[PATCH 4/5] Drivers: hv: make sure that 'struct vmbus_channel_message_header' compiles correctly

[Vitaly Kuznetsov]

Strictly speaking, compiler is free to use something different from 'u32'
for 'enum vmbus_channel_message_type' (e.g. char) but it doesn't happen in
real life, just add a BUILD_BUG_ON() guardian.

Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
 drivers/hv/vmbus_drv.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 0f7bbf952d89..d684cbee7ae6 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -1023,6 +1023,13 @@ void vmbus_on_msg_dpc(unsigned long data)
 	struct onmessage_work_context *ctx;
 	u32 message_type = msg->header.message_type;
 
+	/*
+	 * 'enum vmbus_channel_message_type' is supposed to always be 'u32' as
+	 * it is being used in 'struct vmbus_channel_message_header' definition
+	 * which is supposed to match hypervisor ABI.
+	 */
+	BUILD_BUG_ON(sizeof(enum vmbus_channel_message_type) != sizeof(u32));
+
 	if (message_type == HVMSG_NONE)
 		/* no msg */
 		return;
-- 
2.25.1