Staging: hv: Fix vmbus event handler bug

The flag ENABLE_POLLING is always enabled in original Makefile, but
accidently removed during porting to mainline kernel. The patch fixes
this bug which can cause stalled network communication.  Credit needs to
go to Eric Sesterhenn <eric.sesterhenn@lsexperts.de> For pointing out a
typo in the original code as well.
Signed-off-by: NHank Janssen <hjanssen@microsoft.com>
Signed-off-by: NHaiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/staging/hv/Channel.c

@@ -611,7 +611,7 @@ void VmbusChannelClose(struct vmbus_channel *Channel)
 
 	/* Stop callback and cancel the timer asap */
 	Channel->OnChannelCallback = NULL;
-	del_timer(&Channel->poll_timer);
+	del_timer_sync(&Channel->poll_timer);
 
 	/* Send a closing message */
 	info = kmalloc(sizeof(*info) +
@@ -978,14 +978,10 @@ void VmbusChannelOnChannelEvent(struct vmbus_channel *Channel)
 {
 	DumpVmbusChannel(Channel);
 	ASSERT(Channel->OnChannelCallback);
-#ifdef ENABLE_POLLING
-	del_timer(&Channel->poll_timer);
-	Channel->OnChannelCallback(Channel->ChannelCallbackContext);
-	channel->poll_timer.expires(jiffies + usecs_to_jiffies(100);
-	add_timer(&channel->poll_timer);
-#else
+
 	Channel->OnChannelCallback(Channel->ChannelCallbackContext);
-#endif
+
+	mod_timer(&Channel->poll_timer, jiffies + usecs_to_jiffies(100));
 }
 
 /**
@@ -997,10 +993,6 @@ void VmbusChannelOnTimer(unsigned long data)
 
 	if (channel->OnChannelCallback) {
 		channel->OnChannelCallback(channel->ChannelCallbackContext);
-#ifdef ENABLE_POLLING
-		channel->poll_timer.expires(jiffies + usecs_to_jiffies(100);
-		add_timer(&channel->poll_timer);
-#endif
 	}
 }
 

drivers/staging/hv/ChannelMgmt.c

@@ -119,7 +119,7 @@ static inline void ReleaseVmbusChannel(void *context)
  */
 void FreeVmbusChannel(struct vmbus_channel *Channel)
 {
-	del_timer(&Channel->poll_timer);
+	del_timer_sync(&Channel->poll_timer);
 
 	/*
 	 * We have to release the channel's workqueue/thread in the vmbus's