtio_device struct, which we leave as
+         * 0.
+         */
         ldev->vdev.id.device = d->type;
         /*
          * We have a simple set of routines for querying the device's