Re: [PATCH] pthread_kill.3: Update to match POSIX.

[Florian Weimer <fw@deneb.enyo.de>]

* enh:

> On Tue, Nov 12, 2019 at 9:51 PM Florian Weimer <fw@deneb.enyo.de> wrote:
>>
>> * enh:
>>
>> > no, because the C library has two choices when a thread exits:
>> >
>> > 1. unmap the thread.
>> >
>> > 2. keep the thread around for recycling.
>> >
>> > if you choose 1 (optimizing for space, like Android), your dereference
>> > is illegal.
>>
>> This choice is only available for threads in a detached state.  For
>> joinable threads, a conforming implementation cannot immediately
>> deallocate all data structures on thread termination.  Among other
>> things, it has to store the future return value of pthread_join
>> somewhere.
>
> ah, you're trying to say "signal 0 is potentially usable for a
> joinable thread that's waiting to be joined"? that's true, but i'm not
> sure how that's relevant to this patch. that wouldn't be an "invalid
> thread ID" until it's joined.

Correct.  That's POSIX's argument why ESRCH wouldn't be valid to
return here.  It's still a forceful loss of information, and
particularly annoying since POSIX doesn't specify pthread_tryjoin.

But I'm glad we've brought our discussion to a conclusion. 8-)