9p/xen: fix version parsing

When connecting the Xen 9pfs frontend to the backend, the "versions"
Xenstore entry written by the backend is parsed in a wrong way.

The "versions" entry is defined to contain the versions supported by
the backend separated by commas (e.g. "1,2"). Today only version "1"
is defined. Unfortunately the frontend doesn't look for "1" being
listed in the entry, but it is expecting the entry to have the value
"1".

This will result in failure as soon as the backend will support e.g.
versions "1" and "2".

Fix that by scanning the entry correctly.

Link: https://lkml.kernel.org/r/20230130113036.7087-2-jgross@suse.com
Fixes: 71ebd71921e4 ("xen/9pfs: connect to the backend")
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Signed-off-by: Eric Van Hensbergen <ericvh@kernel.org>

diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c
index 9630b1275557978dd45a5e4a0322192bbc30af42..6298d773115354c5ecc3d09549e056b66504077d 100644 (file)
--- a/net/9p/trans_xen.c
+++ b/net/9p/trans_xen.c
@@ -379,13 +379,19 @@ static int xen_9pfs_front_probe(struct xenbus_device *dev,
        int ret, i;
        struct xenbus_transaction xbt;
        struct xen_9pfs_front_priv *priv = NULL;
-       char *versions;
+       char *versions, *v;
        unsigned int max_rings, max_ring_order, len = 0;
 
        versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len);
        if (IS_ERR(versions))
                return PTR_ERR(versions);
-       if (strcmp(versions, "1")) {
+       for (v = versions; *v; v++) {
+               if (simple_strtoul(v, &v, 10) == 1) {
+                       v = NULL;
+                       break;
+               }
+       }
+       if (v) {
                kfree(versions);
                return -EINVAL;
        }