[PATCH 5/6] staging: vc04_services: Handle conversion from VCHIQ_SERVICE_HANDLE_T to VCHI_SERVICE_HANDLE_T

[Michael Zoran]

>From 0d80d21f73d6c2f31ccc13527c815276f70ac3e0 Mon Sep 17 00:00:00 2001
F
rom: Michael Zoran <mzoran at crowfest.net>
Date: Sun, 16 Oct 2016 15:13:14
-0700
Subject: [PATCH 5/6] staging: vc04_services: Handle conversion
from
 VCHIQ_SERVICE_HANDLE_T to VCHI_SERVICE_HANDLE_T

A
VCHIQ_SERVICE_HANDLE_T which is an int is stuffed into a
VCHI_SERVICE_HA
NDLE_T which is a pointer, passed around, then
converted back to a
VCHIQ_SERVICE_HANDLE_T. Since the data is
always actually a
VCHIQ_SERVICE_HANDLE_T(int), never actually a
pointer, it is safe to
simply cast the two back in forth.

Note that pointers are never stuffed
into an int.

Signed-off-by: Michael Zoran <mzoran at crowfest.net>
---

.../vc04_services/interface/vchiq_arm/vchiq_shim.c | 22
+++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)


diff --git
a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_shim.c
b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_shim.c
index
8072ff6..49f9d6a 100644
---
a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_shim.c
+++
b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_shim.c
@@
-400,8 +400,16 @@ EXPORT_SYMBOL(vchi_msg_queuev);
 
***********************************************************/
 int32_t
vchi_held_msg_release(VCHI_HELD_MSG_T *message)
 {
-
	vchiq_release_message((VCHIQ_SERVICE_HANDLE_T)message->service,
-	
	(VCHIQ_HEADER_T *)message->message);
+	/*
+	 * Convert the service field
pointer back to an
+	 * VCHIQ_SERVICE_HANDLE_T which is an int.
+	 * This
pointer is opaque to everything except
+	 * vchi_msg_hold which simply
upcasted the int
+	 * to a pointer.
+	 */
+
+
	vchiq_release_message((VCHIQ_SERVICE_HANDLE_T)(long)message->service,
+
			      (VCHIQ_HEADER_T *)message->message);
 
 	return 0;
 }
@@ -445,8
+453,16 @@ int32_t vchi_msg_hold(VCHI_SERVICE_HANDLE_T handle,
 	*data =
header->data;
 	*msg_size = header->size;
 
+	/*
+	 * upcast the
VCHIQ_SERVICE_HANDLE_T which is an int
+	 * to a pointer and stuff it in
the held message.
+	 * This pointer is opaque to everything except
+	 *
vchi_held_msg_release which simply downcasts it back
+	 * to an int.
+	
*/
+
 	message_handle->service =
-		(struct opaque_vchi_service_t
*)service->handle;
+		(struct opaque_vchi_service_t *)(long)service-
>handle;
 	message_handle->message = header;
 
 	return 0;
-- 
2.9.3