I think this is reasonable readable:

    while ((status = systemcall(...)) != SUCCESS) {
        do something with status;
    }

Leave a comment there explaining the assignment.

Likewise:

    if ((status = systemcall(...)) != SUCCESS) goto error;

Or something like that. I don't understand the hate, just make sure it's obvious what you're doing.

   while(status != SUCCESS) {
      status = syscall(...);
      // do something with status
   }