[PATCH v2 2/2] xen/xenbus: let xenbus_map_ring_valloc() return errno values only

[Juergen Gross <jgross@xxxxxxxx>]

Today xenbus_map_ring_valloc() can return either a negative errno
value (-ENOMEM or -EINVAL) or a grant status value. This is a mess as
e.g -ENOMEM and GNTST_eagain have the same numeric value.

Fix that by turning all grant mapping errors into -ENOENT. This is
no problem as all callers of xenbus_map_ring_valloc() only use the
return value to print an error message, and in case of mapping errors
the grant status value has already been printed by __xenbus_map_ring()
before.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
---
 drivers/xen/xenbus/xenbus_client.c | 22 ++++++----------------
 1 file changed, 6 insertions(+), 16 deletions(-)

diff --git a/drivers/xen/xenbus/xenbus_client.c 
b/drivers/xen/xenbus/xenbus_client.c
index 9f8372079ecf..4f168b46fbca 100644
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -456,8 +456,7 @@ EXPORT_SYMBOL_GPL(xenbus_free_evtchn);
  * Map @nr_grefs pages of memory into this domain from another
  * domain's grant table.  xenbus_map_ring_valloc allocates @nr_grefs
  * pages of virtual address space, maps the pages to that address, and
- * sets *vaddr to that address.  Returns 0 on success, and GNTST_*
- * (see xen/include/interface/grant_table.h) or -ENOMEM / -EINVAL on
+ * sets *vaddr to that address.  Returns 0 on success, and -errno on
  * error. If an error is returned, device will switch to
  * XenbusStateClosing and the error message will be saved in XenStore.
  */
@@ -477,18 +476,11 @@ int xenbus_map_ring_valloc(struct xenbus_device *dev, 
grant_ref_t *gnt_refs,
                return -ENOMEM;
 
        info->node = kzalloc(sizeof(*info->node), GFP_KERNEL);
-       if (!info->node) {
+       if (!info->node)
                err = -ENOMEM;
-               goto out;
-       }
-
-       err = ring_ops->map(dev, info, gnt_refs, nr_grefs, vaddr);
-
-       /* Some hypervisors are buggy and can return 1. */
-       if (err > 0)
-               err = GNTST_general_error;
+       else
+               err = ring_ops->map(dev, info, gnt_refs, nr_grefs, vaddr);
 
- out:
        kfree(info->node);
        kfree(info);
        return err;
@@ -507,7 +499,6 @@ static int __xenbus_map_ring(struct xenbus_device *dev,
                             bool *leaked)
 {
        int i, j;
-       int err = GNTST_okay;
 
        if (nr_grefs > XENBUS_MAX_RING_GRANTS)
                return -EINVAL;
@@ -522,7 +513,6 @@ static int __xenbus_map_ring(struct xenbus_device *dev,
 
        for (i = 0; i < nr_grefs; i++) {
                if (info->map[i].status != GNTST_okay) {
-                       err = info->map[i].status;
                        xenbus_dev_fatal(dev, info->map[i].status,
                                         "mapping in shared page %d from domain 
%d",
                                         gnt_refs[i], dev->otherend_id);
@@ -531,7 +521,7 @@ static int __xenbus_map_ring(struct xenbus_device *dev,
                        handles[i] = info->map[i].handle;
        }
 
-       return GNTST_okay;
+       return 0;
 
  fail:
        for (i = j = 0; i < nr_grefs; i++) {
@@ -554,7 +544,7 @@ static int __xenbus_map_ring(struct xenbus_device *dev,
                }
        }
 
-       return err;
+       return -ENOENT;
 }
 
 /**
-- 
2.26.2