Use a "request cookie" for thc_ipc_reply.

We don't want to have to hold on to the request message until
we reply. Instead, the libasync user passes in a "request cookie",
that is just the message id. The libasync user obtains the
cookie via thc_get_request_cookie.

Not tested yet.

fast-ipc-module @ 06c7d47f

-Subproject commit 2cef3d068d3ed2da556d775f8571f5c2c6b67d63
+Subproject commit 06c7d47f536ff569f8ee4d97ee62a7c70ee9b85d

src/common/thc_ipc.c

@@ -196,11 +196,11 @@ EXPORT_SYMBOL(thc_ipc_call);
 int
 LIBASYNC_FUNC_ATTR
 thc_ipc_reply(struct fipc_ring_channel *chnl,
-	struct fipc_message *request,
+	uint32_t request_cookie,
 	struct fipc_message *response)
 {
     thc_set_msg_type(response, msg_type_response);
-    thc_set_msg_id(response, thc_get_msg_id(request));
+    thc_set_msg_id(response, request_cookie);
     return fipc_send_msg_end(chnl, response);
 }
 EXPORT_SYMBOL(thc_ipc_reply);

src/include/thc_ipc.h

@@ -39,6 +39,11 @@ static inline void thc_set_msg_id(struct fipc_message *msg,
 	fipc_set_flags(msg, flags);
 }
 
+static inline uint32_t thc_get_request_cookie(struct fipc_message *request)
+{
+	return thc_get_msg_id(request);
+}
+
 int thc_ipc_recv(struct fipc_ring_channel *chnl, 
                  unsigned long msg_id, 
                  struct fipc_message** out_msg);

src/tests/simple/callee.c

@@ -69,8 +69,11 @@ static inline int send_response(struct fipc_ring_channel *chnl,
 {
 	int ret;
 	struct fipc_message *response;
+	uint32_t request_cookie = thc_get_request_cookie(recvd_msg);
 	/*
-	 * Mark recvd msg slot as available
+	 * Mark recvd msg slot as available.
+	 *
+	 * NOTE: recvd_msg is not valid after this call.
 	 */
 	ret = fipc_recv_msg_end(chnl, recvd_msg);
 	if (ret) {
@@ -89,7 +92,7 @@ static inline int send_response(struct fipc_ring_channel *chnl,
 	set_fn_type(response, type);
 	response->regs[0] = val;
 
-	ret = thc_ipc_reply(chnl, recvd_msg, response);
+	ret = thc_ipc_reply(chnl, request_cookie, response);
 	if (ret) {
 		pr_err("Error marking message as sent");
 		return ret;