This is going to be very, very difficult to do which is why we've removed it from the RHEL board and lowered the priority. Basically, lrmd_send_command implements almost all of the API commands for a lrmd_t. All of those would need to be converted over to an async style, and then all of their callers would be. This includes major portions of the control daemon, which isn't very well set up to call the async versions of these functions. It would require rewriting much of liblrmd and the control daemon, and there's simply not enough time to get around to a project of that size.

cppcheck appears to be fine with pcmk__realloc for me, but I would still be all for investigating removing it in favor of someone else's code.