Some versions of inetd will reread their configuration tables if they receive a HUP signal. This man page is correct for version 2.2 of the Samba suite. The log file name is specified at compile time, but may be overridden on the command line. The number and nature of diagnostics available depends on the debug level used by the server. If you have problems, set the debug level to 3 and peruse the log files.
Most messages are reasonably self-explanatory.
Unfortunately, at the time this man page was created, there are too many diagnostics available in the source code to warrant describing each and every diagnostic. At this stage your best bet is still to grep the source code and inspect the conditions that gave rise to the diagnostics you are seeing. This is to allow transient problems to be diagnosed, whilst still running at a normally low log level. Note that as the signal handlers send a debug write, they are not re-entrant in smbd. This you should wait until smbd is in a state of waiting for an incoming smb before issuing them.