Drivers: hv: vss: Introduce timeout for communication with userspace
In contrast with KVP there is no timeout when communicating with
userspace VSS daemon. In case it gets stuck performing freeze/thaw
operation no message will be sent to the host so it will take very
long (around 10 minutes) before backup fails. Introduce 10 second
timeout using schedule_delayed_work().
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/hv/hv_snapshot.c b/drivers/hv/hv_snapshot.c
index 34f14fd..21e51be 100644
--- a/drivers/hv/hv_snapshot.c
+++ b/drivers/hv/hv_snapshot.c
@@ -28,7 +28,7 @@
#define VSS_MINOR 0
#define VSS_VERSION (VSS_MAJOR << 16 | VSS_MINOR)
-
+#define VSS_USERSPACE_TIMEOUT (msecs_to_jiffies(10 * 1000))
/*
* Global state maintained for transaction that is being processed.
@@ -55,12 +55,24 @@
static __u8 *recv_buffer;
static void vss_send_op(struct work_struct *dummy);
+static void vss_timeout_func(struct work_struct *dummy);
+
+static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);
static DECLARE_WORK(vss_send_op_work, vss_send_op);
/*
* Callback when data is received from user mode.
*/
+static void vss_timeout_func(struct work_struct *dummy)
+{
+ /*
+ * Timeout waiting for userspace component to reply happened.
+ */
+ pr_warn("VSS: timeout waiting for daemon to reply\n");
+ vss_respond_to_host(HV_E_FAIL);
+}
+
static void
vss_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
{
@@ -76,7 +88,8 @@
return;
}
- vss_respond_to_host(vss_msg->error);
+ if (cancel_delayed_work_sync(&vss_timeout_work))
+ vss_respond_to_host(vss_msg->error);
}
@@ -223,6 +236,8 @@
case VSS_OP_FREEZE:
case VSS_OP_THAW:
schedule_work(&vss_send_op_work);
+ schedule_delayed_work(&vss_timeout_work,
+ VSS_USERSPACE_TIMEOUT);
return;
case VSS_OP_HOT_BACKUP:
@@ -277,5 +292,6 @@
void hv_vss_deinit(void)
{
cn_del_callback(&vss_id);
+ cancel_delayed_work_sync(&vss_timeout_work);
cancel_work_sync(&vss_send_op_work);
}