[PATCH 4/5] hv: kvp: use wrappers to propaigate state

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

From: Olaf Hering <olaf@aepfle.de>

The "state" is used by several threads of execution.
Propagate the state to make changes visible. Also propagate context
change in kvp_on_msg.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 drivers/hv/hv_kvp.c |   39 +++++++++++++++++++++------------------
 1 files changed, 21 insertions(+), 18 deletions(-)

diff --git a/drivers/hv/hv_kvp.c b/drivers/hv/hv_kvp.c
index 74c38a9..778d353 100644
--- a/drivers/hv/hv_kvp.c
+++ b/drivers/hv/hv_kvp.c
@@ -61,7 +61,7 @@
  */
 
 static struct {
-	int state;   /* hvutil_device_state */
+	enum hvutil_device_state state;
 	int recv_len; /* number of bytes received. */
 	struct hv_kvp_msg  *kvp_msg; /* current message */
 	struct vmbus_channel *recv_channel; /* chn we got the request */
@@ -74,6 +74,9 @@ static struct {
  */
 static int dm_reg_value;
 
+#define kvp_get_state() hvutil_device_get_state(&kvp_transaction.state)
+#define kvp_set_state(s) hvutil_device_set_state(&kvp_transaction.state, s)
+
 static void kvp_send_key(struct work_struct *dummy);
 
 
@@ -122,8 +125,8 @@ static void kvp_timeout_func(struct work_struct *dummy)
 	kvp_respond_to_host(NULL, HV_E_FAIL);
 
 	/* Transaction is finished, reset the state. */
-	if (kvp_transaction.state > HVUTIL_READY)
-		kvp_transaction.state = HVUTIL_READY;
+	if (kvp_get_state() > HVUTIL_READY)
+		kvp_set_state(HVUTIL_READY);
 
 	hv_poll_channel(kvp_transaction.kvp_context,
 			hv_kvp_onchannelcallback);
@@ -153,7 +156,7 @@ static int kvp_handle_handshake(struct hv_kvp_msg *msg)
 	pr_debug("KVP: userspace daemon ver. %d registered\n",
 		 KVP_OP_REGISTER);
 	kvp_register(dm_reg_value);
-	kvp_transaction.state = HVUTIL_READY;
+	kvp_set_state(HVUTIL_READY);
 
 	return 0;
 }
@@ -177,15 +180,14 @@ static int kvp_on_msg(void *msg, int len)
 	 * with the daemon; handle that first.
 	 */
 
-	if (kvp_transaction.state < HVUTIL_READY) {
+	if (kvp_get_state() < HVUTIL_READY)
 		return kvp_handle_handshake(message);
-	}
 
 	/* We didn't send anything to userspace so the reply is spurious */
-	if (kvp_transaction.state < HVUTIL_USERSPACE_REQ)
+	if (kvp_get_state() < HVUTIL_USERSPACE_REQ)
 		return -EINVAL;
 
-	kvp_transaction.state = HVUTIL_USERSPACE_RECV;
+	kvp_set_state(HVUTIL_USERSPACE_RECV);
 
 	/*
 	 * Based on the version of the daemon, we propagate errors from the
@@ -218,7 +220,7 @@ static int kvp_on_msg(void *msg, int len)
 	 */
 	if (cancel_delayed_work_sync(&kvp_timeout_work)) {
 		kvp_respond_to_host(message, error);
-		kvp_transaction.state = HVUTIL_READY;
+		kvp_set_state(HVUTIL_READY);
 		hv_poll_channel(kvp_transaction.kvp_context,
 				hv_kvp_onchannelcallback);
 	}
@@ -349,7 +351,7 @@ kvp_send_key(struct work_struct *dummy)
 	int rc;
 
 	/* The transaction state is wrong. */
-	if (kvp_transaction.state != HVUTIL_HOSTMSG_RECEIVED)
+	if (kvp_get_state() != HVUTIL_HOSTMSG_RECEIVED)
 		return;
 
 	message = kzalloc(sizeof(*message), GFP_KERNEL);
@@ -442,13 +444,13 @@ kvp_send_key(struct work_struct *dummy)
 			break;
 	}
 
-	kvp_transaction.state = HVUTIL_USERSPACE_REQ;
+	kvp_set_state(HVUTIL_USERSPACE_REQ);
 	rc = hvutil_transport_send(hvt, message, sizeof(*message));
 	if (rc) {
 		pr_debug("KVP: failed to communicate to the daemon: %d\n", rc);
 		if (cancel_delayed_work_sync(&kvp_timeout_work)) {
 			kvp_respond_to_host(message, HV_E_FAIL);
-			kvp_transaction.state = HVUTIL_READY;
+			kvp_set_state(HVUTIL_READY);
 		}
 	}
 
@@ -596,12 +598,13 @@ void hv_kvp_onchannelcallback(void *context)
 	int util_fw_version;
 	int kvp_srv_version;
 
-	if (kvp_transaction.state > HVUTIL_READY) {
+	if (kvp_get_state() > HVUTIL_READY) {
 		/*
 		 * We will defer processing this callback once
 		 * the current transaction is complete.
 		 */
 		kvp_transaction.kvp_context = context;
+		wmb();
 		return;
 	}
 	kvp_transaction.kvp_context = NULL;
@@ -651,12 +654,12 @@ void hv_kvp_onchannelcallback(void *context)
 			kvp_transaction.recv_req_id = requestid;
 			kvp_transaction.kvp_msg = kvp_msg;
 
-			if (kvp_transaction.state < HVUTIL_READY) {
+			if (kvp_get_state() < HVUTIL_READY) {
 				/* Userspace is not registered yet */
 				kvp_respond_to_host(NULL, HV_E_FAIL);
 				return;
 			}
-			kvp_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
+			kvp_set_state(HVUTIL_HOSTMSG_RECEIVED);
 
 			/*
 			 * Get the information from the
@@ -688,7 +691,7 @@ static void kvp_on_reset(void)
 {
 	if (cancel_delayed_work_sync(&kvp_timeout_work))
 		kvp_respond_to_host(NULL, HV_E_FAIL);
-	kvp_transaction.state = HVUTIL_DEVICE_INIT;
+	kvp_set_state(HVUTIL_DEVICE_INIT);
 }
 
 int
@@ -702,7 +705,7 @@ hv_kvp_init(struct hv_util_service *srv)
 	 * Defer processing channel callbacks until the daemon
 	 * has registered.
 	 */
-	kvp_transaction.state = HVUTIL_DEVICE_INIT;
+	kvp_set_state(HVUTIL_DEVICE_INIT);
 
 	hvt = hvutil_transport_init(kvp_devname, CN_KVP_IDX, CN_KVP_VAL,
 				    kvp_on_msg, kvp_on_reset);
@@ -714,7 +717,7 @@ hv_kvp_init(struct hv_util_service *srv)
 
 void hv_kvp_deinit(void)
 {
-	kvp_transaction.state = HVUTIL_DEVICE_DYING;
+	kvp_set_state(HVUTIL_DEVICE_DYING);
 	cancel_delayed_work_sync(&kvp_timeout_work);
 	cancel_work_sync(&kvp_sendkey_work);
 	hvutil_transport_destroy(hvt);
-- 
1.7.4.1