Drivers: hv: balloon: Do not post pressure status if interrupted

When we are posting pressure status, we may get interrupted and handle
the un-balloon operation. In this case just don't post the status as we
know the pressure status is stale.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Cc: Stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hv/hv_balloon.c

@@ -975,6 +975,14 @@ static void post_status(struct hv_dynmem_device *dm)
 				dm->num_pages_ballooned +
 				compute_balloon_floor();
 
+	/*
+	 * If our transaction ID is no longer current, just don't
+	 * send the status. This can happen if we were interrupted
+	 * after we picked our transaction ID.
+	 */
+	if (status.hdr.trans_id != atomic_read(&trans_id))
+		return;
+
 	vmbus_sendpacket(dm->dev->channel, &status,
 				sizeof(struct dm_status),
 				(unsigned long)NULL,