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Commit 64914207 authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Greg Kroah-Hartman
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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: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 1a3c724a

drivers/hv/hv_snapshot.c

+18 −2
Original line number Diff line number Diff line
@@ -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 const char vss_name[] = "vss_kernel_module"; 
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)

{
@@ -76,6 +88,7 @@ vss_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp) 
		return;



	}

	if (cancel_delayed_work_sync(&vss_timeout_work))

		vss_respond_to_host(vss_msg->error);

}
@@ -223,6 +236,8 @@ void hv_vss_onchannelcallback(void *context) 
			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 @@ hv_vss_init(struct hv_util_service *srv) 
void hv_vss_deinit(void)

{

	cn_del_callback(&vss_id);

	cancel_delayed_work_sync(&vss_timeout_work);

	cancel_work_sync(&vss_send_op_work);

}