[PATCH 5/5] Drivers: hv: vmbus: Implement the protocol for tearing down vmbus state

["K. Y. Srinivasan" <kys@microsoft.com>]

Implement the protocol for tearing down the monitor state established with
the host.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 drivers/hv/channel_mgmt.c |   25 +++++++++++++++++++++++++
 drivers/hv/connection.c   |    5 +++++
 drivers/hv/hyperv_vmbus.h |    2 ++
 include/linux/hyperv.h    |    1 +
 4 files changed, 33 insertions(+), 0 deletions(-)

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 865a3af..4b9d89a 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -422,6 +422,30 @@ static void init_vp_index(struct vmbus_channel *channel, const uuid_le *type_gui
 }
 
 /*
+ * vmbus_unload_response - Handler for the unload response.
+ */
+static void vmbus_unload_response(struct vmbus_channel_message_header *hdr)
+{
+	/*
+	 * This is a global event; just wakeup the waiting thread.
+	 * Once we successfully unload, we can cleanup the monitor state.
+	 */
+	complete(&vmbus_connection.unload_event);
+}
+
+void vmbus_initiate_unload(void)
+{
+	struct vmbus_channel_message_header hdr;
+
+	init_completion(&vmbus_connection.unload_event);
+	memset(&hdr, 0, sizeof(struct vmbus_channel_message_header));
+	hdr.msgtype = CHANNELMSG_UNLOAD;
+	vmbus_post_msg(&hdr, sizeof(struct vmbus_channel_message_header));
+
+	wait_for_completion(&vmbus_connection.unload_event);
+}
+
+/*
  * vmbus_onoffer - Handler for channel offers from vmbus in parent partition.
  *
  */
@@ -717,6 +741,7 @@ struct vmbus_channel_message_table_entry
 	{CHANNELMSG_INITIATE_CONTACT,		0, NULL},
 	{CHANNELMSG_VERSION_RESPONSE,		1, vmbus_onversion_response},
 	{CHANNELMSG_UNLOAD,			0, NULL},
+	{CHANNELMSG_UNLOAD_RESPONSE,		1, vmbus_unload_response},
 };
 
 /*
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index b27220a..acd50e9 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -227,6 +227,11 @@ cleanup:
 
 void vmbus_disconnect(void)
 {
+	/*
+	 * First send the unload request to the host.
+	 */
+	vmbus_initiate_unload();
+
 	if (vmbus_connection.work_queue) {
 		drain_workqueue(vmbus_connection.work_queue);
 		destroy_workqueue(vmbus_connection.work_queue);
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 138d663..cddc0c9 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -647,6 +647,7 @@ struct vmbus_connection {
 
 	atomic_t next_gpadl_handle;
 
+	struct completion  unload_event;
 	/*
 	 * Represents channel interrupts. Each bit position represents a
 	 * channel.  When a channel sends an interrupt via VMBUS, it finds its
@@ -741,6 +742,7 @@ void hv_vss_onchannelcallback(void *);
 int hv_fcopy_init(struct hv_util_service *);
 void hv_fcopy_deinit(void);
 void hv_fcopy_onchannelcallback(void *);
+void vmbus_initiate_unload(void);
 
 static inline void hv_poll_channel(struct vmbus_channel *channel,
 				   void (*cb)(void *))
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index e29ccdd..ea93486 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -389,6 +389,7 @@ enum vmbus_channel_message_type {
 	CHANNELMSG_INITIATE_CONTACT		= 14,
 	CHANNELMSG_VERSION_RESPONSE		= 15,
 	CHANNELMSG_UNLOAD			= 16,
+	CHANNELMSG_UNLOAD_RESPONSE		= 17,
 	CHANNELMSG_COUNT
 };
 
-- 
1.7.4.1