4.9-stable review patch. If anyone has any objections, please let me know.
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From: Zhouyang Jia jiazhouyang09@gmail.com
[ Upstream commit 84c029a73327cef571eaa61c7d6e67e8031b52ec ]
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@gmail.com Reviewed-by: Boris Ostrovsky boris.ostrovsky@oracle.com Signed-off-by: Juergen Gross jgross@suse.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/xen/manage.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-)
--- a/drivers/xen/manage.c +++ b/drivers/xen/manage.c @@ -291,8 +291,15 @@ static void sysrq_handler(struct xenbus_ 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("%s: Error %d writing sysrq in control/sysrq\n", + __func__, err); + xenbus_transaction_end(xbt, 1); + return; + } + }
err = xenbus_transaction_end(xbt, 0); if (err == -EAGAIN) @@ -344,7 +351,12 @@ 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("%s: Error %d writing %s\n", __func__, + err, node); + return err; + } }
return 0;