Re: Locks and threads

[Neil Jerram]

Linas Vepstas <address@hidden> writes:

> I don't understand the patch.
>
> libguile/scmsigs.c has a SCM_CRITICAL_SECTION_START
> at line 339, which seems to be balanced by
> SCM_CRITICAL_SECTION_END;
> at lines 442 and 461, right before the return from
> the subroutine.
>
> So why insert this seemingly un-needed SCM_CRITICAL_SECTION_END,
> and worse, nest it in an else block?

Because when scm_sigaction_for_thread decides to throw an out-of-range
error (by the `SCM_OUT_OF_RANGE' call), it will exit non-locally at
that point (by calling `longjmp').  So, in this case, it won't pass
through (either of) the SCM_CRITICAL_SECTION_ENDs just before the
return statement.

Does that make sense now?

      Neil