[PATCH review for 4.4 15/24] xen/manage: correct return value check on xenbus_scanf()

["Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com>]

From: Jan Beulich <JBeulich@suse.com>

[ Upstream commit 4fed1b125eb6252bde478665fc05d4819f774fa8 ]

A negative return value indicates an error; in fact the function at
present won't ever return zero.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
---
 drivers/xen/manage.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
index e12bd3635f83..e8850b0e3272 100644
--- a/drivers/xen/manage.c
+++ b/drivers/xen/manage.c
@@ -275,7 +275,7 @@ static void sysrq_handler(struct xenbus_watch *watch, const char **vec,
 	err = xenbus_transaction_start(&xbt);
 	if (err)
 		return;
-	if (!xenbus_scanf(xbt, "control", "sysrq", "%c", &sysrq_key)) {
+	if (xenbus_scanf(xbt, "control", "sysrq", "%c", &sysrq_key) < 0) {
 		pr_err("Unable to read sysrq code in control/sysrq\n");
 		xenbus_transaction_end(xbt, 1);
 		return;
-- 
2.11.0