2020-05-11 07:33:38

by Jürgen Groß

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

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 <[email protected]>
---
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 d8e5c5e4fa67..5e6b256ca916 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;
}

/**
--
2.26.1


2020-05-11 18:34:08

by Boris Ostrovsky

[permalink] [raw]
Subject: Re: [PATCH 2/2] xen/xenbus: let xenbus_map_ring_valloc() return errno values only

On 5/11/20 3:31 AM, Juergen Gross wrote:
> 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 <[email protected]>


Reviewed-by: Boris Ostrovsky <[email protected]>




Attachments:
pEpkey.asc (4.96 kB)