Man page 9 : rpc_queue_upcall

rpc_queue_upcall - queue an upcall message to userspace

int rpc_queue_upcall(struct rpc_pipe *  pipe , struct rpc_pipe_msg *  msg );

pipe
    upcall pipe on which to queue given message

msg
    message to queue

Call with an inode created by rpc_mkpipe to queue an upcall. A userspace process may then later read the upcall by performing a read on an open file for this inode. It is up to the caller to initialize the fields of msg (other than msg->list) appropriately.