xen: don't print error message in case of missing Xenstore entry

When registering for the Xenstore watch of the node control/sysrq the handler will be called at once. Don't issue an error message if the Xenstore node isn't there, as it will be created only when an event is being triggered. Signed-off-by: Juergen Gross <[email protected]> Reviewed-by: Boris Ostrovsky <[email protected]> Signed-off-by: Juergen Gross <[email protected]>
jimmycarry · Jun 7, 2017 · 4e93b64 · 4e93b64
1 parent 84a0a96
commit 4e93b64
Showing 1 changed file with 10 additions and 2 deletions.
diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
@@ -277,8 +277,16 @@ static void sysrq_handler(struct xenbus_watch *watch, const char *path,
 	err = xenbus_transaction_start(&xbt);
 	if (err)
 		return;
-	if (xenbus_scanf(xbt, "control", "sysrq", "%c", &sysrq_key) < 0) {
-		pr_err("Unable to read sysrq code in control/sysrq\n");
+	err = xenbus_scanf(xbt, "control", "sysrq", "%c", &sysrq_key);
+	if (err < 0) {
+		/*
+		 * The Xenstore watch fires directly after registering it and
+		 * after a suspend/resume cycle. So ENOENT is no error but
+		 * might happen in those cases.
+		 */
+		if (err != -ENOENT)
+			pr_err("Error %d reading sysrq code in control/sysrq\n",
+			       err);
 		xenbus_transaction_end(xbt, 1);
 		return;
 	}