l...@gnu.org (Ludovic Courtès) writes:
> Mark H Weaver <m...@netris.org> skribis:
>
>> It would be good to fix these before 2.0.7 is released, but I'm a bit
>> uncertain of how best to do so, and I don't have time at the moment.
>>
>> ./posix.c:1375: make_rw_port = scm_c_private_variable ("ice-9
>> popen",
>> ./debug.c:217: local_eval_var = scm_c_public_variable ("ice-9
>> local-eval", "local-eval");
>> ./strports.c:541: eval_string = scm_c_public_lookup ("ice-9
>> eval-string", "eval-string");
>
> I’m actually not sure what you mean here.
Those are three bugs where a global static variable is lazily
initialized in a way that is not thread-safe. The one in strports.c
actually caused a reproducible crash bug for a user who created multiple
threads, each of which called scm_eval_string.
Consider the bug in scm_local_eval, which I'm ashamed to say was written
by me before I educated myself on weakly-ordered memory models:
SCM
scm_local_eval (SCM exp, SCM env)
{
static SCM local_eval_var = SCM_BOOL_F;
if (scm_is_false (local_eval_var))
local_eval_var = scm_c_public_variable ("ice-9 local-eval", "local-eval");
return scm_call_2 (SCM_VARIABLE_REF (local_eval_var), exp, env);
}
The problem is that it's possible for a thread to see a non-#f value for
'local_eval_var' before it sees the memory it points to properly
initialized.
> Anyway, I think we ought to release 2.0.7 now. And yes, there will be a
> 2.0.8 with a number of additional fixes. :-)
Okay, that's fine. We can fix these for 2.0.8.
Thanks,
Mark
