[PATCH] xen: add error handling for xenbus_printf

From: Zhouyang Jia
Date: Mon Jun 11 2018 - 23:44:43 EST


When xenbus_printf fails, the lack of error-handling code may
cause unexpected results.

This patch adds error-handling code after calling xenbus_printf.

Signed-off-by: Zhouyang Jia <jiazhouyang09@xxxxxxxxx>
---
drivers/xen/manage.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
index 8835065..159694d 100644
--- a/drivers/xen/manage.c
+++ b/drivers/xen/manage.c
@@ -289,8 +289,15 @@ static void sysrq_handler(struct xenbus_watch *watch, const char *path,
return;
}

- if (sysrq_key != '\0')
- xenbus_printf(xbt, "control", "sysrq", "%c", '\0');
+ if (sysrq_key != '\0') {
+ err = xenbus_printf(xbt, "control", "sysrq", "%c", '\0');
+ if (err) {
+ pr_err("Error %d writing sysrq code in control/sysrq\n",
+ err);
+ xenbus_transaction_end(xbt, 1);
+ return;
+ }
+ }

err = xenbus_transaction_end(xbt, 0);
if (err == -EAGAIN)
@@ -342,7 +349,11 @@ static int setup_shutdown_watcher(void)
continue;
snprintf(node, FEATURE_PATH_SIZE, "feature-%s",
shutdown_handlers[idx].command);
- xenbus_printf(XBT_NIL, "control", node, "%u", 1);
+ err = xenbus_printf(XBT_NIL, "control", node, "%u", 1);
+ if (err) {
+ pr_err("Error %d writing %s\n", err, node);
+ return err;
+ }
}

return 0;
--
2.7.4