binder: return pending info for frozen async txns

An async transaction to a frozen process will still be successfully
put in the queue. But this pending async transaction won't be processed
until the target process is unfrozen at an unspecified time in the
future. Pass this important information back to the user space caller
by returning BR_TRANSACTION_PENDING_FROZEN.

Signed-off-by: Li Li <dualli@google.com>
Acked-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20221123201654.589322-2-dualli@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/uapi/linux/android/binder.h

@@ -450,7 +450,7 @@ enum binder_driver_return_protocol {
 
 	BR_FROZEN_REPLY = _IO('r', 18),
 	/*
-	 * The target of the last transaction (either a bcTRANSACTION or
+	 * The target of the last sync transaction (either a bcTRANSACTION or
 	 * a bcATTEMPT_ACQUIRE) is frozen.  No parameters.
 	 */
 
@@ -460,6 +460,11 @@ enum binder_driver_return_protocol {
 	 * asynchronous transaction makes the allocated async buffer size exceed
 	 * detection threshold.  No parameters.
 	 */
+
+	BR_TRANSACTION_PENDING_FROZEN = _IO('r', 20),
+	/*
+	 * The target of the last async transaction is frozen.  No parameters.
+	 */
 };
 
 enum binder_driver_command_protocol {