xen: make use of xenbus_read_unsigned() in xen-tpmfront

Use xenbus_read_unsigned() instead of xenbus_scanf() when possible.
This requires to change the type of one read from int to unsigned,
but this case has been wrong before: negative values are not allowed
for the modified case.

Cc: peterhuewe@gmx.de
Cc: tpmdd@selhorst.net
Cc: jarkko.sakkinen@linux.intel.com
Cc: jgunthorpe@obsidianresearch.com
Cc: tpmdd-devel@lists.sourceforge.net
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Acked-by: David Vrabel <david.vrabel@citrix.com>

diff --git a/drivers/char/tpm/xen-tpmfront.c b/drivers/char/tpm/xen-tpmfront.c
index 62028f483bbaacfc78b77b3b65ed2e39c8d1e0e7..50072cc4fe5cf7632439be7f10adfba177342d7b 100644 (file)
--- a/drivers/char/tpm/xen-tpmfront.c
+++ b/drivers/char/tpm/xen-tpmfront.c
@@ -337,18 +337,14 @@ static int tpmfront_resume(struct xenbus_device *dev)
 static void backend_changed(struct xenbus_device *dev,
                enum xenbus_state backend_state)
 {
-       int val;
-
        switch (backend_state) {
        case XenbusStateInitialised:
        case XenbusStateConnected:
                if (dev->state == XenbusStateConnected)
                        break;
 
-               if (xenbus_scanf(XBT_NIL, dev->otherend,
-                               "feature-protocol-v2", "%d", &val) < 0)
-                       val = 0;
-               if (!val) {
+               if (!xenbus_read_unsigned(dev->otherend, "feature-protocol-v2",
+                                         0)) {
                        xenbus_dev_fatal(dev, -EINVAL,
                                        "vTPM protocol 2 required");
                        return;